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Granite residual soil is a widely encountered clayey soil with unique microscopic soil structures. Its soil structures mainly stem from the presence of interparticle cementation by iron oxide. An attempt is made herein to experimentally quantify the impact of interparticle iron oxide cementation on soil's mechanical properties, particularly in the high suction range. The amount of interparticle cementation is artificially generated by mixing soil samples with varying mass fractions of iron hydroxide colloid. The mechanical behavior of these soil samples in the full suction range is measured via the drying cake test. Preliminary experimental results demonstrate that interparticle iron oxide cementation can significantly decrease soil shrinkage (by up to 52%), and substantially increase soil elastic modulus (by up to 1.83 times) and negative suction stress change (by up to 0.82 times). [ABSTRACT FROM AUTHOR]

In this investigation, the structural strength of a clayey soil compacted at three different dry densities (1.7, 1.6 and 1.5 Mg/m3) and three different compaction water contents (20%, 16% and 12%) was studied by using a micropenetrometer. The penetration curves at various water contents during the drying and wetting cycle were analyzed. The maximum unit penetration strength and the penetration stiffness were used to represent the structural strength. Experimental results show that the structural strength increases with decreasing water content. At a given water content, the larger dry density, the larger structural strength and the smaller hysteresis loop induced by the drying-wetting cycle. At a higher dry density, the structural strength increases and the drying-wetting cycle induced hysteresis loop becomes smaller. Specimens compacted on the wet side of optimum water content exhibit a dispersed structure and those compacted on dry side of optimum water content have an aggregated structure. For soils with a dispersed structure, the structural strength increases with decreasing water content and the growth rate is gradually accelerated. However, for soils with an aggregated structure, when dried to water content lower than 8%, the structural strength increases by a small degree or even decreases. Moreover, the hysteresis loop of the soil specimens with dispersed structure is much smaller than those with an aggregated structure. [ABSTRACT FROM AUTHOR]

The foundation is the lower part of a structure used as a load distributor for the loads generated by the upper structure, which are then transmitted into the hard soil layers. The selection of foundation types in building construction must consider the type and characteristics of the soil at the construction site to avoid construction failures. This analysis is conducted to determine the bearing capacity of pile foundations using analytical and finite element methods. The type of foundation used in this analysis is a pile foundation with a pile length of 8 meters and a pile diameter of 0.4 meters. For the analytical calculation, Standard Penetration Test (SPT) data obtained from PT. Adhi Karya (Persero) for the Infrastructure Green House Biodiversity LIPI Cibinong-Bogor project are used, employing the analytical method (Alpha Method) and the finite element method with the assistance of Plaxis 2D V.8 software. The results of the analysis show that the bearing capacity of the group pile foundation (Qg) for a pile diameter of 0.4 meters and a pile length of 8 meters on clayey soil, based on SPT data using the analytical method (Alpha Method), is 60.432 tons. Meanwhile, the bearing capacity of the horizontal pile foundation using the Broms method is 6.03 tons. The bearing capacity obtained using the Finite Element Method yields an ultimate load on the group pile (Qq) of 57.89 tons. The bearing capacity of the group pile foundation (Qg) from both sets of data, with a difference of 2.5%, meets the requirement, being greater than the axial load (P) of 42.6 tons that must be supported. [ABSTRACT FROM AUTHOR]

A clear strategy for adapting agricultural drainage to future climate change is important for environmental and economic reasons. In a study aimed at developing recommendations for the subsurface drainage design in clay soils, we evaluated the impact of replacing an old drainage system (1920) with new systems (2018) on nutrient leaching and crop yield. Our field experiment included 12 individually drained plots divided into four treatments: (A) old system with clay tiles at 10 m spacing, without an envelope; (B) new system with plastic pipes at 10 m spacing, gravel envelope; (C) new system with plastic pipes at 5 m spacing, gravel envelope; and (D) new system with plastic pipes at 10 m spacing, gravel envelope and lime incorporated in trench backfill. We conducted flow measurement and flow-proportional, logger-controlled water sampling of the drainage discharge from each plot at a measuring station. Preliminary results (first two years) show a clear effect of the new drainage systems on phosphorus and nitrogen loads in drainage discharge. The lowest total load of phosphorus and highest total load of nitrogen in all treatments were observed in treatment D (with 10 m drain spacing and lime incorporated in trench backfill). The highest total phosphorus load and lowest total nitrogen load in all treatments were observed for the old tile drainage system with 10 m drain spacing (treatment A). The environmental impact of new drainage systems on clay soils may thus be a trade-off between decreased phosphorus loads and increased nitrogen loads with more intensive drainage. Crop data from two experimental years indicated that investing in new drainage systems can be profitable for farmers, as crop yield was 3%-20% higher with new drainage systems compared with old tile drainage. More experimental years are needed to determine the long-term effects of the different drainage system designs. [ABSTRACT FROM AUTHOR]

There are three main electrochemical factors affecting the electroosmotic flow in clay soil: the voltage loss at the clay/electrode interface, the type of current carriers in the soil, and the ion composition change in the clay due to voltage application. Appropriate evaluation of these factors is important to cost effectively implement electroosmosis for in situ soil consolidation projects. In this study, three different experimental systems were developed and used to investigate electrochemical reactions occurring in reconstituted and natural marine clay during electroosmotic consolidation. The results of polarization tests show that the voltage loss at the clay/electrode interface is different depending on the combination of the clay material and electrode material. The results of electroosmotic element test also show that electroosmotic dehydration does not increase if large current–voltage value is applied and that an optimal current–voltage value for causing electroosmosis depends on the cohesive soil composition. If the clay contains a lot of oxidizable ions, such as sodium, these ions affect electrophoresis and chemical reactions that occur in the soil. Therefore, the optimal configuration to apply electric current also differs depending on the clay. The results of laboratory-scale electroosmotic dehydration tests, arranged in a realistic in situ layout, are performed to study the relationship between soil dehydration, consolidation, and surface crack generation. [ABSTRACT FROM AUTHOR]

Information on microbial biomass carbon (MBC) is crucial to assess their stocks and role for plant nutrient release in soil. Next to fumigation-extraction, molecular methods are routinely used to estimate the contribution of fungi, bacteria, and archaea to the soil microbial community. However, more information on the links between these different indices would deepen the understanding of microbial processes. The current study is based on 11 datasets, which contain MBC and MBN data obtained by fumigation-extraction and information on bacterial, archaeal, and fungal gene abundance, totalling 765 data points from agricultural, forest, and rangeland soils. Some of these datasets additionally provide information on double-stranded deoxyribonucleic acid (dsDNA) and fungal ergosterol. MBC varied around the median of 206 µg g−1 soil. MBN followed with a median MB-C/N ratio of 4.1. Median microbial gene abundance declined from bacteria (96 × 108) to archaea (4.4 × 108) to fungi (1.8 × 108). The median ratio of MBC/dsDNA was 15.8 and that of bacteria/dsDNA was 5.8 × 108 µg−1. The relationships between MBC and dsDNA as well as between bacterial gene abundance and dsDNA were both negatively affected by soil pH and positively by clay content. The median ergosterol/MBC and fungi/ergosterol ratios were 0.20% and 4.7 (n × 108 µg−1), respectively. The relationship between fungal gene abundance and ergosterol was negatively affected by soil pH and clay content. Our study suggests that combining fumigation-extraction with molecular tools allows more precise insights on the physiological interactions of soil microorganisms with their surrounding environment. [ABSTRACT FROM AUTHOR]

Evaluating the liquefaction capacity of saturated loose sandy and clayey soils is an important task to be completed in the course of implementing new construction projects in seismic areas. This article addresses the main characteristics and input parameters of three soil models, including HS small, UBC3D-PLM, and PM4Silt. The behavior of the "soil base–pile foundation–structure" system is examined by using these models to simulate the soil behavior during an earthquake. The results demonstrate the main differences between these models and draw attention to the importance of the choice of a soil model for seismic analysis, particularly when soil liquefaction is considered. [ABSTRACT FROM AUTHOR]

Laboratory experiments on clayey soils under dynamic triaxial compression were conducted to establish a nonlinear relationship between the dynamic modulus of soil deformation and the frequency of impact. The most significant increase in the dynamic modulus of soil deformation is observed under an increase in frequency from 5 to 10 Hz. In comparison with fluvioglacial soils, the dynamic deformation modulus in glacial loams grows slower under an increase in frequency. This confirms the dependence of the obtained relations on the genesis of soils. The research results were used to develop vibration protection systems for high-precision equipment in high-tech industries. [ABSTRACT FROM AUTHOR]

Coir is a promising natural fiber that can be used for soil stabilization through fiber reinforcement. In this paper, weight gain, reduction in water absorption, and single-fiber tensile strength tests are performed to evaluate the application of different natural agents such as neem oil, kerosene, and cashew nutshell liquid (CNSL) in improving the mechanical properties and durability of coir fibers. Tri-axial tests are performed on soil specimens cured for 3, 28, and 180 days to determine the improvement in their shear strength when reinforced with coir fibers treated with different agents. The fiber reinforcement led to an increase in the shear strength of the soil by improving cohesion and friction angle. Among the different agents used, the CNSL is found to be the most effective agent for coir fiber treatment. [ABSTRACT FROM AUTHOR]

Based on the perspective of flight technology and flight safety, the unsaturated clayey foundation soil of a high plateau airport in the mountainous area of southwest China is taken as the research object, and the calculation method of the composite modulus of CFG pile composite foundation with the soil between the piles as the unsaturated soil is established according to the relevant characteristics of unsaturated soil, and the calculation method of the composite foundation's settlement is carried out on the basis of this method. At the same time, Plaxis finite element analysis software is used to model the actual project and numerically analyze the settlement characteristics of the composite foundation. Finally, the calculation results of the two methods are compared and studied with the actual settlement monitoring values on site. The study shows that: 1) the theoretical analysis method is able to consider the effects of pile length, pile modulus, and matrix suction in unsaturated soil of rigid piles on the composite modulus, which is more in line with the reality than the conventional composite modulus method that does not consider the unsaturated nature of the soil between the piles; 2) the resultant values computed by the theoretical and numerical analysis methods recommended in this paper are both smaller than those measured at the site but the difference is within the range of 10%, so that in the actual plateau of the High Plains airports can choose the two analysis methods recommended in this paper to conduct related research. [ABSTRACT FROM AUTHOR]

Plate anchors have great advantages that are useful in deep or ultradeep water mooring systems. The keying behaviors have a deep effect on the embedment loss and pullout capacity of strip plate anchors. In this paper, the effect of soil remolding on the keying behaviors of strip plate anchors is studied by large deformation finite-element (LDFE) analysis. First, the LDFE results are compared with centrifugal test results, theoretical solutions, and LDFE data from previous literature, showing good agreement. Then, a series of LDFE cases is studied to investigate the effects of the padeye offset, load eccentricity, soil sensitivity, and initial embedment depth on the embedment loss and pullout capacity of plate anchors during the keying process. The LDFE results show that different load eccentricity corresponds to different soil failure mechanisms, and both padeye offset and soil remolding will reduce the pullout capacity of plate anchors. Finally, an equivalent soil strength is introduced considering rate effect and soil remolding of clay. A combined factor and an equivalent ultimate pullout capacity are used to estimate the ultimate embedment loss and pullout capacity of strip plate anchors in uniform clay, respectively. [ABSTRACT FROM AUTHOR]

Stratum cavity collapse induced by water and sand leakage in a subway tunnel is a sudden urban geological disaster, which can cause serious casualties and economic losses. In response to the hazards of stratum cavity collapse induced by water and sand leakage around subway tunnels, a set of visual test devices with variable hole diameters were designed to simulate the stratum cavity collapse induced by water and sand leakage under comprehensive consideration of the size of the cavity diameter, clay thickness, clay strength, and so on. Based on pressure arch theory and unified strength theory, a critical calculation formula was established for stratum cavity collapse under two modes, of tensile shear and shear failure. Furthermore, the accuracy of the theoretical calculation formula was verified by experiment. The results show that the critical radius increases with the increase of clay strength and decreases with the increase of buried depth and friction angle. Clay soil is more prone to shear failure at the arch foot under the same conditions. The larger the soil sand mix ratio and the cavity diameter, the smaller the critical water pressure of soil collapse. The thicker the soil layer, the greater the critical water pressure. The theoretical analysis method has a clear physical meaning and the theoretical results agree well with the test results. The research results are of great significance for the warning of and prevention of such urban geological disasters. [ABSTRACT FROM AUTHOR]

Plant metabolites significantly affect soil nitrogen (N) cycling, but their influence on nitrous oxide (N2O) emissions has not been quantitatively analyzed on a global scale. We conduct a comprehensive meta‐analysis of 173 observations from 42 articles to evaluate global patterns of and principal factors controlling N2O emissions in the presence of root exudates and extracts. Overall, plant metabolites promoted soil N2O emissions by about 10%. However, the effects of plant metabolites on N2O emissions from soils varied with experimental conditions and properties of both metabolites and soils. Primary metabolites, such as sugars, amino acids, and organic acids, strongly stimulated soil N2O emissions, by an average of 79%, while secondary metabolites, such as phenolics, terpenoids, and flavonoids, often characterized as both biological nitrification inhibitors (BNIs) and biological denitrification inhibitors (BDIs), reduced soil N2O emissions by an average of 41%. The emission mitigation effects of BNIs/BDIs were closely associated with soil texture and pH, increasing with increasing soil clay content and soil pH on acidic and neutral soils, and with decreasing soil pH on alkaline soils. We furthermore present soil incubation experiments that show that three secondary metabolite types act as BNIs to reduce N2O emissions by 32%–45%, while three primary metabolite classes possess a stimulatory effect of 56%–63%, confirming the results of the meta‐analysis. Our results highlight the potential role and application range of specific secondary metabolites in biomitigation of global N2O emissions and provide new biological parameters for N2O emission models that should help improve the accuracy of model predictions. [ABSTRACT FROM AUTHOR]

Climatic wetting‐drying cycles exacerbated by climate change can trigger several weakening mechanisms in surface soils, potentially leading to instability and failure of slopes and earthen structures. This study proposes a bio‐mediated approach based on microbially induced calcite precipitation (MICP) to increase soil resilience to wetting‐drying cycles. To explore its viability and the underlying mechanisms, we conducted a series of laboratory tests on clayey soil that underwent six wetting‐drying cycles. The tests were conducted with different treatment methods to investigate the effect of treatment sequence and cementation solution concentration. After MICP treatment, the initial evaporation rate, surface crack ratio during drying, and total soil weight loss during rainfall erosion were reduced by up to 32%, 85%, and 90%, respectively. Spraying the cementation solution first in the MICP treatment sequence proves more effective in improving soil water retention capacity. On the other hand, initiating the sequence with the bacterial solution demonstrates a more pronounced effect in reducing soil desiccation cracks and erosion. Microstructure analysis reveals that the content and distribution of CaCO3 precipitation are the major factors controlling the effectiveness of MICP for the cementation of clayey soil. Employing MICP can minimize the carbon footprint and contribute to developing environmentally friendly solutions for soil improvement in regions affected by climatic wetting‐drying cycles. Plain Language Summary: The rising frequency and intensity of climatic wetting‐drying cycles driven by climate change pose a threat to surface soil stability, consequently increasing the risk of land degradation, soil erosion, landslide, and other forms of ground instabilities and failures. This study presents a bio‐mediated approach using microbially induced calcite precipitation to enhance soil resilience to wetting‐drying cycles. Experimental results show that MICP is capable of improving soil properties related to water retention, desiccation resistance, and erosion control. The microstructure analysis further elucidates the role of MICP‐induced CaCO3 precipitation in cementing clayey soil and demonstrates that the bio‐created buffer barrier significantly mitigates the adverse effect of climatic wetting‐drying cycles on surface soil. This study is expected to offer an environmentally friendly and sustainable soil improvement solution in regions impacted by cascading climatic extremes. Key Points: A sustainable bio‐mediated approach using microbially induced calcite precipitation (MICP) was applied to enhance soil resilience to climatic wetting‐drying cyclesMICP significantly improves water retention, desiccation and erosion resistance of surface soilThis study provides new insights into the fundamental mechanisms of the interaction between climate and MICP‐treated soil [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Construction of earth fill dams offers a cost-effective solution for various purposes. However, their susceptibility to internal soil erosion, known as piping, poses a significant risk of structural failure and resultant loss of life and property. Soil stabilization emerges as a practical technique to fortify these dams against such threats. This study investigated the impact of lime on the internal erosion properties of clay soils, focusing on CH and ML soil types. Specimens of different lime content were prepared and remolded at 95% relative compaction and optimum moisture content. Hole Erosion tests at varying lime concentrations and curing durations were adapted to conduct the investigation. This investigation aims to optimize lime content and curing time for cohesive soil stabilization against internal erosion. Findings revealed that 2% and 5% of quicklime, by dry weight of the soil, effectively stabilized CH and ML soils, respectively, against internal erosion, with a two-day curing period proving optimal. Furthermore, the addition of lime significantly enhanced erosion rate index and critical shear strength in clay soil, underscoring its efficacy in soil stabilization efforts. [ABSTRACT FROM AUTHOR]

Bidirectional static loading tests were conducted on two strain-gage instrumented barrettes installed to 72 m depth in Ho Chi Minh City, Vietnam. The barrettes were to support a 16-storey building with 5 basements. The soil profile comprised layers of medium coarse to fine sand, medium clay, firm to stiff clayey soil, and dense sandy silt. The region is experiencing an ongoing land subsidence affecting the upper about 40 m of soil and, on average in the city, the ground surface is currently settling 16 mm/year. The test records were processed by means of effective stress analysis to provide the axial pile force distribution, load transfer functions, and equivalent head-down load–movement curve. The analysis was then used to obtain the equivalent pile-head load–movement response adjusted to the planned 22 m deep basement excavation. Load transfer functions were back-calculated from the test records and indicate that the construction will show somewhat large load-transfer movement. However, because the equilibrium plane will be below the subsiding layers, below 40 m depth, downdrag is not expected to affect the building. The load response of the barrettes is compared to the results of a bidirectional (BD) loading test on a 1.8 m diameter bored pile at an adjacent project. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Indoor triaxial tests on geogrid-reinforced clay elucidate the macroscopic changes in soil strength indices post-reinforcement, yet the underlying mechanisms of strength enhancement require further investigation. By conducting indoor triaxial tests and establishing a corresponding discrete element numerical model, we can delve into the fine-scale mechanisms of geogrid-reinforced soil. This includes analyzing changes in fine-scale parameters such as porosity, the coordination number, and contact stress between soil particles. The findings suggest that an increase in the number of geogrid reinforcement layers leads to a more pronounced improvement in peak strength and cohesion, albeit with minimal impact on the internal friction angle of the specimens. Furthermore, analysis of the triaxial test curves of reinforced soils indicates that the stress–strain relationship adheres to the Duncan–Chang model. Parameters derived from this model have been validated against experimental data, confirming their accuracy. The discrete element model was used to analyze the variations in fine-scale parameters such as porosity and coordination number. It revealed that reinforcement reduces the fluctuation amplitude of porosity and significantly increases the number of particle contacts, resulting in a denser soil structure. Further analysis of the change in contact stress between particles in the discrete element model revealed that the contact force between particles increased significantly after reinforcement and that the reinforcement played a role in restraining the soil particles and dispersing the reinforcement stress, which explains the increase in the strength of the mesh-reinforced clays from another perspective. This further elucidates the strength enhancement mechanism in geogrid-reinforced clay, offering a new perspective on the mechanical behavior and strength development of such materials. [ABSTRACT FROM AUTHOR]

Based on the actual situation of the project on the Weihai–Yanhai Expressway section of Rongwu Expressway, the effects of water content change and the dry–wet cycle on the mechanical behavior of unsaturated clayey sandy soil were analyzed in this study. In this study, ventilated undrained triaxial shear tests were carried out on unsaturated clayey sandy soils with different water contents (6%, 8%, 10%, 12%, 14% and 16%). Concurrently, the soil samples were subjected to three distinct wet and dry cycle pathways (2~22%, 2~12%, and 12~22%) to gain an understanding of how the mechanical features of the soil changed under the different conditions. The test findings demonstrate that when the water content increases, the unsaturated clayey sandy soil's cohesiveness and shear strength diminish. The strength of shear decline exhibits a pattern of first being quick, followed by sluggish. The strength of shear and cohesiveness of clayey sandy soil declined under the influence of the dry and wet cycles, with the first cycle primarily affecting variations in cohesiveness and strength of shear. Furthermore, the strength of shear and cohesiveness of clayey sandy soil diminish more with increasing wet and dry cycle amplitude and upper water content limits. Lastly, the drying shrinkage and hygroscopic expansion of clay particles in clayey sandy soils during wet and dry cycles are not significant, resulting in less structural damage and deterioration of the mechanical properties of the soils. The study's findings have a significant impact on the durability of roadbeds made of unsaturated clayey sandy soil in both wet and dry situations. [ABSTRACT FROM AUTHOR]

The single floating stone column behavior in very soft soils with a low undrained shear strength of Cu ≤ 20 kN/m² was studied in the finite-element method to investigate the influence of stone column's area ratio on the normalized pressure-settlement curves of circular footings of different diameters. The studied cases consist of stone columns of 1.0 m in diameter Ds and lengths Ls of (4 m, 6 m, and 7.5 m). The diameter of footings Df is (1.0 m, 1.2 m, 1.4 m, 1.6 m, 2.0 m, 2.5 m, and 3.5 m) which covers the area ratios with a range of 100 to 8.16 %. A total of 28 runs were carried out using the Ansys program to simulate the case for improved and unimproved soil. In the axisymmetric numerical model, the connection between the stone column and the adjacent contact clay soil was modeled as bonded type. The results of the analysis showed that there is a clear relationship between the bearing ratio (q/cu improved) / (q/cu unimproved) and the normalized settlement (S/Df) of the composite structure and the area ratio Ar% of the stone columns. The deformation ratio (Streated/Suntreated) and the footing diameter are related using a straightforward equation. In comparison to footings with a low area ratio, the footing displays a lower value of settling when subjected to the same pressure. By decreasing the diameter of the footing, the normalized settlement decreases for the same normalized q/cu values. The bearing ratio depends on the stone column length ratio Ls/Ds and settlement ratio. It is from 2.2 at a 100% area ratio and 1.23 at a 16% area ratio. [ABSTRACT FROM AUTHOR]

Soft clay soil is known for low bearing capacity and is prone to soil collapse under shallow foundations through Local Shear Failure. An approach to enhance the load-bearing capacity of such soil is by adopting micro-piles as reinforcement. This study aims to determine the effectiveness of micro piles in strengthening shallow foundations on soft clay soil through laboratory-scale testing. The soft soil used comes from kaolin clay characterized by a cohesion (cu) of 20.692 kN/m² and water content (wc) of 58.631%. These properties guided the crafting of test specimens, formed with a diameter (ds) of 0.33m and a height (Hs) of 0.185m. Micropiles were constructed from bamboo with varying numbers (n = 4, 9, 16, 25), lengths (L1= 1.33B, L2= 1.73B, L3= 2.13B), and diameters (d1= 0.03B, d2 = 0.04B, d3= 0.07B). The shallow foundation model with a square shape of BxB (where B=0.075 m), incorporated diverse configurations for the installation of micro-piles (K1, K2, K3). The results showed that more micro-piles (n) led to a higher bearing capacity ratio at a 0.1B reduction (Rqult-mp). The most significant enhancements occurred with the longest micro-piles (L3 = 2.13B), the highest number (n4 = 25), and a diameter of 0.04 B. Additionally, configurations including micro-piles installed beneath and extending up to the foundation's edge (K1 and K2) exhibited significant enhancement in Rq0.1B for identical micro-piles numbers (n). The installation of micro-piles beyond the foundation perimeter did not yield substantial increases in Rq0.1B and, therefore, is not recommended. [ABSTRACT FROM AUTHOR]

Mollisols region of China is a ballast stone of Chinese food security. In this study, 484 soil organic carbon (SOC) data points from the documented soil surface (0–20 cm) samples in the typical Chinese Mollisols region were selected. The regional soil fertility was divided into high, medium, and low levels based on the SOC content from the long‐term positioning fertilization stations in Shenyang, Harbin, and Hailun of Northeast China. Furthermore, the regional SOC balance point (SOCb) model was built driven by the factors of annual mean temperature, annual precipitation, annual effective accumulative temperature, the ratio of precipitation and temperature, soil clay content, and pH. Using geographic information systems (GIS) interpolation method, the regional mean SOCb and SOC sequestration potential (SOCsp) at the SOCb's status were simulated to be 40.10 g kg−1 and 10.71 kg m−2, respectively. Moreover, the SOC content increased (SOCc) and the SOC sequestration capacity increased of medium‐ or low‐fertility soil were evaluated by GIS subtraction. Consequently, the means of SOCc in medium‐ and low‐fertility soils could be 16.88 g kg−1 and 26.79 g kg−1, respectively. Furthermore, the means of SOCsp in medium‐ and low‐fertility soils could be 4.30 kg m−2 and 7.43 kg m−2, respectively. The sensitivity analysis of this model showed that the high SOCb area was distributed in study region with low temperature, dry, high clay content, and low pH. The results provide an actual perspective on estimating regional SOCsp and soil fertility promotion target induced by the different soil fertility levels. Core Ideas: A soil organic carbon (SOC) balance point concept was innovatively put forward.The SOC sequestration potential of typical Chinese Mollisols region was estimated based on the SOC balance point.Both regional SOC content increased and sequestration capacity increased were estimated. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) is responsive to boron (B) fertilization when there is low soil availability, but the best source and rate to be used and whether this response is dependent on soil texture are still unknown. This study aimed to adjust boron fertilization for cotton as a function of the production environment and B source used. Two field experiments were conducted in the 2020/2021 season in Chapadão do Sul, MS (clayey soil—adequate B content) and Dracena, SP (sandy soil—low B content), Brazil. Treatments consisted of B sources (ulexite [low solubility], borax pentahydrate [BP] [intermediate solubility], and boric acid [BA] [high solubility]), and B rates (0, 1, 2, 4, and 6 kg ha−1) applied to the soil at 25 days after plant emergence. In sandy soil with low B content, application of 2 (high and medium solubility sources) and 4 kg B ha−1 (low solubility source) improved fiber yield between 10% (210 kg ha−1 fiber) and 28% (555 kg ha−1), respectively, as well as micronaire index, strength, elongation, uniformity, and short fibers. Application of B greater than 4 kg ha−1 via soluble sources reduced (between 9% (175 kg ha−1)—BP and 14% (257 kg ha−1)—BA) fiber yield only in sandy soil. When B content in the soil is adequate, B fertilization did not improve yield, but increased fiber strength (4%—1.1 g tex−1) and reduced the short fiber index (16%) by applying 1 kg B ha−1, regardless of the source used. The highest fiber yields were obtained with leaf B contents between 12 and 17 mg kg−1 (sandy soil) and 25 and 27 mg kg−1 (clayey soil). We recommend applying 2 kg B ha−1 (solubility sources) and 4 kg B ha−1 (low solubility source) in sandy soils with low B content to improve yield and fiber quality, and 1 kg B ha−1 in clayey soil with adequate B content to improve fiber quality and replace B amounts removed through harvesting. Core Ideas: Boron fertilization in sandy soils increased fiber yield by 210–555 kg ha−1.There are no effects of B fertilization in clayey soils on fiber yield, but there are improvements in fiber quality.Rates greater than 4 kg ha−1 of B via soluble sources reduce fiber yield in sandy soils.Cotton grown in clayey soil is more resistant to B toxicity. [ABSTRACT FROM AUTHOR]

The application of sanitary sewage using subsurface drip irrigation can mitigate current challenges related to water availability and food production. However, before implementing these techniques, it is crucial to conduct studies to assess their impacts on soil and plants. The objective of this study was to evaluate chemical changes in the soil and the development of cowpeas subjected to sanitary sewage applied by drippers with different flow rates and installation depths. Drippers were positioned at various depths (0 to 30 cm) and operated with flow rates of 1.6 and 3.8 L h−1. Cowpeas were cultivated in pots with clayey soil, using synthetic sanitary sewage based on the maximum limit of nitrogen fertilization. Irrigation management was controlled in terms of soil moisture, which was monitored using TDR probes. The results indicated that reducing the depth of the drippers positively affected grain production and the development of cowpeas. Fertigation with sanitary sewage at greater depths increased soil phosphorus concentrations and base saturation. Dripper depth also influenced soil concentrations of phosphorus, potassium, calcium, and magnesium, while sodium concentrations decreased with greater depth. It is concluded that dripper flow rates did not impact soil chemical parameters or the agronomic characteristics of cowpeas. However, despite nutrient supply at greater depths, the subsurface drip irrigation system proved unsuitable for cowpea production in clayey soil. [ABSTRACT FROM AUTHOR]

Purpose. To study the effect of hardened cement waste and compare it to the effect of fresh cement in the treatment of expansive soil. Methodology. To show the performance of hardened cement waste compared to that of fresh cement, an experimental study is conducted concerning a swelling clay soil in the Mila region of eastern Algeria. The study involves a series of soil treatment tests with fresh cement and hardened cement waste (with reasonable proportion) for each type of cement. Finally, a comparison of the influence of the addition of hardened cement waste and the addition of fresh cement on the physical and mechanical behavior of the soil. Findings. Treatment with fresh cement provides a good improvement in certain properties, and in this work we show that the use of hardened cement waste could also improve the physical and mechanical characteristics of the treated soil. Originality. The originality of this work is to replace fresh cement with the waste of hardened cement in the treatment of clay soils in general and swelling soils in exceptional cases to minimize the cost of treatment with fresh cement and protect the environment from waste of the cement. Practical value. This study shows that the results obtained by adding 6 % of fresh cement and 6 % of hardened cement waste changed the physical and mechanical properties of the soil (plasticity, bearing capacity, swelling and settlement). Comparison of the results obtained shows that the performance of hardened cement waste represents 90 to 98 % of the performance of fresh cement. The convergence of the treatment results indicates the possibility of replacing fresh cement with hardened waste cement in soil stabilization. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of the soil type on the torsional response of buildings experiencing torsional pounding due to earthquake excitations. Six buildings (one 4-storey building and five 6-storey buildings) with different configurations have been considered. First, pounding between different structures has been analysed for a specified soil type and the effect of the torsional pounding and the contact asymmetry on the torsional response of colliding buildings has been investigated. Then, these pounding cases have been considered for different soil types to study the effect of the soil type on the torsional response of buildings experiencing torsional pounding. Five soil types have been considered, i.e. hard rock, rock, very dense soil and soft rock, stiff soil and soft clay soil. The results of the study indicate that the earthquake-induced torsional pounding causes an increase in the peak storey rotation of the colliding buildings as compared to the symmetric pounding in all cases. Higher peak storey rotations have been experienced for colliding buildings founded on the soft clay soil, then for buildings founded on the stiff soil, then for buildings founded on very dense soil and soft rock, and finally for buildings founded on the rock and hard rock. [ABSTRACT FROM AUTHOR]

The study investigated the adsorption of dissolved organic carbon (DOC) on Chinese soils from four long-term experiments involving five treatments: (1) no fertilization (control), (2–4) inorganic nitrogen (N), phosphorus (P), and potassium (K) fertilization (N, NP, and NPK), (5) NPK plus manure (NPKM). The results showed that DOC adsorption followed a modified Langmuir isotherm model effectively (R2 = 0.912 ~ 0.991). The maximum adsorption capacity (Qmax) (i.e. saturation deficits) generally increased with increasing soil organic carbon (SOC) due to fertilization in Luvic Phaeozem, Haplic Gypsisols, and Eutric Cambisols. However, it decreased significantly in acidic soils (Haplic Acrisols) from 15.59 g/kg for control, to 13.96, 13.03, 9.30 and 8.02 g/kg for N, NP, NPK and NPKM, respectively. Moreover, long-term fertilization, particularly with organic fertilization (e.g. NPKM), resulted in an increase of carbon (C) saturation by 1.42 g/kg (5.52%) in Luvic Phaeozem, 9.27 g/kg (44.29%) in Haplic Gypsisols, and 3.75 g/kg (27.66%) in Eutric Cambisols; however, there was a slight decrease by 1.70 g/kg (−7.49%) in Haplic Acrisols. Canonical correlation analysis (CCA) revealed that clay content and soil available iron (AFe) might be the crucial factors controlling C deficits, and subsequently, C saturation, along with current SOC. In conclusion, long-term fertilization contributed to C saturation in neutral-to-alkaline soils, but not in acidic soils. Thus, further attention should be paid to the long-term effects of fertilization on C saturation. [ABSTRACT FROM AUTHOR]

In this study, fast-growing poplar reclaimed from abandoned homestead in Xixian New District, Xi'an City, Shaanxi Province, was used as the research object to explore the multi-fractal characteristics of soil particle size distribution under different management modes of abandoned land (control), irrigation, fertilizer irrigation and mixed fertilizer irrigation. The results showed that the mean values of soil clay, silt and sand in abandoned land were 14.58%, 81.21% and 4.22% respectively, 14.08%, 79.92% and 5.99% under irrigation, 15.17%, 81.19% and 3.64% under fertilizer irrigation, and 16.75%, 80.20% and 3.05% in mixed fertilizer treatment. From 40 cm, with increasing soil depth, soil clay particles increase under irrigation, fertilizer irrigation, and mixed fertilizer irrigation modes. The single fractal dimension of soil particle size distribution (D) in each treatment ranges from 2.721 to 2.808. At 60–100 cm, D shows fertilizer irrigation > mixed fertilizer irrigation > irrigation > abandoned land, indicating that fertilization and irrigation can increase the fine-grained matter of deep soil particles and reduce soil roughness. Compared with abandoned land, under irrigation, fertilizer irrigation and mixed fertilizer modes the capacity dimension (D0), entropy dimension (D1), correlation dimension(D2), shape characteristics of the multifractal spectrum (Δf) and overall inhomogeneity of the soil particle size distribution (D0–D10) indicate an uneven distribution of soil particle size; fractal structure characteristics of soil (D−10–D0) indicate a simplified soil structure, and degree of dispersion of soil particle size distribution (D1/D0) indicates that soil particle size is distributed in dense areas. Pearson correlation analysis showed that D was significantly correlated with clay, sand, D0–D10, soil organic matter (SOM) and soil available phosphorus (SAP) (P < 0.05). Stepwise regression analysis showed that clay was the main controlling factor of D and D0–D10 changes. The research results can provide some potential indicators for the quality evaluation of abandoned homestead reclamation. [ABSTRACT FROM AUTHOR]

The paper presents the results of systematic investigations on the gamma dose rates in air, natural radioactivity in soil and the dependence of radioactivity on the mineralogy of soils in the environs of the Belagavi, Karnataka, India. The gamma dose rates were measured using a portable survey metre and the activity in soils were measured using NaI(Tl) based gamma ray spectrometer and the mineral composition was studied using FTIR spectroscopy. The activity of 40K varies from 72.52 to 324.76 Bq kg−1 with an average of 153.17 Bq kg−1. The 226Ra activity varies from 16.53 to 70.53 Bq kg−1 with an average value of 23.88 Bq kg−1 and the activity of 232Th varies from 10.95 to 59.07 Bq kg−1 with an average value of 25.75 Bq kg−1. Elevated levels of 226Ra, 232Th and 40K in soils were observed in some part of Belagavi, which was traced to the mineralogy of the region. The higher activity of natural radionuclides poses radiological implications to the population of the region. The activity utilisation index was found to be is above the normal levels in some locations. The pattern of distribution of radionuclides in the region was studied using SPSS statistical software. The soil with clay minerals Haematite, Calcite, Kalonite, Albite and Feldspar showed higher radionuclide content. [ABSTRACT FROM AUTHOR]

Soil pressure in clay formation tunnels is closely related to soil arch effect and the development of slip surfaces. Firstly, numerical simulation software is used to simulate the actual situation of tunnel excavation, and the change rule of the slip-cracking surface of cohesive soil is analyzed. Secondly, based on the numerical simulation results and the ellipsoid theory, the pressure formula of Terzaghi loose Earth is modified considering that the principal stress trace is catenary. Finally, the calculation results are compared with the finite element calculation results to verify the rationality of the formula in this paper. The relationship between the internal friction angle, cohesion force c, eccentricity ε, looseness coefficient β, and the pressure of loose Earth is further studied. The results show that there is a gap between the sliding crack angles with or without dilatancy angle and it will affect the development form of soil arch. The slip angle decreases gradually with the increase of the buried depth ratio H/D and becomes stable when the buried depth ratio H/D≥3. Compared with deep-buried tunnels, the increase of internal friction angle in the shallow-buried tunnel is more conducive to reducing the overlying soil pressure. The loose soil pressure decreases with the increase of eccentricity ε and loose coefficient β, and the influence of eccentricity ε on loose soil pressure is significantly greater than that of loose coefficient β. Therefore, the change of eccentricity ε should be paid close attention in the project. [ABSTRACT FROM AUTHOR]

Bottom-initiated radial cracking is a special phenomenon for soil as it is subjected to desiccation. This study aims to simulate the initiation and propagation of radial cracks in soil using both experimental and discrete-element method (DEM) approaches. Under controlled conditions of constant temperature and humidity, a laboratory desiccation test of clayey soil samples with bottom-constrained boundary conditions was carried out to illustrate the soil bottom-initiated radial desiccation cracking behavior. The evaporation characteristics as well as the development of radial cracking initiating from the subsoil were captured. To simulate this phenomenon, a desiccation model based on discrete-element method was used in DEM. Based on the laboratory testing results, appropriate parameters are selected for the numerical simulations. The DEM approach was calibrated by reproducing the experimental results of radial desiccation cracking. Subsequently, the initiation and propagation mechanisms of this typical soil cracking phenomenon was analyzed and discussed. With the constraint of the bottom boundary, the initiation of radial desiccation cracking was associated with the arched distribution of inter-particle tensile force in the soil samples. The propagation direction of the cracks was perpendicular to the inter-particle tensile forces. Finally, the effects of basal friction, evaporation gradient and shrinkage parameter on the bottom-initiated radial cracks in the simulation were analyzed. The size of the bottom particles and interface bonding factor played a significant role in the effect of basal friction. Compared with the samples under uniform water loss conditions, the bottom shrinkage rate was relatively low for the sample under a gradient water loss. In addition, an increase in the shrinkage parameter of the soil particles led to a greater extent of crack propagation. [ABSTRACT FROM AUTHOR]

Skirt–pile foundations have gained widespread attention in the field of offshore engineering due to their ease of installation and high bearing capacity. In this study, the ultimate bearing capacity, pile bending moment distribution and development, cumulative deformation characteristics, and cyclic stiffness development of skirt–pile foundations were investigated using physical model tests. The experimental results indicate that the ultimate bearing capacity and deformation resistance of the foundation can effectively be improved by increasing the skirt diameter. The cumulative deformation of the skirt–piles exhibited rapid development during the initial stages of cyclic loading, eventually stabilizing. Under long-term cyclic loading, the existence of the skirt can share the bending moment, which then affects the internal force distribution of the pile foundation along the axis. The pile foundation's cyclic stiffness reduces as the loading cycles increase and increases as the skirt diameter and length grow. Meanwhile, the horizontal cyclic stiffness decreases as the number of cycles increases, stabilizing after 3000 cycles. This study can not only deepen the understanding of the deformation laws of skirt–pile foundations in clay soil but also offers some references for the design of offshore pile foundations. [ABSTRACT FROM AUTHOR]

The present study has focused on stabilizing the soils of the embankments and improving the mechanical properties of gravel in subbases of pavements with different contents of bottom ash from thermal power plants and low percentages of lime. The density, humidity, simple resistance strength and bearing capacity of the new materials resulting from this combination have been studied. The results indicated that the optimal proportion of bottom ash added to the analyzed soil is 15%, while the optimal addition of lime is 1% for application in embankments and 2% for application in road subgrades. In clay soil that has a low simple resistance strength when 25% of bottom ash is added without lime, it can double the resistance. In the case of the gravel evaluated, it was found that the optimal ratio between the addition of bottom ash and lime is 6.5. In conclusion, it can be noted that soil that does not have any resistance when certain percentages of bottom ash are added, its properties are improved to be used in embankments. [ABSTRACT FROM AUTHOR]

Understanding the efficacy of alternative phosphorus (P) sources in tropical soils is crucial for sustainable farming, addressing resource constraints, mitigating environmental impact, improving crop productivity, and optimizing soil-specific solutions. While the topic holds great importance, current literature falls short in providing thorough, region-specific studies on the effectiveness of alternative P sources in Brazilian tropical soils for maize cultivation. Our aim was to assess the agronomic efficiency of alternative P sources concerning maize crop (Zea mays L.) attributes, including height, shoot dry weight, stem diameter, and nutrient accumulation, across five Brazilian tropical soils. In greenhouse conditions, we carried out a randomized complete block design, investigating two factors (soil type and P sources), evaluating five tropical soils with varying clay contents and three alternative sources of P, as well as a commercial source and a control group. We evaluated maize crop attributes such as height, dry weight biomass, and nutrient accumulation, P availability and agronomic efficiency. Our results showed that, although triple superphosphate (TSP) exhibited greater values than alternative P sources (precipitated phosphorus 1, precipitated phosphorus 2 and reactive phosphate) for maize crop attributes (e.g., height, stem diameter, shoot dry weight and phosphorus, nitrogen, sulfur, calcium and magnesium accumulation). For instance, PP1 source increased nutrient accumulation for phosphorus (P), nitrogen (N), and sulfur (S) by 37.05% and 75.98% (P), 34.39% and 72.07% (N), and 41.94% and 72.69% (S) in comparison to PP2 and RP, respectively. Additionally, PP1 substantially increased P availability in soils with high clay contents 15 days after planting (DAP), showing increases of 61.90%, 99.04%, and 38.09% greater than PP2, RP, and TSP. For Ca and Mg accumulation, the highest values were found in the COxisol2 soil when PP2 was applied, Ca = 44.31% and 69.48%; and Mg = 46.23 and 75.79%, greater than PP1 and RP, respectively. Finally, the highest values for relative agronomic efficiency were observed in COxisol2 when PP1 was applied. The precipitated phosphate sources (PP1 and PP2) exhibited a similar behavior to that of the commercial source (TSP), suggesting their potential use to reduce reliance on TSP fertilization, especially in soils with low clay contents. This study emphasized strategies for soil P management, aimed at assisting farmers in enhancing maize crop productivity while simultaneously addressing the effectiveness of alternative P sources of reduced costs. [ABSTRACT FROM AUTHOR]

Flooding constitutes a major problem for the inhabitants of Douala City in general and those of the Tongo Bassa watershed (TBW) in particular. Faced with this situation, public authorities need to put in place measures to mitigate the vulnerability of populations to these disasters. This article aims to map flooding risk areas in the TBW using the geographic information system, field data (historical flood points), remote sensing data (Sentinel II image) and the frequency ratio model. The map produced shows that 1.41, 8.88, 28.51, 33.86 and 27.33% of the basin area are respectively delimited into very low, low, medium, high and very high flood vulnerability classes. High and very high flooding risk areas (those where flooding is most likely to occur) occupy more than half of the basin (61.19%). These areas are characterized by significant imperviousness, low altitudes, weak slopes, significant proximity to watercourses and clayey soils. Most of the houses in the basin (66.92%) are located in areas affected by these two levels of exposure (high and very high). With respective success and prediction accuracy rates of 89 and 96.78%, a certain confidence deserves to be placed on the map of flooding risk areas produced. [ABSTRACT FROM AUTHOR]

The recent maize experiment commenced in the 2022 fall crop season at the District Al-Hussainiya, Kerbala, Iraq. The experiment comprised two factors, with the first factor a combination of different levels of nitrogen (0, 150, and 300 kg N ha-1) with corresponding labels, N0, N1, and N2, respectively, and three levels of potassium (0, 80, and 160 kg K ha-1) symbolized as K0, K1, and K2, respectively. The second factor was a foliar application of organic nutrients (potassium humate) with two concentrations (1 and 2 g L-1). The organic nutrient application occupied the main plots, while the inorganic fertilizer combinations were in the subplots. The experiment used the maize cultivar 'Sumer,' planted in clay mixed soil in a randomized complete block design (RCBD) with a split-plot arrangement and three replications. The results showed a significant effect of adding fertilizer combinations of nitrogen and potassium and foliar application of the organic nutrient potassium humate (2 g L-1) individually and in combinations in most growth, yield, and quality-related traits. The combination of inorganic and organic fertilizers also revealed a significant superiority in enhancing the plant height, number of leaves, ear length, grain rows per ear, grains per row, grain yield, and the percent oil and protein in the maize grains. The interaction between the two study factors contributed to reducing the used amount of mineral fertilizer to 50%, as there was no significant difference between the fertilizer combinations of nitrogen and potassium 150 N + 80 K and 300 N + 160 K kg ha-1 in addition with organic nutrient application at the rate of 2 g L-1. [ABSTRACT FROM AUTHOR]

Sesame (Sesamum indicum L.) is an oilseed crop flourishing in marginal lands. It has a high nutritional value because it is rich in protein and fat and has many health benefits. However, the varieties of this crop available in Egypt are very few. Seventeen new sesame lines incurred evaluation in two crop seasons, 2021-2022, for seed yield under eight environments comprising normal and drought conditions in sandy and clay soils. Applying 16 parameters and non-parameters of stability helped select stable and adaptive sesame lines under ideal and drought conditions, with the genotypes arranged in a randomized complete block design with three replicates. Line C5.8 achieved the highest relative productivity in sandy and clay soils and exhibited a good source for breeding programs under drought conditions. Four lines, C1.3, C9.15, C9.6, and C9.20, under eight different environments had higher seed yield than the control. A genetic-environment interaction (GEI) effect on seed productivity occurred in all sources of the combined analysis. The association between seed yield and stability parameters showed the possibility of using a selection index that included some of them to identify sesame genotypes with higher yield and genetic stability. [ABSTRACT FROM AUTHOR]

Mineralogical and geotechnical properties used to analyse the swelling potentials of Al-Hartha City. According to mineralogy, montmorillonite is a dominated clay mineral (33.61%) followed by montmorillonite-chlorite (33.34%), kaolinite (9.18%) and illite (5.38%). While calcite, Quartz, Feldspar, and dolomite are non-clay minerals that are also present. According to geotechnical analysis, the percent of clay range between 9-42% with an average of 25.5%, silt 55-80% with an average of 67.5% and sand 0-17% with an average of 8.5%. While liquid limits and plasticity index are, respectively, 10–25% with an average of 17.5% and 35%–51% with an average of 43%. According to the unified soil classification system (USCS), these soils are mainly low plasticity lean clay soils (CL) and 10% classified as medium stiff elastic silt (MH). According to activity values, soils are primarily inactive-(70%), normally active-(20%), active-(10%), and their consistency is plastic. according to an assessment of soil expansivity based on index properties and activity, a significant amount of the soil is expansive. Additionally, there is an agreement between the results of the mineralogical tests performed on these soils and the results of the measures of soil expansivity obtained from the evaluation of the swelling of the soil based on assessments of its index properties. [ABSTRACT FROM AUTHOR]

In recent times, large-scale infrastructural projects are being constructed on varieties of soil, especially in highly compressible marine clays and soft soil. The coefficient of consolidation (cv) is one of the most important technical parameters used to estimate the consolidation characteristics of the soil. The experimental laboratory techniques used to obtain cv are time-consuming and possess different practical limitations. In this study, a reliable method for predicting cv is presented based on machine learning (ML). The study considered 11 inherent soil variables, among which the least significant variables are discarded using univariate feature selection technique. Different ML models were developed like the random forest, artificial neural network, and support vector machine for nonlinear mapping of the cv using dimensionally reduced independent variables. Verification against experimental data demonstrates that the Random Forest model accurately predicts the cv (with MAE = 0.0231, MSE= 0.00148, and RMSE = 0.03854). Further, a comparative study of the proposed model is presented with available empirical equations and numerically simulated data. Moreover, the strengths and shortcomings of different ML algorithms are also discussed in detail. [ABSTRACT FROM AUTHOR]

Identifying strength parameters under drained conditions is crucial for monitoring and evaluating long-term soil deformations caused by structures built on or in soils. Geotechnical engineers carry out direct shear tests (DSTs) and triaxial tests (TAs) in the laboratory to identify strength parameters under such conditions. However, it can take considerable time to ascertain the failure envelope of even a single soil in the TA tests commonly used to evaluate drained conditions. This study explores whether the effective internal friction angle (ϕ′)—as one of the drained shear strength parameters of remolded soils—can be identified with a vane shear test (VST) at very low (down to 0.001/min) rotation speeds, which is easy to implement and takes a relatively shorter time. For this aim, 18 different remolded soil samples with a wide range of plasticity were prepared using static compaction in the laboratory. DST tests were conducted under drained conditions to evaluate the drained shear strengths of the remolded soil samples. VST results indicate that the peak shear strength decreases with the rotation speed as expected. Shear strengths obtained from the slowest VSTs were correlated with ϕ′s from DSTs. While the results were not encouraging, it was observed that the results of VSTs still could be used in a predictive equation for ϕ′ which, as a function of LL and total density as well as VST strength parameter, the regression coefficient rose to 0.92. Some effective cohesion intercepts were observed during DSTs, which in turn somewhat reduce the predicted ϕ′s. [ABSTRACT FROM AUTHOR]

Low-volume roads are anticipated to have less traffic and provide access to socio-economic activities in rural areas. The present study deals with the stabilisation of soil with locally available waste materials, i.e. low calcium fly ash (FA) and brick dust (BD). These two wastes are available abundantly and lead to an increase in pollution levels. Initially, lime was added to make the silty clayey soils plastic-free. The initial consumption of lime was found to be 5%. Then, the soil was stabilised with cement fly ash and cement brick dust techniques for strength, durability and shrinkage evaluation. The cement was varied from 2 to 8% with FA and BD by fixing the ratio to 1:3 as per AASHTO guidelines. The unconfined compressive strength (UCS), indirect tensile strength test and California bearing ratio were conducted for strength evaluation. The wetting and drying cycles were evaluated for durability analysis. The linear shrinkage cracking was evaluated after the curing period of 28 days. It was observed that there was a magnificent increase in strength and durability values. The maximum UCS attained value was so high that it could act as a replacement for the granular sub-base layer in the pavement structure. The linear shrinkage evaluated at fixed relative humidity was significantly reduced. The statistical analysis reported that there was a significant difference between the two admixtures. The utilisation of these wastes not only enhances strength, but also deficits the cost of construction along with reducing the pollutants in the environment. [ABSTRACT FROM AUTHOR]

Electrokinetics has gained importance as a sustainable soil modification and remediation method for improving problematic sites. The formation of cracks during the electrokinetic treatment is an important concern during the field implementation of the process. Therefore, considering this, this study investigated the impact of a voltage gradient on the performance evaluation of electrokinetic consolidation clayey soil after adding a lime. The performance was evaluated regarding cumulative discharge, surface settlement, power consumption, reducing water content, alteration in soil pH, and crack formation. The surface settlement increases by 50% for the applied voltage gradient of 1.00 V/cm compared to that of 0.25 V/cm. The power consumption in the case of 1.00 V/cm after the addition of lime is 3.67 times compared to that without lime; however, the difference is insignificant for 0.50 V/cm. Further, the pH near the cathode increases to 10.94 from 7.81 after the addition of lime in the case of 0.50 V/cm. Finally, adding lime helps drastically reduce the surface crack formed during the electrokinetic treatment. [ABSTRACT FROM AUTHOR]

The piezocone penetration test (CPTu) is a common geotechnical field test to evaluate soil properties. In interpreting the CPTu field measurements, soil drainage conditions are mostly considered completely drained or undrained; however, partial drainage conditions govern for such soils as silts or clayey sand mixtures. Previous studies show that neglecting partial drainage conditions causes incorrect estimation of soil geotechnical parameters. Most studies have been conducted using calibration chambers and centrifuge tests on clayey soils. Due to the complications in modeling the piezocone test, few numerical studies have been performed under partially drained conditions, especially on coarse-grained soils. Among the challenges of numerical modeling of CPTu, one can mention the difficulty of modeling soil structure in large strain mode and soil–water interaction behavior. In this paper, piezocone penetration tests were modeled using the advanced hypoplastic constitutive model and finite-element method. The behavior of Firoozkooh sandy soil under different drainage conditions and relative densities was analyzed. Then, the effect of cone penetration on the surrounding soils was discussed. It was shown that drainage conditions and the soil relative densities significantly affected the trend of variations in excess pore-water pressure (EPWP) generated around the piezocone. [ABSTRACT FROM AUTHOR]

Green roofs' (GR) positive impact on indoor thermal conditions in hot areas may have possible negative impacts during hot and cold weather. Most previous studies have focused on GR's positive effects as a standalone strategy without mitigating these side effects of GR application. This study contributes to a more comprehensive understanding of the impact of GR and how to mitigate the negative aspects by integrating it with other passive techniques (natural ventilation and thermal insulation). Therefore, this study experimentally compares the seasonal impact of various soil layer configurations, integrated with natural ventilation, on improving Indoor Thermal Comfort (ITC) throughout the day in summer and winter. Field experiments were conducted using two identical validated test boxes. The results revealed that clay soil reduced Indoor Air Temperature (IAT) during the daytime in summer by up to 4.7 and 4°C for low and high soil thickness, respectively. Increasing clay soil thickness improved average IAT during the daytime in summer and winter by up to 6.49% and 2.61%, respectively. Additionally, adding thermal insulation is preferred in winter, while uninsulated soil had a slight positive effect on IAT and Indoor Relative Humidity (IRH) in summer. The use of natural ventilation at night and closed-ventilated systems during the daytime in summer and winter is recommended. Clay soil could save cooling and heating energy by up to 34.8% and 12.18%, respectively. These findings might inform designers by adjusting different GR soil parameters and the importance of natural ventilation in improving multi-seasonal thermal and energy performance. [ABSTRACT FROM AUTHOR]

This study aims to assess the impact of the sand-clay ratio on the detection of simulated forensic targets resembling human burial evidence using ground-penetrating radar (GPR). To achieve this goal, we established a controlled site consisting of four experimental graves (SEPs), with each SEP representing a distinct burial scenario. The project's objectives encompass evaluating how varying the clay soil content influences the detection of swine targets using 2D, quasi-3D, and 4D GPR imaging techniques. We observed signal attenuation in the GPR data during the rainy season and after reflection from larger targets, primarily due to the conductive behavior of the soft tissues within the targets. We achieved more precise results in an SEP that was 85% sand and 15% clay material, regardless of seasonality. We obtained better results in the dry season due to the greater penetrability of electromagnetic waves and more explicit reflections. In comparison, we achieved more precise results for SEP03, which was 70% sand and 30% clay material. In conclusion, controlled sites are invaluable tools for geophysical investigations, as they provide a controlled environment where we can meticulously adjust various parameters, leading to a more precise and insightful analysis of the results. By systematically manipulating factors such as the soil composition, target depth, and environmental conditions, researchers can effectively calibrate their instruments and methodologies, enhancing the accuracy and reliability of their findings. Therefore, controlled sites not only facilitate comprehensive data collection but also serve as essential platforms for refining and validating geophysical techniques, ultimately advancing the field of geophysical forensics. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive examination of the effects of quicklime (QL) addition on the stabilization of two distinct clayey soils with high (CH) and low plasticity (CL-tuff). The results showed that incorporating QL into the soils substantially improves their stabilization characteristics. Specifically, the addition of QL results in a notable decrease in the final water content of both soils, as shown by a reduction from 23.04 to 19.06% in CH and from 18.07 to 17.1% in CL-tuff at 4% QL addition. Furthermore, this study reveals a transformation in the plasticity properties of soils. Liquid Limit (LL) and Plasticity Index (PI) were reduced, with CH-tuff exhibiting a significant decrease in PI from 48 to 12 and an increase in Plastic Limit (PL) from 21.8 to 55 at 4% QL. CL-tuff also showed reduced plasticity, with PI decreasing to 8.33 at 4% QL. Additionally, the Immediate Bearing Index (IBI) was improved for both soil samples, indicating improved load-bearing capacities. For CH samples, IBI improved from 6.37 to 11.99 at 4% QL addition, while for CL-tuff, it increased dramatically from 4.5 to 23.6 for the same QL percentage. The findings underscore the effectiveness of QL in improving soil properties crucial for chemical stabilization, providing evidence that QL addition can be a key technique in soil stabilization, especially for soils with high plasticity or those requiring increased bearing strength. [ABSTRACT FROM AUTHOR]

This study aims to assess the deflection and elastic modulus (Es) of subgrade in flexible pavements, focusing on a comparative analysis between pavements with clayey soil subgrade and subgrade modified with tire scrap. The research utilized Falling Weight Deflectometer (FWD) for measuring subgrade deflection, essential in evaluating pavement performance. The FWD applied a dynamic load to the pavement, with deflection measurements processed using the KGP-BACK software to calculate the Es of the pavement subgrade. This approach included assessing the Lower Layer Index (LLI) and Es of the subgrade. Findings revealed a notable reduction of 37.5% in deflection and 2.68 times increase in Es for the tire scrap modified subgrade pavement compared to the standard clayey soil subgrade pavement. These results demonstrate significant enhancements in pavement structure, underlining the potential of recycled materials in sustainable civil engineering practices. [ABSTRACT FROM AUTHOR]

Purpose: The use of sewage sludge associated with natural rock-based fertilizers can increase nutrient solubility and soil fertility. From this perspective, this study evaluated changes in the chemical soil attributes and the nutrient availability rate after the application of sewage sludge, natural phosphate, and elemental sulfur in soils with different clay contents. Method: The study was conducted in a controlled environment and was set up in a completely randomized design with four replications in a 3 x 5 x 5 factorial arrangement consisting of soil with three clay contents: 28%, 34%, and 42%; five fertilization managements: unfertilized (Control), fertilized with natural phosphate (NF), fertilized with sewage sludge (SS), fertilized with natural phosphate and elemental sulfur (NF+S), and fertilized with NF+S+SS; and five evaluation times: 0, 30, 60, 90, and 120 days after fertilization. The chemical soil attributes and the nutrient availability rate were evaluated. Results: The application of sludge, natural phosphate, and sulfur increased the contents of SOM, N, P, K, Ca, Mg, Al, H + Al, SB, and CEC and reduced the soil pH, in addition to favoring the rate and time of availability of P, Ca, and Mg, with means higher than 50% in the soils from 30 to 120 days after application. At 120 days after application of sludge, the average availability rate of P, K, Ca, and Mg corresponded to 37, 13, 144, and 157%, respectively. Conclusion:These improvements imply savings with mineral fertilizers and contribute to adopting conservationist and sustainable practices. The individual application of sewage sludge or its application with natural phosphate and elemental sulfur increased soil fertility and the nutrient availability rate in soils with different clay contents. [ABSTRACT FROM AUTHOR]

Landslide disasters in Indonesia often cause significant damage to public facilities, agricultural lands, and result in human casualties. This study was conducted to deeply understand the dynamics and causes of landslides and to develop effective disaster mitigation strategies in areas vulnerable to soil movement. The focus of the research is on the rotational landslide incident that occurred on the Trans Timor National Road KM 73, Noelmina Village, Takari District, Kupang Regency, East Nusa Tenggara Province, on February 17, 2023. Through a methodological approach that includes geomorphological analysis, evaluation of hydrological conditions, and land use study, this research identifies the main factors causing the landslide, including the changeable nature of Bobonaro clay soil, increased soil saturation due to hydrological conditions, and increased water load in the basin area due to land use. The findings emphasize the importance of efficient hydrological management, careful land use planning, and strengthening the capacity of local communities in landslide disaster mitigation. Recommendations for disaster mitigation include the development of infrastructure that is resistant to soil movement, vegetation planting for slope stabilization, and community education on sustainable land use practices. This research provides a significant contribution to disaster mitigation efforts in Indonesia by highlighting an approach based on a comprehensive understanding of the causes of landslides and effective adaptation strategies. [ABSTRACT FROM AUTHOR]