超深地连墙施工对软弱地层扰动现场试验研究

Field measurements of disturbance of ultra-deep diaphragm wall construction to weak stratum

为研究软土地层中超深地连墙施工对周边地层扰动影响,对苏州地铁5号线某车站地下连续墙施工进行现场监测研究.针对3幅相邻槽段施工,采用现场监测对施工过程中的土体侧向位移、地表沉降、分层土体沉降、周边建筑物沉降和土压力变化进行观测.发现单幅施工过程中,成槽开挖施工对地层扰动最大,地层变形显著;混凝土浇筑会对土体产生应力补偿,抑制地层变形;在混凝土硬化阶段,土体应力轻微释放,地层变形继续发展并趋于稳定.地层变形规律表明,浅层土体受扰动较大,土体变形较明显,最大土体侧向位移发生在地表,离槽段越近,沉降越明显,深层土体受到扰动则较小.相邻槽段施工对地层变形累积增加,但变化幅度较小.现场地连墙施工引起的周边建筑物沉降和倾斜均在可控范围内.

This study investigates ground movement based on field instrumentation during the installation of deep concrete diaphragm wall panels for the Suzhou Metro Line 5 Project.The field measurements,including lateral ground movement,ground surface settlement,subsurface settlement,adjacent building settlement,soil and hydrostatic pressure,are conducted during the installation of three adjacent wall panels.The measurement shows that the construction disturbs the ground significantly at shallow depth and generates relatively large lateral movement.The maximum lateral ground movement occurs at the ground surface and the movement decreases along depth.The trench excavation releases ground stress and generates the major portion of the lateral ground movement.The trench concreting reduces the lateral ground movement by compensating the ground stress release.The concrete hardening releases the ground stress again but on a much smaller magnitude and the soil displacement tends to be stabilized.The installation of adjacent panels contributes to the ground movement which occurs along a line perpendicular to the centerline of the previously installed panel,but the contribution is relatively small.The settlement and inclination of surrounding buildings caused by the panel installation are relatively small and controllable.