黄泛区跨线桥承台基坑开挖对既有路基稳定性的影响研究

发布时间：2019-06-04 18:54

【摘要】：目前,我国道路呈现横纵交叉状,数量逐年增加,造成了路线设计时,道路需要下穿或上跨,从而致使多数跨线桥承台必须要紧靠高填方路基边坡进行排列。而新的承台基坑开挖将直接影响原有路基的力学平衡状态,而且原有道路上的车辆瞬时动荷载和高地下水位基坑渗流也会增加基坑被破坏的风险,造成失稳。本项目通过收集现场监测数据,考虑基坑渗流及路基超载作用,针对路基和基坑的稳定性进行了分析计算。根据现场监测分析和数学建模计算,主要提出结论如下：1)基坑开挖阶段,基坑距路基坡脚较远时,浅层土体侧向位移较大；当距路基坡脚较近时,则深部土体侧向位移量明显增大。基坑拔桩阶段,在侧向土压力作用下,基坑周围发生局部坍塌。2)基坑开挖深度及路基超载越大,基坑侧向位移量及坑底隆起量均越大,同时,引起路基底部的负孔压区域面积增大,加剧路基不均匀沉降的发生。3)为提高既有路基旁基坑开挖时的稳定性,应合理考虑板桩入土深度及支护方式,并加强施工现场监测。
[Abstract]:At present, the number of roads in China is increasing year by year, resulting in the need for lower or upper span of the road, resulting in most of the bridge caps must be arranged close to the slope of the high fill subgrade. The excavation of the new cap foundation pit will directly affect the mechanical balance of the original subgrade, and the instantaneous dynamic load of vehicles on the original road and the seepage of foundation pit with high groundwater level will also increase the risk of foundation pit destruction and cause instability. In this project, the stability of subgrade and foundation pit is analyzed and calculated by collecting the field monitoring data, considering the seepage of foundation pit and the overload effect of subgrade. According to the field monitoring analysis and mathematical modeling calculation, the main conclusions are as follows: 1) in the excavation stage, when the foundation pit is far from the foot of the subgrade slope, the lateral displacement of the shallow soil is larger; When it is close to the foot of subgrade slope, the lateral displacement of deep soil increases obviously. In the stage of foundation pit pile pulling, the local collapse occurs around the foundation pit under the action of lateral earth pressure. 2) the greater the excavation depth and subgrade overload, the greater the lateral displacement of foundation pit and the amount of uplift at the bottom of the pit, at the same time, The area of negative pore pressure area at the bottom of subgrade increases, which aggravates the occurrence of uneven settlement of subgrade. 3) in order to improve the stability of foundation pit excavation next to the existing subgrade, the depth and supporting mode of sheet pile should be considered reasonably, and the monitoring of construction site should be strengthened.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.55;U416.1

【相似文献】