开挖地应力释放诱致岩质高边坡灾变的机制研究

Southwest hydropower rock slopes not only retain the general characteristics of the rock slope, but also have high ground stress characteristics. In high ground stress area in which the rock excavation can usually lead to serious unloading effect, failure of rock and further induce slope engineering catastrophe. High stress fully embodies the nonlinear characteristics of rock mass, and thus determines the study on excavation stability of slope must pay attention to the action of stress path, the adjustment of strength parameters of rock mass, and the choose of constitutive relation. This project stands on the hydropower rock high slope in southwest high geo-stress areas. The influence law of initial stress field on slope stability is discussed by the geomechanics model of different slope structures. The disturbance degree of strength parameters of slope rock mass induced by geo-stress release caused by excavation through field sampling and laboratory tests of rock mass. Based on the strength criteria of rockmass and the damage mechanics theory, the statistical damage constitutive model taked into account stress release is built. The stability factor for different parts of slope mass in the excavation disturbed zone is defined by the stress analysis of rock mass. On the basis, through the calculation of stability factor to the part of deformation damage, taking the calculation result is consistent with the deformation failure phenomina of slope mass as a basis, the strength parameters of defomation part are inversed. Furthermore, according to the disturbance laws of rock mass strenght caused by excavation, the parameters of other parts in slope mass are also inversed. Finally,used the numerical sumulation method, the course of rockass damage evolution and the formation of failure surface caused by slope excavation are researched. The research results could be used to analyze the mechanics behavior of catastrophic damage and the spatial stability coursed by the excavation of slope engineering. Supposing that the project can be successfully implemented, for the reasonable design of high rock slope engineering, chose of targeted protection measures and disaster prevention and mitigation in southwest high ground stress areas, the achievements could have great theoretical significance and application value.

高地应力区岩体开挖引起的卸荷效应非常严重，常常导致岩体甚至岩块产生应力破坏，诱发边坡工程灾变。高应力充分体现了岩体的非线性特征，由此决定了对边坡开挖稳定性的研究必须注意应力路径的作用、岩体强度参数的调整和本构关系的选择。项目立足于西南高地应力区岩质高边坡，现场采样进行室内强度指标测试，研究开挖地应力释放对边坡岩体强度参数的扰动影响。基于岩体强度准则和损伤力学理论，建立一种考虑地应力释放的岩体统计损伤本构模型，通过对开挖影响区内岩体的应力分析来表征坡体不同部位的稳定系数。基于此，通过对变形破坏部位稳定系数的计算，以稳定系数计算结果与坡体变形破坏现象一致为依据，反演破坏部位岩体的强度参数，进一步根据开挖对岩体强度的扰动规律，反演坡体其它部位岩体的强度参数。最后，运用数值模拟手段探讨高应力条件下边坡开挖引起的岩体损伤演化过程和破坏面形成，将成果应用于边坡工程开挖致灾的机制研究。

高地应力区岩体开挖引起的卸荷效应非常严重，常常导致岩体甚至岩块产生应力破坏，诱发边坡工程灾变。高应力充分体现了岩体的非线性特征，由此决定了对边坡开挖稳定性的研究必须注意应力路径的作用、岩体强度参数的调整和本构关系的选择。项目立足于西南高地应力区岩质高边坡，现场采样进行室内强度指标测试，研究开挖地应力释放对边坡岩体强度参数的扰动影响。基于岩体强度准则和损伤力学理论，建立一种考虑地应力释放的岩体统计损伤本构模型，通过对开挖影响区内岩体的应力分析来表征坡体不同部位的稳定系数。基于此，通过对变形破坏部位稳定系数的计算，以稳定系数计算结果与坡体变形破坏现象一致为依据，反演破坏部位岩体的强度参数，进一步根据开挖对岩体强度的扰动规律，反演坡体其它部位岩体的强度参数。最后，运用数值模拟手段探讨高应力条件下边坡开挖引起的岩体损伤演化过程和破坏面形成，将成果应用于边坡工程开挖致灾的机制研究。