桩承式路堤“土拱结构”形成演化规律离散元分析

“土拱结构”作为桩承式路堤中的主要荷载传递媒介,对路堤荷载传递和路堤填料位移有显著影响。基于室内模型试验,采用颗粒流软件PFC^2D建立桩承式路堤离散元（DEM）数值分析模型,基于应力主方向、接触力链及路堤填料沉降分布规律对路堤中“土拱结构”形态及其演化规律进行深入分析。研究结果表明：路堤中“土拱结构”随桩土相对位移的增加而逐渐发展并最终趋于稳定,最终的“土拱结构”形态呈0.8倍桩净间距高的抛物线形;路堤填筑高度对“土拱结构”形态、演化规律以及荷载传递效率有显著影响;路堤填料粗糙度、桩净间距及桩梁宽度对路堤荷载传递效率有显著影响,但对“土拱结构”最终形态几乎无影响。

Discrete element analysis of the development and evolution of “soil arching” within a piled embankment

“Soil arching”, as the major medium of load transfer for a piled embankment, has significant influences on the behaviors of load transfer and of embankment fill displacements. Based on the laboratory model tests, a series of numerical models by discrete element method (DEM) are established with the particle flow code PFC^2D to investigate the features and evolution of “soil arching” by analyzing the distribution of principal stress direction, contact force chains and embankment fill settlements. The numerical results indicate that the “soil arching” develops gradually with the increase of pile-soil relative displacement and maintains a relatively stable state finally. Meanwhile the relatively stable “soil arching” is roughly parabola-shaped with a height of 0.8 times the clear spacing of cap beam. Additionally, the embankment height has significant influences on the features and evolution of “soil arching”, as well as the load-transfer efficacy. However, the roughness of embankment fill, the clear spacing of cap beam and the width of cap beam have significant influences on the load-transfer efficacy, but not on the “soil arching” features.