Research on progressive failure and the establishment of analytical method based on constitutive

点击翻译按钮获取中文摘要

1.The derivation of elasto-viscoplastic model with strain-softeningBased on Adachi-Oka's model with strain softening, and elasto-viscoplastic model which can both describe the time dependency and strain-softening, is proposed for soft rock. In the derivation of the model, three new assumption are adopted. That is, the new definition of stress history, the introduction of time measure and the decline of shearing strength with time.2.Investigation of the validity of the proposed elasto-viscoplastic modelThe time dependent behavior includes three aspects as strain rate dependency, creep and stress relaxation. The proposed model is applied to the drained triaxial shearing tests of Ohya-stone and the drained triaxial creep tests of Ohya-stone. It is found that the model can well simulate the all aspects of time dependent behavior.3.Analysis of progressive failure on model groundBased on above mentioned model, a finite element analysis of progressive failure on model ground is carried out. As a result, the mechanism of progressive failure that occurs at first in local point and develops to other place progressively is well simulated. The validity of the model in boundary problems is proved.4.Finite element analysis of progressive failure on soft-rock-slope excavationBy considering the strain-softening, the deterioration of strength with time and the initial k_0-stress state in the ground, a finite element analysis of elasto-plasticity is carried out for the excavation on slope to investigate the progressive failure caused by slope excavation. As a result, it is found that the ground yields progressively with the deterioration and the stress in the ground redistributed with deformation.