Triaxial shear test

About: Triaxial shear test is a research topic. Over the lifetime, 5394 publications have been published within this topic receiving 107930 citations.

The shear strength of unsaturated soils

Abstract: The shear strength of an unsaturated soil is written in terms of two independent stress state variables. One form of the shear strength equation isThe transition from a saturated soil to an unsatur...

Model for the prediction of shear strength with respect to soil suction

Abstract: Experimental studies on unsaturated soils are generally costly, time-consuming, and difficult to conduct. Shear strength data from the research literature suggests that there is a nonlinear increas...

On the generalized stress-strain behaviour of wet clay

Abstract: THE BASIC CAMBRIDGE THEORY OF THE STRESS-STRAIN BEHAVIOUR OF WET CLAYS, AS DEVELOPED FOR 'TRIAXIAL' (AXI-SYMMETRIC) COMPRESSION TEST CONDITIONS, IS EXTENDED TO INCLUDE GENERALIZED THREE-DIMENSIONAL STRESS AND STRAIN CONDITIONS. THE THEORY IS DEVELOPED IN THE LIGHT OF A NEW WORK EQUATION PROPOSED BY BURLAND. TWO OTHER NEW CONCEPTS ARE INTRODUCED. FIRST, A NEW YIELD LOCUS TO TAKE ACCOUNT OF THE SHEAR DISTORTION THAT OCCURS, WITHOUT PLASTIC VOLUME CHANGE, FOR STATE PATHS BENEATH THE STATE BOUNDARY SURFACE. SECONDLY, THE MOHR-COULOMB CRITERION IS INCORPORATED IN THE THEORY TO PREDICT RUPTURE WHEN WET CLAYS ARE SUBJECTED TO STRESS PATHS IN THREE-DIMENSIONAL STRESS SPACE. THE MECHANICAL BEHAVIOUR OF A GIVEN WET CLAY UNDER SUCH A GENERAL SYSTEM IS PREDICTED FROM THE THREE SOIL CONSTANTS, M, LAMBDA AND KAPPA OBTAINED FROM TRIAXIAL COMPRESSION TESTS. AFTER SHOWING THAT TRIAXIAL EXTENSION TEST RESULTS CAN BE SATISFACTORILY PREDICTED FROM TRIAXIAL COMPRESSION DATA, PARTICULAR ATTENTION IS PAID TO PLANE STRAIN WHICH IS SO FREQUENTLY RELEVANT IN PRACTICAL PROBLEMS. THE PLANE-STRAIN BEHAVIOUR AS PREDICTED FROM TRIAXIAL DATA IS COMPARED WITH OBSERVATIONS IN A PLANE-STRAIN APPARATUS, AND A SIMPLE-SHEAR APPARATUS. EXCELLENT AGREEMENT IS OBTAINED, AND CONFIRMS THE PREDICTION THAT FOR WET CLAYS THE ANGLE OF INTERNAL FRICTION IN DIRECT SHEAR TESTS IS LESS THAN THE TRIAXIAL VALUE. TO ILLUSTRATE THE POWER AND PRACTICAL SIGNIFICANCE OF THE THEORY, IT IS USED TO PREDICT THE STRAINS THAT ARE REQUIRED TO DEVELOP THE ACTIVE AND PASSIVE RANKINE STATES IN A MASS OF WET CLAY. THESE PREDICITIONS ARE IN AGREEMENT WITH EXPERIENCE. /RRL/A/

Hyperbolic Stress-Strain Response: Cohesive Soils

Abstract: The divergent concepts of a stability analysis, as compared with a load-deformation approach to soil mechanics, are shown to be compatible within the framework of a hyperbolic stress-strain relation. The two-constant hyperbolic form of the stress-strain response is such that the ultimate shear strength of the soil is contained within the general formulation and appears in the mathematical limit of the stress as the strain becomes excessive. This is quantiatively demonstrated for a remolded cohesive soil tested in consolidated-undrained triaxial compression. The variables contained in the hyperbolic stress-strain relation include the preconsolidation pressure, rebound stress, lateral pressure during the test, vertical normal stress, strain, and rate of strain. History effects are included in terms of the overconsolidation ratio. The general formulations obtained for the consolidated-undrained triaxial tests are compared with the results reported in the literature by other investigators for both drained and undrained consolidated triaxial tests under various conditions.

Non-Associated Plasticity for Soils, Concrete and Rock

Abstract: With reference to practical engineering problems it is shown that considerable differences may be encountered between the results from associated and those from nonassociated plasticity theories. Next, the need for a non-associated plasticity theory is demonstrated by considering test results for sand, concrete and rock. Elementary material parameters are discussed such as Young's modulus and Poisson's ratio for the description of the elastic properties; and a cohesion and a friction angle for the determination of the strength. The salient difference from associated plasticity theory concerns the introduction of a dilatancy angle which controls the inelastic (plastic) volume changes. This dilatancy angle is not only a suitable parameter for the description of soils, but also appears to be useful for concrete and rock. Basically, the paper consists of three parts as we consider three types of models of increasing complexity. The first model is a perfectly-plastic model, which employs the five aforementioned parameters. It is based on test data rather than on Drucker's hypothesis of material stability. The consequences thereof are examined. The second model is a straightforward extension of the first model by augmenting it with friction hardening and cohesion softening. This novel idea is introduced to account for the degradation of the cohesion of cemented granular materials with increasing inelastic deformation. The model is employed in an analysis which shows that plastic deformations tend to localize in thin shear bands, which may occur even before peak strength is reached. Finally, a review is given of concepts for modelling hysteresis and strain accumulation in cyclic loading. The concept of a bounding surface in addition to a yield surface is discussed and is adapted for use in a sophisticated model for loose and cemented granular materials under cyclic loading.