Performance of an Overexcavated Metro Station and Facilities Nearby

Abstract

This paper examines the performance of an overexcavated metro station in soft clay within Shanghai metropolitan area, in which there are many high-rise buildings and buried utility pipelines in the proximity. The excavation was supported by stiff concrete diaphragm walls braced by steel pipes. The measured performance included deflections of diaphragm walls, ground settlements, and settlements of the adjacent buildings and utility pipelines. On the basis of daily monitored data, the effects of overexcavation on wall deflections, deflection rates, and the locations in which the maximum wall deflections and the maximum wall deflection rates occurred were investigated. For those buildings in the proximity, the heavy high-rise steel-reinforced concrete buildings supported by deep foundations experienced limited uniform settlements, whereas the light brick buildings resting on shallow foundations experienced substantial total and differential settlements. For the adjacent utility pipelines, the excavation-induced settlements were relatively uniform.