杂填土-强风化岩地层中下穿铁路通道工程的开挖稳定性分析

Stability Analysis of Excavation of Railway Underpass in Fill Overlying Strongly Weathered Rock Ground

为不影响列车的正常运行和避免对周边地表及建筑物的产生过大扰动,既有铁路下方下穿通道的开挖稳定性尤为关键。以十堰市林荫大道3号线下穿东风铁路通道工程为研究对象,利用有限元软件ABAQUS对该下穿通道的基坑开挖过程进行数值模拟,结合现场实测数据,对开挖施工引起的周边地表、支护桩及轨道的位移响应进行系统分析。结果表明:有限元数值分析能较好地预测基坑开挖过程中周边地表及支护桩的位移响应,而由于忽略了列车的荷载效应,数值计算所获的轨道竖向位移明显偏小;基坑开挖过程中,越靠近基坑中心位置,支护桩及地表的位移响应值越大,而当距离基坑中心位置一致时,离支护桩较近的地表监测点的位移响应值较小。最后,基于分析结果,对该下穿通道工程的开挖稳定性进行评价。

To avoid affecting the normal operation of train and considerable disturbance to the surrounding ground and buildings,the excavation stability of underpass underneath existing railway should be ensured.Taking the Linyin Avenue Line 3 underpass that is underneath Dongfeng railway in Shiyan as an example,the excavation process of a railway underpass was simulated using the finite element software ABAQUS;in combination with the in-situ monitoring data,the excavation-induced displacement responses of the surrounding ground,retaining pile and railway were systematically analyzed.It was found that the finite element analysis could generally perform well for predicting the displacement responses of ground surface and retaining pile;however,likely due to that the train travelling-induced load was not considered in the numerical simulations,the computed displacements of railway were evidently smaller.During excavation of the railway underpass,the nearer to the center of underpass,the larger are the displacement responses to both the ground surface and retaining pile;when the distance to the underpass center is the same,the displacement response at a ground surface observation point closer to a retaining pile was generally smaller.Furthermore,based on the analysis results,the excavation stability of the railway underpass was evaluated.