高地应力地区围岩劈裂破坏现场监测和能量耗散模型及应用

In the construction of deep buried underground cavern,the surrounding rock masses of underground caverns are prone to appear splitting failure due to the high in-situ stress and the brittleness of rock mass.In this study,based on the energy dissipation principle and a transversely isotropic model,a kind of new custom transverse isotropic calculation model is estabilished which is judged by the splitting failure criterion of model element stress state,and the stability of excavation of large underground caverns in Dagangshan hydropower station is evaluated based on this new custom model.Besides,the displacement and the entire process of rock splitting failure of each excavation steps of the main house have been achieved through field monitoring on side walls of the construction site of large-scale caverns in Dagangshan.Then,the results of field monitoring are compared with the calculated results of the stability analysis of different constitutive models,and the following conclusions are obtained:during the excavation of the Dagangshan Hydropower Station underground caverns,the average depth of splitting zone of the sidewall in the main power house calculatedby the new model is quite consistent with the field monitoring result; compared with other models,the new model is better to reflect the change trend of surrounding rock displacement between the main power house and the main transformer chamber.According to the results of the stability analysis,the key point displacement of the downstream side wall and the position near the crane beam of the main power house is larger,the maximum horizontal displacement of the sidewall is 29.46 mm.The vault displacement of the main powerhouse is larger in the initial stage of excavation,and the maximum vertical displacement of the vault is 10.58 mm.The results show that,compared with other existing FDTD model,calculation results by the new custom model is closer to the actual monitoring value,which reflects the displacement of the surrounding rock mass in different excavation steps and the change trend of the surrounding rock displacements of the key points.This new model is reasonable to calculate and predict the splitting zone of the surrounding rock when the underground cavity in high geostrese areas during excavation and is also appropriate to the stability analysis on the surrounding rock after excavation.or Referring to the strengthen the monitoring and management of key areas,our proposed model is beneficial for reducing the splitting failure effect on tunnel stability.