Experimental and theoretical investigation on the stability of deep excavations against confined aquifers in Shanghai, China

Abstract

Urban development often requires deep excavations, such as for deep basements, cut-and-cover tunnels, and underground transportation systems. Pressure from a confined aquifer can cause a sudden failure of a deep excavation and have disastrous effects on the surrounding buildings. In this study, a series of centrifugal model tests were conducted on different aquitards in Shanghai to investigate the failure process and types. Two types of failure were identified from the centrifugal model tests: local failure (sand piping and sand boiling) and general upheaval. An approach to the stability analysis of deep excavation against a confined aquifer was developed. To increase the reliability of the analytical approach, the calculated results were compared with the experimental results. The results showed good agreement.