Qingdao Subway Complex Deep Excavation Support The FLAC Numerical Analysis

Deep foundation pit has been wide-spread applying in high-rise buildings and subway project and municipal engineering.This paper, based on the analysis of many relevant researches at home and abroad, using the methods of theoretical analysis and numerical simulation, explores the law of force and deformation in the deep foundation pit retaining structure. At the same time, combined with engineering practice, analysis the influence of the convex effect and the suitability of different soil constitutive models in deep crossing foundation pit engineering. The major works and conclusions are as follows:(1) Based on the summarizing and analyzing of the development of deep foundation pit and research status at home and abroad, combined the complexity and shortcomings in design and construction, introduces the development trend of deep foundation pit engineering;(2) Describes the deformation behavior of the foundation pit in the envelope structure and surrounding soil strata. Then analysis the deformation mechanism and summarizes the common theory and calculation method in design of deep foundation pit;(3) Based on the deep foundation pit of line 1 and 3 in Qingdao metro, using the method of finite difference, established FLAC numerical model. Using the above model, the double-row piles structure design parameters of its deformation to study the impact of the law;(4) This paper presented a 3D numerical model considering the soil-structure interaction to examine the ground movement and internal force during the construction of North Metro Station in Qingdao, with special focus on the convex effect of the crossing excavation. The influences of intersection angles and soil resilience coefficient on deformation behavior were discussed and the suitability of different soil constitutive models applied to numerical analysis of deep excavations was also compared.