软土地区深大基坑工程支护参数影响规律研究

Research on the Influence Law of Support Parameters on Deep and Large Foundation Pit Engineering in Soft Soil Areas

摘要: 本文以嘉兴软土地区某中医院深大基坑工程为研究背景，通过ABAQUS软件建立基坑三维模型，与实际监测结果进行对比，分析基坑开挖过程对支护桩水平位移的影响。同时，通过改变混凝土支撑位置、截面尺寸以及支护桩桩径等因素分析支护参数对基坑开挖变形的影响规律进行研究。研究结果表明：数值模拟计算结果与实际监测结果相接近，验证了ABAQUS软件计算的准确性；根据监测结果表明，基坑变形受坑角效应的影响，靠近坑角部分的支护桩水平位移较小；在本基坑工程中，基坑前三层最佳开挖深度为总开挖深度的0.2，0.6，0.8，在每层开挖完成后，在坑底架设混凝土支撑；在原支撑横纵向截面尺寸0.2 m变化范围内，支撑的截面尺寸对于支护桩水平位移影响较小；当支护桩桩径在0.85 m到1.15 m之间时，支护桩最大水平位移降低幅度与桩径变化大致成正比关系，当支护桩桩径超过1.15 m时，对支护桩水平位移降低幅度减弱，不利于充分发挥桩体性能。

Abstract: This article takes the deep and large foundation pit project of a traditional Chinese medicine hospi-tal in the soft soil area of Jiaxing as the research background. A three-dimensional model of the foundation pit is established using ABAQUS software, and compared with the actual monitoring re-sults to analyze the impact of the excavation process on the horizontal displacement of the support piles. At the same time, the influence of support parameters on the deformation of foundation pit excavation was studied by changing factors such as the position of concrete support, cross-sectional size, and diameter of support piles. The research results indicate that the numerical simulation calculation results are close to the actual monitoring results, verifying the accuracy of ABAQUS software calculation; According to the monitoring results, the deformation of the foundation pit is influenced by the pit angle effect, and the horizontal displacement of the support piles near the pit angle is relatively small; In this foundation pit project, the optimal excavation depth for the first three layers of the foundation pit is 0.2, 0.6, and 0.8 of the total excavation depth. After each layer of excavation is completed, concrete support is erected at the bottom of the pit; Within the range of 0.2 m variation in the cross-sectional size of the original support, the cross-sectional size of the sup-port has little effect on the horizontal displacement of the support pile; When the diameter of the support pile is between 0.85 m and 1.15 m, the maximum horizontal displacement reduction of the support pile is roughly proportional to the change in pile diameter. When the diameter of the sup-port pile exceeds 1.15 m, the reduction in horizontal displacement of the support pile is weakened, which is not conducive to fully utilizing the pile performance.