供水管网大口径管道爆管事件形成机理与精细模拟

Dynamic Simulation and Mechanical Analysis of Large-Diameter Water Main Burst

摘要:

近年来城市供水管网爆管事件频发对城市的运行安全造成直接影响。结合2017年上海“11?16”溧阳路四平路爆管事件，系统介绍了本次爆管事件概况，同时，利用本次爆管事件现场调查数据，采用3D激光扫描技术和三维数值建模方法，对本次爆管管道进行了建模分析，研究了供水管道在存在初期裂缝情况下，裂缝末端应力集中与管内水压力和裂缝长度发展变化影响关系，采用动力分析方法模拟了管道从裂缝发展到管体破坏形成爆管的物理全过程。结果表明：在供水管网管道早期裂缝末端，由于应力集中管体裂缝继续发展，且随管道水压增大而增大，其增速与裂缝长度密切相关；管道发生开裂后其临界破坏水压随早期裂缝长度的增加而降低，结合本次爆管事件周边获得的3个测点实测水压分析可知，爆管管道早期裂缝断面圆心角应大于26°；管道爆管破坏过程模拟显示，管道残片随裂缝开展向管顶转动，直至形成贯通裂缝完全脱离管道，脱落管片在内水压及外部荷载作用下会发生剧烈的转动和向外弹射，从而形成爆管并产生极大的瞬间破坏作用。

Abstract:

Pipe burst in urban water supply networks often pose serious threats to urban operation safety. Based on the pipe burst accident at Siping-Liyang Road in Shanghai on November 16， 2017， the pipe burst was modeled and analyzed by using the finite element method（FEM） with in-situ investigation and the damaged pipeline data collected from 3D laser scanning. The effect of pipe pressure and initial crack length on the stress concentration at crack tip was studied assuming the existence of some potential cracks in the pipe. The full failure process was also simulated from the initial crack to pipe burst by dynamic analysis. The results show that the stress concentration at crack tip grows as water pressure increases， the rate of which varies with crack length. The critical water pressure at crack tip failure decreases as crack length increases sharply. The central angle of initial crack length is evaluated to be more than 26° through the monitoring the data of pipe pressure around. The pipe failure simulation shows that the pipe shards rotate towards the pipe top with the development of crack and finally break along the pipe while the penetrating crack forms. The rotation and outward translation of the shards is considerably large due to external loads and internal pressure， and thus the burst of pipe causes great damage instantaneously.