桩承式路堤土拱形成及荷载传递机制离散元分析

土拱效应是桩承式路堤中影响荷载传递的关键因素。基于前人的室内模型试验，建立了桩承式路堤离散元（DEM）数值分析模型。基于路堤中应力偏转规律对土拱随桩土相对位移的形成规律进行了分析。在该基础上提出了合理拱轴线土拱模型，并引入荷载传递系数? 对土拱与土拱下方路堤填料间的荷载传递进行量化分析。模拟结果表明，桩土相对位移引起路堤中应力主方向发生偏转并形成虚拟土拱；土拱形态及高度随桩土相对位移的变化而变化，最大拱高约0.8倍桩净间距；? 随土拱高度的增加呈对数关系减小。

Discrete element analysis of development and load-transfer mechanism of soil arching within piled embankment

Soil arching effect is a key factor for the load transfer in a piled embankment. Based on the previous model test, a DEM model of a piled embankment is conducted by the PFC2D. The development of soil arching with the pile-subsoil relative displacement is analyzed based on the deflection of principal stress direction. Then, a soil arching model with a reasonable arch axis is proposed to depict the soil arching in a piled embankment. Meanwhile, a load-transfer coefficient α is introduced for the quantitative analysis of load transfer between the soil arching and the embankment fill below the arching. Numerical results indicate that the pile-subsoil relative displacement will induce the deflection of principal stress direction, which forms the soil arching in embankment. The features and heights of soil arching are related to the pile-subsoil relative displacement, and the maximum soil arching height is about 0.8 times of clear pile spacing. The decrease in α with the increase of soil arching height is found to follow a logarithmic relation.