微型抗滑桩单桩设计计算模型及算法研究

Calculation model and algorithm for designing single anti-slide micropile

考虑微型桩与周围岩土体间摩擦力的作用,提出了一种新的微型抗滑桩单桩设计计算模型,并给出了具体算法。由微型桩加固滑坡体的变形特点,分析微型桩与岩土体之间的相互作用机制,将微型桩与周围岩土体的摩擦作用引入其受力分析中;根据微型桩上各部分受力特点的不同,将微型桩分成上部摩擦受拉段、中部滑坡推力作用段和下部锚固段3段进行分析,推导了微型桩总的变形控制方程及各分段的变形控制方程;采用初参数法对控制方程进行求解,得到了微型抗滑桩上的内力分布及变形规律。计算结果表明,在滑坡推力作用下,微型桩的变形主要发生在滑面附近及以上桩段,滑面附近桩段将产生较大的内力和弯曲变形,受拉段弯曲变形较小,近似水平移动;桩与岩土体间的摩擦力是微型桩与周围岩土体相互作用的重要组成部分,摩擦力的作用能显著减小微型桩的弯曲变形,有效控制滑坡体的位移。

With considering the friction between a micropile and the surrounding soil mass, a new design calculation model of single anti-slide micropile is developed; and a detailed calculation algorithm is presented. Based on the deformation characteristics of mieropile in reinforcing a slope, the interaction mechanism between the micropile and the surrounding soil mass is analyzed, and the friction between the micropile and the soil mass is introduced into the force analysis of single anti-slide micropile. According to the different loading distributions along different parts of the micropile, the micropile is divided into three parts along its length, namely, the friction part, the landslide thrust part and the anchoring part. The governing equations for the deformation of different sections of the micropile are derived. The governing equations are solved by using the initial parameter method, and the internal force distribution and deformation characteristics are determined. The calculated results show that, under the action of a landslide thrust, the deformation of micropile mainly occurs near the sliding surface and the upper parts of the pile. The internal force and bending deformations near the sliding surface are larger than those at the other parts of the micropile. Along the friction part of the micropile, the bending deformation is small, and the relatively small bending deformation leads to nearly horizontal movement of the micropile. The friction is an important part of the interaction between micropiles and the surrounding soil mass, and it can significantly reduce the bending deformation of the micropile, so that the landslide displacement can be effectively controlled.