关键词: 隧道工程, 既有深坑, 地震工况, 位移, 应力, 地震加速度响应

Abstract: The first domestic existing pit-Foding palace mine pit slope under static state and seismic condition was simulated and analyzed by three dimensional finite element. Some results were obtained that after which cutting or reinforcement with anchor cable(rod), the maximum displacement all occurred on the slope top and the surface was filled with soil, residual soil and highly weathered rock; the maximum stress all occurred in the depth inside slope and the maximum shear stress occurred at interface between slope toe and ground. The acceleration response is in trend of expanding with increase of slope height and the surface soil acceleration response expanded significantly. Under limit state condition, the generalized plastic strain area concentrated on slope top and surface. Under static loading case, with anchor cable(rod) reinforcement, the maximum side slope displacement was reduced by 11.9%~28.4%, stress decrease by 11.9%~28.4%, 5.6%~67.1% respectively while slope safety factor increased by 34.5% compared with the condition without support, all of which showed strong strengthening effect of anchor cable(rod). Under seismic condition, compared with static condition, maximum displacement was increased by 3.03~19.73 times, main stress was increased by 6.5%~146.7%, maximum shear stress was increased by 168.4%~474.6%, safety factor was decreased by 0.6%~23.1%. Under major earthquake condition, compared with small earthquake condition, slope surface acceleration peak and magnification was increased by 15.04~27.00 folds and 1.44~1.93 folds respectively. The calculation results from applying earthquake on the mine pit from initial north-south and later east-west directions respectively show that the former generated greater seismic displacement and dynamic stress than the latter and the former safety factor was less than the latter indicating that the earthquake striking from pit longer axis direction is worse than that striking from shorter axis to slope stability.

Key words: tunnel engineering, existing pit, earthquake, displacement, stress, seismic acceleration response