边坡桩-土相互作用的土拱力学模型与桩间距问题

桩-土相互作用机制是边坡抗滑桩设计需要考虑的重要因素之一。基于抗滑桩在侧向荷载作用下的受力条件，通过土力学和弹性力学的基本理论，导出了桩-土作用下桩后土体任意点的应力解析解，建立了土拱的力学模型；获得了土拱应力的等值线分布，得出了双曲拱、扩肩拱、马鞍拱和圆弧拱4种土拱形态，分析了不同桩间距、桩宽、桩后距离及土体力学特性对土拱效应的影响及其变化规律，阐明了土拱的作用机制。以拱体内土体破坏时的极限平衡状态为依据，基于Mohr-Coulomb抗剪强度理论建立了最大桩间距控制方程，并给出了具体的工程实例，对桩-土相互作用机制和抗滑桩设计理论研究具有一定的参考价值。

Mechanical model of soil arch for interaction of piles and slope and problem of pile spacing

The interaction mechanism of piles and slope soil is one of the important factors for the design of anti-sliding piles. On the basis of stress condition of the passive piles subjected to lateral force, the stress expression of arbitrary point of the soil behind the piles is derived from the basic theory of soil mechanics and elastic mechanics. Accordingly, the mechanical model of soil arch is created; and distribution of soil stress isolines is given. The shape of soil arch is found to be hyperbolic, shoulder expansion arch, saddle and domal which are distributed in different zones behind the pile groups. In addition, the mechanism of arching effect is completely interpreted; the relationship between pile spacing, pile width, distance behind piles and varying effect of soil arch are discussed in detail. Moreover, some factors influencing soil arching effect, such as inner friction angle and cohesion, are discussed as well. Furthermore, with regard to the problem of maximum pile spacing, in view of the stress condition of limiting equilibrium of soil at the arching crown, the control equation of maximum pile spacing is built based on the Mohr-Coulomb theory of soil shearing strength. Finally, a practical case of slope prevention engineering is studied for the design of pile spacing. This paper will play a great role for the realization of pile-slope interaction and contribute a lot to the theory of design of anti-sliding piles in the field of slope engineering.