Seismic Dynamic Response Analysis Of Hydraulic Tunnels Under Complex Conditions

The earthquake not only causes heavy damages to the structures above ground, but also inevitably poses great threat to the underground structures. Therefore, it is quite necessary to study the dynamic response of structures when earthquake strikes. Hydraulic tunnels are common structures in hydraulic engineering, which can bring about severe consequences once there is an accident and require huge amounts of works to repair and reconstruct. This thesis theoretically analyzed the dynamic response of hydraulic tunnel under seismic action, carried out the numerical simulation on entity model using the finite element software and studied the stress and strain of hydraulic tunnel under different conditions using time history analysis method. The following works were mainly done.(1) Detailed theoretical analyses were conducted on dynamics response of hydraulic tunnel under seismic load to provide a strong theoretical basis for numerical calculation and results analysis for the following chapters;(2) Reasonable parameters of the materials and boundary conditions were selected, finite element analysis software ANSYS was adopted to establish the three-dimensional finite element simulation model of a certain project under different conditions and reasonable model vibration frequency value were selected through modal analysis.(3) Seismic excitation were applied in different directions of the model, under which condition the dynamic response of the model was calculated. The maximum displacement and principal stress position of the model was found. The results obtained with the changing of corresponding factors were compared and summarized, which provide reference value for the design of similar projects and calculation;(4)By selecting the appropriate reference point on the model and using time history analysis method, the dynamic response of the tunnel was analyzed under seismic action with different depth, different lining thickness, different surrounding rock parameters and different water filling depth. The time point when the maximum principal stress and displacement occurs was found. Through the comparative analysis, the effects of different factors on seismic wave propagation were analyzed.