红黏土的膨胀性对基坑支护结构加固的影响

为了研究红黏土对基坑的不利影响，以广西宜州市城中路地下通道商业街项目基坑支护工程为依托，运用PLAXIS有限元程序，选取合理的岩土体本构模型对基坑开挖支护过程进行数值模拟，对比分析了三种不同的结构加固方案加固前后的竖向应力、水平位移、剪力、弯矩等计算。结果表明:在不考虑红黏土膨胀的情况下，原设计已能满足变形、护壁桩承载力限值要求，但若考虑红黏土膨胀，按照原设计方案进行计算，发现桩身最大水平位移29.36 mm，桩顶位移24.87 mm，已超过21 mm的限值；在3种结构加固的方案中，方案2、方案3都无法有

Influence of Expansibitity in Red Clay on Supporting Structure Reinforcement for Foundation Pit

In order to study the adverse effects of red clay on foundation pit, this paper, on basis of the foundation pit supporting works for the underground passage commercial street of Chengzhong Road in Yizhou City, Guangxi, selected proper constitutive model of rock-soil mass to make numerical simulation with PLAXIS finite element program on the excavation and supporting process, and then compared and analyzed, under three reinforcement schemes, the calculation of vertical stress, horizontal displacement, shear force, bending moment before and after reinforcement. The result shows that, without consideration of red clay expansion, the deformation and bearing capacity of retaining piles can be satisfied in the original design; however, with consideration of red clay expansion, the horizontal displacement of pile body calculated by the original design may be up to 29.36 mm, that of pile top 24.87 mm, exceeding the limit by 21 mm; in the three schemes herein, the scheme 2 and 3 can not cannot control the deformation effectively, but the scheme 1 can. Therefore, it is advised to use the scheme 1 to reinforce the foundation pit structure.