管道渗漏诱发路面塌陷的DEM-CFD耦合模拟

DEM-CFD coupling simulation for road collapse induced by pipeline leakage

针对给水管道渗漏冲蚀土体诱发路面塌陷问题,基于离散元(DEM)和计算流体力学(CFD)理论,提出了DEM-CFD耦合模拟方法。采用颗粒流模拟软件PFC建立管道渗漏的地层模型,并与FiPy建立的流场模型结合,实现颗粒-流体双向耦合,研究路面塌陷机理以及砂土流失率和漏损口宽度对地下空腔形成和发展的影响。结果表明:给水管道渗漏冲蚀土体致灾主要经历流化初始、稳定冲蚀和冲蚀破坏等三个阶段。其中稳定冲蚀阶段持续时间最长,且空腔在此阶段已趋于稳定;随着砂土流失率和管道漏损口宽度的增大,土体扰动区域范围和空腔的规模变大,当管道漏损口宽度达到一定值后,渗漏量会趋于稳定并保持在一个较高水平,空腔和扰动区范围也会稳定在一定规模。研究结果可为管道渗漏诱发路面塌陷的评估和防治提供技术支持。

A DEM-CFD coupling simulation method is proposed to address the problem of road collapse induced by leakage erosion of water supply pipelines,based on the Discrete Element Method(DEM)and Computational Fluid Dynamics(CFD)theories.The method combines a geological model of pipeline leakage established using Particle Flow Code(PFC)with a flow field model established using FiPy to achieve bidirectional coupling of particles and fluids.The study investigates the mechanism of road collapse,as well as the influence of sand erosion rate and leakage orifice width on the formation and development of underground cavities.The results indicate that the disaster induced by leakage erosion of water supply pipelines mainly goes through three stages,namely initial fluidization,stable erosion,and erosion failure.The stable erosion stage lasts the longest,and the cavity tends to stabilize during this stage.With the increase of sand erosion rate and pipeline leakage orifice width,the disturbance area of the soil and the scale of the cavity also increase.When the pipeline leakage orifice width reaches a certain value,the leakage tends to stabilize at a high level,and the cavity and disturbance area stabilize at a certain scale.The research results can provide technical support for the evaluation and prevention of road collapses induced by pipeline leakage.