一种微型桩组合抗滑结构内力分析方法

Analytical method of internal forces of a combining micropiles structure

微型桩组合抗滑结构是指把若干根以一定间距排列的微型桩在顶部用板体连接起来,以抵抗滑坡推力的一种新型支挡加固结构。因其具有桩径小、施工快捷、施工人员安全保障高、经济性好等优点,可用于中小型边(滑)坡的治理工程中,尤其是快速抢险工程。根据此种结构的一般受力特征,在计算桩体内力时,提出把该结构在滑面以上的部分视为在滑坡推力作用下的刚架结构,等效分解后对各桩按弹性地基梁利用m法进行解析,其间考虑了受荷段桩间岩土体对桩的推力作用,各桩体在滑面以下的部分视为弹性桩利用k法进一步计算,于是按照先分析上半部分再计算下半部分的方法可确定出该结构内力。分析结果表明,各微型桩承受轴力、弯矩和剪力,其中轴力作用更为主要。以该类结构在四川省广巴高速公路路堑边坡工程中实际应用为例,通过试验说明了所提算法的合理性。

A combining micropiles structure is a new retaining and reinforcement structure for slopes.This structure consists of several separated micropiles connected by a roof plate.The structure has the advantages of small pile diameter,easy and quick construction,operational safety and low cost.It can be applied to a moderate or small slope or landslide control projects.In particular,the structure is very suitable for dealing with project emergencies.According to the general load features of the structure,it is put forward that the part of the structure above the slip surface of a landslide may be regarded as a single rigid frame under landslide thrust.The part of each pile above slip surface can be analyzed by m-method in terms of elastic foundation-beam theory after the combined structure is equally deposed.The pressure on each pile by soil or rock mass among the piles above the slip surface are considered.Furthermore,the part of each pile below slip surface can be analyzed by k-method in terms of elastic foundation-beam theory.In this way,internal forces of the structure can be obtained after several iteration calculation.Analytical results show that each micropile in the structure is loaded by an axial force,a bending moment,and a shear force,but the axial force is principal.The new structure and its analytical method are successfully used in practice for a cutting slope in Guangyuan–Bazhong expressway project in China’s Sichuan Province.The performance of this structure is verified by experiments.