综合管廊深基坑施工对邻近桥梁的影响

Influences of Deep Foundation Pit Construction of Comprehensive Pipe Gallery on Adjacent Bridges

为了解综合管廊基坑施工对邻近桥梁的影响规律,以平潭某区间段管廊深基坑为研究对象,采用PLAXIS 3D岩土有限元分析软件建立三维数值模型,模拟综合管廊深基坑开挖回填,分析围护结构、周边土体变形以及桥桩和桥台的响应情况。结果表明:在桥台影响范围内,地层变形和围护墙侧移明显高于其他部位;越靠近管廊基坑的桥台及桥桩附加位移越大,桥台侧移和沉降极值约为4.00 mm;桥桩水平方向都是朝基坑内移动,在基坑开挖及管廊施工过程中,其竖向主要表现为上浮,随着基坑回填才缓慢发生下沉;邻近的桥台及桥桩位移随基坑围护桩桩长减小而增大,总体上管廊基坑开挖对邻近桥梁引起的位移变化不大。通过对管廊基坑的监测数据分析,表明数值模型可靠,基坑总体上安全稳定,邻近桥梁有足够的安全度。

In order to understand the influence of foundation pit construction of comprehensive pipe gallery on adjacent bridges,a three-dimensional numerical model of deep foundation pit of pipe gallery in Pingtan was established by using PLAXIS 3D geotechnical finite element analysis software.The backfilling of deep foundation pit excavation of comprehensive pipe gallery was simulated,and the response of retaining structure,surrounding soil deformation and bridge pile and abutment was analyzed.The results show that within the influence range of abutment,the stratum deformation and lateral displacement of retaining wall are obviously higher than those of other parts,the larger the additional displacement of abutment and pile near the pipe gallery foundation pit,the maximum value of lateral displacement and settlement of abutment is about 4.00 mm,the horizontal direction of bridge pile is moving towards the foundation pit,and the vertical direction of pile is mainly floating in the process of foundation pit excavation and pipe gallery construction,and only slowly with the backfilling of foundation pit.Subsidence occurs the displacement of adjacent abutment and bridge pile increases with the decrease of the length of retaining pile in foundation pit,but the displacement of adjacent bridge caused by the excavation of pipe gallery foundation pit has little change on the whole.Finally,the monitoring data analysis of the pipe gallery foundation pit shows that the numerical model is reliable,the foundation pit is generally safe and stable,and the adjacent bridges have sufficient safety.