中文摘要：

龙游石窟5号洞顶板在多处有破坏痕迹和离层变形，经现场调研和实测，在洞室出口处顶板离层变形达75～78mm，侧面岩层出现悬臂梁式的破断现象。为了探讨龙游石窟5号洞顶板破坏过程，了解洞室的长期稳定性，基于最大拉应力追踪法和岩石断裂过程的反演数值模型，利用现场实测破坏形态及变形数据，对5号洞进行了流变断裂过程的数值模拟与反演分析。在反演分析过程中，运用正交试验方法，设计了27种数值模拟方案，通过正交试验设计的直观分析，获得了洞室顶板岩层与薄夹层的流变参数和其他敏感参数的最佳组合方案。利用所获得的参数最佳组合方案，对洞室进行了长期稳定性分析和流变断裂过程的数值模拟，数值模拟结果表明，在洞室出口处顶板离层变形达54．24mm，断裂部位与现场破断部位基本相同。此外，流变模拟分析中出现在洞室深部的顶板离层也十分明显，这一现象与现场观察到的表观变形形态比较相近。

英文摘要：

There are some in-situ investigation find m damages and separating deformation in the roof of Longyou grotto No.5. According to measurement, separating deformation of roof at the grotto exit accumulated to 75 - 78 mm, and there are damages and fracture phenomenon like cantilever beam at lateral side of grotto roof. In order to understand the fracture process of the roof for grotto No.5 and long-term stability, the numerical simulation and back analysis ofrheologic fracture are carried out by using in-situ damage pattem and deformation data, based on the tracking method of maximum tensile stress and the back analysis of rheologic fracture presented by the authors. In the process of back analysis, the orthogonal experiment is used to design 27 kinds of the schemes of numerical simulation. The optimum scheme of parameters which are composed of the rheologic parameters of rock layer, thin double-layer and other sensitive parameters is obtained by analyzing the orthogonal experiment results. The long-term stability and the process of rheologic fracture are analyzed by utilizing the obtained optimum scheme. The calculated results show that the separating deformation of the roof at the grotto exit is 54.24 mm and the fracture location is same as the location of in-situ fracture. In addition, the separation deformation of roof at the grotto recess is also very obvious in rheologic numerical simulation; and the phenomenon is similar to the apparent form of in-situ deformation.