Monitoring And Numerical Simulation Analysis For Deep Foundation Pit In Soft Soil Foundation

This paper, which is based on the deep foundation pit of Chao Zong Yu Yuan district in Changsha city, explores the variation regulation of the force and deformation of retaining structure, the sedimentation of surrounding surface and the surrounding buildings during the excavation of deep foundation pit with the methods of on-site monitoring, theoretical analysis and numerical simulation. The major works and conclusions were summarized as follows:(1)The design theory and calculation methods of deep foundation pit were introduced in this paper at first, a supporting program was designed for this foundation pit by using Lizheng geotechnical software, and a practical monitoring plan was formulated by combining the practical engineering and related specifications at the same time.(2)According to the monitoring program, a long-term monitoring has been done for this foundation pit, and the monitoring data shows:With the increase of excavation depth, the deep-displacement curve of soil turns into arched curve form the early straight line, and location the maximum displacement fells down from the surface. The process of building settlements can be divided into three stages, slowly increasing, rapid increasing and gradually slow stages.(3)Based on the deep foundation pit of Chao Zong Yu Yuan district, a three dimensional numerical model was established by using FLAC3D. The calculated results and field measured results were proved to be consentaneous by compared with each other. Further analysis based on the model has been done for the variation regulation of the positive corner and negative corner, surface and bottom of the foundation pit.(4)A numerical model with inverted-L shaped was established to research spatial effect in special-shaped pit, the results show that the coverage range of spatial effects is about2-3times of the depth of excavation for the foundation pit, the top beam can limit the displacement around corner of the pit and increase the coverage range of spatial effects. 107figures,25tables,110references.