桩承式路堤承载特性颗粒流细观模拟

Mesomechanical analysis of bearing characteristics of pile-supported embankment with particle flow code

采用离散元法软件PFC2D,建立了桩承式路堤承载特性颗粒流试验模型.分析了路堤荷载下填土颗粒间接触力、应力和竖向位移等的分布规律以及桩土应力比的变化规律,并研究了桩间距、桩帽宽度、颗粒间内摩擦角和颗粒形状等因素对桩承式路堤承载特性的影响.结果表明:填土颗粒中土拱结构主要存在于桩顶1倍桩净间距高度范围内;桩帽宽度越大,桩间距越小,桩土应力比越大但土拱结构稳定性越弱;填土颗粒表面越粗糙,内摩擦角越大,桩土应力比越大且土拱结构稳定性越强;随着路堤荷载的增加,填土颗粒中土拱结构呈现出形成-破坏-再形成的变化规律.

Based on a two-dimensional discrete element method program PFC2D, a numerical model was established to simulate the bearing characteristics of pile-supported embankment. The variations of contact forces, stresses, vertical displacements and pile-soil stress ratios were analyzed. Further- more, a parametric study was carried out to investigate the performance of pile-supported embankment and the selected influencing factors consist of the pile spacing, the width of pile cap, the friction angle of cushion and the particle shape of cushion. The numerical results show that the soil arching struc- ture in embankment fill mainly exists above the pile cap of one time clear pile spacing. The wider the pl e cap as well as the smaller the pile spacing are, the higher pile-soil stress ratio but the weaker sta bility of soil arching structure will be. If the surface of soil particle is rougher as well as the friction angle is greater, pile-soil stress ratio will be higher and the stability of soil arching structure will be stronger. With an increase of surcharge loads, the soil arching structure presents a changing process of forming-failure-reforming.