壳单元在钢板桩支护基坑有限元分析中的应用

Application of Shell Element in Finite Element Analysis of Steel Sheet Pile Supporting Foundation Pit

采用壳单元模拟钢板桩支护基坑能准确反映钢板桩的实际变形及受力情况,但有限元模型的建立较为复杂繁琐,不利于工程应用。对此,以某基坑工程为例,采用壳单元模拟钢板桩真实截面,同时利用刚度一致原则分别建立等效壳截面和等效实体截面模型,对三种情况进行有限元计算。对比发现三种情况下钢板桩及土体的变形、支撑内力情况基本吻合,钢板桩的内力值存在一定的修正关系,且等效壳截面的计算结果更接近真实值。表明在基坑钢板桩的有限元模拟中,可采用等效壳截面或实体截面代替真实情况,其中等效壳截面的精确度略高,在保证分析结果可靠性和准确性的基础上,可简化模型建立,提高有限元计算速度。

Shell element simulation of steel sheet pile supporting foundation pit can accurately reflect the actual deformation and stress of steel sheet pile,but the establishment of model was complicated,which was not conducive to engineering application.To solve this problem,taking a foundation pit project as an example,the real section of steel sheet pile was simulated by shell element,and the equivalent shell section model and the equivalent solid section model were established via the stiffness consistency principle.Through the calculation of those three cases,it is found that both the deformation of steel sheet pile and soil and the stress of support are basically identical.There is a certain relationship between the stress of steel sheet pile,and the results of equivalent shell section are closer to the true value.The results show that the equivalent shell section and solid section can substitute the real situation in finite element analysis of steel sheet pile supporting foundation pit.The former is slightly accurate.On the basis of ensuring the reliability and accuracy of the analysis results,it can simplify the establishment of the model and accelerate the finite element computation.