Establishment of strain softening elasto-visco-plastic constitutive model and studies on the progressive failure of ground material

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By the centrifuge modeling tests and the finite element analyses, the purposes of this research work are to establish the constitutive model which can expresses both strain-softening and time dependency behavior of soft rock and over-consolidated clay, to discuss the stability of the slope which consists of soft rock and/or over-consolidated clay, and then to grasp the mechanism of the progressive failure. Moreover, it is considered that the time dependency behavior of soft rock is equivalent to the change of the effective stress with the change of pore pressure, the constitutive model is applied to the boundary value problem as the water-coupling problem. Then, the constitutive model with soil-water coupling is also applied to the collapse of the slope.The remarkable mechanical behavior of soft rock and over-consolidated clay can be presented by the strain hardening and softening in the stress - strain relation and the positive dilation with progressed the strain softening. In this re … More search work, the elasto-plastic constitutive model with strain softening whose yielding function is defined by the stress-history tensor are established.In the centrifuge modeling tests, the modeling ground makes of mixed Gypsum to Fukakusa clay. Displacement vectors and strain vectors are observed and estimated through the movement of the targets installed in the modeling ground, and then the mechanism of the progressive failure of the slope is discussed.Various parameters of the proposed constitutive model are determined through the element experiments, and then the finite element soil-water coupling analyses are carried out to simulate the progressive failure of the slope. As compared the numerical simulations with the experimental results, the progressive failure of the slope is discussed.Finally, actual progressive failure of cutting slope in the sedimentary mudstone is simulated by the soil-water coupled analysis based on the elasto-plastic constitutive model with strain softening. Compared the actual collapse with the numerical results, the validity and the problem of the proposed model are discussed. Less