地铁隧道联络通道冻结施工引起地表变形实测分析

Measurement Analysis of Surface Deformation Caused by Freezing Construction of Connection Passages in Metro Tunnels

在地铁建设过程中,联络通道的冻结法施工仍然存在许多安全问题。以苏州轨道交通5号线长江路站—塔园路站区间的2#联络通道兼泵房施工为例,根据监测数据分析了软土地层中联络通道冻结法施工引发的地表沉降变形趋势,主要结论为:联络通道位置的地表竖向位移变化大致经历了钻孔微变、冷冻隆起(冻胀)、开挖起伏、解冻下沉(融沉)和注浆趋稳共5个阶段;垂直于联络通道中轴线的各断面地表最大冻胀变形呈凸起的半椭圆型,最大融沉变形呈V型;距离联络通道中轴线约25 m范围内的地表变形受到冻结法施工的影响较大,超出这个范围则影响较小。

In the process of metro construction,there are still many safety problems in the freezing method construction of connection passage.Taking the construction of 2#connection passage and pump room of Changjiang Road Station—Tayuan Road Station interval of Suzhou Rail Transit Line 5 as an example,the trend of surface settlement and deformation caused by the freezing method construction of connection passage in soft soil layer is analyzed according to monitoring data.Main conclusions are:the surface vertical displacement variation at the position of connection passage generally experiences five stages including drilling micro-change,freezing uplift(frost heave),excavation undulation,thawing subsidence(thaw subsidence),and grouting stabilization;the surface maximum frost heave deformation of all sections perpendicular to central axis of connection passage is in the shape of a‘convex semi-ellipse’,and the maximum thawing deformation is in V-shape;the surface deformation within a range of about 25 meters from the central axis of the connection passage is largely influenced by freezing method construction,and the impact beyond this range is relatively small.