小桩距下的抗滑桩后滑坡推力分布规律分析

Thrust Distribution Law of Anti-slide Pile under Small Pile Spacing

从土拱效应出发来阐述抗滑桩桩距与桩土变形机制之间的联系,将桩后水平土拱效应分为4个阶段,根据各阶段指出压力法中各方法的适用范围,楔体滑动法适用于土拱稳定阶段,塑性变形理论法适用于土拱塑性变形阶段,绕流阻力法适用于土拱破坏阶段。基于小桩距下适用的滑动楔体法,提出考虑竖直方向上的土拱效应、桩的位移模式下的极限侧土压力计算的改进方法,并与实测数据进行对比,结果符合其大致变化规律,为桩的内力验算提供参考。最后,提出“二段式”侧向力分布计算的方法:当滑动面倾角不可忽视,而滑坡体产生桩顶剪出破坏时,此时滑动楔体法计算的土压力属于抗滑桩的上段,而下段为非极限平衡段,解释了滑坡推力呈“中间大、两头小”抛物线分布规律的实质,为抗滑桩设计提供理论依据。

The relationship between pile spacing and pile soil deformation mechanism is expounded based on soil arching. The horizontal arching effect after pile is divided into four stages, and then applicable scope of each method in "pressure method" is determined for different stages. It is found that the wedge sliding method is suitable for the stable stage of soil arch, the plastic deformation theory method is suitable for the plastic deformation stage of soil arch, and the flow resistance method is suitable for the failure stage of soil arch. Based on the sliding wedge method applicable under the small pile distance, this study proposes an improved method for calculating the ultimate lateral earth pressure in the vertical direction of the soil arching and the displacement mode of the pile. Compared with the measured data, the result obtained by this method accords with the general rule of change, providing a reference for the internal force checking of the pile. Also, the study suggests the method of calculating the lateral force distribution of "two section".When the slide angle can not be ignored and the landslide body is damaged by the top of the pile, the earth pressure calculated by the sliding wedge method should belong to the upper part of the anti-slide pile, and the lower part is the non limit equilibrium section.Therefore, this explains the essence of the parabolic distribution law of the landslide thrust, which is large in the middle and small at both ends, providing a theoretical basis for the design of anti-slide piles.