Study On Stability Of The Medium Partition In Double-arch Tunnel

After more than ten years of engineering practice, the double-arch tunnel highway projects in China has been widely used. However, as the structure of a novel form of double-arch tunnel in the application process there are also many problems. In the wall is a double-arch tunnel structure by the force of the core components, the complexity of forces at the tunnel site of stress concentration (pull, pressure, bending, twisting, shearing both), its force structure to the overall structure of the tunnel adjustment. The wall of the mechanical behavior and its settlement indicators directly related to displacement double-arch tunnel to the overall stability.Methods and Content of researching:(1)Through the investigation of double-arch tunnel engineering to analysis the stability of Medium Partition in Double-arch tunnel in different forms and construction methods.(2)Theoretical calculation and analysisChoose the prototype of the actual tunnel, using the finite element numerical method of double-arch tunnel wall construction process and the internal force and deformation analysis. Analysis of different construction processes in the wall under the conditions of stress changes and stability in the Medium Partition as well as a reasonable distance between surface excavation.(3)Monitoring the volume of the test-site inspectionRelying on the project for Nanjing Subway Line Extension Andre South Station ~ NingDan Road Station interval double-arch tunnel in the Medium Partition to monitor the situation of internal force and deformation. Can be verified through field trials and improve the theoretical analysis of the main conclusions, as well as feedback on the theoretical calculation and model test of the test results is reasonable. The main results:(1)The double-arch tunnels are in a bias state. The vertical stress was stepped from top to bottom convergence, changes in the side of the first large cavern construction, the largest in the Medium Partition at the bottom of the vertical stress in the septum Medium Partition below.(2)The Medium Partition is in the settlement status during the process of tunnel construction; the maximum horizontal displacement is at the top of the central minimum, but a relatively small horizontal displacement of the stability in the partition have little effect; as a result of a high number of disturbances, the three-hole method in the guide hole for the law - step method arising from the larger displacement.(3) with the working face of the left hole to move forward, working face of the rear wall of the right arising from the overall deflection, the wall to the right side of the centralUplift, the base of the left wall toe lifted up. When the apparent bias should be in the wall structure of the corresponding measures taken to improve the stability of the wall, such as reducing the wall height, the lower part of the structure to increase the size or asymmetric structure, in order to ensure the overall stability and security lining the structure.(4) Construction of a three-hole lead method, the left hole in the wall construction of the stress around the impact of the range of 18m, the construction of the right hole in the wall stress to 24m around the affected area, working face so as to arrive at a reasonable distance between the two single-hole 2 times the span.