软土地区地铁道床沉降特征及其诱发因素分析

以上海4条地铁线路道床长期沉降监测资料为基础,分析了地铁隧道的纵向沉降特征;结合该地区地质环境调查资料,深入分析地铁隧道沉降与下卧层地层结构、浅部地下水位变化以及区域地面沉降三个地质环境因素之间的相互作用关系。结果表明,地铁隧道下卧地层结构差异是地铁隧道沉降差异性的重要地质环境因素,深基坑降排水引起降水目的含水层地下水位下降,使得降水目的层以及相邻软黏性土层发生较大的压缩变形,导致以降水目的层上覆软黏性土层为承载体的地铁隧道也随之发生沉降,区域地面沉降也是地铁隧道沉降的重要影响因素。

Characteristics of track- bed settlement and its inducing factors for subway in soft soil districts

Based on long- term monitoring data of four metro lines and environmental geological survey in Shanghai，we conducted research on the longitudinal settlement characteristics of the lines and in- depth analyzed the interaction between subway- tunnel settlement and geological environmental factors，such as geological structure of underlying layer，shallow groundwater environment and regional land subsidence． Ｒesults show that the differ- ence of geological structure underlying the subway tunnel is the most important factor affecting the tunnel- settle- ment． In addition，dewatering of deep foundation pit caused the water level to decline in the objective aquifer， making the layer and adjacent soft clay compressed，resulting in the settlement of metro tunnels，for the subway tunnel settlement supported by the soft layer above the pit． Besides，regional land subsidence also played a signifi- cant role．