溶洞对轨道交通车站基坑开挖稳定性的影响规律

Influence Law of Karst Cave on Rail Transit Station Foundation Pit Excavation Stability

当轨道交通车站基坑位于溶洞地层上开挖时,会面临很大的安全问题,研究溶洞对车站基坑开挖稳定性的影响规律有助于改善轨道交通工程施工安全。以南京—句容城际轨道交通工程为例,建立三维有限元模型分析了溶洞对轨道交通车站基坑开挖稳定性的影响。根据基坑开挖及支护过程中支护桩的水平位移、基坑坑底土体隆起量和支护桩后地面沉降的变化规律,确定了溶洞的空间影响范围,并将数值模拟结果与实际监测结果进行了对比,验证了数值模拟结果的准确性。通过模拟基坑与溶洞的不同位置关系、不同溶洞尺寸下的基坑开挖与支护过程,得到相应的围护结构变形和基坑土体位移,进而总结出溶洞位置及其尺寸对基坑开挖及围护结构的稳定性的影响规律。

When rail transit station foundation pit is excavated above Karst cave stratum,serious safety problem will occur.Research on the influence law of Karst cave on station foundation pit excavation stability can help to improve rail transit project construction safety.Taking Nanjing-Jurong intercity rail transit engineering as an example,a three-dimensional finite element model is established to study the influence of Karst cave on the stability of rail transit station foundation pit excavation.According to the variation law of horizontal displacement of supporting pile,soil heave amount of foundation pit bottom and land subsidence after pile support during foundation pit excavation and supporting process,the spatial influence range of Karst cave is determined,and the numerical simulation results are compared with the actual monitoring results to verify the reliability of the numerical simulation results.Through simulation of the excavation and supporting process of the foundation pit under different location relations and different cave sizes,the influence law of cave position and size on foundation pit excavation stability is studied from the aspects of retaining structure deformation and foundation pit soil displacement.