Study On Excavation Induced Deformation And Ground Settlement Of Deep Subway Foundation Pit In Tianjin

With the rapid development of civil engineering, there are more and moreconstruction of high buildings and the subways. This brings a large number ofexcavations of deep foundation pits. In our country, the excavation of deepfoundation pit on soft subgrade area often induces some accidents. These accidentsbring great loss in economy and bad influence on society. The main reason is thelack of study on the alarm value of deformation. Under this circumstance, theengineers can't be aware of the danger and take action accordingly in time.The wall deflection and ground settlement induced by excavation of foundationpit on soft subgrade area are important indexes of the security. And we should try ourbest reducing the influence of deformation induced by excavation of deep foundationpit. After exploring and studying for many years, several cities that have alreadycompleted the construction of subway, such as Shanghai, Beijing and Shenzhen, havealready had a series of monitoring data and theory which can supervise theconstruction of local engineering. It includes strict and reasonable regulation of thewall deflection and the ground settlement during the construction. Because of lackingof corresponding research, the excavation of deep foundation pit in Tianjin can onlybe supervised by corresponding parameter of Shanghai. But the soil characteristics aredifference between Tianjin and Shanghai. It is of great blindness that using theexperience of Shanghai directly. The alarm value of deformation during constructionthat would work well in Tianjin is indispensable.This paper relies on the construction of Tianjin Subway Line 1. And by theoryanalysising and finite element simulation, the ground settlement was calculated. Andthe appropriate calculation parameter were chosen and the finite element model wasadjusted according to a large number of observed data. With the analysis modelsuitable for the soil characteristic in the area of Tianjin, the limit of the steady statewas studide. The results provide the alarm value of deformation of the deepfoundation pit.