三峡库区滑坡抗滑桩设计地基系数取值的探讨

The Value of Foundation Coefficient in the Design of Anti-slide Pile of Landslide in Three-Gorges Reservoir Area

从岩土体性质、地下水、时间效应、深度、桩截面尺寸及桩周地基土的变形量方面,讨论了影响地基系数的几个因素,给出了线弹性地基反力法计算弹性桩内力的通解,比较了几种线弹性地基反力法的分布形式、适用条件及其不足之处。以三峡库区万州区二层岩滑坡为例,对于3种不同地质环境中的抗滑桩分别采用K法、C法、M法计算抗滑桩的内力,结果表明:M法计算得到的抗滑桩承受的弯矩、剪力最大,桩水平位移最大,对桩周岩土体的应力最小;K法计算得到的弯矩、剪力最小,桩水平位移最小,对桩周岩土体的应力最大。根据万州区滑坡抗滑桩嵌岩段岩土体的质量等级,认为万州区抗滑桩设计采用M法较适宜,这对万州区今后滑坡治理设计具有重要的指导作用。

This paper introduces the influencing factors of foundation coefficient such as characters of rock mass and soil body, underground water, time effect, depth, section size of pile, compress variation of soil. At the same time, it discusses the adoptation of the value by the present design code. Besides, it presents the general solution of calculating internal forces for elastic pile by linear elastic foundation reaction method and the distribution of foundation coefficient, applicable conditions as well as its disadvantages. Taking a project in Wanzhou City of Three Gorges Reservoir area for example, it calculates the internal forces of anti-slide pile from different geological environments by methods of K-method, C-method, and M-method. The results show that, when M-method is used in the design of anti-slide pile, the bending moment, shearing force and the horizontal displacement of anti-slide pile bearing are the maximum, and the stress acted on the soil are the minimum. However, if the K-method is used in the design of anti-slide pile, the bending moment, shearing force and the horizontal displacement of anti-slide pile bearing are the minimum, and the stress acted on the soil are the maximum. Finally, according to the quality grade of rock socketed of anti-slide piles, the conclusion is reached that M-method is more suitable for calculating internal forces of anti-slide pile in Wanzhou City, and that this will be helpful for the design of landslide control works.