Analysis Of Buried Pipelines Induced By Shield Tunneling Construction

With the development of underground space technology, the subway has generally became an important means to reduce the pressure of urban traffic. Subway tunnels are usually built in the area with intensive pipelines. The tunneling process will inevitably cause ground deformation and stress changing, which certainly cause additional displacement and bending moment to pipelines. Therefore, the analysis of ground settlements and deformation behavior of adjacent existing pipelines induced by tunneling process is an important issue of shield tunneling in urban construction. This paper built 3D finite element model to further study the parameter analysis on adjacent pipeline with the displacement controlled and stress controlled method. Finally, this paper presents the failure criteria and controlling protection measure to pipeline. The main working contents and results of this paper are as follows:1、Based on the current existing research, centrifugal model tests were carried out to verify the simulation model of tunneling construction on adjacent pipelines by ABAQUS with the displacement controlled method. The verified finite element model which choosing the typical soil of Nanning area was built to study the parameter analysis on adjacent orthogonal and paralleled pipeline, such as different ground loss, tunneling diameter, material of pipelines and distance between tunnel and pipeline. The results show that ground loss and tunnel diameter has a larger influence to adjacent pipeline than the different material and buried depth of pipeline.2、Based on the current existing research, real engineering instance were carried out to verify the simulation model of tunneling construction with adjacent pipelines by ABAQUS with the stress controlled method. The verified finite element model was built to study the parameter analysis on adjacent orthogonal and paralleled pipeline, such as different tunneling rate, grouting pressure, overexcavation and tunneling distance. The results show that the factor has significantly influenced to adjacent pipeline, such as tunneling rate, grouting pressure, overexcavation.3、 On the basis of parameter analysis on the buried pipeline, the damadge criteria of buried pipeline was summarized to predict the safety condition of pipeline which combine with the computed results. The predict results are as follows:cast iron pipe has a largely risk of damage on the condition of different material pipeline. When the ground loss achieved to 1.5%, grouting pressure less than 0.01MPa, the pipeline has a risk of damage. When the distance between the tunnel and pipeline achieved to 1.2 times of tunneling diameter and tunneling rate achieved to 1.25 times of tunneling diameter, the bending stress of pipeline is larger than the allow bending stress. Conttrol measures are presented to provide protecting plan.