Stability Analysis Of Surrounding Rock Of Diversion Tunnel Of Jinping Hydropower Station Ⅱ Based On Generalized Particle Dynamics

Underground tunnel is a complex engineering.Its surrounding rock is in extremely complex geological environment,which makes the stability analysis of surrounding rock become a very important geological mechanics problem in underground engineering.The underground caverns of increasing size,on the surrounding rock stability requirements are also increasing,at the same time because of complex geological conditions and unpredictable affects the stability of surrounding rock,which directly affect the engineering design and construction management,and evaluation of surrounding rock stability has very important practical significance for engineering.Meshless method is based on point approximation.It uses different shape functions to integrate.In the process of discontinuous media and large deformation problems,there is no need to reconstruct and reclassify grids in the process of computation.In this paper,the general particle dynamics method is developed to study the surrounding rock stability of the Yalong River Jinping II Hydroelectric Power Station’s diversion tunnels which are in different depth of the excavation process of the tunnel by numerical simulation analysis.The main research work is as follows :(1)Based on the discrete method and the kernel approximation method of SPH method,three general conservation control equations of mass conservation,momentum conservation and energy conservation are used to compile the general GPD numerical simulation program based on C++ language.Besides a general-purpose post processor based on Matlab is written for data imaging analysis.(2)According to the problems of computing model scale and computing speed,the time of searching pairs and computing single step is greatly reduced by the GPD numerical simulation program which is optimized by the memory management technology based on memory pool,parallel computing technology based on multithread and linked-list search algorithm based on KD-tree data structure.(3)The rock elastoplastic constitutive model is introduced into the GPD numerical simulation program,and the GPD particle generating program is developed for the visual modeling according to the model of Jinping II Hydroelectric Power Station’s diversion tunnels.The excavation unloading process of the diversion tunnel under different buried depth is simulated,and the visual data of the stress field,displacement field and plastic zone distribution of the model section are analyzed.(4)The numerical simulation results of the GPD method are compared with the numerical simulation results of the finite element method.