Saturated Clay Soil Research Articles

Deformation and Failure in Wet Clay Soil: Part 3, Finite Element Analysis of Cutting of Wet Clay by Tines

The finite element method (FEM) was used to model cutting of wet clay by a wide tine using measured soil stress-strain characteristics as input data. The incremental method was used to deal with this geometrically nonlinear problem and correspondingly a revised tangent stiffness formula was derived and employed in the calculation. The incompressible property of the saturated clay soil was considered when determining Poisson's ratio of the soil. A continuously updated interface element was used to simulate the behaviour at the soil-tool interface. Calculation results provided soil displacement, strain, stress and failure state, and tool force-displacement curves. Calculated soil deformation patterns were qualitatively similar to those measured and tool forces were close to measured values.

Analysis of Earthquake Fault Rupture Propagation through Cohesive Soil

An improved understanding of earthquake fault rupture propagation through saturated clay would assist engineers in siting and designing facilities to be constructed in regions where cohesive soils overlie potentially active faults. The results from numerical analyses suggest that the finite-element method can be applied to this class of problem provided that the soil's nonlinear stress-strain behavior is adequately modeled. It was found that the height of the shear rupture zone in the overlying saturated clay soil at a specified base rock fault displacement depends primarily on the soil's failure strain. As the clay's failure strain decreases, the shear rupture zone in the clay overlying the bedrock fault propagates further at a specified base displacement. Other material parameters such as soil shear strength and stiffness also affect the fault rupture process, but not to the extent of failure strain. The orientation of the shear rupture zone through the soil depends largely on the orientation of the underlying bedrock fault plane.

A Parameterization Scheme for the Mminimum Surface Temperature of a Saturated Vegetated Clay Soil

Based on model calculations with a combined radiation-turbulence model, a simple relation to estimate the minimum surface temperature of a saturated vegetated clay soil from the 2 m air temperature is proposed. The parameterization scheme is tested against observations taken at the meteorological observational site near the village of Cabauw in the Netherlands. This comparison shows that the parameterization scheme is able to reproduce the minimum surface temperature under these circumstances with approximately 2.5°K.

A dynamic equation for the pressure-sinkage relationship in saturated clay soils

Abstract Experiments showed that the plate pressure-sinkage relationship in a saturated clay soil was strongly dependent on deformation rate. An equation for the pressure-sinkage relationship incorporating deformation rate was developed, using visco-plastic theory, and was found to describe the measured data well.

Consolidation analysis for partly saturated clay by using an elastic–plastic effective stress–strain model

AbstractThe theory of consolidation is extended to partly saturated clay soils, and formulated for finite element analyses. This formulation couples the effects of both stress and flow. It takes account of variations of this permeability of the soil and compressibility of the pore fluid with changes in void ratio, and the non‐linear stress–strain behaviour of soil. The Cam Clay model is revised to model the stress–strain behaviour of compacted soils. The compressibility of pore fluid is derived using Boyle's Law and Henry's Law, taking into account the effect of surface tension. An empirical equation is developed for permeability of pore fluid. An example of settlement of a footing on partly saturated soil is described and discussed.

Initial Pore Pressure from Vertical Surface Loads

In estimating the initial settlement of footings supported on saturated clay soils, it is necessary to evaluate the instantaneous excess pore pressure developed in the soil upon application of the load. In this study, an explicit formula is derived for the instantaneous excess pore pressure beneath a corner of a uniformly loaded rectangular area. The pressure at an arbitrary point within the soil, then, is obtained by simple superposition of the basic result.

Mechanisms controlling the secondary compression of clays

This Paper deals with the mechanism controlling the one-dimensional secondary compression behaviour of saturated clay soils. The behaviour of the clays has been explained in the light of the modified effective stress concept which takes into consideration the interparticle attractive and repulsive forces. A non-dimensional secondary compression coefficient is defined as the ratio of the secondary compression per unit of log (time) to the final thickness of the sample for any pressure increment. It is shown that the secondary compression coefficient is directly related to the strength of soil skeleton at particle level which is governed by the modified effective stress concept. Seven organic fluids, water and air of different dielectric properties were used to vary the interparticle forces in the one-dimensional consolidation tests. To confirm the nature of the mechanism, tests were also conducted in which load increments, load increment ratio and void ratio were varied. The rectangular hyperbola method is used to identify the magnitude of secondary compression. The experimental results show that the secondary compression coefficient decreases with increase in effective stress (or strength), with decrease in pressure increment and with a decrease in void ratio. Le présent article traite du mécanisme régissant le comportement en compression secondaire uni–dimensionnelle de sols argileux saturés. Le comportement des argiles est expliqué en fonction du concept de contrainte effective modifié qui tient compte des forces d'attraction et de répulsion interparticulaires. Un coefficient de compression secondaire non–dimensionnel est défini comme étant le rapport de la compression secondaire par unité de log (temps) et de l'épaisseur finale de l'ećchantillon pour tout incrément de pression. Il est démontré que le coefficient de compression secondaire est directement fonction de la résistance du squelette du sol au niveau particulaire, laquelle est régie par le concept de contrainte effective modifié. Sept fluides organiques, de l'eau et de l'air ayant des propriétés diélectriques différentes ont été utilisés en vue de faire varier les forces interparticulaires darts le cadre des effets de consolidation uni-dimensionnelle. Afin de confirmer la nature du mécanisme, d'autres essais ont également été effectués en faisant varier les incréments de charge, le rapport des incréments de charge et le rapport des vides. La méthode de l'hyperbole rectangulaire a servi à déterminer l'importance de la compression secondaire. Les résultats expérimentaux démontrent que le coefficient de compression secondaire diminue en fonction de l'augmentation de la contrainte effective (ou de la résistance), de la diminution de l'incrément de pression et d'une diminution du rapport des vides.

Foundations in trenches tamped into saturated clayey soils

1. The method proposed for tamping makes it possible to construct trenches of a given shape and depth in saturated clay soils under separately standing foundations, even where the water table is situated at a depth 0.3–1 m from the graded surface of the ground. 2. The effective pressure on a bed for foundations with a flat lower surface in tamped trenches can be assumed equal to 0.3–0.35 MPa at which the settlement does not exceed 30 mm. 3. The tamping of a loose rigid material (gravel, crushed stone), and also a local clay soil with an optimum moisture content into the trench bed makes it possible to increase significantly the effective pressure on the bed and reduce the foundation settlements. 4. It is expedient to continue study of the method in question to investigate the effect of the shape and size of the tamper on the trench-tamping process under different soil conditions; the effect of the composition and quantity of material being tamped in on the shape and size of the distributing cushion and on the reduction in foundation settlements; the distribution of moisture and the density of the soil; and, the position of the water table in the beds of tamped trenches.

Experimental investigation of the shear strength of saturated clay soil by the plate shearing method

Experimental investigation of the shear strength of saturated clay soil by the plate shearing method

Effects of Drainage in Repeated Loading of Clays

An effective stress model for the response of saturated clay soils experiencing cyclic loading is described. Using undrained response as a basis, the influence of periodic drainage during the cyclic loading is illustrated and is quantified within the effective stress model. Behavior is separated for contractive and dilative soils. For contractive soils drainage results in volume decrease and eventual equilibrium under a particular constant level of cyclic loading. As a result of the drainage there is significant strength increase. Dilative soils increase in volume as a result of cyclic loading with drainage and there is a resulting decrease in strength. Stress changes, water content changes, and strength after cyclic loading are predictable using this model.

Winter placement of moraine material in the dam of the Ust'-Khantaisk hydro development

1. Stockpiling the usable bed of a borrow pit in low piles is a reliable and tested method of creating reserves of soil with a high initial temperature for good-quality placing of cohesive soils under low-tem-perature conditions. 2. With consideration of the good mixing of the soil during piling it is recommended to use artificial soil mixtures with prescribed characteristics of the soil obtained by layer-wise piling of different soils: loams, clays, sandy loams, sand-gravel mixture, and gravel deposits. 3. In humid regions it is best to dump the soil directly into the pile bypassing intermediate embankments. For better accumulation of the heat of solar radiation by the soil it is recommended to dump the soil into the pile in 2-m layers. 4. The process of placing saturated coarse-grained clay soils in the cutoff zones of dams at temperatures to — 30°C developed at the construction of the Ust'-Khantaisk hydroelectric station broadens the possibilities of using local materials in dam construction in the North. 5. Since in humid regions natural drying of soil is difficult, at the design stage it is necessary to make a technical and economic comparison of variants of dams with consideration of placing saturated soils in the cutoff zones or drying the soil at the borrow pit by means of special equipment (electric heating, furnaces, etc.). 6. As the practice of constructing the Ust'-Khantaisk hydroelectric station showed, it is possible, as an exception, to permit during construction the freezing of individual zones of the cutoffs of dams provided that the frozen soil has a homogeneous structure and will be compacted in a thawed state to the design density.

Diffusion coefficient of I-ions in saturated clay soil

The diffusion of I-ions was measured in saturated clay soil using radioactive I131 and I-ions. The measured diffusion coefficient of I-ions was 1.96×10−7 cm2/sec in disturbed soil and 0.67×10−7cm2/sec in undisturbed soil. The positive adsorption of I-ions resulted in lower diffusion coefficient of I-ions than that of C1-ions.

The effective stress response of a saturated clay soil to repeated loading: D. A. Sangrey, D. J. Henkel and M. I. Esrig.Can. Geotechnical J., 6, 241 (Aug. 1969)

The effective stress response of a saturated clay soil to repeated loading: D. A. Sangrey, D. J. Henkel and M. I. Esrig.Can. Geotechnical J., 6, 241 (Aug. 1969)

Discussion of Stress-Strain Characteristics of a Saturated Clay Soil at Various Rates of Strain

Discussion of Stress-Strain Characteristics of a Saturated Clay Soil at Various Rates of Strain

Stress-Strain Characteristics of a Saturated Clay Soil at Various Rates of Strain

Stress-Strain Characteristics of a Saturated Clay Soil at Various Rates of Strain

THE EFFECTIVE STRESS RESPONSE OF A SATURATED CLAY SOIL TO REPEATED LOADING

The results of a series of tests designed to examine the behavior of saturated clay soil under repeated loading are reported. Triaxial tests, under conditions of axial symmetry, were used and the rates of deformation were chosen so as to permit the accurate measurement of pore water pressure at all stages of the tests.It was found that, for any particular consolidation history, a critical level of repeated stress existed. Below this critical level, a state of nonfailure equilibrium was reached in which the stress-strain curves followed closed hysteresis loops. Above the critical level of repeated stress, effective stress failure occurred; and each cycle of loading produced cumulative increases in deformation.An interesting feature of the test results was that a linear relationship between the magnitude of the applied repeated stress and the increase in pore water pressure was found for stress levels below the critical value.

Method of determining creep parameters of incompletely saturated clay soils based on results of undrained tests

THE DEFORMATION CHARACTERISTICS OF SOILS ARE USUALLY DETERMINED IN COMPRESSION INSTRUMENTS WITH FREE ESCAPE OF WATER FROM THE VOIDS. IN THIS CASE WE MUST CONDUCT LONG (AT LEAST A MONTH) TESTS TO DETERMINE THE CREEP PARAMETERS OF THE SOIL SKELETON. A DESCRIPTION IS GIVEN OF A METHOD FOR DETERMINING CREEP PARAMETERS OF THE SOIL SKELETON WHICH PERMITS REDUCING TEST TIME TO 1-2 DAYS. THIS METHOD HAS BEEN DEVELOPED ON THE BASIS OF RESULTS OF UNDRAINED CREEP TESTS UNDER CONDITIONS OF UNIAXIAL COMPRESSION WITHOUT THE POSSIBILITY OF LATERAL EXPANSION. /AUTHOR/

Construction on weak saturated clay soils (all-union conference in Tallin)

Construction on weak saturated clay soils (all-union conference in Tallin)