再论悬臂式抗滑桩合理桩间距的计算方法

Further discussion on calculation method of rational spacing between two adjacent cantilever piles for stabilizing slope

为了进一步合理确定悬臂式抗滑桩桩间距,在对以往关于开挖边坡抗滑桩桩间距分析模型缺陷讨论的基础上,提出在抗滑桩桩后局部所形成的拱脚处,两侧土拱在此交汇形成的是倒梯形受压区。在计算确定悬臂式抗滑桩桩间距时,除满足桩间静力平衡条件、土拱跨中及拱脚处的强度条件等基本控制条件外,还需满足桩计算宽度条件、桩土变形协调条件等附加条件,得到了确定桩间净距的方程组,通过迭代试算可以求解。依托一工程实例,定量地说明了在其他因素不变的情况下,桩间净距随桩后土体黏聚力或内摩擦角的增大而非线性增大,且桩间净距受黏聚力的影响更为敏感,同时桩间净距随着桩后坡体推力的增大而呈非线性减小。所提出的方法除可用于黏性土外,还可用于无黏性土。

This paper is to determine the spacing of cantilever piles for stabilizing slope more reasonably. The defects of existed analysis models for cutting slopes are discussed. A reversely trapezoidal compressed zone is assumed to present behind a pile. This zone is the arch foot related to soil arching on both sides of the pile. Some control conditions are given for calculating rational spacing between two adjacent piles. These conditions include（1） static equilibrium equation between slope thrust on the soil arching and resistance on its two end sections near the two piles,（2） strength principle of the point at internal edge of medial cross-section of the soil arching,（3） the strength condition of two end sections of the soil arch,（4） calculation width of the pile due to its spatial resistance effect and（5） compatibility of deformation between the pile and the behind soil. The equations to determine the spacing are given and can be solved with iterative and trial and error calculation methods. Results of an engineering example quantitatively show that the spacing between two adjacent piles nonlinearly increases as the cohesion or internal friction angle of soil behind piles increases. It nonlinearly decreases as the upslope landslide thrust on the piles increases. In addition, the effect of the cohesion on the spacing is more sensitive than that of the internal friction angle. The proposed method can be suitable for both cohesive and noncohesive soil.