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为揭示丹巴水电站石英云母片岩的各向异性松弛性特及松弛过程中的损伤演化规律,针对平行片理组和垂直片理组石英云母片岩,采用程控蠕变试验仪,开展为期720 h的单轴应力松弛试验。试验发现,平行片理组和垂直片理组岩样的应力松弛曲线均可分为快速松弛、减速松弛和稳定松弛3个阶段,属于非完全衰减型松弛类型;受片理发育方向影响,平行片理组应力衰减历时较垂直片理组长。结合石英云母片岩的应力松弛特征,将基于能量耗散的损伤因子代入Bingham模型流变本构方程,利用改进Euler差分算法推导应力松弛方程,并用神经网络法对模型参数进行辨识。研究表明,平行片理组与垂直片理组在快速松弛阶段损伤发展较快,且随着松弛过程的进行损伤速率逐渐降低至稳定,损伤演化与应力松弛过程是统一的;考虑损伤演化的Bingham流变模型拟合曲线与试验结果具有较高的吻合度,说明文中提出的松弛方程能很好地描述石英云母片岩的应力松弛特性,对软岩工程研究具有较高的应用价值。
In order to reveal the anisotropy relaxation of quartz mica schist at Danba hydropower station and the evolution of damage during the relaxation process, for parallel mica schist and perpendicular micrito-schist quartz mica schist, a controlled creep tester was used to conduct a 720 h Uniaxial stress relaxation test. It is found that the stress relaxation curves of the parallel and vertical Palyanatom rock samples can be divided into three stages: rapid relaxation, slow relaxation and stable relaxation, belonging to the non-complete attenuation relaxation type. Influenced by the development direction of the palygorsk, parallel The stress relaxation of the treatment group lasted longer than that of the vertical treatment team leader. Combined with the stress relaxation characteristics of quartz mica schist, the damage factor based on energy dissipation was substituted into the rheological constitutive equation of Bingham model. The stress relaxation equation was deduced by the improved Euler difference algorithm, and the model parameters were identified by neural network. The results show that the damage of parallel treatment group and vertical treatment group develops rapidly in the rapid relaxation stage, and the damage rate gradually decreases to stable with the relaxation process. The damage evolution and stress relaxation process are uniform. Considering the damage evolution of Bingham The fitting curve of the rheological model has a good agreement with the experimental results. The relaxation equation proposed in this paper can well describe the stress relaxation characteristics of quartz mica schist, which is of high application value to soft rock engineering.