The Research Of Supporting Structure System And Digging Strategies For Deep Foundation Pit In The High-speed Railway Underpass

In a long history, deep foundation pit which is significant both in theory and engineering application for the structure optimization analysis and practical monitoring, is a key issue in the construction of high-speed railway underpass.Based on the excavating and supporting of deep foundation pit in SHANGHAI West Station of BEIJING-SHANGHAI high-speed railway, commercial software ANSYS is employed to build up the numerical models, and to simulate the construction excavating and supporting process; according to the analysis results, combined with the monitoring data, the supporting structure is improved and optimized. The deformation principles of deep foundation pit supporting structure are derived and concluded.Based on the numerical models of deep foundation pit supporting structure, and the chief coefficient of foundation pit stability, optimization design of supporting structure is conducted. To save the project cost, the field monitored deformation data is adopted to redesign the reinforcement of supporting pillars.The numerical models built in this paper are basically consistent with the practical projects. Through modifying models, numerical simulations of deep foundation pit excavation in perfect operation condition, operation condition of extra excavation of 4 meters and operation condition of modifying longitudinal segment excavation length are conducted, respectively. The principles of horizontal displacement deformation of supporting pillars are obtained. The methods employed in this paper could provide technical basis for the familiar deep foundation pit excavation.