基于修正主应力旋转理论的抗滑桩桩间土绕流计算方法

桩间土绕流验算是抗滑桩设计三大验算流程之一,研究绕流计算方法对于在保证抗滑桩工程稳定安全的前提下,提高设计精度、节省资金具有重要意义。为弥补现有"拱结构物"假设理论的不足,引入Terzaghi松动土压力理论,建立Terzaghi松动土压力与桩间距的关系以及修正主应力旋转理论。并在Ito塑性变形理论假设基础上提出塑性变形理论适用的上限与下限桩间距,结合修正主应力旋转理论与Terzaghi土拱计算理论建立了极限桩土荷载分担比计算模型,根据所提模型计算结果获得了桩土荷载分担比与土体性质、桩间净距的关系。然后与数值模拟的计算结果进行了对比分析,并提出了桩间土绕流验算方法:定义桩间土稳定性系数为极限桩土荷载分担比与实际桩土荷载分担比之比,稳定性系数大于1表示桩间土较稳定,不发生绕流。

Calculation method of soil flow around anti-slide piles based on modified main stress rotation theory

The checking calculation of soil flow around piles is one of the three checking calculation proce-dures in the design of anti-slide piles. On the premise of guaranteeing the stability of anti-slide pile engi-neering,it is of great significance to study the method for checking calculation of soil flow around the pile to improve the design accuracy and save money. In order to make up for the deficiency of "arch structure" theory,Terzaghi''s theory of loosing earth pressure is introduced into stabilizing pile in this paper,the rela-tionship between Terzaghi loosing earth pressure and pile spacing is established, and a modified principal stress rotation theory is proposed. Based on Ito''s plastic deformation hypothesis, the upper limit and the lower limit of the plastic deformation theory are proposed,combining with the modified principal stress rota-tion theory and Terzaghi soil arch calculation theory, a calculation model of pile-soil load-sharing ratio is established. According to the calculation results of the proposed model, the relationship between the pile-soil load sharing ratio and soil properties and the clear distance between piles is obtained, which is consistent with the numerical simulation results, thus verifying the correctness of the method. A checking method of soil flow around piles is proposed. The stability coefficient of soil between piles is defined as the ratio of the ultimate load sharing ratio of pile to soil and the actual load sharing ratio of pile to soil, the stability coefficient greater than 1 indicates that the soil between piles is more stable and no flow around piles occurs.