基于率效应的岩石材料次加载面动态模型在岩体工程中的初步应用

为较准确反映岩体工程在地震荷载下的响应,结合Drucker-Prager屈服准则和次加载面理论,初步构建基于Drucker-Prager准则的次加载面应力路径模型,在此基础上,除计算弹性模量的率效应之外,还在Drucker-Prager准则上考虑强度的率效应,提出岩石材料的动态模型,并把该模型运用到滇中引水香炉山隧洞中。计算结果表明,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,由于没有考虑率效应,表现出应力–应变曲线的斜率没有试验曲线大,且累计应变也比试验曲线大;在岩石循环加卸载过程中,动态模型得出的模量上比次加载面应力路径模型模拟的要大,同时变形量也较次加载面应力路径模型要小,因此该模型能较好地反映岩石的动态力学性质和变形性质;相比于Drucker-Prager准则下,采用动态模型得出隧洞的左侧监测点和右侧监测点的瞬时相对变形峰值增大了0.67 cm,同样底部和顶部以及左右两侧的永久相对变形也分别增大了0.19和0.77 cm,说明动态模型可以较好地反映围岩残余大变形;岩石动态模型相对于Drucker-Prager准则和线弹性本构,更具有滤掉高频的功能。说明该模型能很好地运用到岩石动力学中,同时也为准确分析岩体工程在地震作用下的响应奠定了一个很好的基础。

#br# Preliminary application of dynamic constitutive model with subloading surface for rock materials considering rate effect in rock engineering

A stress path model with the subloading surface based on the Drucker-Prager yield criterion and the subloading surface theory was established to reflect accurately the response of rock under the action of earthquake. A dynamic constitutive model of rock material was proposed considering the rate effect of elastic modulus and strength. The proposed model was applied to the Xianglushan tunnel. The results show that the stress path model describes the Masing effect and the ratchet effect of basalt better than Drucker-Prager criterion under cyclic loading. When the rate effect is not taken into account，the slope of the stress-strain curve is smaller than that of test curve and the cumulative strain is larger than that of test curve. In the process of cyclic loading and unloading，the dynamic modulus obtained with the dynamic model is larger than that from the stress path model with subloading surface and the deformation obtained with the dynamic model is smaller than that from the stress path model with subloading surface. Therefore，the proposed model reflected well the dynamic mechanical properties and deformation properties of the rock. In comparison with the results from Drucker-Prager criterion， the instantaneous relative peak deformation between the left and right monitoring points of the tunnel from the dynamic model increased 0.67 cm，and the permanent relative deformation between the bottom and top monitoring points and between the left and right monitoring points are increased 0.19 cm and 0.77 cm respectively. This indicates that the dynamic model reflected better the large deformation of the surrounding rock. The dynamic model of rocks is more effective in filtering the high frequency than Drucker-Prager criterion and linear elastic constitutive.