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Wildfires are hazards of increasing significance in recent decades. Our ability to forecast the evolution of fire regimes is inhibited by the lack of records of key fire parameters such as fire severity. Boron isotopes in the soil clay fraction have been shown to vary with fire severity, where increased δ 11B coincides with higher fire severity. To elucidate the relationship between the B isotope composition of soil clays and fire events, we performed adsorption experiments by reacting rainwater with combusted leaves to analyse how B isotopes are fractionated during processes leading to the imparting of boron from plants to clay minerals in soil during and following combustion. We find that < 5% of B is volatilised during combustion of leaves and barks, where 11B is preferentially volatilised. No isotopic fractionation was detected during the leaching of leaves ash with rainwater, possibly due to the large water:clay ratio in our experiments. Adsorption of B from leaching solutions onto clay minerals shows isotopic fractionation, and hysteresis of the adsorbed B fraction. For experiments at pH between 7 and 9, the isotope fractionation between adsorbed and dissolved B (Δ 11B adsorbed-dissolved) ranges from −8.8 to −14.5 ‰ , indicating preferential adsorption of 10B onto clays compared to 11B. For experiments at pH > 10, the Δ 11B adsorbed-dissolved values range from +11.2 to +19.4 ‰ , indicating a preferential adsorption of 11B over 10B. Irregardless of pH, clay fractions in all experiments show increases in δ 11B, as the leaching solutions have high δ 11B relative to the soil clay minerals prior to their interaction. Ash of leaves combusted at 550 °C (highest temperature in our experiments) induce the greatest increase in solution pH and δ 11B in clays. Our experiments suggests that the higher B isotope composition of clays following a high severity fire is likely imparted by solutions that leach isotopically heavy B from the combusted canopy. [ABSTRACT FROM AUTHOR]

• Calibration of red clay with different water contents based on EDEM software. • The Hertz-Mindlin with JKR Cohesion model was used to model red clay soil's physical properties. • Experimental studies provide insights into the impact of soil moisture content on its properties. • Technical references for future research on soil-tool interactions were provided. Distinct physical properties of red clay soil in hilly and mountainous regions of southwest China, including high adhesiveness and density, challenge the operation of agricultural machinery. A scarcity of accurate discrete element simulation parameters for this soil type restricts computational modeling. The study was focused on red clay soil with a moisture content of 12.50% ± 1% and a measured repose angle of 35.54°. The soil's inherent physical properties were identified through experimental assessments. Soil contact mechanical parameters were obtained from the GEMM database, and optimal contact parameter ranges were determined using Steepest Ascent Experiments, with the simulated soil particle repose angle serving as the response value. A second-order regression model was developed using a quadratic regression rotation orthogonal combination test. By taking the actual repose angle as the optimization criterion, parameters were optimized. The optimal contact mechanical parameters in EDEM simulations were identified as: JKR surface energy at 8.981 J/m2, recovery coefficient at 0.474, dynamic friction coefficient at 0.196, and static friction coefficient at 0.45. The model yielded a repose angle of 36.21°, closely corresponding with the observed value, with a relative error of 1.80%. The parameters calibrated in this study offer a valuable reference for future soil-tool interaction studies and tillage implement optimization in these regions. [ABSTRACT FROM AUTHOR]

Advanced hyperspectral remote sensing technology can identify various clay minerals in the soil. The improved spectral and spatial resolution of the airborne hyperspectral sensor can be used for a better interpretation of clay mineral abundance in the soil. This research utilizes the high-resolution image data acquired from Advanced Visible Infrared Imaging Spectrometer Next Generation (AVIRIS-NG) on an airborne platform to map the abundance of clay minerals in the Udaipur region of Rajasthan (24° 34′ 16.5720′' N, 73° 41′ 29.5584′' E). The representative soil samples for various soil clay minerals, e.g., kaolinite, montmorillonite, and illite, were classified from AVIRIS-NG data using a spectral feature fitting algorithm. A total of thirty sites were selected from agricultural and wastelands for soil sample collection. X-ray diffraction (XRD) analysis of representative soil samples was carried out to find the percentage and type of clay minerals present. Regression analysis between absorption peak depth values estimated from the hyperspectral image of the sampling sites in the spectral region from 2205 to 2214 nm and corresponding clay content value showed a significant relationship. The regression line obtained for the known pixels was used to prepare the mineral abundance map over the study area. This study significantly indicates the dominance of montmorillonite clay mineral over kaolinite and illite in the soils of the Udaipur region. [ABSTRACT FROM AUTHOR]

• Montmorillonites reduced GLP and AMPA bioavailability in soil, corn roots and leaves. • Kinetic studies with different concentrations, doses, and duration showed dose- & time-dependency. • Acid processed montmorillonite reduced mixtures in roots by 76% and in leaves by 57%. • Decrease in roots, leaves and soil was consistent and continuous without detectable dissociation. • Montmorillonites can serve as soil supplements to remediate GLP and AMPA in soil. The co-occurrence of glyphosate (GLP) and aminomethylphosphonic acid (AMPA) in contaminated water, soil, sediment and plants is a cause for concern due to potential threats to the ecosystem and human health. A major route of exposure is through contact with contaminated soil and consumption of crops containing GLP and AMPA residues. However, clay-based sorption strategies for mixtures of GLP and AMPA in soil, plants and garden produce have been very limited. In this study, in vitro soil and in vivo genetically modified corn models were used to establish the proof of concept that the inclusion of clay sorbents in contaminated soils will reduce the bioavailability of GLP and AMPA in soils and their adverse effects on plant growth. Effects of chemical concentration (1–10 mg/kg), sorbent dose (0.5%-3% in soil and 0.5%-1% in plants) and duration (up to 28 days) on sorption kinetics were studied. The time course results showed a continuous GLP degradation to AMPA. The inclusion of calcium montmorillonite (CM) and acid processed montmorillonite (APM) clays at all doses significantly and consistently reduced the bioavailability of both chemicals from soils to plant roots and leaves in a dose- and time-dependent manner without detectable dissociation. Plants treated with 0.5% and 1% APM inclusion showed the highest growth rate (p ≤ 0.05) and lowest chemical bioavailability with up to 76% reduction in roots and 57% reduction in leaves. Results indicated that montmorillonite clays could be added as soil supplements to reduce hazardous mixtures of GLP and AMPA in soils and plants. [Display omitted] [ABSTRACT FROM AUTHOR]

• BHET treatment formed a flocculated bentonite matrix. • The flocculated bentonite matrix entraps water in its micropores. • BHET hydrogel constrained drainage path. • The hydroxyl groups of BHET retain a high amount of water. • The carbonyl and hydroxyl groups adsorb Pb2+. Polyethene terephthalate (PET) waste poses major environmental harm which can be minimized by reusing it in clay soil stabilization. In general, various polymers are known to reduce hydraulic conductivity and increase the shear strength of clays. However, the application of the effect of a chemically depolymerized form of PET, i.e., Bis (2-Hydroxyethyl) terephthalate (BHET) has not been performed as an additive in Compacted Clay Liners (CCLs) for landfills. This research focuses on the effect of the air curing period (1 and 28 days) on the hydromechanical behavior of BHET-treated SBM (0, 1, 2, 3, and 4 % by dry weight). Results from One Dimensional Consolidation tests showed that an increase in BHET content reduced both compressibility and hydraulic conductivity of SBM due to pore clogging mechanism of swollen BHET hydrogel, however, hydraulic conductivity reduced over 28 days of curing due to loss in re-swelling availability of the hydrogel, thereby allowing less tortuous paths to flow. Results from Consolidated-Drained Direct Shear tests showed that for 1 and 28-days curing, BHET treatment to SBM increased the cohesion (c') due to strong polymer interparticle bridging, however, polymer coating over the sand grains causes a reduction in its surface roughness to decrease the frictional angle (ϕ'). SEM (Scanning Electron Microscopy) and EDX (Energy-dispersive X-ray spectroscopy) analysis on BHET-treated specimens support the flocculation of bentonite, polymer bridging of sand and clay-sand polymer links. A significant Pb2+ removal capacity was also observed with BHET-treated SBM from the batch tests. FTIR (Fourier Transform Infrared Spectroscopy) analysis on batch sorption specimens confirms the role of the carbonyl groups (C = O) and hydroxyl groups (OH) present in the BHET structure indicating the possibility to adsorb Pb2+. The findings of the study suggested that a mechanism of interaction exists between sand-bentonite and BHET polymer and it can be adopted in CCLs design. [ABSTRACT FROM AUTHOR]

• Ca-based, non-Ca-based additives and recycled solid wastes reduce PI and enhance TD. • These active ingredients improve soil texture via cation exchange and flocculation. • Transition metal oxides catalyze TD of nonchlorinated POPs via two mechanisms. • We also reviewed alkali, solid wastes and nano metals as catalysts to enhance TD. • Additives in photo- and photo-thermal-catalysis and their mechanisms are reviewed. High temperatures and providing sufficient time for the thermal desorption of persistent organic pollutants (POPs) from contaminated clay soils can lead to intensive energy consumption. Therefore, this article provides a critical review of the potential additives which can improve soil texture and increase the volatility of POPs, and then discusses their enhanced mechanisms for contributing to a green economy. Ca-based additives have been used to reduce plasticity of bentonite clay, absorb water and replenish system heat. In contrast, non-Ca-based additives have been used to decrease the plasticity of kaolin clay. The soil structure and soil plasticity can be changed through cation exchange and flocculation processes. The transition metal oxides and alkali metal oxides can be applied to catalyze and oxidize polycyclic aromatic hydrocarbons, petroleum and emerging contaminants. In this system, reactive oxygen species (•O 2 − and •OH) are generated from thermal excitation without strong chemical oxidants. Moreover, multiple active ingredients in recycled solid wastes can be controlled to reduce soil plasticity and enhance thermal catalysis. Alternatively, the alkali, nano zero-valent iron and nano-TiN can catalyze hydrodechlorination of POPs under reductive conditions. Especially, photo and photo-thermal catalysis are discussed to accelerate replacement of fossil fuels by renewable energy in thermal remediation. [Display omitted] [ABSTRACT FROM AUTHOR]

Green rusts (GR) are important drivers for trace metal and nutrient cycling in suboxic environments. We investigated whether green rusts would incorporate aluminum (Al) or other elements from naturally-formed clay minerals containing easily-weatherable clay minerals (e.g. mica, interlayered clays). We isolated the clay minerals from a Matapeake silt loam soil by removal of silt and sand, organic matter, and reducible oxides to study mechanisms of interaction between Fe(II) and soil-sourced clay minerals. We conducted batch Fe(II) sorption experiments at multiple near-neutral pHs (6.5–7.5) and reaction times (2 h–365 days). Mineral transformations were characterized by selective extractions, X-ray diffraction (XRD), and Fe X-ray absorption spectroscopy (XAS) analyzed by shell-fitting and linear combination fitting (LCF) with natural and synthetic standards. Clay mineral fraction contained a mixture of quartz, kaolinite, interlayered vermiculite, mica, and chlorite with significant structural Fe (2.6% wt). Uptake of Fe(II) increased with pH and kinetics were rapid until 5 days, followed by slow continuous Fe(II) uptake. Citrate-bicarbonate desorption kinetics from Fe(II) sorbed clay released more Al and silicon (Si) compared with unreacted soil clay fraction whereas magnesium (Mg) and potassium (K) were unaffected. Citrate-bicarbonate extracted Fe contained more Fe(II) than an ideal GR with an Fe(II)/Fe(III) molar ratio of 5.50. Analysis of the Fe EXAFS by both LCF and shell fitting was best modeled as a combination of Fe(III)-clay reduction to Fe(II) and precipitation of GR and Fe(II)-Al LDH. After 7 days of Fe(II) sorption, LCF identified 55.2% total Fe in clay, 33.4% GR(Cl) and 11.4% Fe(II)-Al LDH. These results provide novel evidence of Fe(II)-Al LDHs precipitating on naturally-formed soil clay minerals as a minor phase to GR. The geochemical implications are that GRs formed in soils and sediments should be considered to have Al and Si as well as Mg substitutions affecting their structure and reactivity. [ABSTRACT FROM AUTHOR]

Stable isotope ratios of hydrogen (δ2H values) in local meteoric water correlate with those of nonexchangeable H (δ2H n) in bulk soil and organic matter, allowing for probabilistic spatial assignments to soil samples. We hypothesized that there is a similar correlation between the δ2H values of local meteoric water and the δ2H n value of soil clay fractions. The H pool of topsoil clay fractions is usually dominated by pedogenic clay minerals, which contain structural hydroxyl-H, preserving the δ2H values of ambient water at the time mineral formation. We applied a steam equilibration method with water vapors of known δ2H values to determine δ2H n values in soil clay fractions by eliminating the influence of easily exchangeable H. We collected topsoil samples from 24 locations on five continents with a wide variation in δ2H values of meteoric water. To calculate δ2H n values via steam equilibration, the equilibrium fractionation factor between exchangeable H in the clay fractions and equilibration waters (α ex–w) is needed, which is, however, unknown. We therefore assessed the effect of α ex-w values from 1 (no fractionation) to α ex-w = 1.08, which has been used in steam equilibration approaches of organic matter and bulk soil, on the δ2H n values of soil clay fractions. The δ2H n values of the clay fractions ranged from –167 ± SD1‰ for a northern Siberian sample to –44 ± 4‰ in western Kenya for α ex-w = 1 and from −191 ± 5 to –81 ± 5‰ for α ex-w = 1.08. The δ2H values of local meteoric water correlated significantly with the δ2H n values of the clay fractions (r = 0.85 for α ex-w = 1 and 0.65 for α ex-w = 1.08, p < 0.001). A multiple regression model including hillslope as a possible measure of the accumulation of clay minerals with a slightly different δ2H n value from nearby locations by eolian or aqueous transport in addition to the mean seasonal δ2H values of local meteoric water explained up to 89% of the observed variation in δ2H values of the clay fractions. Our results demonstrate that the δ2H n values of soil clay fractions are driven by the δ2H values of local precipitation on a global scale, irrespective of the used α ex–w value and influenced by the mineral type. Overcoming previous methodological limitations opens up opportunities for probabilistic spatial assignments of unknown organic matter-poor topsoil samples, applications to paleosoil problems or to experimentally track clay mineral neoformation in soils by tracer experiments. [ABSTRACT FROM AUTHOR]

• Soil texture sample taken from field area was silt clay soil. • Parameters determine the draft force of ard plow in silt clay soil were identified. • Parameters used to develop draft force of ard plow were reduced using dimensional analysis. • Parameters using to predict draft force was fitted with measured draft force. • Mathematical model was developed and it can help to reduce draft force and can be input for designing ard plow. Due to Ethiopia's rising population, the prediction of a draft force has several crucial in improving tillage performance in smallholder farmland. It helps in proper usage of animal draught; minimizes operator tragedy and full input data for the ard plow designer. This study aimed to develop an effective mathematical model by selecting appropriate soil properties, tool geometries, and tillage operating conditions for estimating the draft force of the ard plow. A mathematical equation was established using dimensional analysis related to PI-Buckingham-pi theorem. The model was verified and validated using the IBM SPSS statistical software. The correlation between draft force between the measured and predicted value of R2 was 0.877. The developed model was effective in predicting the draft force success for ard plow as much as 87.70%. No significant difference existed between the measured and predicted values at a 0.05 significance level. The scoring standard of the measured draft and the anticipated draft force is normally distributed with a level of confidence of 99%. Investigation consequence showed a developed mathematical formula for estimating the draft force of ard plow in silt clay soil is effective. [ABSTRACT FROM AUTHOR]

Flexible conductive materials are widely used in structural health monitoring; it is also known in geotechnical engineering. In this preliminary study, a strain-self-sensing smart geogrid rib was proposed to monitor the induced strain by wetting-drying cycles of the expansive soil. After the calibration, a physical modeling test was conducted with the smart geogrid rib reinforced in expansive soils under three wetting-drying cycles. Results demonstrated: that the smart geogrid rib was capable of self-sensing its strain; the strain self-sensed by the smart geogrid rib was in good agreement with that measured by FBG strain sensors before cracks were generated; it could capture the crack propagation of expansive soils during wetting-drying cycles by the discrepancy compared to FBG sensors. Further study will be continued for the mechanism of the geogrid instead of the geogrid rib and the application to real-time monitoring of the performance of the geosynthetic expansive soil slopes. • A geogrid rib was fabricated with flexible conductive materials to make the strain-self-sensing possible. • A physical modeling test was conducted to demonstrate the application of the smart geogrid rib in the expansive soil. • The geogrid rib could sense the crack propagation of expansive soils, and strains measured agreed with strain sensors. [ABSTRACT FROM AUTHOR]

• Soil thrust allows remotely operated vehicles to move forward. • Three failure modes are geometrically possible at the soil-track interface. • Upper-bound solutions for soil thrust are mathematically derived. • Resultant soil thrust is determined as the least upper-bound solution. • Proposed solution efficiently and accurately predicts the soil thrust. This study proposes a quick and reliable method for estimating the soil thrust in clay ground for a tracked vehicle based on limit analysis in three-dimensional conditions. With respect to the shape and location of failure surfaces in clayey ground, block, triangular wedge, and trapezoidal wedge failure modes were considered. Between the upper-bound solutions from the different failure modes, the least upper-bound solution was proposed as the soil thrust. To verify the proposed solution, it was compared to the model test and numerical simulations for a track system over model clay ground. The proposed upper-bound solution is expected to produce a reliable soil thrust quickly in real time, especially for submerged heavy-weight remotely operated vehicles (ROVs). [ABSTRACT FROM AUTHOR]

The impact of clay mineralogy on engineering properties relevant to road design, such as the strength and stiffness of road materials, has recently been the subject of intensive investigations, aiming at providing indirect measures of soil performance out of mineralogical data. This study deals with the effects of clay minerals on soil strength, expressed in terms of California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS), and stiffness, represented by the constrained modulus, which are commonly used as engineering properties for pavement materials. The study is performed on six clayey soils (S1-S6) of different geographic origins. Five of the six soils are highly plastic, potentially swelling, and one is kaolinitic soil. The mineralogical characteristics of the samples were analyzed through X-ray diffraction (XRD). The testing program included Atterberg limits, sieve analysis, CBR, UCS, and consolidation tests. The measured properties of the samples were compared in light of the mineralogical composition of the soils. The investigation showed that the kaolinite mineral is significantly more effective than the montmorillonite in reducing the plasticity of the clays. Higher strength indicators (CBR and UCS) were observed for samples with high kaolinite content (S4, S5, and S6). Moreover, the kaolinitic soil samples are characterized by a larger constrained modulus (E c) than the other samples. [ABSTRACT FROM AUTHOR]

The paper investigates the feasibility of using fine-grained soil as backfill material of geosynthetic-reinforced walls and slopes, through a laboratory study on pullout behavior of geogrids in granular layers. A series of pullout tests was carried out on an HDPE uniaxial geogrid in thin sand and gravel layers that were embedded in clay specimens. Aside from different soil arrangements, the influences of moisture content and overburden pressure on the geogrid pullout behavior is assessed and discussed. The tests were carried out at four different gravimetric water contents (GWC) on the dry and wet sides of the clay optimum moisture content (OMC), and overburden pressure values within the range σ v = 25–100 kPa. Particle Image Velocimetry (PIV) was used to capture digital images during the tests, which were processed to help with the interpretation and improved understanding of the soil-geogrid interactions at different GWC values. Results show that embedding geogrid reinforcement in layers of sand or gravel can significantly increase the pullout resistance in an otherwise moist clay backfill, and this improved pullout efficiency is greater at higher overburden pressures. The improvement in pullout capacity was observed in clay specimens compacted at both the dry and wet sides of the OMC. • Pullout performance of a uniaxial geogrid in different soils was studied. • Soils included clay, sand, gravel and clay specimens with single layers of reinforced sand or gravel. • The PIV technique was used to observe and interpret soil-geogrid interaction during the pullout process. • Factors examined included moisture content, particle size and thickness of granular layer, and overburden pressure. [ABSTRACT FROM AUTHOR]

• A unified gross traction algorithm is proposed for braked, towed, and powered wheels on clay. • The model is developed using the Database Records for Off-road Vehicle Environments. • The algorithm employs the ratio of average contact pressure to cone index. • The new equation can be implemented in off-road mobility models. A characteristic curve is presented for predicting gross traction of a wheel over a range of powered, towed, and braked modes on clay soils for slip ranging from positive 100% powered slip to negative 100% skid slip. The characteristic curve is a unified approach that relates the ratio of the contact pressure of the wheel to soil strength and predicts the gross traction coefficient over a continuous range of slip. The unified equation is defined by five inflection points: maximum/minimum traction, traction at zero slip, max change in traction with slip, and a shape factor coefficient. The inflection points aim to simplify the calibration of gross traction, slip, soil strength, and contact pressure by using functions adaptable to machine learning. The unified equation is comparable to historic traction equations but is unique in its ability to predict asymmetric braking and powered gross traction. The unified equation is supported and substantiated via error analysis by utilizing the Database Records for Off-road Vehicle Environments (DROVE) – a database constructed around the archived laboratory and field tests for wheels and tracks operating on different soils. The accuracy of the proposed model is assessed and compared to other conventional equations such as the Brixius equation and Maclaurin's extension of the Pacejka equation for off-road traction. [ABSTRACT FROM AUTHOR]

Penicillium oxalicum SL2 (SL2) is a previously screened Pb-tolerant fungus that can promote crops growth. The relationship between SL2 colonization and Pb immobilization was studied to provide a theoretical basis for microbial remediation of Pb-contaminated paddy soil. In this study, green fluorescent protein (GFP) labeled SL2 was inoculated into different Pb-contaminated paddy soils (S1-S6). The Pb extracted from the soil by HNO 3 , EDTA and CaCl 2 were used to characterize the available Pb. The results showed that the colonization of SL2 was divided into lag phase (0-7 days), growth phase (7-30 days), and mortality phase (30-90 days). SL2 colonized well in sandy soils rich in clay and total phosphorus with initial pH of 4.5-7.0. In addition, SL2 increased soil pH and decreased soil Eh, which was beneficial to immobilize Pb. In different soils, the highest percentages of CaCl 2 -Pb, EDTA-Pb, and HNO 3 -Pb immobilized by SL2 were 34.34%-40.53%, 17.05%-20.11%, and 7.39%-15.62%, respectively. Pearson correlation analysis showed that the percentages of CaCl 2 -Pb and EDTA-Pb immobilized by SL2 were significantly positively correlated with the number of SL2 during the growth phase. SL2 mainly immobilized Pb in the growth phase and a higher peak number of SL2 was beneficial to the immobilization of Pb. [Display omitted] [ABSTRACT FROM AUTHOR]

Compressed stabilized earth blocks (CSEBs) reinforced with steel fiber can be a suitable alternative construction material for retaining walls or hydraulic structures, which often face aggressive environmental conditions such as heavy rainfall, strong winds, and high erosion levels. This paper examines the suitability of cement-treated gravelly and clayey soils reinforced with steel fiber as CSEBs based on the requirements for various unfired earthen blocks. Cement contents of 5–7 % and fiber volume fractions of 0.6–1.2 % were utilized to create the CSEBs at the optimum moisture contents for both gravel and clay. Dry and wet compressive strength tests were performed to determine the mechanical characteristics, while wet-to-dry compressive strength ratio, water absorption, and erosion rate tests were conducted to examine the durability properties. Additionally, fiber pullout tests and SEM analyses were carried out to investigate the interface interaction between the soil-cement matrix and steel fiber. The results showed that the gravel blocks had higher strength than the clay blocks by 1.5–5.6 times and were more durable by about 1.5 times. The erosion rates significantly decreased with increasing fiber content for clay blocks due to the fiber's capacity to hold the clay-cement matrix together. The interface bond strength between steel fiber and cemented clay was more than 1.74 times that between steel fiber and cemented gravel, as confirmed by SEM photos. A more compacted interface nature was observed in the cemented clay matrix compared to the cemented gravel. Therefore, the clay blocks reinforced with steel fiber exhibited higher bridging capability than the gravel blocks. The clay blocks demonstrated a ductile response, whereas the gravel blocks showed a semi-ductile response. Considering the improved toughness ratio of 2.0, the gravel block with 5 % cement and 1 % fiber and the clay block with 7 % cement and 1 % fiber were identified as the most suitable mix proportions based on eco-friendliness and economic sustainability. • The CSEBs are reinforced with steel fiber under heavy rainfall and high erosion levels. • Cement-treated gravelly and clayey soils are used. • The CSEB properties are compared with various standards. • Fiber pullout tests and SEM analyses are carried out. • The CSEBs reinforced with steel fiber are suitable based on economic sustainability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Physicochemical characteristics of soils play key roles in the mobility of NTP. • Clay and organic matter components are beneficial for inhibiting NTP mobility. • The effects of amino acids on NTP mobility are soil type-dependent. • The extent of inhibitory or promoted effects depends on amino acid species. Research on the transport characteristics of neonicotinoid pesticides through soil, particularly in the presence of common amino acids, is lacking in the current scientific literature. This study investigated the effects of three amino acids, such as glycine, aspartic acid, and histidine, on the mobility features of nitenpyram (NTP, a typical neonicotinoid pesticide). Two soil samples with diverse physico-chemical properties were used in the experiments. In general, increased levels of clay and soil organic matter were shown to be advantageous in limiting the movement of NTP in the soil columns. Interestingly, the three amino acids inhibited NTP mobility through the soil with higher iron-aluminum oxides over a broad pH range of 5.0–9.0. This can be attributed to the presence of additional sites for NTP deposition, created by the adsorbed amino acids, as well as the enhanced electrostatic attraction force between NTP and the soil. In contrast, these amino acids enhanced NTP transport through soil with higher organic matter. This is because the amino acid coating on soil surfaces hinders the contact between soil organic matter and NTP (e.g., through hydrophobic and π-π interactions). Additionally, the degree of the inhibitory or promoting effects of amino acids was in the order of histidine > aspartic acid > glycine, strongly dependent on their chemical structures (e.g., molecular size and functional group types). Moreover, a numerical model (i.e., the two-site nonequilibrium model) was employed to reveal the mechanisms of the impacts of amino acids on NTP transport through different soils. The results are helpful for understanding the fate of neonicotinoid pesticides in soil and aquatic environments containing various amino acids. [ABSTRACT FROM AUTHOR]

The scientific community's interest in geopolymers keeps on growing under environmental and climate change pressures. Although most studies concern metakaolin or industrial by-products as aluminosilicate precursors, few are those concerning clay cuttings characterized by little or no kaolinite content. This study proposes a method to activate illitic clay in order to obtain a geopolymer with high mechanical performances. The tested illitic material contained 53 wt% of illite/muscovite, 22 wt% quartz, 7 wt% feldspars and low content of calcite. The innovation consists in coupling thermal and mechanical activations favoring both the clay dehydroxylation and the destruction of the clay crystalline structure. Such increase of amorphous rate in the precursor is required to make the material reactive. The evolution of the precursor material after activation was followed by ThermoGravimetric Analysis (TGA/DTG), X-Ray Diffraction (XRD), Fourier-Transform InfraRed spectroscopy (FTIR) and Scanning Electron Microscopy coupled to Energy Dispersive X-ray spectrometry (SEM-EDX). The impact of the variations of the mechanical activation duration and ball:powder mass ratio (b:p) were mainly explored, as well as the Liquid:Solid mass ratio (L:S) which is a key parameter of the geopolymerization. Finally, an optimized geopolymer with a mechanical compressive strength reaching 126 MPa after 28 days has been manufactured with a grinding duration of 240 min, a b: p = 15 and a L:S = 0.5. The demonstration was done that a geopolymer can be manufactured from 100% illitic clay precursor, in addition to a relatively low amount of alkaline solution (L:S mass ratio of 0.5) then lowering the cost and the environment impact of the final geopolymer material. The resulting illitic clay based geopolymers can display very high mechanical resistance (compressive strength up to 126 MPa after 28 days), fully competitive with conventional building materials. • Illitic geopolymer from clayey soil reached a 126 MPa compressive strength after 28 days • Illitic geopolymer from clay soil reached a 126 MPa of Rc after 28 days. • The grinding time, heating temperature, L:S and b:p ratios allowed to increase Rc. • Only a 50% amorphous content after precursor amorphization was enough for high Rc. • Incomplete amorphization of illitic precursor induced non or partially reacted particles • Non or partially reacted particles in geopolymer hardened paste impacted Rc. [ABSTRACT FROM AUTHOR]

Soil erosion is a detrimental consequence of water flow that poses serious threats to the functionality/stability of earthen structures, dykes, river banks, canals, etc. Soil treatment/stabilization with additives remains a conventional and feasible technique to enhance soil erosion resistance. This study investigates the application of recycled concrete aggregates (RCA)- as a sustainable and environmentally-friendly additive- to lower the erosion propensity of clay soil. Jet Erosion Tests (JETs) were performed on treated soils comprising clay stabilized with 3 %, 5 %, 10 % and 15 % recycled concrete aggregates, and erosion parameters; namely, critical shear stress (τ c) and erodibility/detachment coefficient (k d) were measured. Laboratory findings elaborated that the increase in the RCA content and curing time of clay-RCA mixture significantly improved the erosion resistance as compared to the clay. The clay treated with 15 % RCA (after 28 days curing) demonstrated a 45 fold increase in τ c and 92 % decrease in k d , to the extent that the 'erodible' clay converted into the erosion 'resistant' clay-RCA blend. Concerning the practical implications, clay treatment with recycled concrete aggregates lowers the likelihood of concentrated leak erosion initiation and decelerates the progression of piping. [Display omitted] • Recycled concrete aggregate (RCA) is used as a stabilizer to decrease clay erodibility. • Jet Erosion Test (JET) is conducted to measure soil erosion parameters. • Stabilization with RCA turns the 'erodible' clay into an erosion 'resistant' mixture. • Clay stabilization with RCA reduces the possibility of erosion initiation. [ABSTRACT FROM AUTHOR]

Soil is one the most extracted natural raw materials. The vast expanses of fertile alluvial soils of the Indo Gangetic Plains have long remained as abundant soil resource pool for brick manufacturing and construction sectors. Unmonitored continuous removal of soil is reported to cause depletion of soil reserves, loss of soil fertility and affect crop yield. Excavation and removal of soil from isolated patches of land creates low lying and elevated degraded areas which disrupts normal crop cultivation pattern. Natural gamma-ray spectrometry (NGS) can be used as a non-destructive and rapid geophysical sensing method, for identification and delineation of areas with suitable soils. During this work brick kiln areas were visited to understand soil's availability and extraction pattern. NGS measurements of samples from soil profiles were carried out to find if gamma-ray intensities varied with soil clay content. Soil texture and plasticity of the same samples were obtained following standard testing procedures. Winkler and Plasticity charts were used to assess suitability of the soils. A strong linear relationship between gamma-ray potassium (K) intensity and clay contents of soil profile samples (R2 = 0.88) was observed. NGS based devices can be used to scan soil samples rapidly and log shallow depth boreholes in grid sampling design. The gathered spectral gamma-ray data can be then used to predict and generate high resolution 3D models of soil properties, based on which resource areas of suitable soils can be delineated for long term soil extraction without affecting cultivated areas. This will help in delineating areas restricted for soil extraction, which will not only make soil mining sustainable but also address soil conservation by setting aside large cultivated fertile soil areas untouched. Adopting NGS methods will prevent unsystematic removal of fertile soil and creation of degraded lands. This will ultimately result in efficient soil resource management. [Display omitted] • Natural Gamma-ray spectrometry (NGS) scanners can quickly assess quality of soil for brick and earthenware manufacturing. • NGS logging of shallow-depth boreholes in alluvial soils can help generate layer wise map and 3D models of soil resources. • Suitable areas can be demarcated using soil information for long term soil extraction without affecting cultivated areas. • Sustainable extraction of soil resources can be attained by Intervention of Natural Gamma-ray spectrometry (NGS) method. [ABSTRACT FROM AUTHOR]

Proximal soil sensing is a highly advanced and rapidly evolving technique for predicting soil chemical properties. NIR spectroscopy is expected to offer an easier and more cost-effective alternative to traditional soil chemical analysis methods for broader agricultural applications. This review aims to address the challenges in high-clay content soils by 1) understanding the relationship between NIR spectroscopy and its predictive capabilities of chemical properties, and 2) proposing the application of advanced technologies to improve their practical applications. The high-clay content soils increase the adsorption of various cations, including Al3+, Ca2+, Mg2+, K+, Na+, and NH 4 +, and affect crop root density, absorption area, and nutrient uptake efficiency. However, predicting soil characteristics using NIR spectra can be difficult due to the complex nature of soil metrics. Under clay-rich soils, the high moisture content leads to a significant presence of O-H vibrations (1395 and 1415 nm), which overlaps with crucial function groups. Recent advancements using deep learning models have significantly improved prediction accuracy and efficiency for soil properties. The results showed that the R² values for predicting soil organic C, total N, and pH were 0.94, 0.89, and 0.87 for S-AlexNet; 0.95, 0.94, and 0.90 for GADF-Swin Transformer; and 0.88, 0.84, and 0.87 for PLSR, respectively. Additionally, integrating hyperspectral and multispectral sensors further improves prediction efficiency by providing higher spatial and spectral resolutions. In conclusion, this review suggests that adopting cutting-edge technologies can improve the predictions accuracy of chemical properties in the clay-rich soils. Nevertheless, overcoming the limitations of advanced technologies, such as high computational resource requirements, is necessary for practical application in agriculture. [Display omitted] • Challenges of model prediction using NIR in soils with high clay content. • Impact of overtones in hydroxyl (O-H) functional groups on NIR spectral interpretation. • Advancements in model accuracy by noise reduction in NIR analysis. • Developing novel models for improved soil chemical property prediction. • Utilizing UAV and AI technologies for enhanced soil analysis. [ABSTRACT FROM AUTHOR]

Water availability explains a large part of the spatial and temporal yield variability of ware potato in the Netherlands. Climate change is projected to lead to greater variability in water availability. Therefore, an accurate simulation of crop yield as a function of water availability is of high importance. Many crop models can simulate water-limited potato yields, but as detailed experimental data on drought and oxygen stress are scarce, models are often not well calibrated and evaluated. We set up a large experiment and an on-farm observational trial to calibrate and evaluate the simulation of water-limited yield of different potato cultivars across the Netherlands. In addition, we investigated the required model complexity to accurately simulate water-limited potato yields. The crop growth model WOFOST was used for simulations either as a single model or coupled with SWAP. Yields were simulated applying either only drought stress or by including both drought and oxygen stress. We employed two methods for simulating oxygen stress in SWAP-WOFOST. The calibration improved accuracy of simulated water-limited yields as demonstrated in our model evaluation. Both on sandy and clayey soils, water-limited yields were best simulated using SWAP-WOFOST while simulating oxygen stress using a process-based method in combination with a rooting density that decreases linearly with rooting depth. On sandy soils, the bottom boundary condition of free drainage was applicable. On clayey soils measured groundwater levels (or soil water pressure heads when measurements are not available) should be used as bottom boundary condition. On sandy soils both WOFOST and SWAP-WOFOST may be used, as results were similar. On clayey soils, WOFOST is less suitable, as it cannot simulate capillary rise. SWAP-WOFOST however has many options and parameters, which can result in large differences in results. Hence, a careful model set up and evaluation is required for each application. • The models WOFOST and SWAP-WOFOST have been recalibrated for water-limited potato yields. • On clayey soils with shallow groundwater levels SWAP-WOFOST outperformed WOFOST. • On clayey soils there seemed to be an effect of oxygen stress on yield. • Effects of oxygen stress were smallest in WOFOST, and largest in SWAP-WOFOST using a process-based method. • On sandy soils there was an inconsistent benefit of using SWAP-WOFOST over WOFOST. [ABSTRACT FROM AUTHOR]

This study quantified the immediate impact of soil deformation caused by agricultural vehicle traffic on the anisotropy of the topsoil pore system and gas transport properties (air permeability, gas diffusivity). A field experiment was conducted with five repeated passes of a two-axle self-propelled agricultural vehicle (wheel load 8 Mg, tyre size: 1050/50 R32, tyre inflation pressure: 100 kPa) on an arable clay soil (crop at the time of the experiment: grass ley) in north-western Switzerland. Undisturbed cylindrical soil cores were collected in non-wheeled areas, at the edge of the wheel rut (i.e., at 0.5 m lateral distance from the centre of the wheel track), and at the centre line of the wheel track. The soil cores (0.1 m diameter, 0.06 m in height) were taken in two directions (vertical and horizontal) in the topsoil (0.1 m depth). Air-filled porosity (ε a), air permeability (k a) and relative gas diffusivity (D p / D 0) were measured at three matric potentials (corresponding to p F 1.5, 2.0, and 2.5, respectively). The vehicle-induced deformation resulted in significantly reduced ε a , k a , D p / D 0 in the topsoil. Air permeability was highly anisotropic in non-wheeled soil, with higher k a in vertical direction. Compaction mainly affected macropores and hence k a at the wet end (p F 1.5), decreased the vertical k a more than the horizontal k a , and consequently, k a became less anisotropic due to compaction. This effect was stronger under the edge of the wheel rut than in the centre of the wheel rut. The anisotropy of D p / D 0 was little affected by the vehicle-induced soil deformation. Our results show that soil deformation due to vehicle traffic not only decreases the gas transport capacity of soil but also changes the anisotropy of air permeability, with consequences on soil aeration and soil-atmosphere gas exchange. • Impacts of wheeling are different under the centre and under the edge of the wheel rut. • Wheeling decreased the gas transport properties and changed the anisotropy. • Air permeability was more affected than gas diffusivity. [ABSTRACT FROM AUTHOR]

Laboratory model tests were conducted to investigate the stability of the L-shaped caisson quay wall installed on the sandy soil with clay interlayer. A total of three L-shaped caisson models were cast to explore the effects of the loading position and the position and thickness of the clay interlayer on their stability under plate loading. The ultimate bearing capacity of the L-shaped caisson quay wall on clay interlayer foundation was reduced by a maximum of 41 % compared to sand foundation. The ultimate bearing capacity was significantly reduced when the distance of the clay interlayer to the rubble mound was less than 1/5 of the quay wall height. The applied surcharge made the lateral earth pressure coefficient higher than the active earth pressure coefficients and triangularly distributed along the L-shaped caisson wall. The modified Beton's method considered the effect of the toe length of the L-shaped caisson could more accurately predict the lateral earth pressure. The failure of the L-shaped caisson quay wall on the clay interlayer foundation has three forms Type-I, Type-II, and Type-Ⅲ which are influenced by the loading position, L-shaped caisson dimensions, and positions of the clay interlayer. [ABSTRACT FROM AUTHOR]

To prevent the cracking of silty clay under cyclic wet-dry cycling (W-D), which leads to the increase of deformation and strength attenuation of silty clay, microencapsulated phase change material (mPCM) was used to improve it. The deformation and strength characteristics of silt with different dosages (1 %, 2 % and 4 %) of mPCM and their changing patterns were analyzed and studied by indoor compaction test, crack observation test, consolidation test and straight shear test, and compared with silt without modifier. The results showed that with the increase of mPCM dosage, the optimum water content of silt and the maximum dry density decreased. A 2 % dosage of mPCM inhibited the development of silty clay cracks, reduced crack width and deformation, and increased the compression modulus of the soil samples by nearly 2.3 times. Under dry and wet cycling conditions, the cohesion decay of silty clay is greater than the angle of internal friction. The addition of 2 % mPCM significantly increased the shear strength of silty clay, cohesion by nearly 2.1 times, and internal friction angle by 1.4 times. The mPCM inhibits crack development mainly by regulating the internal temperature field of soil samples, thus improving soil strength. This study provides a reference for inhibiting soil cracking from a new temperature perspective. • A new method for controlling the temperature gradient of silty clay to inhibit soil cracking using microencapsulated phase change materials is proposed. • With the addition of mPCM, the silty clay's optimum water content increased, and the maximum dry density decreased. • Incorporation of mPCM reduces the attenuation of shear strength of silty clay under dry and wet cyclic action. • This method can significantly improve silty clay's cracking resistance and reduce the soil's deformation characteristics. [ABSTRACT FROM AUTHOR]

In this study, the effects of fly ash and granulated blast furnace slag based geopolymer on the mechanical properties of high plasticity clayey soils were investigated. For this purpose, experimental studies were carried out using the Taguchi Method. The Taguchi L 16 orthogonal array was used with various amounts of class F fly ash (12 %, 16 %, 20 %, and 24 %), granulated blast furnace slag (8 %, 10 %, 12 %, and 14 %), and alkaline hydroxide solution NaOH molarity (6, 8, 10, and 12). After 7 and 28 days of curing, unconfined compressive strength (UCS) and California bearing ratio (CBR) were carried out. Permeability test was carried out as well after 28 days of curing. The effects of the variables on the experimental results were determined using S/N and variance analyses (ANOVA). The microstructure and phase composition of geopolymer samples were identified via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The findings indicate that the strength of geopolymer-stabilized soil is significantly affected by the stabilizer content, fly ash–slag ratio, and molarity of alkaline activator (M). The optimal mix proportions for geopolymer-stabilized high plasticity clayey soil were found to be as follow: 38 % geopolymer content (24 % fly ash, 14 % slag) and an alkaline activator content of 25.75 % with a molarity of 12 M. This study concluded that fly ash and granulated blast furnace slag based geopolymer can serve as a feasible alternative material to cement, being sustainable and applicable. It could be utilized to enhance the strength characteristics of high-plasticity clay soil, while simultaneously, reducing permeability. • The Taguchi methodology was applied for optimization of geopolymer. • Utilizing FA-GBFS contributes to environmental conservation. • An increase in NaOH concentration leads to an improvement in geopolymerization. • Significant results in UCS, permeability and CBR have been achieved. [ABSTRACT FROM AUTHOR]

A new model for laterally loaded piles is proposed, consisting of a linear part and a non-linear iterative part. The linear part is based on the Green's function method, which strictly satisfies the displacement and stress continuity conditions at the pile-soil interface and leads to a rigorous solution. The non-linear iterative part assumes that the shear modulus of the soil around the pile decreases with the average strain of the soil layer. Only two soil parameters need to be calibrated, including the initial shear modulus of the soil and the reference shear strain at half the initial modulus. Compared to the finite element model, the advantage of this model is that it converges quickly while maintaining accuracy, which greatly improves computational efficiency. The advantage of this model over the p-y curve model is that it does not have the difficulty of selecting p-y spring parameters, especially for monopiles. The accuracy of this model is verified by comparison with three-dimensional finite element models and nine existing studies, including numerical models, field tests and centrifuge tests. These cases cover various piles with diameters of D∼0.273–10 m and aspect ratios of L/D∼3–40, installed in sand or clay by driving, jacking or vibration. • A new model for laterally loaded piles is proposed. • Only two soil parameters need to be calibrated in the model. • The model is suitable for piles of any aspect ratio in both clay and sandy soils. • The accuracy of the model is similar to that of the FEM model. • The computation time is comparable to the p-y curve model. [ABSTRACT FROM AUTHOR]

This study examines the application of nano-colloidal silica (NCS) in enhancing the mechanical properties of sandy clay soils. Consolidated undrained (CU) triaxial tests were performed on specimens containing varying percentages of NCS (0 %, 5 %, 10 %, and 20 %), which were then cured for different curing periods (1, 7, and 28 days) and subjected to three different confining pressures (50, 100, and 200 kPa). The findings revealed that the inclusion of 10 % NCS resulted in a significant 65 % increase in strength after 28 days compared to the untreated sample. However, higher NCS percentages, exceeding 10 %, led to a decline in strength as the excess NCS was not effectively utilized. The inclusion of NCS and increased curing time led to an increase in the brittleness of the soil and the application of confining pressure was able to reduce this brittleness.Furthermore, the use of 10% NCS and a curing period of 28 days significantly increased the stiffness and absorbed energy of the soil. Despite boosting the peak shear strength, NCS reduced the residual strength. Finally, polynomial modeling (Poly4) provided an excellent fit, enabling the characterization of the stress-strain and pore pressure-stain responses from the triaxial test. • A series of CU tests were conducted to investigate the strength behavior of sandy clay soil with NCS additive. • 10 % was the optimal content of NCS to modify sandy clay soil, which can improve strength. • The addition of NCS to the sandy clay soil enhances the strength and reduces the failure strain. • Empirical models were developed to predict and satisfactorily simulate q-ɛ and u- ε curves. [ABSTRACT FROM AUTHOR]

This study investigates the impact of seasonality on estuarine soil geochemistry, focusing on redox-sensitive elements, particularly Fe, in a tropical estuary affected by Fe-rich mine tailings. We analyzed soil samples for variations in particle size, pH, redox potential (Eh), and the content of Fe, Mn, Cr, Cu, Ni, and Pb. Additionally, sequential extraction was employed to understand the fate of these elements. Results revealed dynamic changes in the soil geochemical environment, transitioning between near-neutral and suboxic/anoxic conditions in the wet season and slightly acidic to suboxic/oxic conditions in the dry season. During the wet season, fine particle deposition (83%) rich in Fe (50 g kg−1), primarily comprising crystalline Fe oxides, occurred significantly. Conversely, short-range ordered Fe oxides dominated during the dry season. Over consecutive wet/dry seasons, substantial losses of Fe (−55%), Mn (−41%), and other potentially toxic elements (Cr: −44%, Cu: −31%, Ni: −25%, Pb: −9%) were observed. Despite lower pseudo-total PTE contents, exchangeable PTEs associated with carbonate content increased over time (Cu: +188%, Ni: +557%, Pb: +99%). Modeling indicated climatic variables and short-range oxides substantially influenced PTE bioavailability, emphasizing the ephemeral Fe oxide control during the wet season and heightened ecological and health risks during the dry seasons. [Display omitted] • Soil clay contents and soil pH were higher during the wet season. • Higher Fe availability in the estuarine soils during the dry seasons. • Potential toxic elements bioavailability increased over time. • Climatic factors explained 48% of PTEs' bioavailability in the estuarine soils. • Short-range ordered oxides exert control over PTEs' bioavailability. [ABSTRACT FROM AUTHOR]

• Parent material exerts a significant influence on the soil texture and pH. • Parent material affects the soil water-holding capacity by affecting the soil texture. • Quartz sandstone soil exhibits the lowest water-holding capacity. • Argillaceous limestone soil exhibits the highest water-holding capacity. • Argillaceous limestone soil exhibits the lowest erosion resistance. The parent materials play an important role in soil hydrologic properties. However, in subtropical hilly areas with complex geological conditions, it appears that there is a lack of full understanding about the effect of parent material on soil water-holding and erosion resistance, which can be helpful for agricultural production and conservation of soil and water. In this study, five red soils developed from shale (Ds), quartz sandstone (Dqs), argillaceous nodular limestone (Danl), argillaceous limestone (Dal), and limestone conglomerate (Dlc) in subtropical China were selected. Soil properties, soil water-retention curves (SWRCs), water-stable aggregate fractions, and soil erodibility factor (K) were tested and calculated. The results showed that there are significant differences in soil texture among soils developed from different parent materials, soils with higher clay content have stronger water-holding capacity, and the average water-holding capacity of the five soils followed the order Dal > Danl > Ds > Dlc > Dqs. Furthermore, the erosion resistance of soil is closely related to the clay content and the stability of soil aggregates, and the sequence of average K -value among the five soil types is as follows: Danl > Dal > Dlc > Ds > Dqs. Partial least squares regression revealed that the stability of aggregates has a more significant influence on soil erodibility than the clay content. Therefore, soils with higher mean weight diameter (MWD) and geometric mean diameter (GMD) are more resistance to erosion. This paper evaluated the distinctions in basic properties and hydraulic properties between different parent materials under similar climatic conditions, elevations and vegetation in subtropical hilly area of Southern China, which can serve as a scientific foundation for soil and water conservation in the environments characterized by complex geological conditions. [ABSTRACT FROM AUTHOR]

Humic substances (HS) are frequently incorporated into soils to improve soil health and nutrient availability. However, existing literature presents discrepancies regarding the soil-HS interactions and their impact on orthophosphate (inorganic phosphorus (IP)) adsorption, specifically, concerning the influence of soil clay mineralogy on these interactions. This study aims to investigate whether the impact of soluble humic acid (HA) on IP adsorption in semi-arid Mediterranean soils is contingent upon their clay mineralogy. This was tested by constructing IP- adsorption isotherms in the presence and absence of HA of four illite/smectite (I/S) or kaolinitic dominated soils. The results revealed that the addition of HA increased IP adsorption to I/S soils by up to 80%, yet IP did not affect HA adsorption to these soils. This suggests that while HA and IP are adsorbed onto different sites on the I/S clay, HA adsorption probably increases the number of adsorption sites accessible for IP. In contrast, IP and HA adsorption onto the kaolinitic soil was fully competitive: IP reduced HA adsorption and vice versa. It is suggested that new adsorption sites for IP resulted from the HA interactions with the I/S clay planar surfaces. In addition, HA moieties containing cationic (ionized) nitrogen, could possibly interact with clays to increase the number of platelets per tactoid. Unlike I/S clays, kaolinite that possesses low degree of isomorphic substitution, low net negative charge, and high degree of platelets stacking, does not tend to such interactions with HA. Instead, HA will be adsorbed mostly onto the clay edges, competing with IP on adsorption sites. • Humic acid (HA) – inorganic P (IP) adsorption to kaolinitic soil is competitive. • Dissolved HA increases IP adsorption to illite/smectite (I/S) soils by 5 to 72%. • HA increases IP adsorption through interactions with negatively charged clay surfaces. • HA increases the IP-buffering capacity of the I/S soils by up to 60%. [ABSTRACT FROM AUTHOR]

Here, we investigated the effects of biogas digestate application on flow pathways and soil properties in a sandy soil aiming at unraveling phosphorus accumulation and depletion processes in fertilized soils. Dye tracer experiments were conducted to visualize and distinguish between various flow pathways, while X-ray tomography was utilized to characterize the soil structure. The dye tracer experiments revealed differences between the control and the digestate-treated group of soil profiles in the top-soils although no statistical verification was possible amid a single plot per treatment. The stained soil profiles in both treatments indicate extensive areas of homogeneous and heterogeneous matrix flow. However, the digestate-treated group showed a decrease in homogeneous matrix flow and a notable presence of preferential flow with low interaction. The application of biogas digestate impacted various soil properties, including organic carbon content, water drop penetration time, and pH levels. Accordingly, the topsoil experienced an increase in soil organic carbon, water repellency, and a decrease in pH levels. The fraction of macropores also increased in the topsoil of the digestate-treated group, accompanied by an increase in tortuosity. Double lactate-extractable phosphorus (DL-P) distribution varied across the different flow pathways, with higher concentrations detected in matrix flow and a depletion observed in preferential flow regions in both treatments. These findings confirm the close relationship between the type of flow pathway and phosphorus distribution in soils. Additionally, a significant correlation was observed between pH levels and DL-P in the digestate-treated group, indicating potential implications for phosphorus availability. Overall, the results of this study suggest that the long-term application of biogas digestate is likely to improve soil properties as related to soil organic matter content, particularly in the topsoil of sandy soils. The study highlights the significance of the prevailing flow and transport pattern on nutrient distribution, with potential implications for nutrient management in agricultural systems. While the study design presented prevents the unequivocal assignment of differences to treatment effects, our data likely illustrate the impacts of biogas digestate amendment on the investigated sandy soil. Further research should focus on assessing the long-term effects of digestate application in loamy and clayey soils. • The impact of digestate on topsoil organic matter and water repellency is notable. • The application of biogas digestate tends to reduce the extent of homogenous matrix flow. • Macroporosity, air-filled porosity, and tortuosity alter with digestate application. • The spatial distribution of soil phosphorus exhibits high variability and is influenced by the flow field. [ABSTRACT FROM AUTHOR]

The ternary nature of soil texture, defined by its proportions of clay, silt, and sand, makes it challenging to predict through linear regression models from other soil attributes and auxiliary variables. The most promising results in this field have been recently achieved by Machine Learning methods which are able to derive non-linear, non-site-specific models to predict soil texture. In this paper we present a method of constructing a pair of Deep Neural Network (DNN) algorithms that can predict clay and sand soil contents from Airborne Gamma Ray Spectrometry data of K and Th ground abundances. We tested the algorithm's hyperparameters through various configurations to optimize the DNNs' performance, effectively avoiding underfitting and overfitting of the models. This led to the creation of a high-resolution 20 m × 20 m soil texture map from dense AGRS data, significantly refining the previous map's granularity. The application of the obtained DNN models to unseen sites can be supported by future training on additional textural classes. • Airborne radiometric data abundantly feed DNNs for soil texture predictions. • DNNs allow to overcome linear constraints for relations between K and clay content. • We optimized DNN hyperparameters in terms of accuracy and computational time. • We validated the DNNs for the prediction of soil texture from radiometric data. • We obtained a 20 m × 20 m soil texture map of the Mezzano Lowland (Italy). [ABSTRACT FROM AUTHOR]

In this study, the mechanical and durability performance of clay soils reinforced with different proportions of Cherry Marble Powder (CMP) and non-woven geotextile configurations, both independently and in combination, is investigated in detail at both the macro and micro levels. The effectiveness of reinforcement in the stabilization of clay soils in cold climates has been evaluated by means of Gray Correlation Analysis (GCA). The results show that as the CMP ratio and the number of geotextiles increase, the peak strength of the soil increases, with higher CMP levels showing perfect plastic behavior and more geotextiles showing linear strain hardening, particularly in combination. Substantial strength reductions post-7th cycle ranged between 91.09 % and 103.38 % for 12 % CMP and 219.83 % and 270.42 % for three-layered geotextile groups. Cohesion increased by 59.76 % and 179.41 %, while the internal friction angles remained stable and decreased after F-T cycles, except with additives. Failure modes shifted with CMP content, F-T cycles and confining pressure. The transition was from strain hardening to strain softening, with increased shear fracture planes and brittleness. The energy absorption capacity (EAC) increased with the CMP ratio, with the geosynthetic reinforcement increasing the EAC by a factor of 1.5 before and after the F-T cycles. The combined use of CMP and geotextiles in soil stabilization improved the engineering properties in areas of frost, with the optimum gradation being three layers of geotextile and a CMP ratio of 12 %, which effectively mitigated the effects of the maximum F-T cycle. • CMP and geotextile increase soil strength pre and post F-T. • 7 cycles cause significant strength reduction: up to 103.38 % for 12 % CMP, 270.42 % for 3 layers. • Cohesion rises: 59.76 % in 1st stage, 286.96 % in 2nd, 83.99 % in 3rd, and 179.41 % in 4th. • EAC increased with CMP ratio, and geosynthetic boosted CMP's EAC by 1.5 times. • Failure modes shift from strain-hardening to strain-softening with CMP, F-T cycles, and pressure. [ABSTRACT FROM AUTHOR]

The dynamic structural response of a vertical pile port platform under the action of irregular wave loads considering soil-structure interaction is studied. Deck displacement and bending moment on the piles were evaluated for a set of structural, hydraulic, and geotechnical parameters. Static structural analyses with the maximum base shear produced by wave loads and dynamic time-history analyses are performed to study the effects of dynamic amplification on the structural response of the platform. Two types of waves are analyzed, regular and irregular, to analyze the amplification effects due to the superposition of a wave train of different periods in the case of irregular waves. Cases with fixed base support and non-linear spring-modeled soil are considered to evaluate the effect of considering a flexible base for the platform. Eight structures composed of a different number of piles and with different heights were analyzed. Six wave conditions with different characteristics are used, varying the wave period and mean water height. Two sandy and two clayey soil profiles are considered with different densities and consistency. The results show that resonance effects associated with dynamic loading and small-period wave superposition in cases of irregular waves significantly affect the response. Furthermore, considering a flexible base tends to decrease the response for short wave periods, concluding that, in most cases, for wave periods close to 5 s, considering a fixed base model overestimates the response. • A transparent port platform with vertical piles under wave loads is studied. • Effects of dynamic loading, irregular waves and flexible base modeling are analyzed. • Resonance effects are not represented in a study with regular waves. • Resonance effects due to dynamic loading and irregular waves are significant in the displacement and bending moment response. • The use of a fixed base overestimates the bending moment response of the structure. [ABSTRACT FROM AUTHOR]

Soil moisture loss, crack initiation, and propagation can severely damage the structural integrity, weakening the function and stability of soil, causing various problems in geological, geotechnical, hydraulic, environmental engineering fields. The aim of this study is to enhance the water-retaining property and cracking resistance of soil by adding sisal fiber and polyacrylamide. Laboratory tests were conducted to investigate the changes in moisture evaporation, crack initiation, and propagation process in modified clayey soil during three wetting-drying cycles. Soil mass was collected by weighing equipment and the evolution of surface cracks during the wetting-drying cycles were monitored. The resulting photographs of the cracks were further quantified and analyzed (using image processing technology). Results show that sisal fibers prevent the crack from developing downwards. In addition, the frictional force between soil particles and sisal fibers partially counteracts tensile stress when pulled horizontally, reducing the cracks' openings. On the other hand, polyacrylamide combined with water and soil particles to form agglomerates can reduce the evaporation rate, keeping the soil moist for a long time and delaying crack initiation. However, the soil's cracking resistance and water-retaining properties cannot be improved simultaneously when sisal fiber or polyacrylamide is present individually. Furthermore, adding only polyacrylamide increases the difficulty in the cracks healing via filling during the wetting-drying cycle. The composite of these two materials and reasonable control of the content can effectively solve the above problems. The optimal content of sisal fiber and polyacrylamide for enhancing water-retaining property and cracking resistance in clayey soil are 0.6% and 0.5%, respectively. The results of the study can provide some references for soil improvement in foundation treatment, soil and water conservation, and geological disaster prevention and other fields. • Fiber can amplify the anti-cracking effect during the rewetting and redrying. • Polyacrylamide extend the duration of evaporation. • Polyacrylamide delay the crack initiation. • Composite improvement enhances soil's water retention and anti-cracking. [ABSTRACT FROM AUTHOR]

The combustion of coal worldwide creates a large quantity of fly ash (FA), and the application of FA to agricultural soils is being encouraged as a resource utilization strategy. While most of our attention has focused on positive aspects such as nutrient supplementation and pollution mitigation, the negative impacts of FA have likely been overlooked. In this study, we examined the colloidal properties of FA and soil clay, aiming to demonstrate the ability of FA to increase the dispersibility and transportability of soil clay. Dynamic light scattering technique was coupled with the test tube method to track the kinetics and pH-dependent changes in the zeta potential, hydrodynamic size and colloidal stability of FA, soil clay and their mixtures. We found that FA occurred in solution as "negatively charged balls", and its negative surface charges increased with increasing pH. FA itself showed a low dispersibility; however, FA became more dispersive when it was introduced to clay suspensions. The mechanism is that the introduction of FA supplied more negative charges to the clay suspension, inducing electrostatic repulsion with soil clay, from which both FA and soil clay were favoured to disperse. Therefore, it can be inferred that off-site transport of FA is possible. More importantly, excessive application of FA can inadvertently intensify clay dispersibility, eventually resulting in soil clays together with FA being more vulnerable to leaching and/or surface run-off erosion. This suggests that the application of FA needs more careful consideration, and the development of more suitable techniques for the sustainable application of FA is still needed. [Display omitted] • Fly ash (FA) was found to carry negative charges over the pH range from ∼3 to ∼9. • Application of FA for soils can increase soil negative net charges. • Both FA and soil clay were favored to aggregate but their mixtures were dispersive. • Off-site cotransport of FA and soil clay needs to be considered. [ABSTRACT FROM AUTHOR]

[Display omitted] • Invasion by Spartina increased mineral-bound OC in mudflat soil. • Subsequently reclamation for aquaculture decreased soil mineral-bound OC. • Mineral-bound OC was correlated to nitrogen supply and soil clay content. • Habitat change affected Fe[Al]–OC more than Ca-OC and residual-OC. • Soil OC storage increased more strongly with increasing Ca-OC. The formation of mineral-bound organic carbon (OC) complexes is important for the long-term preservation of soil organic carbon (SOC) in wetlands. Many coastal wetlands globally have been threatened by plant invasion and land development, but information on the effects on mineral-bound OC is limited. We measured the soil contents of Ca-OC, Fe(Al)–OC and residual OC across 21 coastal wetlands in southern China that have gone through the same sequence of land cover change, from native mudflats (MFs) to Spartina alterniflora marshes (SAs) then to earthen aquaculture ponds (APs). Residual-OC was the main component of SOC (74.1–78.2 %), followed by Fe(Al)–OC (18.4–22.8 %) and Ca-OC (<3.5 %). All three components in the soil increased when MFs were converted to SAs, but decreased in subsequent conversion of SAs to APs. Land cover change affected Fe(Al)–OC the most, but SOC storage increased more strongly with increasing Ca-OC. Nitrogen supply in the form of NH 4 +-N and clay content both positively affected the changes in mineral-bound OC. Our results suggest that different land cover change scenarios had different effects on the amounts of mineral-bound OC and their liability to microbial turnover, resulting in different degrees of SOC preservation and carbon emissions. [ABSTRACT FROM AUTHOR]

• UAVs show promising utility in monitoring desert rodent activity on a regional scale. • Regional plant variation significantly influences desert rodent burrow density. • Significant lag effects of environmental factors on rodent burrow density. • Elevation, precipitation, vegetation and soil are the key factors influencing rodent. Timely and accurate prediction and early warning of rodent infestation are highly important for the sustainable development of desert ecosystems. This study combines data from 1376 UAV images of actual rodent burrows with natural environmental factor data, aiming to reveal the mechanism through which these factors affect rodent burrow density in the desert areas. The relationships between rodent burrow density and the 9 plant communities and 34 plant species in this area were analyzed by the K-W test and Spearman rank correlation analysis, respectively. The Boruta algorithm and the boosted regression trees (BRT) model were used to determine the six main factors influencing rodent burrow density from a total of 32 factors and to determine the distribution pattern of the burrows. The results show that (1) the density of rodent burrows in the Junggar Basin desert area gradually decreases from south to north and from west to east. (2) There were significant differences in rodent burrow density across the different plant community types (P = 0.048**). A total of 50.0 % of the species significantly influenced rodent burrow density at at least one level. (3) Among the 17 factors with lag effects, nine had the most significant correlation with rodent burrow density in April. Only two natural environmental factors demonstrated lag effects of less than one month. (4) The soil clay content, elevation, Normalized Difference Salinity Index (NDSI), vegetation cover, precipitation, and soil bulk density were the most important influencing factors on rodent burrow density. Considering the pairwise interactions among factors, the collective impact of these factors on rodent burrow density is at least sevenfold greater than the independent effect of a single factor. This study provides a theoretical basis for obtaining a timely and accurate understanding of the spatial distribution of rodent burrows, mitigating the degradation trend of desert ecosystems, and ensuring healthy and sustainable development. [ABSTRACT FROM AUTHOR]

[Display omitted] • Suitable plantations can mitigate global change events, if well-implemented. • China's plantations show increasing above- and below-ground carbon stocks with stand age. • C stocks and rates increase with temperature as compared to humidity. • Soil clay and fertility increase C stocks rather than annualized C rates. • C allocation between tree organs depends on climate and soil conditions. A significant proportion of the Earth's natural forests has been continuously degraded each year as a result of human activities and global environmental changes. Meanwhile, there has been a rise in the establishment of plantations through numerous planting trees initiatives, including those recently spearheaded by the United Nations (UN) Decade (2021–2030). Yet, considerable global uncertainty remains on drivers of carbon (C) sequestration (defined by C stocks and annualized accumulation rates) in plantations. By using the meta -data from 257 plantation plots in China, we quantified above- and below-ground C stocks and annualized C accumulation rates in tree organs, i.e., stems, branches, leaves, and roots, based on biomass allometric equations and scaling rules. Multiple linear regression models were used to explore the drivers (i.e., stand age, climate and soil factors) of plantation above- and below-ground C stocks and accumulation rates. We show that above- and below-ground C stocks increased with stand age (β = 0.55 to 0.66; P < 0.001) followed by temperature (β = 0.29 to 0.36; P = 0.001 to < 0.001), precipitation seasonality (β = 0.23 to 0.41; P = 0.013 to < 0.001), and somehow by climatic humidity (β = 0.17 to 0.35; P = 0.105 to 0.002), but decreased with isothermality (β = -0.14 to -0.16; P = 0.024 to 0.019). Soil clay content increased stem C stock (β = 0.15; P = 0.016) whereas soil cation exchange capacity increased branch C stock (β = 0.23; P = 0.003), even though soil factors did not significantly affect annualized C accumulation rates (β = -0.12 to 0.14; P = 0.908 to 0.078). This coarse-scale study suggests that C sequestration in China's plantations increases over time with increasing climatic temperature and soil fertility, thereby sustaining environmental conditions by capturing C from the atmosphere and storing it in tree organs. Thus, conserving environment-friendly plantations, having no disruption to native biodiversity, as land resources can reduce pressures on natural forest resources while improving environmental integrity through feedback. [ABSTRACT FROM AUTHOR]

A three-dimensional numerical analysis is conducted on a group pile adjacent to a deep multi-strutted excavation in a naturally occurring soil profile comprising both cohesive and non-cohesive layers. The contrasting soil layers affect the soil stiffness, strength, and deformation characteristics, thereby impacting the load transfer mechanism within a pile group. The primary aim of this study is to specifically understand how the presence of a non-cohesive soil layer within a predominantly cohesive soil profile, affects the behavior of a pile group during excavation. By systematically varying the position and thickness of the soil layers, the analysis highlights the significance of considering the actual soil profile's inherent heterogeneity rather than assuming a homogeneous clay layer. 19.2% and 17% deviations respectively are observed for pile group settlement and lateral deflection when a homogeneous clay layer is considered instead of the natural soil profile. The findings also show that the position of the non-cohesive soil layer within a predominantly clay soil profile is more critical than its thickness in determining the pile response to excavation-induced changes. The non-cohesive soil layers within the excavation depth, significantly influence the lateral and axial pile behavior, while those below the final excavation depth have a limited impact. A theoretical simplified framework is proposed for the preliminary assessment of the excavation-induced effect on an adjacent pile group. This simplification helps minimize the initial calculation time and effort while capturing the significant factors affecting the pile group behavior near the excavation. [ABSTRACT FROM AUTHOR]

In this work, the mechanics of cone penetration during CPTu tests in Osaka clay, a natural structured silty clay, was investigated with the Particle Finite Element Method (PFEM). To describe the behavior of the soil, the FD_MILAN model, recently proposed by the Authors, was adopted. The model, based on the multiplicative decomposition of the deformation gradient, incorporates a scalar internal variable, the bond strength P t , to quantify the effects of structure. The macroscopic description of mechanical destructuration effects is provided by the hardening law of P t , according to which the bond strength decreases monotonically with accumulated plastic deformations. The brittle behavior resulting from the softening process associated to destructuration make the soil quite susceptible to the spontaneous development of strain localization in the form of shear bands. In order to deal with strain localization phenomena, the model is equipped with a non-local version of the hardening laws, incorporating a material constant – the characteristic length ℓ c – which provides the material with an internal length scale. The objective of this work was to get some insight on the effects of the characteristic length and of the initial degree of structure on: the kinematics of the soil deformation around the advancing cone tip; the evolution of soil structure with accumulated plastic deformations; the excess pore pressure field generated in the soil as a result of the hydro-mechanical coupling between the solid skeleton and the pore water, and the net cone resistance measured at the base of the cone. The results of the PFEM simulations show that the deformations around the piezocone are strongly affected by the characteristic length. For heavily structured soils, when ℓ c is relatively small with respect to cone radius, the accumulated plastic deviatoric deformation field is characterized by clearly visible shear bands while, as ℓ c increases, the detection of localized deformation regions becomes more difficult, if not impossible. This depends on the fact that, for large values of ℓ c , the shear band width may be of comparable size to the cone radius. In all cases, the soil around the advancing piezocone is subjected to a very strong destructuration process, which leads to the complete loss of bond strength in a large region around the cone tip and shaft. As a consequence, the use of conventional N c values from the literature in the interpretation of the CPTu test performed in heavily structured soils could provide undrained strength values closer to the ultimate undrained shear strength. At the same time, the use of empirical correlation to estimate the yield stress in oedometric conditions would lead to a significant underestimation of the overconsolidation ratio. [ABSTRACT FROM AUTHOR]

This study proposes an innovative and simple method to quantify the effect of wetting–drying history on soil–water retention curve (SWRC) of expansive soils. This method is based on the increment relationship between degree of saturation and initial void ratio corresponding to irreversible swelling or shrinkage after each wetting–drying cycle, following the double-structure scheme for three-phase reactive porous media. The approach satisfies the intrinsic constraints for partially saturated porous media, and the incremental relationship can be applied in any existing SWRC equations for future water retention capacity prediction. In this respect, only one new rate function is proposed, which could be easily calibrated by relevant experimental data. The prediction of the model is verified through the comparison with relevant experimental data of two expansive clayey soils. To evaluate the general applicability of the proposed method, two typical SWRC equations proposed in literature were used. The results showed a very good agreement with experimental data subject to multiple wetting–drying cycles, indicating its potential as an effective tool for estimating preliminary SWRCs of expansive soils. [ABSTRACT FROM AUTHOR]

Up to now, the correlation between soil evaporation and cracking within a multi-scale perspective remains unclear so far. For this purpose, X-ray computed tomography was used to dynamically capture the 3D cracking process of a compacted clayey soil with evaporation. The proposed image processing methods combining CT image segmentation and digital image correlation (DIC) allowed multi-scale quantitative analysis of the temporal evolution of soil water distribution, regional deformation and crack network upon evaporation. Different mechanisms are defined to explain the development of regional crack networks. Evaporation-mobilised tensile stress leads to cracking in the top part of the soil, with a single-peaked change along drying time in the cracking rate. A similar variation appears in the cracking process of the bottom soil, attributed to the basal friction activated by soil desiccation shrinkage. Besides, the cracking rate of this region is nearly independent of the regional evaporation. As for the middle part of the soil, a double-peaked pattern dominates the cracking rate, as the curling contributes to the formation of new inner cracks and the bottom soil cracks propagate upwards. Furthermore, desiccation cracks developing to a certain extent facilitate the water loss of neighbouring soil bodies, whereas this phenomenon is difficult to present over the whole soil scale. The current outcomes are expected to advance insights into the spatial–temporal cracking mechanism of soils under evaporation. [ABSTRACT FROM AUTHOR]

• A novel method based on species diversity theory would assess preferential flow. • Effects of soil properties on the proportion of dye-stained areas (PDA) were studied. • Soil clay content and sand content primarily control PDA in upper soil layers. • Soil drainage capacity and bulk density primarily control PDA in lower soil layers. • Random forest algorithm could provide accurate and stable predictions for PDA. The preferential flow path development is potentially the result of spatial variations in soil properties with soil depth. However, visualizing the evolution of the preferential flow path with soil depth remains a challenge. This paper presents dye tracer and species diversity theory methods for characterizing preferential flow paths. Field dye tracer experiments were performed at three sites (tree, bush, and grass) in the Yellow River Delta wetland and dye distribution diversity indices (Simpson index (D s), Shannon-Wiener index (H), Margalef index (D m), and Pielou index (E)) were applied to verify their availability for preferential flow assessment. The results showed that the uniformity of the shallow-infiltrated dye at the tree site, non-uniformity of the shallow-infiltrated dye at the bush site, and deep dye infiltration at the grass site were the three typical infiltration types. The average proportion of dye-stained areas (PDA) gradually decreased with increasing soil depth. The quantitative effects of soil properties on PDA changes were profound, indicating that soil clay content at 0–10 cm depth, soil sand content at 10–20 cm depth, soil drainage capacity at 20–30 cm depth, and soil bulk density at 30–40 cm depth were the most predictive factors controlling PDA changes. Our results also showed that dye-stained patches with extremely high and high dye concentrations were the most distributed; D s , H , D m , and E were the highest at the tree site and E was the diversity index with the greatest importance for PDA change. The findings reveal the soil properties controlling the formation of preferential flow paths, which will improve our understanding of water resource management in the vadose zones of coastal wetlands. [ABSTRACT FROM AUTHOR]

• Sorption behaviour of soil-oil mix was investigated using vis-NIR Spectroscopy. • A spectral index describes sorption of crude oil on soils. • The amount of clay and the clay mineralogy control sorption behaviour. • A model describes 4 stages of sorption behaviour at micro and macro levels. • Results suggest this technique can model sorption capacity of soils more rapidly. Theoretical models to describe and evaluate sorption of hydrocarbons on soil particles are well documented but experimental results in the literature are scarce. This study describes the use of a spectral index to evaluate sorption phenomena in oil-contaminated soils at micro and macro levels. Experiments involved oil-dosing from 0.25 mL to 4 mL and the application of a spectral index to estimate the sorption capacity of different soils based on change in statistically derived Critical Point (CP). Results show that sorption of oil varies with soil type, specifically the proportion of clay in a soil/sediment and the clay species, in the order smectite > illite > kaolinite. In support of theoretical models, this work proposes a model from experimental data that explains observed phenomena of soil-oil interaction with changing soil composition. The location and prominence of the CP is also strongly affected by soil moisture, particularly in coarse-grained soils, potentially providing insight to soil-oil–water interaction. The methods developed using a simple synthetic crude provide potential to explore other contamination scenarios including different soil compositions, types of petroleum products and different environmental controls. [ABSTRACT FROM AUTHOR]

In this study, three-dimensional numerical analysis has been performed to comprehend the time-dependent behavior of large piled rafts founded in saturated clayey soil, explicitly for the time of superstructure construction and post-construction up to the end of soil consolidation. The performance under different construction times for the corresponding unpiled raft and the piled raft with uniform pile length configuration of varying pile number, spacing, and length have been examined and then compared with that of non-uniform length configuration for the same total pile length. The dissipation of excess pore water pressure, average settlement, and differential settlement are presented and discussed in detail. A quicker dissipation rate of excess pore pressure is noted with either fewer piles, wider pile spacing, or shorter-length piles. An increase in construction time results in a lesser total average settlement at the end of consolidation. The piled raft with uniform pile length configuration shows a higher differential settlement than the unpiled raft. However, by adopting a suitable non-uniform length configuration, negligible differential settlement, higher load-carrying capacity, and a significant reduction in pile material volume can be achieved. Predictive expressions have been proposed to estimate the average and differential settlements of piled raft with uniform length configuration. • Large piled raft performance during and post-construction in clay. • Effects of pile number, spacing and length on time-dependent behavior of piled raft. • Predictive equations to estimate the average and differential settlements. • Comparison and design with non-uniform pile length configuration. [ABSTRACT FROM AUTHOR]

• The failure model of stiff-over-soft clay varying with soil parameter. • A new calculation method for ultimate bearing capacity of spudcan. A jack-up platform is prone to a 'punch-through' accident when working on the stiff-over-soft clay foundation. To assess the risk of punch-through, it is necessary to plot the bearing capacity-penetration curve for evaluating the penetration depth of the pile leg or to calculate the ultimate bearing capacity of the spudcan and compare it with the preload. However, accurate prediction of spudcan bearing capacity is not easy. In this paper, the failure mode about the stiff-over-soft clay under different geological conditions when punch-through occurs is discussed using coupled Eulerian lagrangian (CEL) method, varying the strength ratio between soft and stiff soil layers, the thickness of stiff soil relative to the spudcan diameter, and the non-homogeneity factor of soil strength. Based on the soil failure model with varying soil parameters, a new calculation method for ultimate bearing capacity of spudcan is proposed and then verified against existing centrifuge test results. The results show that the shape of soil shear plane in stiff clay is significantly affected by the strength ratio of soil layer and the non-homogeneity factor of soil strength. And the presented new method whose prediction errors compared with centrifuge test results are less than 5%, has better calculation accuracy than the ISO (International Organization for Standardization) method, which is valuable in guiding the calculation of the ultimate bearing capacity of the spudcan and ensuring the safe operation of the jack-up drilling units on stiff-over-soft clay. [ABSTRACT FROM AUTHOR]

In this paper, an attempt has been made to investigate the impacts of leaching on the geotechnical and microstructural properties of clayey gypseous soils at various percentages of gypsum; 20 %, 40 %, and 60 %, and their respective densities. In this respect, the work delves into the interaction of the properties based on the following experiments: oedometer permeability leaching and modified permeability leaching tests for investigating the effects of gypsum content, density, and leachate on significant soil properties such as compressibility, permeability, and Total dissolved solids (TDS). Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS) used for microstructural analysis reveal how the soil fabric and dissolution patterns change during leaching. The conclusions derived from the results of the study state that with an increase in the content of gypsum in soil, it increases the porosity and permeability of the soil and at the same time decreases the plasticity. The soils which were denser showed lesser leaching strain due to reduced permeability. It can be ascertained that the modified leaching test is a more realistic and accurate method in comparison to the oedometer test. Results from microstructural observations hence bring out important changes in the soil fabric after leaching: increases in voids and cavities responsible for the change of soil stability and engineering properties. This research allows a good contribution to understanding and the management of gypseous soil behavior in geotechnical engineering projects and provides new lines of future investigation for the long-term performance and stabilization technique of effectiveness. [ABSTRACT FROM AUTHOR]

Soil shrinkage during the drying process (water stress) is one of the main issues in expansive soils of paddy fields. It occurs due to decrease in soil water content, resulting in changes in soil volume and the geometry of pores, leading to the formation of cracks and higher water loss. The aim of this study was to assess the shrinkage characteristic curve and pore size of paddy soils to determine the shrinkage -swelling behavior in Guilan province, Iran. 120 soil samples were collected from the study area. Pore size was determined using soil moisture retention curve (SMRC). It was established by plotting the soil water content (θ) versus the corresponding matric suction (h), and the shrinkage curve by plotting the void ratio (e) against the moisture ratio (υ). The suction-pore relationships were also determined. Furthermore, the geometric factors indicating the change in vertical (subsidence) and horizontal (crack) volume of the soils were determined and varied from 1.23 to 2.53, indicating that the vertical change in soil volume is predominant. The zero, residual and proportional shrinkage phases accounted for less than 2 %, 8–38 %, and 61–91 % of the total soil volume change, respectively. The shrinkage capacity of the soils ranged from 0.52 to 1.37. Cation exchange capacity and clay content were identified as the most important factors affecting soil shrinkage properties. In general, the studied paddy soils have great potential for swelling- shrinkage and cracking during the drying process due to the large percentage of expandable clays and the medium to fine pores. The resultant cracks negatively affect crop yield by damaging plant roots and increasing water losses through the soil profiles. • Guilan paddy soils have a great potential for swelling- shrinkage and cracking during drying process. • Predicting indicators related to shrinkage curve can be an effective way to manage soil and water. • Wetting and drying intensity in paddy soil had a greater impact on soil shrinkage. • The cation exchange capacity and clay were the most important factors affecting the soil shrinkage properties. [ABSTRACT FROM AUTHOR]