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Title: Densification and hysteresis of sand under cyclic shear
Authors: Northwestern University (Evanston, Ill.). Technological Institute
Bažant, Z. P.
Krizek, Raymond J.
Keywords: Densification
Sandy soils
Simple shear tests
Stress-strain relations
Soil mechanics
Cyclic shear
Publisher: Soils and Pavements Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Contract Report
Abstract: An extensive set of test data on the densification and stress-strain behavior of a dry sand at various relative densities and confining pressures and subjected to cyclic simple shear strains of different amplitudes is presented and used to verify a previously developed endochronic constitutive law and to determine its material parameters, including their dependence on relative density. In this law the accumulation of inelastic strain due to the irreversible rearrangement of grain configurations associated with deviatoric strains is characterized by a non-decreasing material variable, termed the rearrangement measure, which, in turn, forms the basis of an intrinsic time scale and related variables termed the densification measure and the distortion measure. The shear modulus is identified to be a function of the confining (volumetric) stress and the second invariant of the strain deviator. To fit the test data, step-by-step numerical integration of shear stresses is performed for a prescribed cyclic strain history, In contrast with current empirical methods, the material behavior is described herein by a constitutive law that satisfies all requirements of continuum mechanics; hence, this law should, in principle, be generally applicable, including the cases of non-sinusoidal loadings with varying amplitudes, general multiaxial stress states, and nonproportional stress component histories. In addition, the law automatically exhibits hysteretic damping and is fully continuous, i.e., it contains no inequalities, such as those used in plasticity to distinguish unloading.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Contract Report

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