Influence Of Underground Shield Tunnel Construction On The Existing Pipelines Under Airfield

With the growing social demand for transport infrastructure, the need for the development of underground space is growing, however, various pipes are buried underground cities and airports,some of which are buried deep, so that the soil disturbance in the ground made by tunnel construction may directly cause local subsidence deformation of pipes, and even lead to structural damage and other accidents. In recent years, major airports are at the beginning of massive underground tunnel construction to meet the needs of rapid interchange of ground transportation and air traffic, the tunnel inevitably requires across the airfield in which the aircraf is running, so the existing underground pipes in the airfield need to withstand the impact of the multiple effects of the upper aircraft load and lower soil disturbance induced by tunnel construction, which cause a direct threat to the structural safety of these pipes.In this paper, the mechanical response laws of buried pipes under airfield suffered dual role of upper aircraft load and lower disturbance of shield construction is the research objectives, based on the theoretical analysis of a variety of factors, the deformation and stress calculation formula of the pipes by the impact of tunneling is established,by which the force and deformation characteristics of the pipes are discussed. Based on the simplified analysis of shield construction the finite element analysis model of multiple factors in the pipeline is established, and using ABAQUS to implement the three-dimensional finite element numerical simulation of disturbance effects on soil of shield excavation process under different conditions, the laws of the deformation and mechanical properties of the pipes with different parameters are analysised. Based on the similarity theory the experimental reasearch of simulating shield construction process under buried pipes are designed and completed,and the mechanical variation of the pipes under circumstances of different pipe diameters,different vertical distances between pipes and tunnel and different pipe materials are analysised in the model experiment.Theoretical analysis and numerical simulation results show that in the sandy soil shield tunneling may cause upward displacement on the surface of both sides of the tunnel,as well as the force and deformation of the pipes are the biggest; Increasing soil stiffness can reducethe deformation and stress of pipes,and the effect is more obvious when increasing soil stiffness under the pipes,the bigger depth of the soil,the better effect;The bigger burial depth of pipes,the greater distance between the pipe and tunnel,the smaller force and deformation of the pipes; It’s much more dangerous when the pipe is perpendicular to the tunnel.Experimental results show that the bigger pipe diameter, the smaller tunnel vertical distance and the greater stiffness of pipes, the deformation and stress of pipes may be greater.Comparative analysis of model test and simulation results shows that the deformation rules of the pipes is basically similar, and the results of numerical simulation is larger than the experimental results.