摘要
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 illuminate the anisotropic rheological characteristics and the damage evolution of quartz-mica schist from Danba Hydropower Station, the stress relaxation tests are carried out for the mica-quartz schist samples, which were divided into the parallel group and the vertical group. Each of these samples sustained the different loads for almost 720 hours on the program-controlled creep test instruments. The test results show that the relaxed process contains three phases, i.e. rapid relaxation phase, slow relaxation phase and steady-state relaxation phase, and is non-fully damped relaxation. This conclusion is suitable for both parallel and vertical groups. And the difference exists in that the damped duration of the parallel group is longer than that of the vertical, because of the influence of schistosity direction. Furthermore, based on the relaxation characteristics of mica-quartz schist, the rheological constitutive equation of Bingham model are improved by introducing the damage factor of dissipated energy into the equation. And the stress relaxation equation are derived by the modified Euler method of finite difference, in order to identify the parameters of the improved model for the mica-quartz schist by the method of integrating artificial neural network. The results demonstrate that at the rapid relaxation phase, the damage evolution develops very fast and damage rate decreases with the relaxation processes, which is also fit for both parallel and vertical groups and is parallel to stress relaxation. In addition, it is obvious that the theoretical solution is highly consistent with the test data. So it means that the improved model can well describe the relaxation properties of mica-quartz schist, so as to provide significant guidance for the soft rock engineering.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2016年第S1期101-107,共7页
Rock and Soil Mechanics
基金
国家重点基础研究发展计划(973计划)(No.2015CB057903)
国家自然科学基金(No.51079092)~~
