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Jet-grouting technique is one of the most widespread methods for soil reinforcement, used to make soil suitable to withstand forces transmitted by structures or the redistribution of stresses following excavations. The result of the treatment however is influenced by several factors, including type of treatment, type of soil, original stress state of the soil, machine operating parameters, and water-to-cement ratio. In particular, the strength of the treated material and its stiffness are very useful for designing the intervention for a specific case. Due to the uncertainty of the final strength and stiffness values, a test field is almost always required. But the design of the test field itself and the subsequent design of the intervention require some preliminary information on the expected values of the strength and the elastic modulus. An in-depth analysis of the scientific and technical literature was conducted, allowing for the selection of a significant number of cases. For each case, the type of treatment, the type of soil, uniaxial compressive strength (UCS), and elastic modulus (E) values were recorded. It was possible to determine the trend of the average UCS values and the E/UCS ratio for each type of analyzed soil and for the two studied jet-grouting techniques. In addition to the average values, the variability intervals, centered on the mean, capable of enclosing 90% of the data in the sample were identified. The obtained graphs represent a useful tool for obtaining a preliminary estimate of the strength and stiffness of the treated soil using the jet-grouting technique. [ABSTRACT FROM AUTHOR]

Most structures supporting solar panels are found on thin-walled metal piles partially driven into the ground, optimizing costs and construction time. These pile foundations are subjected to repetitive lateral loads from various external forces, such as wind, which can compromise the integrity of the pile-soil system. Given that the expected operational lifespan of photovoltaic solar plants is generally 20–30 years, predicting their service life under fatigue loads is crucial. This research analyzes the response of H-section piles to lateral fatigue loads in cohesive rigid soils through four field tests, subjected to load cycles of 55%, 72%, and 77% of the static failure load, corresponding to maximum loads of 25 kN, 32 kN, and 35 kN, respectively. Additionally, the effect of load cycles on the degradation of pile-soil adhesion is studied through two pull-out tests following cyclic tests. This study reveals that soil fatigue does not occur under repetitive loads and that soil stiffness remains constant once the cycles causing soil compaction have been overcome. Nevertheless, the accumulated plastic deflection of the soil increases steadily once soil compaction occurs due to cyclic loading. The implications of these results on the fatigue life of photovoltaic solar panel foundations are discussed. [ABSTRACT FROM AUTHOR]

Most structures supporting solar panels are found on thin-walled metal piles partially driven into the ground, optimizing costs and construction time. These pile foundations are subjected to repetitive lateral loads from various external forces, such as wind, which can compromise the integrity of the pile-soil system. Given that the expected operational lifespan of photovoltaic solar plants is generally 20–30 years, predicting their service life under fatigue loads is crucial. This research analyzes the response of H-section piles to lateral fatigue loads in cohesive rigid soils through four field tests, subjected to load cycles of 55%, 72%, and 77% of the static failure load, corresponding to maximum loads of 25 kN, 32 kN, and 35 kN, respectively. Additionally, the effect of load cycles on the degradation of pile-soil adhesion is studied through two pull-out tests following cyclic tests. This study reveals that soil fatigue does not occur under repetitive loads and that soil stiffness remains constant once the cycles causing soil compaction have been overcome. Nevertheless, the accumulated plastic deflection of the soil increases steadily once soil compaction occurs due to cyclic loading. The implications of these results on the fatigue life of photovoltaic solar panel foundations are discussed.

Stress history acquired by any cohesive soil influences, to a large extent, three groups of fundamental properties indispensable in geotechnical design i.e. state of soil, shear strength, and stiffness characteristics. The basic stress history parameter (from which other parameters are derived) determined directly from laboratory tests is a preconsolidation stress σ′p. Since the first method proposed by Casagrande in 1936, value σ′p is determined in the oedometer test as a border between overconsolidated (OC) and normally consolidated (NC) zones. Approach based on division between predominantly elastic, (recoverable) strain, and plastic (irrecoverable) strain is a main principle of several methods of σ′p determination, which have been proposed over the past eighty-six years.

This study conducted a series of trapdoor tests to investigate the soil arching effect in cohesive soils, which are commonly encountered in engineering practice but have not been previously investigated in the existing literature. A detailed discussion was proposed to explore the transformations of soil arching, particle movements, and stress redistribution occurring over the trapdoor. Comprehensive parametric studies were conducted, with a particular focus on trapdoor widths and filling heights, to analyze the effects of different influential factors on soil arching. An advanced digital image correlation (DIC) technique was employed to monitor the displacement field during the test. Through the combination of high-precision displacement nephograms and earth pressure values, the entire evolution process of soil arching was comprehensively revealed, including its initial appearance, gradual development, and stabilization. Typical fracture surfaces were observed in the tests, resulting in a significant discrepancy compared to the trapdoor tests conducted in cohesionless soils. The aforementioned research not only provides a deeper insight into how soil arching will evolve with varying influential factors but will also help engineers to better use the soil arching effect of cohesive soils in the design phase. [ABSTRACT FROM AUTHOR]

North Dakota glaciolacustrine deposits are susceptible to leaching of sodium sulfate, potentially emerging from the Dakota sandstone. The current work is designed to investigate the effects of sodium sulfate on the consistency limits and fully softened shear strength of cohesive deposits of glacial lake Agassiz, around the riverbanks of the Red River reach in the City of Fargo, North Dakota, USA. A decrease in the shear strength of cohesive deposits could increase susceptibility of riverbanks failures of the Red River. Field samples of topsoil, plastic laminated Sherack and Brenna formations were collected and tested for potential change in consistency limits and fully softened shear strength by adding different concentrations of sodium sulfate as pore fluid. It was found that the saline pore fluid significantly controls the consistency limits of these deposits and a decrease in the shear strength is recorded. [ABSTRACT FROM AUTHOR]

Soil - geofoam interfaces have been studied through an extensive experimental program by performing multiple series of interface shear tests using two different granular soils (i.e. beach sand and construction material sand) and one cohesive soil (i.e. bentonite clay) as well as a soil mixture containing 75% sand and 25% clay by dry weight at distinct loading conditions (i.e. normal stresses (s): 25, 100, 250; low, moderate, high loading conditions, respectively). Using the shear stress versus horizontal displacement curves obtained, some important engineering design parameters including peak shear stress, residual shear stress, interface sensitivity (i.e., peak/residual ratio) and displacement required to reach peak stress have been determined and the variations in those interface mechanical properties as a function of loading condition and counterface soil type have been investigated. It was shown that the peak as well as residual shear stresses increased with an increase in normal stress for all the interface systems tested. Further, the granular soil (sand) interfaces demonstrated relatively larger frictional strengths (both peak and residual) as compared to both the cohesive soil (clay) interface and the sand/clay admixture soil interface. Additionally, the higher the angularity of granular soil particles became, the larger the interface shear strengths (peak and residual), when sheared against geofoams, developed in light of experimental results attained as a result of interface shear tests on different material combinations. For comparison, the detected peak strength at average for the construction material sand, the beach sand, and the sand/clay admixture soil interfaces as compared to the bentonite clay interface were improved 59.8%, 43.4%, and 20.3%, respectively. Additionally, the detected residual strength at average for the construction material sand, the beach sand, and the sand/clay admixture soil interfaces as compared to the bentonite clay interface were improved 53.9%, 28.6%, and 15.4%, respectively. [ABSTRACT FROM AUTHOR]

Accurately identifying soil texture and understanding soil behaviour in terms of plasticity is a crucial initial step in properly characterizing a site, which in turn facilitates appropriate sampling and scheduling of laboratory tests. Soil identification techniques in literature are effective at assessing pure clays and silt–clay mixtures. This paper presents a comparative study between field tests, soil plasticity classifications, Atterberg limits, mineralogical and chemical data, SEM imagery, and stereographical microscopy. Natural residual soils comprising varying quantities of clays, silts, and sands were used and subjected to the same field and laboratory protocols. The findings of this study demonstrate that a series of field tests can effectively characterize and classify soils ranging from coarse soils to fine soils exhibiting non- to highly plastic indices with particle sizes less than 2.00 mm. By employing a single list of field tests that only necessitate water and commonly available stationery materials on-site, the researchers have presented a valuable tool for on-site determination of soil texture and inference of the Unified Soil Classification System (USCS). This approach streamlines the process and provides professionals with an efficient means of assessing soil properties and determining problem soils at an early stage of the investigation and during construction of high fills. [ABSTRACT FROM AUTHOR]

Where granular materials are not easily available, local cohesive soils are increasingly employed in geosynthetic reinforced soil walls as a cheap and sustainable option. Conventional design methods do not yet account for the beneficial effect of cohesion in reducing the amount of required reinforcement. Similarly, the contribution of the face to stability is rarely accounted for, despite plenty of experimental evidence in its favour. In this paper, a semi-analytical method based on limit analysis is developed for the design of reinforced soil walls in frictional–cohesive backfills accounting for the wall contribution. A parametric analysis was conducted to evaluate the effect of soil cohesion and friction angle, facing batter, block width, location of the reaction force acting on the face, facing–backfill interface friction, facing–foundation interface friction and reinforcement length. Dimensionless design charts providing the required amount of reinforcement for lengths recommended in design standards are provided for both uniform and linearly increasing reinforcement distributions. It emerges that accounting for the presence of cohesion and the facing element can lead to significant savings in the overall level of reinforcement, and that tension cracks can be particularly detrimental to wall stability for highly cohesive soils so they cannot be overlooked in the design. [ABSTRACT FROM AUTHOR]

The influence of excavation rate, geometric layout, and hydraulic conductivity of basal and retained soils on the fully coupled solid–fluid behavior of braced excavations in cohesive soils is presented. Fully coupled excavation analyses were performed using the hypoplasticity clay model to reproduce the constitutive soil behavior combined with Biot's consolidation theory. A method aimed at predicting excavation-induced ground movements using excess pore-water pressure ratios as a function of site-specific groundwater considerations is presented for the determination of the recommended type of excavation analysis (i.e., drained, partially drained, or undrained). Results obtained from the numerical simulations indicated that excavation rate to hydraulic conductivity ratios, ER/k , smaller than 0.1 and larger than 10,000 can be analyzed under drained and undrained conditions, respectively. The proposed method was validated with published case histories, and its ability to estimate excavation performance in terms of excess pore-water pressures and excavation rates is presented in this paper. [ABSTRACT FROM AUTHOR]

Rigid monopiles with small slenderness ratios (i.e., ratio of monopile embedded length to outer diameter) are widely used as foundations to resist lateral load and moment transferred from superstructures, e.g., large diameter steel pipes used by offshore wind turbines and piers in electric utility industry or sound barriers. A design model for laterally loaded rigid monopiles in cohesive soil is presented in this paper. The proposed design model assumes a constant depth of rotation point as well as a trilinear distribution model of soil lateral reaction along the embedded length of the monopile, and introduces a mobilization coefficient of soil reaction to quantify the magnitude of soil reaction mobilized under a certain load applied at the monopile head. The relationship between the mobilization coefficient and monopile head rotation is established by back-analyzing test results measured from series of laterally loaded pile tests, and then a general design procedure for a laterally loaded rigid monopile in cohesive soil is recommended. The feasibility and reliability of the proposed design model is validated against three cases of numerical simulations on laterally loaded piles in cohesive soils. It shows that this study’s proposed design model produces a relatively satisfactory prediction of the nonlinear load-deformation response, and can be used for laterally loaded monopile design in the sites with undrained shear strength being uniform or increasing linearly with depth. [ABSTRACT FROM AUTHOR]

Validation of the AVISA model Despite advanced design technologies, construction on cohesive soils is still a challenge. Especially when dealing with cyclic loading conditions combined with the time‐dependent behavior of cohesive soils, such as offshore structures or even dams, the tools to predict the long‐term deformations of fine‐grained soil are limited. Due to the complex influence of loading rate, preloading, and soil structure, it is necessary to understand the effects of these influences on cohesive materials through laboratory testing and describe them numerically through accurate and physically based constitutive equations. Researchers (continue to) develop many hundreds of material models each year. Most of them are used for PhDs and not investigated further. In this work, such a model, developed in the first author's PhD, is be validated. The performance of the AVISA model has been previously demonstrated on experiments of various fine‐grained soils. In this paper, a new experimental study on Malaysia Kaolin is used for the validation of the model. Furthermore, the reproducibility of the so‐called Krey and Tiedemann criteria, parameters φ′s , c′ und φ′ is investigated by simulations of simple shear tests. It should be noted that many constitutive models for fine‐grained soils fail in this task. [ABSTRACT FROM AUTHOR]

Different constitutive models, based on principles of mechanics and experimental evidence, have been developed over several decades to represent and predict the stress-strain behavior of soils subjected to various loading conditions. The Generalized Bounding Surface Model (GBSM) is one of them and is defined as a fully three-dimensional elastoplastic constitutive model for saturated cohesive soils that employ the bounding surface plasticity in conjunction with a nonassociative flow rule and a soil microfabric-inspired rotational hardening rule. The GBSM has been successfully validated on numerous laboratory reconstituted soils, but not on natural or undisturbed soil samples. Hence, in this paper the predictive capabilities of the GBSM are evaluated in the simulation of the monotonic behavior of an undisturbed cohesive soil called “Cajicá clay” from the high plain of Bogotá in Colombia. In the first instance, an isotropic consolidation test and a set of axisymmetric triaxial compression and extension tests are conducted using an automated triaxial equipment, to experimentally describe the response of the undisturbed soil. From experimental data, the parameters associated with the GBSM model are calibrated to finally evaluate its capabilities in the simulation of a cohesive natural soil. A comparison between experimental data and numerical simulations is presented to show both performance and advantages of the GBSM model.

The permeability of soil is an important factor controlling the flow of water through the subsoil. The article presents the results of studies of hydraulic parameters for overconsolidated clays using in situ tests. Using the excess pore pressure normalization technique, both in the case of monotonic and dilatory dissipation tests, and the time at which 50% dissipation of excess pore water pressure takes place, as well as taking into account the rigidity index of the analyzed soil, it was possible to estimate the permeability and consolidation coefficients for the analyzed clays. Based on these studies, simple relationships between the permeability coefficient and the soil behavior-type index are proposed. Proposed formulas may be applied for overconsolidated cohesive soils with soil behavior-type index values within the range of 2.05–3.30 and described in Robertson’s chart as overconsolidated silty clays, clays and heavily overconsolidated and cemented fine-grained soils. Although our proposal of determining flow parameters has been calibrated only for two analyzed cases, its utility for wider use in other overconsolidated fine-grained soils may also be taken into account.

Large-diameter piles (commonly called monopiles) are extensively used to support offshore wind turbines (OWTs) for withstanding large lateral and overturning moments. Results from monotonic tests suggested that the design using the current p–y methodology in clay significantly underestimates the pile stiffness. To determine a rational formulation of the undrained clay ultimate resistance on a theoretical sound basis, a plethora of published papers on the ultimate resistance of piles in undrained clays pu were examined first. It has been found that all proposed methods for pu were constructed on the assumption of twofold soil failure mechanisms, which are a shallow passive wedge failure and a deep full flow failure. Study of the transition depth separating the two mechanisms revealed the existence of a third pattern of failure, where the soil deforms three-dimensionally. Taking profit of the axisymmetric geometry of the pile, which is subjected to non-axisymmetric loading, an embedded rigid disk was taken to represent the behavior of the soil around a short segment of the pile in the region where the soil is expected to behave in three-dimensional (3D) mode. An expression for the soil reaction was established first by using an analytical approach. Then, pu resulting from the third pattern was rigorously quantified by extending the obtained formula to failure using some fundamental notions of basic soil mechanics. By joining the obtained pu to two other expressions for modeling the shallow passive wedge and the deep full flow, the variation of the undrained clay bearing capacity factor resulting from the threefold collapse mechanism was examined as a function of the pile normalized depth and for a variety of undrained clay strength parameters. Comparisons with other rigorous methods show the rationality of the proposed approach. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

Deep excavations are essential to harbor the urban needs of the present age. The excavation of pits for foundation construction in an already limited space in urban centers poses damage to the neighboring structures. In this study, two mat foundations on two different types of clay soils have been modeled in PLAXIS to determine the maximum depth of excavation and the minimum safe distance of the excavation pit from these mat foundations. The failure modes under consideration are excessive settlement, angle of distortion of the mat foundation, and pit face failure. A co-relation to determine the safe maximum depth of unsupported excavation pit and minimum horizontal distance from adjacent mat foundation is presented based on results from 195 models. The ratio of critical unsupported excavation depth and critical horizontal distance from an existing building first drops to 1:3 in all cases and then rises in a non-linear manner. The modes of failures at various stages have been highlighted based on 44 critical cases.

The water jet trenching technique is widely used in the burial of submarine pipelines. However, its application in cohesive soils often leads to complexity in trench morphology and challenges in predicting trench dimensions due to unclear soil erosion mechanisms. These issues significantly impact pipeline burials. To investigate the soil erosion mechanism of water jet trenching in cohesive soils, two-dimensional physical simulation experiments of submerged vertical water jet erosion were conducted. The influence of jet pressure, impingement height, and nozzle diameter on the shape of the scour hole was analyzed. The erosion damage patterns of water jets on cohesive soils were studied, and a theoretical model for the development of scour holes was established. The study revealed that when the jet velocity reaches 1000 m/s and the nozzle diameter reaches 1 mm, a contracted neck forms at the upper part of the scour hole. The appearance of the contracted neck is due to excessive jet impact energy causing impact shear failure in the soil. The effective height and width of the contracted neck increase with jet pressure and nozzle diameter and decrease with impingement height. Based on Prandtl's bearing capacity model, a model for predicting impact shear failure in cohesive soils was established, and a predictive formula for the effective height and diameter of the neck was proposed. Experimental validation confirmed the accuracy of the predictive formula. These findings provide theoretical support for the application of water jet trenching techniques in cohesive seabed soils. • The development patterns of scour holes in cohesive soils were analyzed. • A new scour hole development model based on Prandtl's bearing capacity theory was proposed. • Formulas to predict the height and diameter of vase-shaped scour holes were proposed. [ABSTRACT FROM AUTHOR]

• Foam destruction is often observed while tunneling in fine-grained soils using earth pressure balance machines. • Quantifying and estimating foam destruction based on soil types helps in optimizing the conditioning strategies. • The study provides the quantification of foam destruction observed in different soil types. • The study discusses the influence of soil properties and conditioning variables on observed foam destruction. This paper presents the development of a novel methodology and the results of an experimental study to quantify foam destruction (FD) observed during the conditioning of fine-grained soils. A laboratory setup was designed to simulate pressurized mixing conditions prevalent in the cutterhead tool gap and excavation chamber of an earth pressure balance tunnel boring machine (EPBM). The developed FD quantification methodology utilizes the concept of back pressure saturation to determine the volume of the ruptured air from the foam bubbles during the conditioning of soil. The influence of major soil types, fines content (FC), soil consistency index (I c), foam injection ratio (FIR), and foam liquid half-life (t 1 / 2) on FD were investigated. The results showed no FD in sand, 15–30% FD (% of injected foam volume) in silt, and significant FD of 30–85% in clay. FD was found to be directly proportional to FC and inversely proportional to FIR and t 1 / 2. No relationship was observed between FD and I c. The study provides clear experimental evidence of the presence of FD phenomena in fine-grained soils and a methodology for calculating FD. The quantification of FD range in major soil types and insights into influencing factors revealed in this study will help practitioners account for the expected FD in various soil types while deciding FIR , and decide whether to use foam at all while preparing conditioning strategies for EPB tunneling projects in fine-grained soils. [ABSTRACT FROM AUTHOR]

The shear modulus of a soil, G, shows a hyperbolic degradation curve relationship with increasing shear strain, γ. G is usually normalized against the small-strain modulus (Gmax) as G/Gmax vs γ (log). Factors that significantly influence G are shear strain amplitude, γ, soil plasticity index (PI) and effective pressure, σ′. Design curve charts of G/Gmax vs γ have been produced for seismic engineering purposes. Mathematical models have also been developed, using statistically analysed parameters to reflect the influence of γ, PI and σ′. Soil overconsolidation ratio (OCR) has a significantly lesser impact than the three mentioned factors. In this paper, mathematical fitting and shaping functions for PI and σ′ are developed to extend the shear modulus reduction model further. The requirement to calculate reference strain, γref, is removed, and only soil PI and σ′ are required. Cyclic triaxial experiments are conducted with reconstituted kaolin and bentonite in different mix proportions (to achieve varying PI) and at different effective stresses. The model equation matches well against both the established curves and experimental results and can facilitate preliminary prediction of shear stress–strain behaviour and Gmax with different cohesive soil types and at different depths below ground. [ABSTRACT FROM AUTHOR]

Desiccation cracking of cohesive soils is the development of cracks on the soil surface as a result of a reduction in water content. The formation of desiccation cracks on the cohesive soil surface has an undesirable impact on the mechanical, hydrological, and physicochemical soil properties. Therefore, the main aim of this study is to experimentally and numerically investigate eco-friendly soil improvement additives and their effect on the desiccation cracking behavior of soils. Improvement of soil crack resistance was experimentally studied by conducting desiccation cracking tests on kaolin clay. Biopolymer xanthan gum and recycled carpet fibers were studied as potential sustainable soil improvement additives. In addition, image processing was conducted to describe the effect of an additive on the geometrical characteristics of crack patterns. The results show that the soil improvement additives generally enhanced the soil strength and reduced cracking. Furthermore, a hydro-mechanical model was developed to predict the moisture transfer and onset of desiccation cracks in plain and amended kaolin clays. Data obtained show that the inception of the desiccation cracking and radial displacements were delayed in the improved soil specimens, which is in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Eucalyptus harvesting, forwarding and soil tillage operations are among the main causes for compaction of forest soils, with potential impacts on productivity. This concern is especially important in areas with soils that are naturally compacted (fragipans and duripans). In these soils, tillage operations include the use of subsoilers that can reach depths of more than one meter and require heavy tractors that exert high pressure on the soil. One of the ways to try to minimize the effect of this compaction is by retaining harvest residues. The objective of this study was to evaluate the impacts of eucalyptus harvesting on soil physical attributes, as well as to determine the potential of different types of residue management to reduce compaction from the soil tillage operation. Two experiments were conducted in the same area with a Yellow Argisol. In the first experiment, compaction caused by mechanized harvesting with harvester + forwarder was evaluated. In the second experiment, different managements of harvest residues were examined as potential modifiers of soil compaction during tillage for new plantings. For this, three managements systems were tested: (1) retention of all harvest residues and litter from the previous rotation (HR + L), (2) retention of litter from the previous rotation (L), and (3) removal of harvest residues and litter from the previous rotation (WR). Before and after harvest, sampling was carried out in the planting rows and inter-rows, and after tillage, samples were collected in the traffic line of the subsoiler-tractor set. In both experiments, undisturbed soil samples were collected from the center of the 0–10, 10–20, 20–40, 40–60, and 60–100 cm layers to determine soil density and total porosity. In each period and site of evaluation, mechanical resistance to penetration up to the 60-cm depth was also determined. The harvesting operation increased soil density at 0–10 and 60–100 cm depths only in the inter-rows. Retention of harvest residues and litter (HR + L) after harvesting avoided increases in soil density and penetration resistance caused by machine traffic during tillage. The results indicate the importance of retaining harvest residues on forest soils for achieving sustainable utilization and for conserving soil quality. [ABSTRACT FROM AUTHOR]

The creep behavior of cohesive soils is highly related to the plasticity index. To study the relationship between the creep and the plasticity index of soils, a creep model is proposed to apply to the creep behavior of several soils with different plasticity indexes, especially covering the very long 80 year monitoring data on-site and 3.5 year test data in the lab. For the same type of soil, the creep exponent does increase with the plasticity index; however, for different types of soils, there is not a clear trend between them. Besides, because the risk of creep failure depends on the creep exponent and the (normalized) stress–strain curve, it is not certain that the creep failure of one type of soil with a larger creep exponent will be quicker than another type of soil with a lower creep exponent. [ABSTRACT FROM AUTHOR]

The character of morphogenetic processes occurring within river valleys depends on the mechanical and hydrogeological properties of deposits that build up such landforms. In the case of the Polish Lowlands, a series of Pliocene clay lake sediments (so-called Poznań mottled clays) plays a special role. Their current locations and properties are associated with specific sedimentation conditions and glacitectonic deformations, which the soils have been subjected to many times in Pleistocene. Their presence in the lithological profile influences dynamics of slope processes in valleys’ escarpment zones and channel erosion stabilization. In this article, the “Warsaw clay” from the Poznań Series Formation is presented in comparison with other cohesive Quaternary sediments, which are mostly building neighboring outcrops. This article analyzes the Seismic Dilatometer (SDMT) results and a method of interpretation to determine IR, plasticity index, and liquid limit (LL) parameters. The undrained shear strength Su was determined based on the Cone Penetration Test (CPT), SDMT, and laboratory test results. Spatial variability of the strength and deformation parameters in the study area were determined using dilatometer test (SDMT) results. Finally, the nomogram chart is proposed to obtain the rigidity index (IR) of the preconsolidated Pliocene clays, depending on both p0 and p1 pressures from SDMT and effective vertical stress σv0′{\sigma }_{\text{v0}}^{^{\prime} } and pore water pressure u0.

Objective. Determination of the stress state of a ground base with a trapezoidal cutoff from the action of own weight, according to the conditions of equivalence of effects, is reduced to determining the stress state from the external surface load distributed according to the hydrostatic law. Methods. The problem of determining the stresses in the structure foundations at any degree of areas development of a plastic strain of the soil has a strict mathematical formulation, and similarity criteria can be obtained using a simpler construct of similarity theory. The simulation is performed by using similarity criteria based on which the model is executed, the loading conditions are determined, and the transition from the values measured on the model to the corresponding values of the full-scale structure is carried out. Similarity criteria can be obtained either with the help of similarity theory or with the help of dimensional analysis. An even greater effect of increasing the self-weight of a model made of transparent optically sensitive material can be achieved using the immersion method in conjunction with the centrifugal modeling method. If necessary, the stresses in the model area are fixed using the "freeze" method. Result. Using the equations system of the mixed problem of the elasticity and plasticity theory, and the scale method, similarity criteria are established for modeling stresses in the foundations of buildings and structures. Limitations on the choice of similarity multipliers for loose soils, the possibility of using the method of centrifugal modeling, as well as features of modeling connected soils are noted. Conclusion. A necessary condition for the similarity of the stress states of loose homogeneous bases in nature and the model is the equality of the similarity multipliers of the geometric scale and the force factor.

Geosynthetic-reinforced and pile-supported (GRPS) systems provide an economic and effective solution for embankments. The load transfer mechanisms are tridimensional ones and depend on the interaction between linked elements, such as piles, soil, and geosynthetics. This paper presents an extensive parametric study using three-dimensional numerical calculations for geosynthetic-reinforced and pile-supported embankments. The numerical analysis is conducted for both cohesive and non-cohesive embankment soils to emphasize the fill soil cohesion effect on the load and settlement efficacy of GRPS embankments. The influence of the embankment height, soft ground elastic modulus, improvement area ratio, geosynthetic tensile stiffness and fill soil properties are also investigated on the arching efficacy, GR membrane efficacy, differential settlement, geosynthetic tension, and settlement reduction performance. The numerical results indicated that the GRPS system shows a good performance for reducing the embankment settlements. The ratio of the embankment height to the pile spacing, subsoil stiffness, and fill soil properties are the most important design parameters to be considered in a GRPS design. The results also suggested that the fill soil cohesion strengthens the soil arching effect, and increases the loading efficacy. However, the soil arching mobilization is not necessarily at the peak state but could be reached at the critical state. Finally, the geosynthetic strains are not uniform along the geosynthetic, and the maximum geosynthetic strain occurs at the pile edge. The geosynthetic deformed shape is a curve that is closer to a circular shape than a parabolic one. [ABSTRACT FROM AUTHOR]

Currently, knowledge of the failure mechanisms of narrow backfills with retaining walls rotating about the top (RT mode) is still lacking which leads to inaccurate estimations of the earth pressure. Numerical simulations using finite element limit analysis find that under the effects of backfill geometries, interface strengths, and soil properties, the upper soil layer supported by soil arching retains its integrity and the lower soil layer is sheared by multiple curved sliding surfaces in the limit state. Based on the failure mechanisms of narrow backfills, a calculation model is established which considers the soil arching effect, curved sliding surface, and cohesive soils. Analytical solutions for the earth pressure of narrow cohesive backfills with retaining walls rotating about the top are derived by using the limit equilibrium horizontal slice method. Compared with previous studies, the present method predicts the earth pressure distribution with higher accuracy. Several extensive parametric studies have also been conducted. Thus, decreasing the aspect ratio of backfills, increasing the inclined angle of natural slopes, interface strengths, and soil cohesion are beneficial for maintaining backfill integrity and reducing earth pressure against retaining walls. [ABSTRACT FROM AUTHOR]

One of the main reasons for bridge failure is the local scour around the pier. Pier groups are popular in the structural designs due to economical and geotechnical reasons. The mechanism of scouring at the pier groups is more complicated than the single one. In this study, the scour around group piers in the sandy soil and a mixture of sand and clay in some relative compaction equal to 90% and the optimum moisture was studied. The arrangement of the group piers was 1pier * 3pier and 3pier * 1pier along and transverse of the flow direction, respectively, at the interval space of D, 2D and 2.5D intervals. The effect of the Bentonite clay content was investigated. Finally, by using Kaolinite clay, the effect of the clay mineral was studied. The results showed that the scouring depth was different not only in cohesive and non- cohesive soils, but also according to the type of the clay mineral. The use of 10% bentonite clay mixed with sand reduced scour more than 90%, as compared to the sandy soil. On the other hand, using 15% of kaolin in the similar conditions reduced scour depth by only a 34%, in comparison to the sandy soil.

Environmental degradation is a threat to the ecosystem and natural resources. The research investigated the effects of hydrochloric acid contamination on the geotechnical properties of cohesive soils obtained from Oke-Ejigbo area of Abeokuta, South-western Nigeria. The materials used are hydrochloric acid as contaminant, red clay (RCA) and white clay (WCA) soils respectively. The results of optimum moisture content, maximum dry densities, California bearing ratio and unconfined compressive strength of RCA and WCA subjected to 60 days acidic contamination period are (14.88 and 16.21%), (18.30 and 17.93 kN/m³), (5.93 and 11.29%), (89.81 and 87.54 kN/m3) respectively. The acid-soil interaction reduces the geotechnical properties of the cohesive soil samples with an increase in the period of contamination. Furthermore, the contamination period directly affects the strength of the soils due to the change in soil plasticity and structure caused by the pollutant. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum: Architectura is the property of Wydawnictwo SGGW 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.)

Copyright of Association of Arab Universities Journal of Engineering Sciences (JAARU) is the property of Association of Arab Universities 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.)

Deep mixing methods are widely used for stabilizing soft clayey soils and improving their bearing capacity. However, spatial variability in the shear strength of the cement-treated ground introduces uncertainties in estimating the bearing capacity for design. This paper evaluates the reliability of, block-type, cement-treated foundation under inclined load conditions using random field numerical limit analyses. The undrained shear strength is modelled as a random field which is characterized by a log-normal distribution and a spatial correlation length. Monte Carlo simulations are then used to interpret the stochastic bearing capacity factor and failure mechanisms for inclined concentric loading conditions at selected ratios of the shear strength ratio of cement-treated ground to original clay, the coefficient of variation in undrained shear strength and correlation length of the cement-treated zone. Variability of the undrained shear strength can reduce the expected bearing capacity of the cement-treated ground by 50–70% compared to homogeneously mixed clay. [ABSTRACT FROM AUTHOR]

One of the main reasons for bridge failure is the local scour around the pier. Pier groups are popular in the structural designs due to economical and geotechnical reasons. The mechanism of scouring at the pier groups is more complicated than the single one. In this study, the scour around group piers in the sandy soil and a mixture of sand and clay in some relative compaction equal to 90% and the optimum moisture was studied. The arrangement of the group piers was 1pier * 3pier and 3pier * 1pier along and transverse of the flow direction, respectively, at the interval space of D, 2D and 2.5D intervals. The effect of the Bentonite clay content was investigated. Finally, by using Kaolinite clay, the effect of the clay mineral was studied. The results showed that the scouring depth was different not only in cohesive and noncohesive soils, but also according to the type of the clay mineral. The use of 10% bentonite clay mixed with sand reduced scour more than 90%, as compared to the sandy soil. On the other hand, using 15% of kaolin in the similar conditions reduced scour depth by only a 34%, in comparison to the sandy soil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature 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.)

A comprehensive study was carried out to examine the suitability of hyperbolic model to establish undrained stress-strain (σ-ε) response of cohesive soils of Vijayawada region, India. The majority of locations in this region covered with cohesive soils. Standard penetration test (SPT) is the most commonly used in-situ test conducted as a part of geotechnical investigation in this region. In this paper a simplified hyperbolic model was proposed to evaluate the σ-ε curve in terms of SPT value (N value). The present study aims on predicting undrained shear strength/undrained cohesive strength (Cu) and elastic modulus (E) from N value. Empirical correlations would permit consulting engineers to rapidly estimate Cu and E using N value. [ABSTRACT FROM AUTHOR]

The undrained shear strength in cohesive soils can be evaluated based on measurements obtained from the standard dilatometer test (DMT) using single- and multi-factor empirical relationships. However, the empirical relationships presented in the literature may sometimes show relatively high values of the maximum relative error. The add-on seismic module to the seismic dilatometer test (SDMT) extends parameters measurable in a standard dilatometer test by the shear wave velocity Vs as an independent variable. Therefore, a method for evaluating the undrained shear strength in cohesive soils based on data obtained from the seismic dilatometer test is presented in this study. In the method proposed, the two-factor empirical relationship for evaluating the normalized undrained shear strength τfu/σ'v is used based on independent variables: The normalized difference between the corrected second pressure reading and the corrected first pressure reading (p1 − po)/σ'v and the normalized shear wave velocity Vs/100. The proposed two-factor empirical relationship provides a more reliable evaluation of the undrained shear strength in the tested Pleistocene and Pliocene clays in comparison to the empirical relationships presented in the literature, with a maximum relative error max RE at about ±20% and the mean relative error RE at about 8%. [ABSTRACT FROM AUTHOR]

Reliability-based design concepts have been widely adopted in structural engineering but remain less prevalent in geotechnical practice due to the challenges of characterising ground uncertainties. To facilitate the unification of structural and geotechnical designs in complex engineering systems, we focus on square shallow foundations as crucial elements. Before a complete transition to load and resistance factor design, understanding the reliability of foundations designed using traditional factors of safety is essential. This paper presents a simplified analytical method for evaluating the probability of failure of square shallow foundations on 3D cohesive soils, utilising local average theory. The approach efficiently computes local averages and covariances of soil properties without the need for time-consuming 3D finite element computations. Verified against random finite element analysis, the method accurately determines required factors of safety for bearing capacity designs. Site-specific parameters, including sample location, shear strength coefficient of variation, and spatial variability fluctuation scale, influence the derived factors of safety. We advocate a pragmatic approach that calibrates traditional factor of safety methods with rigorous reliability theories, easing the transition to reliability-based design for practicing engineers. Moreover, the determined factors of safety can aid in establishing appropriate resistance factors by considering suitable load factors. [ABSTRACT FROM AUTHOR]

Abstract The objective of this work was to evaluate the agronomical performance of 'Piemonte' mandarin grafted on 11 rootstocks grown under the edaphoclimatic conditions of the Coastal Tablelands, in the state of Sergipe, Brazil. The following combined agronomical parameters were evaluated: vegetative growth, abundance of phytophagous mites, plant yield, drought tolerance, and physicochemical quality of fruit. 'Piemonte' mandarin had the best productive performance when grafted on 'Santa Cruz Rangpur' lime, 'Red Rough' lemon, 'Sunki Tropical' mandarin, and 'Riverside' citrandarin, and it was more tolerant to drought when grafted on 'Santa Cruz Rangpur' lime and on the LVK x LCR-010 hybrid. Rootstocks did not affect pest population levels. 'Piemonte' mandarin grafted on 'Santa Cruz Rangpur' lime and 'Red Rough' lemon produced lower-quality fruit. The 'Indio' and 'San Diego' citrandarins, the HTR-051 hybrid, and 'Swingle' citrumelo have potential for high-density plantings. 'Sunki Tropical' mandarin and 'Riverside' citrandarin are a good option for the diversification of rootstocks in orchards in the agroecosystem of the Brazilian Coastal Tablelands.

The physical and mechanical properties of the soil can be determined based on laboratory tests by testing soil samples obtained from field drilling. At one point it can be done simultaneously between SPT testing and drilling. Therefore, it can be known simultaneously the value of N-SPT with the physical and mechanical properties of the soil. The purpose of this study was to obtain a relationship between the cone resistance value (qc) obtained in the field and the cohesion value for cohesive soil types. This study uses primary data, and secondary data. The results of the correlation between the cone resistance value (qc) obtained in the field and the cohesion value for cohesive soil types show a strong correlation. This is indicated by the regression value which reaches a value of 0.75, which is 0.7809. The regression equation obtained is y = 0.0138x – 0.0063. The coefficient of the cone resistance value is 0.0138, indicating that every 1 constant increase in the cone resistance value variable will increase the cohesive value in the cohesive soil by 0.0138. The positive regression coefficient indicates that the higher the cone resistance value (qc), the higher the value of cohesion (c) for cohesive soils.