Research On Seismic Response And Shock Absorption Measures Of Tunnel Entrance In High Intensity Earthquake Zone

Because of the frequent earthquake, people gradually noticed the seismic damage of tunnels, and because of the greater damage of the entrance or exit of tunnels, we should focus seismic design on tunnels'entrance or exit. The thesis takes the entrance of Galongla tunnel and its shock absorption measurements to research, mainly studies on the peak stress and displacement effect of the lining under different single part of seismic wave, the responded acceleration magnified modulus and frequency trait of slope and inner earth, the peak vertical displacement of ground which in different perpendicular distance away from the middle line of lining, the waving earth stress of lining through tunnels, the transverse and vertical peak stress and peak displacement of tunnels'lining through faultage, the damage mode of lining and earth, the shock absorption ability of absorber and anti-seismic slot, and affection of absorber's elasticity quotiety on peak stress and peak displacement of lining under earthquake. All these study is done by large shaking table experiment and numerical simulation, and their main result is:â‘ The damage of tunnels is mainly caused by transverse vibration of the seismic wave;â‘¡Soil will absorb the high frequency of seismic wave; the responded acceleration magnified modulus of slope is increasing from its foot to ground, also the responded acceleration magnified modulus of inner earth is increasing from deep to ground; the main damage mode of slope is partial soil glided from the top and collapse, while the main damage mode of ground is the long and wide transverse crack, also some slightly crack along the tunnel.â‘¢The side-wall of lining at the very entrance of tunnel will split through the tunnel first, and the vault and bottom of lining in faultage will be snipped first; the main frequency response of lining is the same as which of the surround soil, means lining is vibrated just as the surround soil, and the lining won't show off its own vibration trait. The main damage mode of lining is longitudinal cracks in side-wall at the entrance, inclined cracks in side-wall near the entrance, linings stagger to each other at the anti-seismic slot when tunnel passing faultage, and longitudinal cracks at the bottom of invert in tunnel.â‘£Absorbers and anti-seismic slot won't change the response frequency of lining, but they will increase the acceleration of lining; absorbers will decrease lining'peak stress much more than decrease lining'peak displacement; Young's modulus of absorbers will mainly affect the decreasing ratio of lining's responded stress; anti-seismic slot will decrease the peak responded stress of lining, will average the peak responded stress at the inner part between the slot, will average the stress of all linings, but will increase its responded peak shear stress, will lead to stress concentrate of lining at the anti-seismic slot.