Application Research On Steel Support System Of Prefabricated Prestressed Fish Bellied Beam Foundation Pit

With the rapid development of urbanization in China,the number of deep foundation pit projects is also increasing rapidly,and the control requirements of foundation pit are becoming more and more strict.In order to ensure the safety of underground engineering construction,a reasonable selection of foundation pit engineering support scheme is the most important.At present,there are mainly two kinds of internal support system in deep foundation pit: concrete internal support and traditional steel structure internal support.However,due to the defects of concrete internal support system,high cost,small stiffness and variability of steel support system,this paper studies a prefabricated prestressed fish bellied beam steel support system which is rising in recent years.Compared with other internal support systems,this kind of support system has the characteristics of green environmental protection,safety and stability,and can effectively control the deformation of foundation pit under the premise of ensuring the cost.In this paper,the steel support system of prestressed fish bellied beam is studied as follows(1)This paper discusses and analyzes the composition and stress deformation mechanism of prefabricated prestressed fish bellied beam steel support system,and uses Midas GTS NX finite element software to simulate the displacement of soil layer along with the downward excavation of foundation pit.(2)Through modeling of MIDAS GTS NX,the paper analyzes the effect of prestressing on the supporting system,and compares the effect of prestressing in construction and after construction on the deformation control.The results show that the prestressing in construction can reduce the structural deformation to a certain extent.(3)Through the control variable method,it is analyzed that the connecting rod,diagonal web member,section and other factors in the structure can improve the ability of controlling soil deformation to a certain extent.Considering the control cost and structural deformation,the optimal rise span ratio and the number of top chord beam segments are obtained.(4)Through ABAQUS finite element software,the paper analyzes and calculates the layout of prestressed fish bellied beam in different support length,obtains the layout scheme of corresponding support length in different load interval,and summarizes the rules.