单双线盾构隧道下穿对油罐群变形影响的数值分析

Numerical Analysis on Deformation of Oil Tank Group Caused by Single or Twin Shield Tunnels under Crossing

随着城市建设的不断推进,城市建(构)筑物日渐密集,新建盾构隧道不可避免地会下穿既有建(构)筑物。分析盾构穿越对周边结构在全寿命周期内的影响,对既有结构物的维护极为重要。基于此,本文采用三维有限元方法分析某越江盾构隧道穿越工程地面油罐群变形的影响,重点研究施工期隧道穿越、运营期隧道内发生火灾及地震工况下地面油罐群的沉降情况,并对比分析采用单管双层盾构与双管单层盾构隧道建设方案造成的影响。研究结果表明:施工期盾构顶推时,双管盾构造成的地层扰动大且范围广,故双管方案导致的地表油罐群沉降及倾斜率大于单管方案;当油罐群下方范围隧道发生火灾时,双管盾构同时发生火灾对油罐群的变形影响大于单管盾构发生火灾时带来的影响,而双管盾构中某一条隧道发生火灾对油罐群的影响介于以上二者之间;地震作用下,建设单管隧道与双管隧道后地面油罐的地震响应相对于未建隧道时的地震响应差异不大。

With the continuous advancement of urban construction,urban construction buildings are becoming increasingly dense.Newly built shield tunnels inevitably underpass existing buildings.Analysis of the influence of shield crossing on the surrounding structure during the whole life cycle is extremely important for the maintenance of existing structures.Based on this,the influence of a cross-river shield tunnel crossing project on the deformation of surrounding oil tank group is analyzed by using the three-dimensional finite element method.The research focuses on the deformation of ground oil tank groups under tunnel construction condition,fire and seismic conditions during tunnel operation period. And comparative analysis of the impact on the single-tube double-layer shield and double-tube single-layer shield tunnel construction plan is carried out.The results show that:(1) During the construction period,the stratum disturbance caused by the double-tube shield is large and wide,so the settlement and inclination rate of the surface oil tank group caused by the double-tube scheme is greater than that of the single-tube scheme.(2) When a fire occurs in the tunnel below the tank group,and the double-tube shield is fired at the same time,the deformation of the oil tank group is greater than that of the single-tube shield fire,and the deformation of the oil tank group in a fire in a tunnel of the double-tube shield is between the above two.(3) Under the action of earthquake,the seismic response of the ground oil tanks after the construction of tunnel is not much different from that of the unbuilt tunnel condition.