Unsaturated soil

The objective of the paper is to compare and evaluate analytical and numerical solutions of one-dimensional consolidation of stabilized peat. The type of analytical method used to solve the problem is exact method by separation of variables and utilization of Fourier series. Plaxis 2D 8.2 Professional version software was used to find numerical solution to the problem by employing the finite element method. One-dimensional consolidation problem of stabilized peat was solved numerically and validated with the one solved analytically based on laboratory experimental results. From the results, it was discovered that the consolidation characteristics of stabilized peat evaluated numerically were found to have close approximation to those evaluated analytically. There is a novel value in developing an accurate numerical prediction for the vertical consolidation of stabilized peat considering the complexity of the soil treatment method. It must be noted that peat is highly problematic because it is produced from plant decomposition with extremely high organic matter.

This paper presents an experimental study on the influence of the principal stress direction and magnitude on the stress-strain-strength behavior of Bangkok Clay. The results of undrained torsion shear hollow cylinder test with various principal stress directions and various magnitudes of intermediate principal stress on undisturbed Bangkok Clay specimens are presented and analyzed. The discussions include: (i) stress-strain and pore pressure behavior, (ii) stiffness characteristics, and (iii) strength characteristics. The results show some evidences of anisotropic behavior of Bangkok Clay in various aspects.

The main objective of this study is to investigate the impact of the micro-fabric and soil mineralogy on the overall macrobehavior of the completely decomposed granite soil through a set of drained and undrained triaxial shearing and isotropic compression tests on a medium-coarse grading completely decomposed granite soil. The mineral composition of the soil was a substantial factor governing the compressive behavior. The soil compressibility increased significantly in the case of existence crushable and weak minerals within the soil minerals like fragile feldspar, as well as the high content of fines, especially the plastic fines. The scanning electron microscopic photos indicated that the micro-fabric of the soil had a paramount impact on the compressive behavior. The mechanism of the volumetric change depended on the stress levels, the soil mineral composition and the grain morphology. In the low consolidated stress levels, the soils' grains rearrangement was the prevailing mechanism of the volumetric change, particularly with the absence of weak and crushable minerals. On the other hand, at the high consolidated stress levels, particles' crushing was the prevailing mechanism in the volumetric change. Both the mechanisms of volume change could occur simultaneously at the low stress levels in the case of presence crushable minerals in addition to micro-cracks in the soil grains. The soil showed an isotropic response after 250 kPa, as this stress level erased the induced anisotropy from the moist tamping preparation method. Under the drained shearing conditions, the soil showed a contractive response, while during the undrained shearing conditions, the soil exhibited both the contractive and dilative responses with phase transformation points. The studied soil showed a unique critical state line, irrespective of the drainage conditions and initial states, the critical state line was parallel to the isotropic compression line in the void ratio-effective stress space. In the deviator-effective mean stresses space, the studied soil approached a unique CSL with a critical stress ratio equal 1.5, corresponding to critical friction angle of 36.8°.

Dike construction has been widely used because of its potential to protect people and properties from overtopping flows. Water levels may exceed a dike crest and cause overtopping flow during high river discharge. This phenomenon has caused serious damage to the dike body due to the reduction of soil shear strength. The increase of water content within particles and its relationship with the development of breach channel failure in downstream and upstream slopes are affected by a series of geotechnical and hydraulic aspects. Transient seepage and slope stability analyses (FOS) were performed in this study using 2D finite element methods and time-history measurements under the effect of sandy and very silty sand soils. The numerical model of SLIDE 2018 was limited by its inability to incorporate all physical processes governing an overtopping breach failure. Numerical analyses were performed to simulate the development of pore pressures and water content at six positions in the dike's upstream and downstream slopes in physical experimental tests using the van Genuchten Equation and the limit equilibrium method. The numerical results revealed that fine particles increase the pore water pressure and reduce the FOS. Appropriate dike design and maintenance are dependent on surrounding hydraulic conditions, dimensions, and soil types. Non-cohesive materials with fine particles were preferable.

Soil suction and its relationship with water content (gravimetric or volumetric) are inevitable in the study of unsaturated soil mechanics. Suction-water content relationship (designated as SWR), is an important input parameter for the mathematical modeling of unsaturated soil behavior response pertained to physico-mechanical, hydraulic, and volume change behavior. The experimental procedures adopted for determining SWR are time consuming and cost-intensive. Therefore, recent researches have laid a major focus on the indirect estimation of SWR. Such an estimated SWR can be used as initial guidelines for planning important geoenvironmental projects such as waste containment facilities. As such, it is important that these estimation procedures are precise and suitable for different type of soils. With this in view, effort has been made in this paper to critically evaluate an estimation procedure for a particular type of soil. The SWR has been established using two commonly adopted procedures. The study indicates that the estimated SWR does not match well with the measured SWRs for the type of soil investigated in this study.

One of the main hydraulic properties of unsaturated soils is the Soil-Water Characteristic Curve (SWCC). It is essential to understand, predict soil water storage and determine the hydraulic and mechanical behaviour of soils. These curves can be obtained by direct and indirect measurements. The measurements to obtain these curves are expensive, delicate to perform and can be really slow for fine soils, so predictive models become necessary. In order to make a numerical model, a couple of identification tests were carried out to obtain the physical properties of each sample among the four subgrade materials collected in the regions of Dakar and Thies (Senegal). The measurement tests of the matric suction were then conducted depending on the nature of the material (fine-grained soil or coarse-grained soil) and allowed to draw the SWCC of each soil. Among numerous predictive models developed for SWCC in the last decades; this study used the Perera model to fit the SWCC of four (04) subgrade materials, which did not give a satisfactory coefficient of correlation (R 2 = 58% and a relatively low sum of the squared residuals (SSR)). This leads to modifying the Perera model to better fit the SWCC on the basis of an understanding of the effect of each parameter on the shape of the SWCC. The proposed modified model was validated by checking the adjusted R 2 , minimizing the SSR in order to approach at most the experimental air entry value. The modified model works pretty well on coarse-grained and fine-grained soils. This modified model of Perera provided a very good correlation R 2 equal to 99.98, 98.74, 99.64, and 99.73 for the sandy soils (Sebikotane and Keur Mory) and the Marley and Clayey soils of Diamniadio, with a minimal SSR obtained compared to Perera's and Hernandez model.

The importance of the unsaturated zone as an integral part of the lithosphere for water flow and solute transport modelling has long been recognized. The hydraulic properties of the variably saturated zone are often comprehensively described by means of the van Genuchten–Mualem model. This paper deals with an inverse modelling approach using the software code HYDRUS2D and field infiltration data for determination of the van Genuchten–Mualem parameters. For that purpose, laboratory and field hydraulic tests have been performed using respectively undisturbed core samples collected from a multilayered loess complex and an in-situ borehole infiltration set-up in the same sediments near the town of Kozloduy, Northern Bulgaria. The obtained data was used to inversely estimate hydraulic properties with HYDRUS-2D at spatial scales much larger than the traditional laboratory-based analysis. The resulting large-scale parameters can be further implemented into water flow and solute transport m...

Characterizing hydraulic properties of the unsaturated zone at spatial scales commensurate with the numerical model grid size is key to reliable predictive modeling of the fate and transport of contaminants in the environment. We used the HYDRUS (2D/3D) model and inverse modeling to determine the hydraulic properties of a 10-m deep vadose zone from borehole infiltration tests. The investigated soil profile is located in the Pleistocene loess complex near the town of Kozloduy, Northern Bulgaria, in the vicinity of the Kozloduy Nuclear Power Plant (NPP). Four constant-head infiltrometer tests were carried out several meters below the ground surface to determine the unsaturated hydraulic properties of a silty loess, clayey loess, clayey gravel, and a highly carbonated layer. Infiltration tests provided data on cumulative infiltration and the movement of the wetting front in the initially unsaturated sediments surrounding the infiltrometer. A cylindrical TRIME-IPH/T3 time-domain reflectometry probe was used to measure water content variations with time during the movement of the wetting front. An axisymmetric model was developed in HYDRUS (2D/3D) for each of the four infiltrometer tests. The inverse optimization routine implemented in HYDRUS (2D/3D) was used to determine field-scale soil hydraulic parameters θ r , θ s , α, n, and K s for all layers of interest. Results suggest the size of the affected volume of soil was large enough to reduce the effect of spatial variability and to produce effective field-scale hydraulic parameters that are relevant for prediction of large-scale, variably-saturated water flow and radionuclide migration pathways at the Kozloduy NPP site.

The failure of natural dam may occur with a variety of failure modes which includes overtopping, seepage or piping, sudden sliding etc. Natural dams may fail due to seepage or piping because they have not undergone systematic compaction and they may have high porosities. In-depth knowledge of the mechanism of the dam failures by seepage or piping and measured data are still lacking. Extensive laboratory experiments are carried out to study enlargement of the pipe due to internal erosion and resulting outflow hydrographs by varying size of initial pipe, lake water level, lake water volume, slope and location of the pipe. This paper highlights limitations of simplified models used to predict outflow hydrograph due to piping failure of the dam based on experimental results and provides data set for the validation of numerical model. Experimental results show that the initial size, slope and location of pipes have significant effects on magnitude and occurrence time of peak discharge.

Process of failure of landslide dam can be classified into three types; overtopping, instantaneous slip failure and progressive failure. For similar hydraulic conditions peak discharge produced by failure of landslide dam depends on failure modes. Potential disaster in the downstream largely depends on magnitude of peak discharge so this study attempted to derive graphical relationships to predict failure mode by laboratory experiments in the flume. Critical channel slope for sediments, Mix 1-6 and Mix 1-7 are derived from flume experiments. Morevere, experimental data shows peak discharge produced by progressive failure is higher compare with peak discharge produced by instantaneous slip failure and overtopping. The concept of physically based integrated model is essential which can detect failure mode based on initial and boundary conditions and predict outflow hydrograph based on predicted failure mode for downstream hazard management.

The quaternary aquifer of Abidjan city, is often subjected to pollution because groundwater occurs at shallow depths (<6 m). However, this water is increasingly sought by one part of the population. Unfortunately the properties of this aquifer are not well known to define a management plan. This work aims to study quaternary aquifer through the hydrodynamic properties determination (porosity, saturated and unsaturated hydraulic conductivity and water retention curve) by prediction methods (Kozeny Carman, Kovac's modified and Brooks and Corey).The methods for predicting hydrodynamic properties tested gave good results. These methods have the advantage of using the physical properties of soil easy to measure. This is an original approach to the study of the hydrodynamic properties of the very extensive aquifers like the quaternary aquifer of Abidjan. These parameters are difficult to measure in situ.This work also highlighted risk areas for human settlements and infrastructure construction. Indeed, it is created permanent moisture above the water table in the fine sands. This moisture is the result of capillary rise which is important in fine soil particles.

This paper presents selected aspects of the model preparation and the experimental procedures used for testing the unsaturated soil behaviour in centrifuge environment. The study is based on the results of centrifuge tests carried out to investigate the influence of partial saturation on the behaviour of laterally loaded piles. The soil used in the experimentation is a high permeability silty clay soil, named B-grade kaolin. The models were statically compacted at two different densities with the same water content. In order to reduce the after compaction suction, the samples were subjected to an imbibition process at 1×g connecting the bottom of the model with the water reservoir. The influence of the compaction process and the imbibition stage on the subsequent inflight soil conditions are discussed and analysed. The centrifuge tests were realised at the centrifuge centre of the University Gustave Eiffel, in Nantes, France, in the framework of the GEOTRANSALP project.

An experimental study was carried out to investigate the effects of soil partial saturation on the behaviour of laterally loaded piles. The proposed study was conducted by means of centrifuge tests at 100g, where a single vertical pile was subjected to a combination of static horizontal load and bending moment. The study was conducted on a silty soil characterized with laboratory testing under saturated and unsaturated conditions. During flight, two different positions of water table were explored. The influence of density was investigated by compacting the sample with two different void ratios. Finally, the effects of a variation of saturation degree on the pile response under loading were studied by raising the water table to the ground surface. Data interpretation allows drawing different considerations on the effects of partial saturation on the behaviour of laterally loaded piles. As expected, compared to saturated soils, partial saturation always leads to a stiffer and resista...

The Shafdan case (Israel) offers the unique opportunity to investigate the long-term behaviour of a large scale Soil Aquifer Treatment system over a timescale of several decades. Specific problems occurred only after 20 years of successful operation, like the reduction of infiltration capacity, partly due to physical and chemical clogging, and the sudden appearance of significant concentrations of dissolved manganese in several wells. In the framework of the European FP6 ReclaimWater project, a new injection system through dug wells was developed and tested, destined to complete the existing infiltration basins, and the design and testing of the dug-well prototype was accompanied by different modelling activities. A preliminary 3D flow and conservative transport model was set up a the onset of the project to plan and design the dug well prototype and the monitoring wells. The radial pattern of solute transport obtained by the D model showed that a 2D radial model could satisfyingly ...

The paper presents the MUSE project to academics and practitioners who have an interest in the area of unsaturated soil mechanics. The MUSE ("Mechanics of Unsaturated Soils for Engineering") project is a major research and training network funded by the European Union involving six European universities and five industrial partners. Further details can be obtained visiting the MUSE website (2005). The project started in December 2004 with a planned duration of four years. It aims at undertaking a comprehensive programme of research on unsaturated soils divided in the following four main tasks: laboratory testing, constitutive modelling, numerical analysis and application to practical problems. An equally important objective of the project is to offer training to a new generation of engineers and scientists in the area of unsaturated soil mechanics by involving them in the planned research activities and encouraging transnational mobility through participation in a programme of workshops, schools, hands-on training sessions and secondments/visits organized at the different participating institutions. The paper outlines the main targets that the project intends to achieve in terms of both research outcomes and training activities. Due to the early stage of the project, it is currently not possible to present any detailed scientific results from the collaborative research programme. The paper, however, gives a description of the proposed benchmarking exercises that will be undertaken in the areas of laboratory testing and constitutive modelling.

Two stress ®elds, combination of total stresses, liquid pressure and gas pressure have to be considered to explain the deformational behaviour of unsaturated media. Elastoplastic models developed for these materials consider generally two yield surfaces, each one associated to a stress ®eld, and whose intersection produces a corner in the space of generalised stress components. In this paper, a stress point algorithm is proposed to cope with the integration of such constitutive laws, which can be seen as non smooth multisurface plastic models in the space of the two stress ®elds. The basic model developed by Alonso et al. (Alonso, E.E., Gens, A., 1990. A constitutive model for partially saturated soils. Ge otechnique 40 (3), 405±430), which will be used to test the algorithm, is ®rst described. Generalised stress and strain variables are then de®ned. Implementation of the return mapping algorithm, based on an implicit integration scheme, is presented with special attention devoted to the problem of mixed control imposed by the F.E. formulation generally used to analyse the hydromechanical behaviour of unsaturated media. Validation results on distinct generalised stress paths are given at the end.

This communication presents an overview of the MUSE Research Training Network. The MUSE project is funded by the European Commission and involves six European universities and five industrial partners in a cooperative research and training programme over a period of four years in the area of unsaturated soil mechanics. The research activities include laboratory testing, constitutive modelling, numerical analysis and application to boundary value problems. The training activities include the participation of ...

The generally unsaturated residual soils segment located above the groundwater table possess negative pore-water pressures. This amount of water content and resulting matric suction is an important geotechnical relationship for the unsaturated residual soil. This paper describes a field study that examined the water content and matric suction in the unsaturated weathered residual soil over one of the commonly found

This paper shows that the theory describing gas diffusion with no consideration of the total gas pressure leads to an underestimation of the water vapor diffusive permeability. This experimental method, called cup method, can be considered as one of the most popular tests in the domain of heat and mass transfer for building applications. Thus, it is likely that the water vapor permeability defined for most current building materials is underestimated. Thanks to the approach proposed in this paper, provided that there is an advective gas permeability, it is possible to know whether a given water vapor permeability has been underestimated or not. However, it is not possible to estimate the magnitude of this measurement error. In the last part, a new experimental procedure is proposed, integrating a total gas pressure measurement on both sides of the sample. This modified test method makes it possible to simultaneously determine the advective gas permeability and the diffusive vapor transfer coefficient.

Engineering properties of soils is controlled mainly by microstructures. In past studies on the relationship between microstructure and engineering properties of soil have been carried out. But in Loess it has been less or the microstructure components have been studied incompletely. Generally, the microstructure of Loess consists of three components grains, cement and pours. The frequency, type and distribution procedure of each of them control the geological – engineering of this soil against the static and dynamic loads. Using technology and new technology, measuring and calculating the parameters of the microstructure can be done easily. In recent years, fractal geometry has also been used to examine microstructure parameters and a numerical analysis is based on studies of the Loess. For general microstructure features, there are four statistical methods, geometric methods, modeling techniques and signal processing techniques. In this study, the two geometric and modeling method...

Electrical resistivity of soils is dependent upon various factors, including soil type, water content, saturation and pore fluid property. Experimental works have been performed to investigate the relationship between electrical resistivity and unsaturated subsurface conditions with varying physical property and landfill leachate contamination. The moisture density can be the most effective indicator for describing the relationship between electrical resistivity and physical property of unsaturated subsurface. For three different tested soils, the electrical resistivity of soil exponentially decreased as moisture density increased. The adding of leachate having various ions decreased the electrical resistivity. Also, the formation factor can be described by the term of moisture density in unsaturated sand. The formation factor was higher when soil and pore water were contaminated by higher concentration of leachate than when soil and pore water are uncontaminated, since ionic movement is restrained by electro-chemical interactions between soil particles and leachate constituents.

The process of drying in soil is often associated with complex deformations. Due to the complexity of both the soil structure and the coupled hydro mechanical processes occurring during drying, different forms and shapes can be created during drying. Soil curling is recognized as one of the typical phenomena taking place during shrinkage, when the surface layer is curled up or down by different mechanisms triggered during drying. A precise non-contact electro-optical technique based on a 2D laser profile scanner with motion controller to systematically track the evolution of the exposed surface of a natural soil during controlled drying conditions was used in this research. Different stages of curling were identified at different elapsed times. These stages are discussed in detail. To gain a better understanding of the different curling stages and their associated mechanisms, a set of drying experiments were performed on artificially prepared mixtures of kaolin and silica sand. Particularly, two basic mechanisms were studied: differential drying and differential shrinkage effects. A simple conceptual model is also proposed and discussed to help in the interpretation of the test results involving the curling.

Slate is a natural stone widely used for building, for which is subjected to regulations and standards in order to be commercialized. As far as the influence of water is considered, only detailed studies are compulsory when the water absorption is higher than 0.60%. However, the mechanical behavior of this layered material depends on water content, which is function of the relative humidity of the environment, and not considered in existing standards. In order to investigate its influence on foliation tensile strength, an experimental study was performed, which consists on carrying out Brazilian tests in slate samples with known water content, applied and controlled by using vapor equilibrium technique. This technique allows controlling the relative humidity of the environment surrounding the material and that of the air on its pores. Relative humidities between 55% and 92% were applied during the tests and defined considering climate data from the north of Spain. Despite the maximum water content tested in the slates was low (0.10%) in comparison with its saturation content (0.57%), the experimental results show a decreasing of the foliation tensile strength that reaches up to three times less with an increment of the environmental relative humidity of 37%. The results achieved can be important in order to quantify the layering weakness due to a natural alteration factor such as the environmental relative humidity. Moreover, the procedure employed is proposed as a convenient method for adequating each variety of slate stone to different climates according to its vulnerability to water.

If the cyclic sequence of faces for all the vertices in a polyhedral map are of the same types then the map is said to be a Semi-equivelar map. In this article we classify all semi-equivelar and vertex transitive maps on the surface of Euler genus 3, i.e., on the surface of Euler characteristic -1.

One of the challenges in hydrologic modelling in Indonesia is data limitation. Rainfall data quality is rarely evaluated, and in some cases, the data are unavailable. The Tropical Rainfall Measuring Mission (TRMM), satellite rainfall data provided by NASA, is an alternative method to solve such problems. This study aims to promote the use of TRMM data to analyze water availability and flood discharge in Duriangkang Dam, Batam City, Indonesia, in comparison with the use of available ground station data. Results show that the ground station data contain some errors; however, overall, the data show similar patterns and acceptable differences compared with the TRMM data. The NRECA and HEC-HMS models are used to analyze water availability, and both models are calibrated using the available reservoir water level data. The NRECA model generally shows a good fit of monthly discharge, although the use of TRMM results in slightly overestimated values in dry years. Similar results are obtained...

Oligomer of Unsaturated Polyester (UPol) Oligomer of Unsaturated Polyester (UPol) Unsaturated Polyester Resin (UP) Unsaturated Polyester Resin (UP) 4 INTRODUCTION UP resin Curing process of UP resin is a free-radical chain polymerization, exothermic and inhomogeneous process Growth of chains Cyclization of chains Phase separation (microgels formation) Microgel-Microgel Crosslinking (Percolation)

Bioremediation is a cost-efficient cleanup technique that involves the use of metabolically active bacteria to degrade recalcitrant pollutants. To further develop this technique it is important to understand the migration and deposition behavior of metabolically active bacteria in unsaturated soils. Unsaturated transport experiments were therefore performed using Deinococcus radiodurans cells that were harvested during the log phase and continuously supplied with nutrients during the experiments. Additional experiments were conducted using this bacterium in the stationary phase. Different water saturations were considered in these studies, namely 100 (only stationary phase), 80, and 40%. Results from this study clearly indicated that the physiological state of the bacteria influenced its transport and deposition in sands. Metabolically active bacteria were more hydrophobic and exhibited greater deposition than bacteria in the stationary phase, especially at a water saturation of 40%. The breakthrough curves for active bacteria also had low concentration tailing as a result of cell growth of retained bacteria that were released into the liquid phase. Collected breakthrough curves and deposition profiles were described using a model that simultaneously considers both chemical attachment and physical straining. New concepts and hypotheses were formulated in this model to include biological aspects associated with bacteria growth inside the porous media.

vegetation by moving to off-site areas, and may contaminate drinkable water sources. Conversely, persistent We investigated atrazine [2-chloro-4-(ethylamino)-6-(isopropylnonselective herbicides that are immobile in soils can amino)-s-triazine] leaching, sorption, and desorption in a Brazilian Oxisol under no-till (NT) and conventional (CON) agricultural man-cause problems with carryover. Therefore, the mobility agement. The specific objectives were (i) to infer characteristics of of herbicides in soils is both of agronomic and of envithe sorption process (equilibrium vs. nonequilibrium sorption, reversronmental concern. Scientists have concentrated their ible vs. nonreversible sorption) from breakthrough experiments, (ii) efforts on the elucidation of herbicide mobility in differto compare sorption parameters derived from breakthrough and batch ent studies on sorption, dissipation, and leaching of pesexperiments, (iii) to predict the distribution of atrazine on reversible ticides using soil samples in the laboratory or under and irreversible sorption sites within the soil columns using transport field conditions. parameters derived from breakthrough data, and (iv) to evaluate the Atrazine is a herbicide widely used in Brazil to control atrazine metabolites during breakthrough experiments. Breakthrough broadleaf weeds in corn (Zea mays L.) and sorghum curves of radiolabeled atrazine and of a nonreactive tracer, Br Ϫ , were [Sorghum bicolor (L.) Moench] under both NT and measured during miscible displacement experiments in unsaturated soil columns. The concentration of metabolites in the leachate was CON agricultural managements. It is applied in predetermined at three different times. At the end of the displacement emergence treatment and inhibits the Hill reaction in experiment, which lasted 494 h, the distributions of atrazine and its photosynthesis (Rodrigues and Almeida, 1995). metabolites within the soil columns and their partitioning in de-Atrazine and its dealkylated metabolites deethylsorbable, extractable and nonextractable fractions were determined. atrazine (DEA) and deisopropylatrazine (DIA) have Atrazine breakthrough curves were fitted with a three-site chemical been detected in surface and groundwater (Thurman et nonequilibrium convective dispersive transport model considering ir-

Conventional coupled elastoplastic deformation-flow finite element methods are not suitable for stability problems, since numerical results often become unstable as stresses in the elements arrive at the critical state. An analytical method using the imaginary viscosity method, a standard viscoplasticity computation scheme, is developed to analyse soil behaviour from start to failure. The procedure is validated using the examples of the bearing capacity of a footing on clay and an embankment on soft soil.

In coastal regions, land subsidence that results from industrial pumping of underground fluids, such as methane, is documented by in situ surveys. Laboratory characterization of gas bearing formations has also been published, which complements knowledge of reservoir compaction due to variation of fluid pressures. Gas withdrawal is reproduced in the laboratory by injecting water under a constant uniaxial or hydrostatic load to simulate the overburden. The water injection experiments provoke plastic compaction of the samples. This paper proposes a new modelling of the observed compaction of samples, as well as the changes in compressibility and size of the elasticity domain during water injection. The conceptual framework relies on the mechanics of unsaturated weak rocks, provided that the subsidence phenomenon concerns a threephase material with solid minerals, liquid water and gas. The proposed constitutive model called ACMEG-s describes the water retention capability of the studied soils and their mechanical behaviour. Consequently, the elasto-plastic volumetric changes within the porous medium incorporate the effects of water saturation and capillary pressure, or suction. The yield locus is formulated such that the shape of the yield limit depends on suction to model the apparent added stiffness that results from low water saturation. The modelling framework, based on generalising the effective stress principle to three-phase media, also provides an elastoplastic explanation of the well-known "wetting pore collapse" phenomenon. The ACMEG-s model shows consistent understanding of compressibility changes as the quantity of retained water varies. The successive phases of isotropic compression and uniaxial mechanical compaction are used for the model calibration. Interestingly, the phases of plastic compression during the water injection are captured accurately, which indicates that the model is applicable to reservoir-related subsidence studies.

This article experimentally evaluates the influence of the sample preparation method on the undrained monotonic and cyclic response of a saturated Malaysian kaolin. Two different sample preparation methods were adopted: slurry consolidation and moist compaction. The results of undrained monotonic triaxial tests showed the same critical state friction angle regardless of the sample preparation method and overconsolidation ratio. Under undrained cyclic loading, the well-known reduction in the number of cycles required to reach failure conditions with increasing cyclic stress ratios was evident regardless of the sample preparation method. However, important qualitative differences were observed depending on the sample preparation method, such as the degree of inherent anisotropy manifested in terms of the inclination of the effective stress paths, and the asymmetric vertical strain accumulation in the stressstrain space. The reasons for the observed differences in behavior are analyzed and discussed in the manuscript.

Which of the following statements is NOT a basic assumption of Terzaghi's onedimensional consolidation theory? a-The soil is homogeneous and isotropic. b-The soil is fully saturated. c-Water flow is one-dimensional. d-The coefficient of permeability and the coefficient of volume compressibility remain constant during the consolidation process. e-Darcy's law is not valid for flow in soil 2-In a consolidation test, if the coefficient of volume compressibility (mv) decreases with increasing effective stress and if the permeability (k) remains relatively constant, what does this imply for the coefficient of consolidation (cv)? a-cv increases. b-cv decreases. c-cv remains constant. d-The relationship between mv and cv cannot be determined. e-cv is inversely proportional to the square of mv. 3-What is the main effect of preconsolidation on the behaviour of clay soil during consolidation? a-Increased total expected settlement. b-Decreased total expected settlement. c-Increased rate of consolidation. d-Decreased coefficient of permeability. e-Increased coefficient of volume compressibility a. 280 mm b. 220 mm c. 250 mm d. 180 mm e. 313 mm 7-What is meant by the "average degree of consolidation U"? a-The ratio between the current settlement and the expected final settlement. b-The ratio between the current time and the total consolidation time c-The ratio between the current stress and the final stress. d-The ratio between the current void volume and the initial volume. e-The percentage of total settlement that has occurred at a distance z at any time t at a given time. 8-What is the "time factor" (Tv) in consolidation theory? a-A dimensional quantity representing time. b-A dimensionless quantity related to the degree of consolidation. c-A coefficient representing the permeability of the soil. d-A coefficient representing the compressibility of the soil e-The ratio between the cross-sectional area of the sample and its height 9-What is the main purpose of the consolidation test in a soil mechanics laboratory? a-To determine the shear strength of the soil. b-To determine the permeability of the soil. c-To determine the consolidation characteristics of the soil. d-To determine the particle size distribution of the soil. e-To determine the dry density of the soil. 10-Which of the following statements correctly describes the behaviour of an overconsolidated soil? a-It has been subjected to stresses in the past greater than the current stresses. b-It has not been subjected to any previous stresses. c-It always behaves elastically. d-It has very high permeability. e-It has very low shear strength. 11-What is the Mohr-Coulomb failure criterion? a-A criterion that defines the relationship between stress and strain in soil. b-A criterion that determines the tensile strength of soil. c-A criterion that determines the shear strength of soil in terms of normal stress and cohesion. d-A criterion that determines the permeability of soil. e-A criterion that determines the particle size distribution of soil 12-In a direct shear test, what type of stress is applied to the soil sample? a-Tensile stress. b-Triaxial compressive stress. c-Normal and shear stress. d-Bending stress. e-Torsional stress. 13-What is an advantage of the triaxial test compared to the direct shear test? a-Easier and faster to perform b-Less expensive. c-Better control over the stress path. d-Gives more accurate results for sandy soils. e-Does not require saturated samples. 14-What is meant by "excess pore water pressure"? a-The total water pressure in the soil pores. b-Is the temporary rise in pore water pressure within a saturated soil due to rapid loading. c-The pressure resulting from the weight of the soil grains. d-The pressure resulting from the weight of the water above the soil surface. e-The pressure required to drain water from the soil.

An experimental program is used to look at the impact of different parameters on the collapsibility of treated and untreated gypseous soil which is one of the most intricate soils. It is experiencing a high strength when it dry, but when subjected to wetting, it experiences a high collapse and volume change. A single odometer test was utilized to specify the collapsibility of soil. Lime and silica fume were utilized to detract the collapsibility of gypseous soil at a percent from 0 to 8%. The soil compacts at its field dry unit weight. Hence, while applying treatment material to stabilize the soil, it is crucial to specify the beginning ratio of saturation (So) that yields a satisfactory compaction result and optimal connection among soil particles. These factors were examined to determine the effects of varying starting suction amounts and starting saturation ratios on the collapsibility of both treated and untreated gypseous soil. Furthermore, a saturation-effective ratio that achieves the lowest collapse potential would be defined. The filter paper method was utilized to specify the initial matric suction to examine how it affects the soil's ability to collapse. The primary findings indicate that for both natural and treated soils, compacting the soil at a starting saturation ratio of 10, 20, and 30 percent results in a reasonably high collapsibility. Between 40 and 50 percent was the effective saturation ratio that yielded the lowest collapsibility. Soils' collapsibility was seriously affected by suction pressures. The disparity in the matric suction of the compressed specimens during the soaking had less of an influence on the collapsibility of the treated gypseous soil (particularly treated with silica fume) than untreated soil. To imitate the collapsibility of both natural and treated gypseous soil, an empirical equation is expected.

We present a three-dimensional discrete-element approach for numerical investigation of wet granular media. This approach relies on basic laws of contact and Coulomb friction enriched by a capillary force law between particles. We show that the latter can be expressed as a simple explicit function of the gap and volume of the liquid bridge connecting a pair of spherical particles. The length scales involved in this expression are analyzed by comparing with direct integration of the Laplace-Young equation. We illustrate and validate this approach by application to direct shear and simple compression loadings. The shear and compression strengths obtained from simulations reproduce well the experimental measurements under similar material and boundary conditions. Our findings show clearly that the number density of liquid bonds in the bulk is a decisive parameter for the overall cohesion of wet granular materials. A homogeneous distribution of the liquid within the bridge debonding distance, even at low volume contents, leads to highest cohesion. The latter is independent of the liquid content as far as the liquid remains in the pendular state and the number density of liquid bonds remains constant.

We present a 3D discrete‐element approach for numerical investigation of wet granular media. This approach relies on the basic laws of contact and Coulomb friction enriched by a capillary force law between particles. We show that the latter can be expressed as a simple explicit function of the gap and volume of the liquid bridge connecting a pair of spherical particles. The length scales involved in this expression are analyzed by comparing with direct integration of the Laplace–Young equation. We illustrate and validate this approach by application to direct shear and simple compression loadings. The shear and compression strengths obtained from simulations reproduce well the experimental measurements under similar material and boundary conditions. Our findings clearly show that the number density of liquid bonds in the bulk is a decisive parameter for the overall cohesion of wet granular materials. A homogeneous distribution of the liquid within the bridge debonding distance, even...

We analyse the Coulomb cohesion of wet granular materials and its relationship with the distribution of capillary bonds between particles. We show that, within a harmonic representation of the bond and force states, the shear strength can be expressed as a state equation in terms of internal anisotropy parameters. This formulation involves a dependence of the shear strength on loading direction and leads to the fragile behaviour of granular materials. The contact dynamics simulations of a wet material, in which a capillary force law is prescribed, are in excellent agreement with the predictions of this model. We find that the fragile character decreases as the local adhesion is increased or the mean stress is decreased.

Engineering properties of soils is controlled mainly by microstructures. In past studies on the relationship between microstructure and engineering properties of soil have been carried out. But in Loess it has been less or the microstructure components have been studied incompletely. Generally, the microstructure of Loess consists of three components grains, cement and pours. The frequency, type and distribution procedure of each of them control the geological – engineering of this soil against the static and dynamic loads. Using technology and new technology, measuring and calculating the parameters of the microstructure can be done easily. In recent years, fractal geometry has also been used to examine microstructure parameters and a numerical analysis is based on studies of the Loess. For general microstructure features, there are four statistical methods, geometric methods, modeling techniques and signal processing techniques. In this study, the two geometric and modeling method...

The basis of the design of earth and rockfill dams is focused on ensuring the stability of the structure under a set of conditions expected to occur during its life. Combined mechanical and hydraulic conditions must be considered since pore pressures develop during construction, after impoundment and in drawdown. Other instability phenomena caused by transient flow and internal erosion must be considered. The prediction of the hydromechanical behavior of traditional and non-traditional materials used in the construction of dams is therefore fundamental. The materials used for dam's construction cover a wide range from clayey materials to rockfill. In a broad sense they are compacted materials and therefore unsaturated materials. A summary of the current level of knowledge on the behavior of traditional materials used in the construction of dams is presented in the paper. Regular compacted materials (with a significant clay fraction), rockfill and compacted soft rocks are studied with more detail. The latter are non-traditional materials. They are analysed because their use, as well as the use of mixtures of soil and rock, is becoming more necessary for sustainability reasons.

Self potential (SP) anomalies over Piton de La Fournaise volcano (La Réunion Island) are generally inter-preted as resulting from meteoritic water porous flow. However, there is no clear evidence that the subsurface is permanently saturated. Recently, a convective subsurface airflow has been evidenced within a quiescent cone at Piton de La Fournaise (Formica Leo). SP and thermal anomalies are reported on the unsaturated edifice and are seen to be correlated. It is proposed that the SP signal is generated by the movement of water films present on the porous matrix, induced by the intense humid airflow within Formica Leo. The structure of the cone, determined from electrical resistivity tomography (ERT), ground penetrating radar (GPR), microgravimetric and kinematic GPS data, is used to constrain a 3D numerical model of the air convection. The calculated temperature is then used to derive the related SP signal, the electrokinetic coupling coefficient being estimated from direct observations of the electrical resistivity of the soil. Extrapolating these results to the scale of the volcano, it is thus proposed that a cold humid air-flow enters the flanks of the 400 m-high terminal dome, flows up along the sloped and stratified volcanic layers before exiting through the vertical fractures around the Dolomieu collapse. It is demonstrated that the SP anomalies catches the main features recovered over the entire volcano. This result strongly sug-gests that humid airflow may play a major role on the generation of SP anomalies at Piton de la Fournaise volcano, and perhaps in other unsaturated volcanic edifices.

La consolidación es un proceso fundamental en la ingeniería geotécnica, que describe la disipación del exceso de presión de poros en suelos saturados bajo carga. La teoría de consolidación unidimensional de Terzaghi proporciona la ecuación diferencial parcial que gobierna este proceso. Aunque existen soluciones analíticas, los métodos numéricos, como el método de diferencias finitas (MDF), son herramientas poderosas para obtener soluciones aproximadas, especialmente en casos complejos. Este documento describe la derivación de la ecuación de consolidación, detalla la aplicación de los esquemas de diferencias finitas explícito e implícito para su resolución numérica, y explica cómo incorporar diferentes condiciones de contorno (drenantes e impermeables) en la formulación numérica. Se discuten las ventajas, desventajas y criterios de estabilidad de cada esquema.

The soils of Jinka in Southern Ethiopia were studied based on the detail works on soil pit description, characterizing and classification following the FAO and USDA guidelines. For this, along with the toposequence and landscape, six soil profiles were opened on an area of 100 ha of research field to make them suit for sustainable soil management practices. The soils were generally described as dark reddish brown to very dark brown and deep. These soils were characterized as slightly (4.87) to moderately acidic (6.18). The OC and available phosphorus were found to range from low to medium. All micronutrients were found to be highly associated with lower soil reaction. These soils group can be classified as Cambisols. Therefore, amending the soil with lime based on exchangeable acidity, essential and deficient nutrients will be vital for supplying food and feed crops in the region. However, continuous assessment of the nutrient status at every five to seven years is necessary to make sure that the soil quality is maintained.