抗滑桩桩间形成的土拱是水平土拱和竖向摩擦拱的共同体现，具有明显的三维特征。利用颗粒流分析软件PFC^3D建立数值模型，在桩后不同高度处及同一水平面不同位置设置一系列测量球，监测桩后土体应力变化情况。结合颗粒位移变化情况对抗滑桩桩间三维土拱效应的形成演化进行分析，并对土拱厚度的演化规律做了深入研究，提出结合相对位移和最大主应力等值线综合确定土拱厚度的新方法。分析表明：桩后土拱由桩间临空面靠近桩底开始并不断向土体内部和上部发展，土拱的破坏过程由桩底向桩顶扩展；土拱厚度随深度变化表现为沿桩底向桩顶先增加后减小的趋势；土拱厚度随时间的变化表现为随着加载时间增加，土拱厚度先增加后减小直至土拱破坏。

Soil arching between anti-sliding piles is the interaction of horizontal soil arch and vertical friction arch, with distinct three-dimensional characteristics. Numerical model by the particle flow code PFC^3D was developed and a series of measurement balls to numerically monitor stress variations at different positions behind the anti-slide piles were set. Combined with the displacement of numerical model balls, we analyzed the formation process and evolution pattern of the soil arching effect were analyzed. Also the thickness of soil arch had been studied and finally we proposed a new method to determine the its thickness was proposed. The study shows that the soil arch initiates s from the free face near the bottom of pile and develops to the inner and upper part of the soil, and the failure process of arch expands from the bottom of pile to the top; The thickness of soil arch varies with depth, increasing first and then decreasing along the bottom of pile to the top; The thickness of soil arch varies with time. As the loading stage proceeds, the thickness of soil arch increases first and then decreases until the soil arch is destroyed.

TU473.1

国家重点研发计划（2018YFC1505501）。