桩承式路堤土拱效应下的荷载传递机制离散元分析

Discrete Element Analysis of Load Transfer Mechanism under Soil Arching Effect of Piled Embankment

土拱效应是路堤填料因沉降特性诱发的一种应力重分布现象,也是桩承式路堤中影响荷载传递的关键因素。文章基于离散元法构建了桩承式路堤二维数值模型并验证其有效性,然后利用路堤荷载传递效率、应力主方向以及接触力链等宏细观指标,对土拱效应下荷载传递机制进行研究。主要结论如下:不同桩间距的桩承式路堤的荷载传递效率E随填料高度h增大呈指数增长;格栅加筋能够有效提高桩承式路堤荷载传递效率;离散元裂隙网络能够较好展现桩承式路堤模型中应力重分布现象并验证了土拱效应的存在,同时也表明应力主方向偏转是土拱效应产生的实质;接触力链能够有效反映桩承式路堤荷载传递规律以及土拱效应随着桩间距的增大逐渐减弱的趋势。

Soil arching effect is a phenomenon of stress redistribution induced by settlement characteristics of embankment filling,and also a key factor affecting load transfer in pile-supported embankment.In this paper,a two-dimensional numerical model of pile-supported embankment is constructed based on the discrete element method and its validity is verified.Then,the load transfer mechanism under soil arching effect is studied by using macro and micro indexes such as load transfer efficiency,principal stress direction and contact force chain of embankment.The main results show that the load transfer efficiency E of pile-supported embankment with different pile spacing increases exponentially with the increase of filling height h;the grid reinforcement can effectively improve the load transfer efficiency of pile-supported embankment;the discrete element crack network can better show the phenomenon of stress redistribution in the model of piled embankment and verify the existence of soil arching effect;at the same time,it also shows that deflection of stress principal direction is the essence of soil arching effect;in addition,contact force chain can effectively reflect the law of load transfer of pilesupported embankment and the trend of soil arching effect weakening with the increase of pile spacing.