Indoor Model Test And Numerical Simulation Analysis On Deformation Of Underground Pipelines Under Shield Construction

With the acceleration of the process of modern urbanization,the problem of urban road traffic congestion is becoming more serious.Ordinary urban roads have not met the transportation needs in many cities.Underground rail transit has become the primary choice for many large and medium-sized cities to solve traffic congestion problems.On the background of the construction of Hexi Metro Line 3 at Hexi subway station,this article uses the indoor model test to study the effect of shield construction on the deformation of underground pipelines,and simulates the deformation of underground pipelines under the shield excavation conditions.The model tests were used to study some regular results,including the subsidence of underground pipelines,the internal forces of pipelines,and the bending moments of pipelines,when the pipeline and the tunnel are vertical to each other.The experiment also explored the relationship between the amount of bottom-level loss and over-excavation volume and settlement through the measurement method.A tentative study was conducted on the deformation laws of pipelines and tunnels when the pipelines and the tunnels are parallel and oblique to each other.This study obtained the following results,namely the settlement of parallel pipelines,the relative rotation angle of the pipelines,and the internal forces and bending moments of the pipelines in the oblique pipelines.Besides,numerical software FLAC3 D was used to establish a three-dimensional numerical model with which the pipeline settlement caused by the step-by-step excavation of the shield in the double-line tunnel under the vertical condition of the tunnel was analyzed.Numerical results and experimental results were compared and these two kinds of results were basically consistent.The main content of this article has the following aspects;(1)Using the indoor model test,the influence of soil type,namely sand and clay,on the displacement and internal force of underground pipelines when the pipelines and tunnels are vertical to each other was simulated.(2)The deformation of underground pipelines was studied when the pipeline and the tunnel are vertical,oblique and parallel to each other in clay.(3)When the pipeline and the tunnel are vertical to each other,the loss of the stratum were compared in sand and clay.(4)The three-dimensional numerical model was used to simulate the deformation of the pipeline and tunnel when the pipeline and the tunnel are vertical to each other under the condition of shield excavation.The results were compared with the model test results under the same conditions.