Two dimensional displacement back analysis of left bank slope of Longtan hydropower station

A method of slope displacement back analysis considering excavation unloading effect is presented. In the stability analysis of section 1-1 of left bank of Longtan hydropower station, the geology generalization, excavation step and disturbing zone are analyzed to establish the computing model of finite element method. The mechanical parameters of rock masses are solved by using finite element method with neural network-genetic algorithm. The results of forward analysis with these parameters show that the displacements are reasonable and very agreement with the monitoring results. The maximum compressive stress is 1.0MPa and no tension stress at the excavation zone. The plastic zones are distributed at the slope top, excavation zone and near the big fault.