内支撑替换对深基坑变形影响的数值分析

Numerical Analysis of the Influence of Replacement of Internal Support on the Deformation of Deep Foundation Pit

深基坑开挖工程相对一般基坑工程而言比较复杂,因为大开挖深度使整个基坑维护结构的稳定性控制变得更为困难;目前的主流的做法是理论设计和实际监测相结合,实时把控基坑施工的具体情况。利用有限元分析软件Midas GTS NX对合肥某地铁区间站第一道预留砼支撑用钢支撑代替进行了数值分析,得出基坑支护结构的受力及其变形特性。结果表明:钢支撑代替第一道钢筋砼支撑会使得围护结构最终弯矩增大4%,最终水平位移增大0.5 mm;围护结构的最大位移会发生在基坑开挖深度的0.4~0.7倍。从而为支撑代替提供理论依据。

The excavation of deep foundation pit is more complicated than that of general foundation pit,because the depth of excavation makes it more difficult to control the stability of the whole foundation pit. The current mainstream practice is the combination of theoretical design and actual monitoring,and real-time control of the construction of the foundation pit. In this paper,steel support to replace the first reserved reinforced concrete support of a subway station in Hefei was analyzed by the finite element analysis software Midas GTS NX.Results show that the steel support instead of the first line of reinforced concrete brace palisade structure made the ultimate bending moment increases by 4%,final horizontal displacement increases 0. 5 mm; the maximum displacement of the surrounding structure occurred at 0. 4 ～ 0. 7 times of the excavation depth of the foundation pit. Therefore,the construction process could be accelerated by providing theoretical basis for support instead.