Seepage erosion test and its mesoscopic mechanism at different pipeline-leaking locations
The effects of different pipeline-leaking locations on losses of soil and water were investigated using uniformly graded Fujian standard sand,for the ground collapse induced by pipeline leaking.Discrete element method-finite difference method(DEM-FDM)numerical analyses were carried out to reveal the mesoscopic mechanism for pipeline leakage.The effects of different leaking locations on seepage erosion and the change of soil stress were analyzed.The development of water and soil pressure as well as the soil arching were explored during pipeline leaking.Both experimental test and numerical simulation results are as follows.1)The process of erosion includes three stages,initial erosion,development stage and convergence stage.2)The leakage occurring at the pipeline side causes serious erosion and induces catastrophic ground collapse due to more disturbance to the stratum and greater seepage force.3)The soil pressure shows decreasing trend near the pipeline leakage location and increasing trend further away pipeline leakage location.Also,the sum pressure of soil and water near the pipeline leakage location remains unchanged.4)The developments of soil pressure on pipeline are different for various leaking locations.For the leakage at the top of the pipeline,the soil pressure around the leakage gradually decreases.For the leakage at the side of the pipeline,the development of soil pressure shows three trends,increasing,decreasing and unchanging.
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