预留大尺寸洞口的地铁地下车站结构受力分析

Mechanical performance of subway station with large size of holes in the floor

为了研究围护桩与地下车站大尺寸开洞结构共同承受侧土压力时结构的内力变化规律,以某地铁车站为工程背景,采用岩土与隧道结构分析软件MIDAS/GTS,建立了包括周边土体、支护结构和预留轨排井地铁车站的地层—结构三维有限元模型,土与结构的接触算法基于Goodman无厚度接触单元,土体的本构关系采用摩尔—库伦模型模拟,对预留轨排井地铁车站施工全过程进行了模拟,并分析了预留轨排井阶段支护桩刚度、地面超载、纵梁截面高度等参数对结构受力性能和变形的影响。结果表明,支护桩刚度一定范围内的折减对主体各构件的受力影响较小。地面超载对结构顶纵梁受力影响较大,对中纵梁的影响次之,对侧墙底部应力分布的影响最小;增大轨排井的纵梁截面高度可显著减小结构纵梁端部附近侧墙的弯矩,但对侧墙底端与底板相交处的弯矩的影响不大。

In order to study stress variation of subway station with large size of holes in floor when piles and station structure bear earth pressure together,based on a subway station project,a three dimensional finite element model considering the interactions between soil and station structure was setup to simulate construction procedure of the subway station with track panel wells using MIDAS/GTS software. The Mohr-Coulomb constitutive model was used to present the mechanical behaviors of soil. The interaction between soil and diaphragm wall was simulated by Goodman contact element. The effects of pile stiffness,overloads,soil properties and longitudinal beam section size on mechanical performance and deformation of the subway station with track panel well were investigated in details. The analyzed results indicate that stiffness reduction of supporting piles has little influence on main structure. Stress distribution of top stringer is greatly affected by groundoverload,but the overload has the slightest effect on stress distribution of side wall bottoms,and its influence on stress distribution of medium longitudinal beam is smaller than that on top stringer and larger than that on side wall bottoms. The bending moment of side walls close to the end of longitudinal beam is remarkable decreased with the increase of longitudinal section height,but the increase has little effect on the bending moment at intersections between side walls and floor.