软土地区基坑降水对下方越江隧道的影响

Effect of Dewatering on the Existing River-Crossing Tunnel in Soft Ground

基于工程实际,采用有限元法并结合一维固结理论和三维渗流理论分析越江隧道上方基坑降水对其结构的影响,探讨了降水水位、抽水层次、降水时间及方式等因素对越江隧道沉降的影响.结果表明:基坑降水将造成下方越江隧道的沉降;降水深度与其沉降量呈线性变化关系;若抽取微承压水或延长降水时间,都将增加越江隧道下卧土的沉降量.控制隧道上方的基坑降水应采取坑内降水的方式.

Based on a history case of excavation above the existing tunnel,this study analyzed the effect of nearby dewatering on the existing river-crossing tunnel by the finite element method.The influence factors such as the declined depth of groundwater,the extracting layer,the dewatering time and the dewatering method are considered.The results show that dewatering above will cause the settlement of the tunnel.The dewatering depth of groundwater and the tunnel settlement present a linear relationship.Pumping from the low-pressure artesian aquifer will lead to larger tunnel settlement.The longer the dewatering lasts,the larger settlement of tunnel will occur.The result also shows that dewatering inside the foundation pit will cause less amount of tunnel settlement than dewatering outside.