砂土粗颗粒形状对管道破损致地面塌陷影响的离散元模拟

Discrete Element Simulation of the Affect of Particle Shape onFormation Collapse Caused by Damaged Pipeline

地下管线在外部荷载以及人为因素的作用下会出现破损的情况,从而引起地面塌陷。为研究砂土颗粒形状对管道破损后地层塌陷的影响,采用PFC-2D软件设计了3种粗颗粒形状,对地层塌陷进行了数值模拟,分析了颗粒形状对地层损失量、地表沉降量以及塌陷形态的影响。模拟结果表明:①不同形状颗粒组成的地层,其中心颗粒达到相同沉降所需要的时间不同,类三角形所需时间最短;②定义了相对运动角来区分塌陷过程中相对运动和相对静止的颗粒,发现颗粒形状越规则,受影响的土层范围越大;③不同形状颗粒之间的滑动接触率和颗粒累计旋转角度存在差异,因此不同形状颗粒影响地层塌陷的机理可能是颗粒运动方式的差异控制的。

Underground pipelines will be damaged under the action of external loads and human factors,resulting in ground collapse.To investigate the impact of particle shape on ground subsidence following pipeline breakage,numerical simulations strata subsidence were conducted by PFC-2D.About 3 kinds of coarse particle shapes were defined by PFC-2D,and the effects of particle shapes on formation loss,surface settlement and collapse form were analyzed.The simulation results show these as follou's.The time required for the classification is shortest when particles of different shapes reach the same degree of settlement at the center.The relative motion angle is defined to distinguish between particles that are relatively stationary during collapse.It is determined that the range of the soil stratum affected increases as the particle shape becomes more regular.There are variations in the sliding contact rate and cumulative rotation angle of particles among different particle shapes,which may result in different particle movement modes and,therefore,different ground subsidence mechanisms.There study findings are useful in preventing ground subsidence.