Research On The Method Of Real-time Forecast Of Seepage Field In Tunnel Excavation

Seepage problem has become an important subject in geotechnical engineering, and the determination of permeability parameter is the key problem in the research of seepage. How to determine and modify permeability parameter during tunnel excavation is researched systematically in the thesis. The main contents are described as follows:1. The basic theory and the calculation model of seepage for fractured rock mass are simply introduced. Then the three-dimensional finite element method of seepage based on the eight-node isoparametric element is given. In addition, the discussion of the treatment of free surfaces and flow boundary are given.2. The basic process of SGA is introduced. The efficiency of genetic algorithm is greatly improved by mending genetic operators and crossover operators and adding the accelerating genetic operators. At last, the hybrid genetic algorithm which greatly improve the local search efficiency of genetic algorithm is presented with the combination of local simplex search and genetic algorithm.3. Based on Kalman filtering formula of linear problem, the Kalman filtering expansion formula of nonlinear problem is deduced and the coupling algorithm of finite element method of seepage and Kalman filtering expansion method is presented, which can be used for real-time forecast of seepage, the corresponding program is compiled.4. Based on the above method, a forecast of seepage field during excavation of diversion tunnel in Jinping Hydropower Station is performed, and a simple analysis of forecast results is made.