Study On Stability And Support Measures Of Underground Powerhouse Group Of Wuyue Pumped Storage Power Station

The research on the stability of underground caverns of hydropower stations is an important research object in water conservancy project survey,design,construction and operation.A series of relatively complete theoretical systems have been established for the evaluation of the stability of surrounding rock,and the actual research has carried on the special research on the excavation and the surrounding rock stability of the large underground caverns which have been built in China and have achieved good effect,Resulting in a huge economic and social benefits,so for the Wuyue Pumped Storage Power Station underground powerhouse group to carry out the stability analysis of surrounding rock is very necessary.This paper takes the underground powerhouse of Wuyue Hydropower Station as an example,a three-dimensional numerical model is established through analysis of complex rock mass structure.And based on the ground stress of the measured point,the initial geostress field of underground powerhouse is retrieved by three-dimensional finite element method.Elasto-plastic finite element analysis of the stability of the surrounding rock mass of underground powerhouse,optimization of supporting parameters of underground caverns,and reasonable support measures and construction procedures.The results are as follows:(1)The geostress shows a general increase with the increase of burial depth.The geostress field in the engineering area is not affected by the mechanical properties of the rock mass,but the weak structure of the rock,such as the fault,the impact of is more obvious than wall rock,the performance is produced significant stress release in the cutting site.(2)According to the principle of side excavation and side support,based on the actual situation of the project and the combination of a large number of underground caverns,designed the excavation process combination scheme.The deformation,stress and plastic zone around the hole are systematically analyzed by numerical calculation,it is concluded that the excavation of the caverns has a greater disturbance to the surrounding caverns,and appropriate increase in excavation process is beneficial to improve the stability of the surrounding rock.(3)On the basis of determining the reasonable excavation scheme,optimized three support schemes,using FLAC3D to simulate the excavation side of the underground cavern excavation construction process,compared and analyzed the deformation,stress value and the distribution of the plastic zone around the hole and the optimal support scheme is compared with the optimal support scheme.(4)Based on the study of displacement,stress and plastic zone volume change around the hole,the influence of mechanical parameters on the stability of surrounding rock is analyzed.The results show that the most sensitive factor of the displacement of the feature points is the deformation modulus.The shear parameters have a great influence on the stress and shaping area of the surrounding rock.