MATHEMATICAL MODELING OF UNDRAINED BEHAVIOR OF SOILS
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Abstract
Mathematical modeling of the undrained behavior of soils is carried out on the basis of theoretical paths of effective stresses under undrained deviatory loading in a triaxial compression chamber. The recommendations of normative sources and scientific papers on the application of undrained calculations in practice are analyzed. The basic laws of soil mechanics are considered in calculations taking into account the formation of excess pore pressures in the base. Theoretical calculations obtained by A. Skempton for the law of effective stresses of C. Terzaghi are applied for mathematical modeling of paths. Based on the results of mathematical modeling of an ideal elastic-plastic body it is shown that an accurate description of the paths of effective soil stresses using the elastic theory does not correspond to real soil tests. The influence of the law of volumetric plastic deformation on the paths of effective stresses and on the undrained shear strength is analyzed. The formula for determining the undrained strength parameter for the Modified Cam Clay model is presented. Attention is drawn to the fact that in addition to volumetric plastic deformation which affects the undrained calculation it is necessary to take into account the shear component of plastic deformation which is decisive for the calculations of excavations. Simulation of laboratory tests of soils in the Soil Test for the Mohr-Coulomb, Modified Cam Clay and Hardening Soil Models was carried out. A comparison of the obtained results with the data of laboratory tests is presented. The influence of the choice of soil model on the value of resistance to undrained shear is shown. Recommendations are given for choosing a soil model for numerical simulation based on the results of laboratory triaxial consolidated undrained tests.
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References
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