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以大东山隧道的石英岩为研究对象,进行循环加卸载条件下岩石蠕变–渗流耦合试验,分析了岩石加卸载过程中的蠕变、渗透性变化规律和渗流–蠕变耦合机理,得到压密阶段、裂纹扩展阶段和裂纹贯通阶段岩石体积应变的发展规律,总结了渗透率与体积应变之间的关系。试验表明:轴向荷载0~50 MPa为压密阶段,继续加载则产生不可恢复变形,当达到160 MPa时蠕变曲线进入加速段;随着轴向荷载水平的增加,渗透率总体趋势先降低后增高,最小值出现在最大压密点,蠕变过程进入加速段以后渗透率急剧增大。采用FLAC3D中的Cvisc模型为蓝本,以体积应变为桥梁建立ZSI(zone state index)与渗透率的关系,自主开发了基于应变软化的改进非线性蠕变西原模型,对试验结果进行验证。数值模拟表明:靠近进水端的渗透率比出水端变化快,不同应力下ZSI值云图的破损区与试验中岩样的“V”型剪切带破坏模式基本一致,渗透率的理论曲线与计算曲线吻合较好。说明提出的模型能够很好地反映加卸载条件下岩石蠕变–渗流耦合特性和局部破坏规律。
Taking the quartz rock of Dadongshan tunnel as the research object, the creep-seepage coupling test of rock under cyclic loading and unloading was carried out. The variation of creep and permeability during rock loading and unloading and the seepage-creep coupling mechanism were analyzed. Dense stage, crack growth stage and crack volume through the stage of rock volume strain development, summed up the relationship between permeability and volumetric strain. The results show that the axial load of 0 ~ 50 MPa is the compaction stage, and the unloading force is caused by continued loading. When the load reaches 160 MPa, the creep curve enters the acceleration stage. With the increase of axial load, the general trend of permeability decreases first After the increase, the minimum appears at the maximum pressure point, the creep process into the acceleration after the sharp increase in permeability. Based on the Cvisc model in FLAC3D, the relationship between ZSI (zone state index) and permeability was established by using volume strain as a bridge, and an improved non-linear creep model based on strain softening was developed independently and the experimental results were verified. Numerical simulations show that the permeability near the inlet is faster than that at the outlet, and the failure modes of the ZSI cloud under different stresses are basically consistent with the failure modes of the “V” shear zone of the rock samples under test. The theoretical curves of permeability Good agreement with the calculated curve. It shows that the proposed model can well reflect the creep-seepage coupling characteristics and local failure rules of rock under loading and unloading conditions.