Compared with those bearing symmetrical surrounding rock pressure, the unsymmetrical - pressure tunnels have worse stability and are more sensitive to seismic. The dynamic response of the shallow - embedded, bias and small clear distanced tunnels under horizontal seismic loading was studied by using the commercially available finite difference code FLAC. A comparative analysis of the internal forces (axial force, shear force and bending moment) and dynamic safety coefficients of the left tunnel and right tunnel was carried out. The results show that the stress state of lining structures induced by seismic load is closely related to the topographic condition of tunnels. Moreover,in the case of large depth difference between the two tunnels, the seismic response of the left shallow - embedded tunnel is significantly more intense than that of the right tunnel. And the tunnel with shallower depth is in much more unfavorable stress states. The right deep depth tunnel meets the seismic strength requirements, but some reinforcement measures must be taken to the left shallow - buried tunnel which does not meet the the seismic strength requirements. The obtained conclusions can provide useful guidance to the seismic design of the similar bias tunnels.%与非偏压隧道相比,浅埋偏压隧道稳定性较差,受地震动荷载的影响更为敏感.结合实际工程,运用FLAC有限差分法研究了浅埋、偏压、小净距隧道结构在水平地震荷载作用下的动力时程响应,对比分析了左、右两洞的内力(轴力、剪力、弯矩)变化规律和动力安全系数.研究结果表明:衬砌结构的地震响应、受力状态与地形条件密切相关;在两洞埋深差异较大的情况下,埋深较浅的左洞的地震响应明显比右洞剧烈,其受力比右洞更为不利;位于埋深较深侧的右洞满足抗震强度要求,而位于埋深较浅侧的左洞不满足抗震的强度要求,需要采取一定的抗震加固措施.所得结论可为类似偏压隧道工程的抗震设计提供指导.
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