Analysis of water inrush of a deep excavation triggered by river bank failure and its reconstruction

Abstract

Many deep excavation projects are adjacent to river, and hence face the seepage risk. In this study, a through-wall seepage failure of a foundation pit adjacent to river is investigated. It is found that, the accident was initiated by the breakage of revetment along the construction joint and cracks of rubble stone masonry, which further caused the slope failure of river bank and the subsequent seepage of river water through the cold joint of waterproof curtain. The remedial works including construction of cofferdam in the river, backfill outside the foundation pit, reinforcement of cold joint, backfill inside the foundation pit, controllable dewatering outside the foundation pit and axial force adjustment of struts are designed. The monitoring results indicate effective implementation of the remedial works and the following successful reconstruction of the project. A summary of reported seepage failure cases adjacent to river is finally made to provide suggestions for the design and construction of future similar deep excavation projects.