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

Abstract

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.