Analysis Of Influence Of Metro Tunnel Construction On Adjacent Buildings In The Loess Area

In recent years the regions of midwest loess areas in China ing to develop urban underground rail transit,while,the geology in central and western regions in our country determines that the design and construction experiences of the coastal developed areas of metro tunnel or mountain tunnel cannot be directly used.In this paper,the uneven settlement,tilt,horizontal displacement and structure internal force of adjacent structures in the process of the urban subway construction has been analyzed in Midwest loess areas in China.At the same time has the study on the influence during by the distance parameter and the sequence of two tunnels' excavation to construction.In order to analysis the influence of the subway tunnel construction to adjacent building in loess area,based on the referencing a large amount of relevant literature,uses the Lanzhou Metro Line 1 under construction as the research background,through sampling analysis carried out on from the tunnel construction site,obtains the actual parameters of the loess samples in laboratory.After determining the relevant characteristic properties of loess samples,using ansys numerical simulation software,frame structure is established in the calculation model in the process of tunnel construction,used to analyze the characteristics of the building settlement and internal force in the process of the tunneling construction.Main research contents and achievements in this article are as follows:(1)We take the undisturbed soil sampleon the constraints of digging out in the Lanzhou subway tunnel construction site,then through moisture content of real test and density test,liquid plastic limit test,penetration test and triaxial compression test in the laboratory,achieved loess sample moisture content,density,liquid plastic limit,permeability coefficient,cohesive force and Angle of internal friction and other parameters more reliable,ensure the reliability of numerical simulation later.(2)According to the actual loess sample parameters measured,application of ansys software to establish the frame structure of the adjacent tunnel in construction of the tunnel model for calculating the three-dimensional entity model.Made the analyze of the vertical displacement and horizontal displacement for every building basis point of contact with the ground,then analyses the structure of the tilt,makes a analyze of internal force variation law of structure at last.Found the characteristics of uneven settlement,the horizontal moving rule and change characteristics of tilt of the buildings in the process of tunnel construction.Found the variation law of the structure internal force in the process of tunnel excavation at the same time.(3)By changing the sequence of the two tunnels' excavation,analyzed the displacement,inclination,and variation law of the structure internal force of the building under different excavation sequence.It turned out that excavation the far tunnel first has the minimal influence to the internal force of the building components,and excavation the two tunnels at the same time is most favorable to control the differential settlement of the building.(4)By changing the position of the model building,making a research on the effects of distance parameters on the structure analysis.Make a compare of the displacement,inclination and internal force of the building with the different distances.