Study On The Impact Of Subway Shield Construction On Adjacent Buildings In Loess Area

In 2018,Xi’an was formally identified as the "National Center City",therefore,higher requirements were placed on urban infrastructure.Metro,as an important part of urban infrastructure,the efficiency and safety of subway construction are particularly important.Even the most efficient and safe shield method at this stage will inevitably lead to disturbances in the soil at the time of excavation,which will have a certain impact on adjacent buildings.The ’impact of the subway shields construction on the adjacent buildings in the loess area will be analyzed on The first-phase project of the Xi’an Metro Line 5 under construction as the study subject,using the finite difference software FLAC3D forming numerical simulation,building the 3D dynamic model of tunnel excavation.This model will be used to investigate the tilt of the adjacent building during excavation,the overall uneven settlement,and the damage of the pile foundation.(1)Build a reasonable numerical model based on various material parameters in actual projects.Focus on studying of the horizontal and vertical stress and deformation of the soil around the excavation surface on the model,compare the model data with the actual monitoring data,that the deformation pattern of the two are basically the same,which proves that the calculation model is reliable.(2)By changing the distance between the tunnel and the building,analyze the change of impact on buildings of different distances.The calculation results show that as the distance between the building and the tunnel becomes further;the corresponding maximum settlement decreases from large to small and finally stabilizes beyond 32m.The settlement at this time is 28.334mm.(3)Study the impact on the soil and buildings caused by shield excavation in different locations.Studies show that the vertical displacement of the stratum increase in direct ratio to continuously deepening of the excavation face until the 24th excavation when the settlement value has basically stabilized.At this point,the shield has completely passed the building.(4)Analyze the influence of different horizontal distances from the excavation surface to the pile foundation and the influence of different pile lengths,compare the difference in the top thrust of the shield and whether the grouting is performed in time for the settlement differences,displacement changes,etc.The timely processing,maintenance of the structural safety of the building,ensuring its safety and applicability,and providing a reference for similar projects in the future.