基于高应力下花岗岩卸荷试验的力学变形特性研究

Study of mechanical deformation characteristics of granite in unloading experiments of high stress

进行了高应力条件下卸围压并增大轴压的花岗岩卸荷试验,描述了卸荷过程中岩石渐进破坏的应力-应变曲线和力学参数损伤劣化规律;分析了能较好反映岩石卸荷强度破坏特征的Mogi-Coulomb准则和强度参数变化规律;建立了岩石由压剪破裂逐渐过渡到张剪破坏的渐进演化体系。在此基础上,通过对岩石卸荷破坏起主要作用的横向变形将压剪Mogi-Coulomb准则和拉剪Mogi-Coulomb准则联系起来,建立了描述岩石卸荷渐进破坏的新强度准则。基于上述的卸荷试验成果,结合描述岩石卸荷渐进破坏的应力-应变曲线,在应变空间中推导了考虑岩石力学变形参数损伤劣化效应、横向变形作用、卸荷渐进破裂演化机制的力学本构方程。

By carrying out unloading experiments of high stress on granites in the style of unloading confining pressure with loading axial pressure, the stress-strain curves which describe the gradual damage of rock and the degradation laws of mechanical deformation parameters are both acquired, the Mogi-Coulomb strength criterion is applied to explain deformation characteristics, the varying laws of strength parameters and the evolutionary features from compression-shearing cracks to tension-shearing cracks of rocks are also built up. Then the relation between compression-shearing Mogi-Coulomb criterion and tension-shearing Mogi- Coulomb criterion is expressed by the lateral deformation which has a primary affect on unloading damage of rock; and the new strength criterion is established. Finally, based on the above experimental results and stress-strain curves from the unloading experiments, the mechanical constitutive equations, which involves the degradation laws of mechanical deformation parameters, the effect of lateral deformation and the evolutionary features of unloading damage are deduced in the strain space.