Regulation Of Surface Settlement In Multi-stratum Geological Condition Shallow Tunnels Construction

With the development of urban underground traffic, the network is more complex and changeable, emerged many engineering and technical problems, also lead to different surface subsidence change forms. Generally urban subway is shallower and ground have many buildings, a proper system to predict the ground settlement and summarize the rules, not only provide technical support for the similar projects, but also can reduce safety accidents induced by tunnel construction. Founded by the excavation engineering section in No.5line of Guangzhou metro, the paper used the methods of numerical simulation, theory analysis and Engineering monitoring data to research the support optimization of3-D shallow tunnel, the selection of tunnel construction scheme, the rules of surface settlement of dual-tunnel arrangement and the double arched tunnel Construction technology, also the double arch tunnel in seismic wave dynamic response were studied systematically, the main contents and conclusions are as follows:(1) Explained the deformation mechanism of surrounding rock and the support mechanism, and showing the necessity to choose the support timing. The finite element software ABAQUS is used to simulate the exploitation processes to the typical section of3D tunnel, drawing load-deformation curves of surrounding rock and initial support system, fitting and interpolation the two characteristic curves, the best initial supporting time is determined.(2) Relying on underground tunnel of Guangzhou metro line NO.5, established mechanical model of three dimensional parallel A4type section tunnel. Calculation and compared of the tunnel in different construction conditions of surrounding rock stress, displacement field shape, plastic zone distribution and supporting structure stress, the optimal construction scheme was determined.(3) According to the subway line in the form of complex, based on the former two research results, and3D double-line tunnel in underground space several arrangement forms were systematically studied. Obtained in the same geological conditions before or after the tunnel excavation stress of tunnel, displacement and other characteristics, formed a certain change rule.(4) Based on A4type and J type tunnel section, using middle pilot heading and CRD construction method studied the nearly arch tunnel in the mining method of construction technology. It is concluded that the lateral and longitudinal surface subsidence rules and other distribution characteristics and compared with Field monitoring results, at the same time take simple research on the have completion double-arch tunnel under the direction in seismic vibration dynamic response.