The time-dependent deformation and damage constitutive model of rock based on dynamic disturbance tests

Abstract

In the deep rock excavation process, the rock will produce deformation and damage under multiple dynamic disturbances, while there is also unrecoverable time-dependent deformation. In order to research this deformation characteristic, a sine wave disturbance triaxial loading test was carried out on red sandstone to simulate the failure process of deep underground rock mass under dynamic disturbance loads with low confining pressure. Based on the results that the deformation of the rock increases suddenly during dynamic disturbances and varies with the number of disturbances, a novel disturbance damage model relating the number of disturbances to the deformation of the disturbances is created to describe the deformation and damage accumulation of the rock under multiple disturbances and an operator is developed to ensure that the model works. In order to describe the time-dependent deformation of rocks, the elasticity model in the traditional Bingham model was improved to a nonlinear elasticity model that varies with time, and its viscous and plasticity models were retained. The time-dependent deformation and damage constitutive model is obtained by combining the improved Bingham model with the disturbance damage model. The model parameters were identified according to the test data, and the finite-element calculation of the model was realized with the secondary development program. The results show the strain of rock increases suddenly under multiple disturbances, and the main reason for rock damage is the action of dynamic disturbances. The fitted curves and finite-element results are consistent with the experimental results. The time-dependent deformation and damage constitutive model of rock not only reflects the decaying rheological and steady-state rheological properties of rock under static loading but describes the characteristics of strain surge and disturbance damage accumulation caused by dynamic disturbances. This article contributes to the characteristics of the deformation of deep rock mass.