Study On Physical And Mechanical Characteristics Of Altered Rock And Stability Of Underground Factory Building In Panan Pumped Storage Power Station

In recent years,altered rocks have been encountered in the construction of water conservancy and hydropower projects,and there are obvious differences in altered rocks in different degrees.The engineering geological characteristics of altered rocks will directly affect the site selection of dam bodies and the stability and layout of underground projects.Based on the exploration,surveying and mapping data of the project area of Panan pumped Storage Power Station in Zhejiang Province,there are varying degrees of alteration in the rock mass in the project area,in order to ensure the smooth construction and operation of the project,It is necessary to carry out in-depth study on the altered rock of Panan pumped Storage Power Station,and to carry out geological investigation,sheet identification and physical and mechanical properties test of altered rock in engineering area by means of qualitative and quantitative analysis.The mineral composition,alteration types and physical and mechanical properties of altered rocks are grasped,and the rock and mineral characteristics and physical and mechanical properties of altered rocks are systematically studied.On the basis of the study of engineering geological conditions,altered rock and ore characteristics and physical and mechanical characteristics of altered rock,and combined with the actual layout characteristics and structural forms of underground powerhouse of the project,The 3D simulation model of underground powerhouse area of Panan pumped Storage Power Station is established by using MIDAS GTS NX software,and the main powerhouse and main transformer room of underground powerhouse area are obtained by FLAC 3D numerical calculation.The displacement and stress of tailing gate chamber and other caverns are changed step by step,so as to quantitatively analyze the influence of excavation of underground powerhouse in engineering area on the stability of surrounding rock of caverns.The results show that the altered rocks of Panan pumped Storage Power Station in Zhejiang Province are mainly formed by chemical metasomatic alteration under hydrothermal slurry,which are closely related to magmatic activity and volcanic activity,and the alteration phenomena of rock mass in the engineering area are widely distributed.There are different degrees of alteration in rock mass,among which the physical and mechanical properties of altered tuff are obviously different.the higher the degree of alteration,the higher the moisture content of rock,the increase of water absorption and the decrease of rock mechanical properties.The displacement and stress of underground powerhouse are changed greatly under the condition of excavation,which affects the stability and layout of underground engineering.