Case Analysis Of Deep Foundation Pit Support Based On Prefabricated Prestressed Fish Belly Beam Structure Syste

Compared to traditional supporting methods,prestressed fish-belly beam supports have many advantages,such as small deformation,easy installation and demolition,short construction period,and convenient unearthing,especially when they are applied in large underground engineering foundations.Reinforced concrete supports or traditional steel supports are the major supporting forms in Jiangsu Province.However,the fish-belly beam supports are far less applied because their control factors are still not clear.Based on the engineering structure of Haian Brickstone Business Building,this paper investigated the working characteristics and working mechanism of the assembled prestressed fish-belly beam support system to promote its application.The analysis of numerical simulation and field measurement data was carried out in the paper.The main work and conclusions of this paper are as follows:(1)The key technology,the construction requirements,and the working mechanism of controlling the deformation of the foundation pit for prestressed fish-belly steel supports are analyzed.The results show that the prestressed fish-belly steel support has large excavation space,convenient installation and demolition,reliable performance,large support stiffness,and good control of foundation pit deformation.(2)Two kinds of internal support schemes for Haian Masonry Business Building are modeled,calculated,and compared.The advantages and disadvantages of assembled prestressed fish-belly beam internal support system are analyzed and compared with a traditional internal support system.The assembled prestressed fish-belly beam internal support can effectively control the displacement during the excavation of the foundation pit and has great advantages in the safety and economy of the foundation pit.(3)Combined with the engineering case study,the influence of prestress on the stress of enclosure structure and fish-belly beam structure is analyzed,which provides a reference for optimizing the design and stress of the fish-belly beam.The results show that increasing prestress can effectively reduce the displacement and deformation of the retaining structure,but too much increase will lead to a smaller negative bending moment and a larger positive bending moment of the retaining structure.In practical engineering,prestress should be set reasonably and support design should be optimized in time.(4)The monitoring data of foundation pit engineering are analyzed and compared with the simulation results.The results show that the monitoring data are in good agreement with the finite element calculation results.The steel support performance of the fish-bellied beam is stable.The deformation of the foundation pit is reasonable.