深基坑桩锚支护中桩内力变化规律数值模拟研究

为了解深基坑桩锚支护结构的工作性能,考虑到桩、锚索和土相互作用的情况下,采用FLAC^3D对桩锚支护结构在不同工况下受力特性进行了模拟与研究,本文仅讨论桩的受力变化规律。研究表明:随着基坑开挖深度的增加,桩身轴力值、剪力值逐渐增加,在基坑底面处达到最大;不同的桩长度、锚索长度及预应力值大小对桩身轴力、剪力值的变化影响较小;桩身刚度存在一个最佳值,无限度增加和减小桩身刚度分别会造成经济浪费和不安全因素。所得变化规律曲线与现场试验、理论计算得到的桩内力变化曲线形式和发展趋势相吻合,进一步解释了桩锚支护结构中桩与土的相互作用机理,为桩锚支护优化设计提供一些参考。

Numerical Simulation on the Variation Law of Pile Internal Force of Pile-Anchor Retaining Structure in Deep Foundation Pit

To understand the performance of pile-anchor retaining structure in deep pit, considering the interactions among pile, anchor and soil, the authors only analyze the internal force of pile of pile-anchor system under different conditions using FLAC^3D. The results show that the axial force and shear force increase with the excavation depth growing, reaching the maximum at the bottom of each excavation. Influences of various parameters on pile response, axial force and shear force are investigated, and the influence of length of pile and length of cable and change of prestressing value is less. There exists an optimum value for the stiffness of pile body, and the infinite increasing and decreasing the stiffness of pile body would lead to waste in economy and being unsafe, respectively. In addition, the curves of axial force and shear force and moment are compared with the results got from theory and experiment. The curves change tendency from computation match well with the results from theory and experiment. The conclusions allow one to gain a better understanding of interaction of pile-anchor and soil, which provide some references for pile-anchor retaining optimization.