The Research Of Enlarged Excavation And Surrounding Rock Stability In The Green Schist Area Of Jinping Hydropower Station

National economy is developing more and more quickly, in the same time the number of large construction projects such as hydropower stations and communication projects keeps growing. The tunnels of these projects are longer and deeper. In the condition of high geostress and bad geological property, the tunnels deep-buried exist large deformation, rock burst and collapse. the solution of problems is the key to projects.The tunnels of Jinping hydropower station is buried deep and have large radius lied in high geostress and bad geological property. These conditons result in collapse, underground gushing, rock burst and large deformation. Necking and collapse makes construction progressing slow down, damages the equipment and threatens the safety of engineers. When the Hydropower Station comes into use, necking will lower the capacity of power generation.This paper depends on research of enlarged excavation and surrounding rock stability in the green schist area of Jinping hydropower station, introduces Heterogeneity of rock materials from mesoscopic perspective, mainly, considers humidity as main factors and uses the RFPA invented by Prof Tang Chunan for numerical simulating. The contents include the inversion of mechanical parameters of the greens chist, analysis of the stability of surrounding rock and initial support system while enlarged excavating, comparison with three schemes of bottom falling, simulation of bolt support..The research supplies guidance of construction activity and predicts safety of excavating process. The solution of enlarged excavation and surrounding rock stability in the green schist area of Jinping hydropower station also can be reference materials for other similar projects.