Study On Pipeline Deform Due To Metro Construction

ABSTRACT:Urban underground space’s development and utilization is the development trend of urban construction in the modern world. But along with this, the underground engineering construction disturbance effecting on the surrounding environment has become more serious. The urban tunnel construction may damage the existing pipelines which buried up the tunnel, and how to ensure safety is an issue that you should take into consideration during the entire subway construction. Asessing the impact on the pipelines around tunnel induced by metro construction is a pressing problem, which is also one most important research subjects in civil and environmental engineering research area. Giving a study on this research subject has important theoretical consequences, and has important practical value to engineering practice The main research contents ale as follows:(1) Based on Winkler elastic foundation beam theory, for each positional relationship between the pipeline and tunnel parallel, vertical and oblique space, analyzed the deform and Internal forces of the rigid pipeline and flexible pipeline just above the tunnel, and given the general formula.(2) Utilizing ANSYS software, fine models are established to study the effects of tunnel excavation on pipelines with rigid interface, in the simulation, soil properties, pipeline details and shield construction parameters are considered. The results indicate that pipeline details (in addition to material and diameter) have smaller influence on pipeline settlement, while soil properties and shield construction parameters have great influences on pipeline settlement, and should attract particular attention.(3) The safety evaluation of flexible pipelines include evaluation of the pre-construction and construction evaluation. At first, the analysis is about four cases which single-lane tunnels and double tunnels parallel and perpendicular to the pipeline respectively. Joints angle of the pipeline are used as the control indicators under pre-construction evaluation. Settlement of the pipeline are used as the control indicators during construction. Then, based on the analysis of several adverse factors, the coefficient Ki are used to revise the flexible pipeline safety evaluation formula. Finally, specific examples of projects carried out on the safety evaluation, which is provided to approve that this safety evaluation is practical and effective. (4) The damage control standard of existing pipelines is analyzed. Because of the complexity of interaction between pipe, soil and tunnel, the settlement control values which put forward during the existing engineering practice were rather conservative. Meanwhile the specific settlement control values had not been proposed with the actualities in the construction. Then for the rigid pipelines, we get analytical results of their settlement control values by making theoretical analysis of the calculation of the settlement control values. Finally, we also get the specific settlement control values by computational analysis of an engineering practice example. And the analysis show that concerning practical tunnel construction situation and detail parameters of pipelines, we should calculate and determine the control standard of pipelines.