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通过有限元计算,研究了大面积深基坑开挖对群桩的受力和变形特性的影响。群桩基础的受力及变形性状明显不同于单桩。对于坑底群桩,随着基坑开挖深度增加,桩身轴力随之增加,桩身轴力最大值位置由桩身中上部转移到中部,与单桩的轴力最大值位置(桩身中下部)有一定程度的差别。在同一开挖深度中,距离地下连续墙近的桩身轴力较小,距离基坑中心近的桩身轴力较大。其主要原因是基坑中心处的土体回弹大于基坑边部,相应的桩土位移及桩侧摩阻力发挥程度也较大。由于基坑开挖造成支护结构发生侧向变形,使得靠近支护结构的桩产生弯曲,整体表现为桩身上部变形较大,中下部变形较小。
Through the finite element calculation, the influence of deep excavation on the stress and deformation characteristics of pile groups is studied. The stress and deformation characteristics of pile foundation are obviously different from single pile. For pit group piles, as the excavation depth increases, the axial force of the pile increases, and the maximum axial position of the pile body is transferred from the upper middle part to the middle part of the pile, Body in the lower part) have a certain degree of difference. In the same excavation depth, the axial force of the pile near the underground continuous wall is small, and the axial force of the pile near the center of the pit is relatively large. The main reason is that the springback of the soil at the center of the pit is larger than the edge of the foundation pit, and the corresponding displacement of pile-soil and frictional resistance of pile-side are also greater. Due to the lateral deformation of the supporting structure caused by the excavation of the foundation pit, the pile near the supporting structure is bent. The overall performance is that the deformation of the upper part of the pile is larger and the deformation of the middle and lower parts is smaller.