考虑率效应的岩石材料次加载面动态本构模型

Dynamic constitutive model for subloading surface of rock materials considering rate effect

为反映岩石材料在循环荷载下的滞回圈特性及在动态荷载作用下的率效应,首先基于次加载面理论,建立了基于Drucker-Prager准则的次加载面应力路径模型;其次,在此基础上,通过分析岩石材料率效应的体现,分别在弹性模量上考虑了刚度的率效应和在Drucker-Prager准则上考虑了强度的率效应,进而提出了考虑率效应的岩石材料次加载面动态本构模型;通过自编程序,实现了动态本构模型的植入,并模拟了岩石材料在动态荷载下的力学响应。结果表明,相对于Drucker-Prager准则,应力路径模型能较好地描述玄武岩在循环荷载下体现的曼辛效应和棘轮效应,同时揭示了玄武岩的发展形态;利用动态模型对岩石材料的动态单轴加载和循环加载模拟,发现加载的应变率越大,岩石材料的弹性模量越大,变形则越小,正好反映了岩石材料在动态加载过程中所体现的率效应;动态本构模型能同时反映岩石材料在地震荷载下的滞回圈特性和率效应,正好说明了地震荷载不但具有等效循环荷载的形式,还具有动态荷载的形式,也说明了次加载面动态本构模型模拟岩石材料在地震荷载作用下的力学性质是可行的。

In order to reflect the characteristics of the hysteresis loop under cyclic loading and the rate effect under dynamic loading of the rock materials, firstly, based on the theory of subloading surface, the stress-path model for the subloading surface considering Drucker-Prager criterion is proposed. Secondly, on this basis, the rate effect of rock materials is analyzed. The rate effect of stiffness is considered in the elastic modulus and the rate effect of strength is taken into account in the Drucker-Prager criterion, and then the dynamic constitutive model for subloading surface of rock materials is established. Finally, through the self-programming, the dynamic constitutive model for the sub-loading surface of the rock materials is implanted, and the mechanical response of the rock materials under dynamic loads is simulated. The results show that the stress path model, compared with the Drucker-Prager criterion, can describe the Massing effect and the ratchet effect of basalt under cyclic loading, and reveal the developmental pattern of basalt. Through the simulation of dynamic uniaxial loading and cyclic loading by using the dynamic model, it is found that the larger the strain rate is, the larger the elastic modulus is and the smaller the strain is, which is in accordance with the mechanical properties of the rock during dynamic loading. Under the seismic load, the stress-strain curve of the rock also exhibits the hysteresis loop and rate effect. The seismic load has the equivalent cyclic load and the form of dynamic load, and the dynamic constitutive model for subloading surface is feasible to simulate the mechanical properties of the rock materials under seismic loads.