水岩耦合作用下岩石黏弹塑性分析及屈服准则研究

Study on rock visco-elastic plasticity analysis and yield criterion of water and rock interaction

为了描述岩石在不同孔隙水压下蠕变特性,采用MTS815.02岩石试验机进行饱和砂岩流固耦合蠕变试验,并根据改进后Druck-Prager屈服函数求出岩石蠕变本构模型。研究结果表明:在有效应力和时间的共同作用下,强度参数在蠕变过程中不断劣化,总体上黏聚力下降了16.89%,内摩擦角下降了7.93%,岩石在外荷载作用下的损伤主要由黏聚力下降引起。因此,在工程实际中防止巷道围岩损伤破坏主要控制黏聚力的减小,其次考虑控制内摩擦角变化。最终,根据改进后Druck-Prager屈服函数,建立岩石蠕变本构模型,可表征描述岩石衰减蠕变、稳定蠕变阶段和加速蠕变,且拟合曲线与试验曲线性系数均在0.95以上。

In order to describe the creep features of the rock under different pore water pressure,a MTS815.02 rock testing machine was applied to have a fluid-solid coupling creep test of the saturated sandstone and according to the improved Druck-Prager Yield Function,the creep constitutive model of the rock was conducted. The study result showed that under the joint function of the effective stress and time,the strength parameters would be continuously deteriorated. Generally the cohesion strength was reduced by 16.89% and the internal friction angle was reduced by 7. 93%. Under the external loading,the rock failure was mainly caused by the reduction of the cohesion strength. Therefore in the engineering practices,to prevent the failure and damage of the surrounding rock should control the cohesion strength and secondary should consider the control of the internal friction angle variation. Finally according to the improved Druck-Prager yield parameters,the creep constructive model of the rock was established as for describing on the rock attenuation creep,stable creep stage and accelerated creep.The fitting coefficients of the fitted curve and the experimental curve would be both above 0.95.