Abstract: In order to get the dynamic construction mechanical behaviors such as pile-net structure implementing and new embankment fractional filling , the dynamic simulation model of expressway embankment unilateral widening on soft ground treated by pile-net structure was estab!ished , comprehensively considering the soil-structure interaction. The critical mechanical responses , such as post construction settlement , lateral displacement , geogrid tension , stability and safety , with and without pile-net structure treatment were compared. The results show that pile-net structure could significantly decrease the post construction settlement and differential settlement at the top of old and new embankment , and effectively slow down the old embankment lateral disturbance impacted by new embankment; geogrid tension reaches the peak value at the edge of pile top , and the potential s!ip surface changes to the side of old embankment from the side of new embankment; stability safety factor keeps relatively high in the full process; the water pressure peak value of excess pore decreases extensively and the dispersing time shortens significantly. Pile-net structure can be used to treat the old embankment widening project on soft ground quickly and safely

Key words: soft ground, embankment widening, pile-net structure, finite element method, mechanical behaviors

摘要： 综合考虑土-结构间相互作用，建立了桩网结构处治软土地基高速公路路基单侧式拓宽的全过程动态仿真模 型，模拟了桩网结构实施及新路基逐层分步填筑等动态施工力学行为，对比分析了有无桩网结构处治措施时工后沉 降、侧向位移、土工格栅拉力和稳定安全性等关键力学响应。结果表明:软基经桩网结构处治后，可显著减小新旧路 基顶面的工后沉降及差异沉降，有效减缓新路基对旧路基的侧向扰动;土工格栅拉力在桩顶边缘处出现峰值;潜在 滑动面由新路基侧转移至老路基侧;稳定安全系数全过程保持相对较高;软基内的超孔隙水压力峰值大幅减小，消 散时间明显缩短:桩网结构可用于软土地基旧路拓宽工程的快速安全处治。

关键词: 软土地基, 路基拓宽, 桩网结构, 有限元法, 力学行为