Mechanical Characteristics And Optimization Of Deep Foundation Pit Support Structure Of Innovation Avenue Station Of Hefei Metro Line 4

With the rapid development of social economy,urban underground rail transit has developed rapidly.Many second-tier cities and even third-tier cities have begun to construct underground rail transit.The deep foundation pits for subway station construction are often located in the prosperous areas of the city,with many surrounding buildings and underground pipes.The network distribution is complex and the traffic volume of the road is large.In this case,the design of deep foundation pit support is difficult.In order to control the impact of the foundation pit excavation construction on the surrounding environment,the design of some deep foundation pit support structure exists.A conservative situation.Nowadays,the design theory of deep foundation pit supporting structure is more mature,and it is necessary to ensure safety and economical and environmental protection.Therefore,based on the original foundation pit support scheme,the design is optimized to ensure the safety and stability of the deep foundation pit construction of the station while striving to shorten the construction period.Improving economic efficiency has important engineering value.This paper takes the deep foundation pit engineering of Xinhua Avenue Station of Hefei Metro Line 4 as the research background.According to the geological and support plan data provided by the project overview,the finite element Midas numerical simulation software is used to simulate the dynamic process of deep foundation pit excavation.Comparing the on-site monitoring data,the research and analysis of the supporting structure and the ground settlement of the foundation pit excavation are carried out.The specific research contents are as follows:(1)According to the design specifications of the relevant foundation pit support and the support design of the deep foundation pit of the Innovation Avenue Station of Hefei No.4 Line,the standard section and the end section of the deep foundation pit of the Innovation Avenue Station are respectively determined by the computer software of Lizheng Deep Foundation Pit.Carry out the design check and calculate that the existing support plan meets the requirements.(2)The dynamic simulation of 3D simulation was established by using Midas/GTS finite element numerical software.The simulation results show that the surface settlement trend outside the pit at the end of the innovation avenue station increases from the edge of the crater to the “recessed spoon” shape.The waterdisplacement of the retaining structure is a parabolic shape with two small and large intermediates.The axial force of the steel support gradually increases with the excavation of the foundation pit and eventually stabilizes.(3)Comparing the ground settlement,the horizontal displacement of the retaining structure,the simulation results of the supporting axial force and the on-site monitoring data,it is found that there is a slight error between the two maximum values,but the trends of the two laws are basically consistent,considering the limitations of numerical simulation parameters selection.The impact of the accidental factors on the site construction can be considered as reliability of the simulation results.(4)Considering the dangerous value of the overall force deformation distance of the foundation pit under the original support scheme,there is still a large space.In order to improve the construction efficiency and economic benefits,the eastern end of the station foundation pit is supported on the basis of the previous model.The structural scheme is optimized and simulated.It is concluded that the surface settlement,the internal force deformation of the retaining structure and the support axial force value are all improved compared with the original scheme,but still within the safety limits.The feasibility of the program.