软弱地层联络通道冻结法施工变形监测分析

Measurement and Analysis of Construction Deformation of Connecting Passage in Weak Stratum by Freezing Construction

复杂地层中地铁区间联络通道冻结法施工往往会引起地层的显著抬升或下沉,进而影响地层内部既有结构以及周围环境。以苏州轨道交通S1号线金沙江路站—洞庭湖路站区间联络通道兼泵房施工为例,通过分析现场实测数据可知:地表竖向位移变化曲线可分为钻孔施工、冻结隆起、冻结起伏、融沉注浆、注浆完成5个阶段,钻孔初期地表出现隆起和下沉且最终逐渐趋于平稳,冻结期间地表逐渐隆起,开挖期间地表出现沉降和隆起,两者相互叠加使得地表位移发生起伏变化;各阶段在联络通道附近处地表隆起值最大,随着距离联络通道变远,地表隆起值逐渐减小,其中垂直联络通道中轴线方向距离隧道约20 m范围内土体受冻结施工影响较大,平行联络通道中轴线方向距离隧道约10 m范围内土体受冻结施工影响较大,超出上述范围影响逐渐减小;隧道从冻结起伏阶段过渡到融沉注浆阶段表现出了较大的收敛变化,在现场监测时需提高管片应力监测频率。

The freezing method for the construction of subway contact channels in complex strata often causes significant uplift or subsidence of the strata,which in turn affects the existing structures inside the strata as well as the surrounding environment.The construction of the liaison channel cum pump room between Jinshajiang Road Station and Dongting Lake Road Station of Suzhou Railway Line S1 is taken as an example.By analyzing actual measurement data on site,it is known that the surface vertical displacement changing curves can be divided into five stages of drilling construction,freezing uplift,freezing undulation,melting and sinking grouting,and grouting completion.At the beginning of drlling,the surface appears to uplift and sink.And finally it tends to be stable gradually.During the freezing,the surface gradually uplifts.During the excavation,the surface appears to settle and uplift.The two superimposed on each other make the surface displacement change undulatively;The surface uplift value is the largest in the vicinity of the liaison channel at each stage and gradually decreases with farther of the distance from the liaison channel.The soil in the direction of the vertical liaison channel within the range of about 20 m from the tunnel is more affected by the freezing construction,and the soil in the direction of the parallel liaison channel in the range of about 10 m from the tunnel is more affected by the freezing construction.The influence beyond the above range gradually decreases;From the frozen heave stage to the melt and sink grouting stage,the tunnel transition shows a large convergence change,and the frequency of tube sheet stress monitoring need be enhanced during the field monitoring.