基于有限元的给水管道外包式管件设计及修复试验

发布时间：2018-11-23 16:30

【摘要】：在我国经济快速发展的同时,城镇供水管网总长度也在快速增长,但供水漏失率一直居高不下,这不但造成水资源及供水能源的极大浪费,对漏失点周边的生态环境也产生了重大影响。管道漏失主要是由于管道薄弱位置剩余强度较低,在管道内部较大的水压下发生失效破坏,从而使管内的高压水从缺口处漏出,因此有必要了解管道薄弱位置的应力及应变分布特点,研究相应的补强方法。选取给水管道典型薄弱位置——法兰接口和局部腐蚀区域,利用有限元软件ANSYS进行模拟分析。对于腐蚀缺陷,以柱状沟槽缺陷为模拟对象,分别模拟了腐蚀缺陷在三类几何尺寸(轴向长度,环向宽度以及腐蚀深度)变化下应力及应变分布规律,得出缺陷轴向长度是制约腐蚀区域剩余强度的主要因素,不同轴向长度下缺陷周围等效应力分布云图差异较大,其次是腐蚀深度,至于缺陷的环向宽度,其尺寸的改变对缺陷周围剩余强度影响不大。对于法兰接口,以简化的平焊钢制法兰为模拟对象,模拟了在螺栓预紧力和不同水压下法兰盘和螺栓的应力分布和垫片的形变特点。模拟结果显示,随着管内水压的增大,螺栓与法兰盘一直处于低应力水平,而垫片在不同位置形变差异较大,螺孔下方靠近垫片内侧形变最小,相邻螺孔之间垫片外边缘形变最大,漏失很有可能发生在螺孔附近。基于模拟结果,设计了用于管道局部薄弱位置补强的外包式管件,提出“主动修复”的概念,并首次将吸水膨胀橡胶应用于给水管道修复领域。结合相关试验,进行了管件漏失报警及漏失自修复的研究。通过在管件腔体内部填充吸水膨胀橡胶和安装应变片,实现了外包式管件自修复与漏失监测两大功能。为验证外包式管件的应用效果,分别用有机玻璃和碳钢材质的外包式管件进行了“静态加压”和“动态通水”试验。在“静态加压”试验中,外包式管件为有机玻璃材质,应变传感器粘贴在管件耳板内侧,外包式管件能在漏失发生数小时内监测到漏失信号,并在漏失发生的72小时将漏失率降低90%以上。在“动态通水”试验中,管件为碳钢材质,应变传感器粘贴在硫化型膨胀橡胶表面,在漏失发生半小时内就可以监测到明显的漏失信号,在漏失发生的72小时漏失率降低90%以上。城镇供水管网绝大部分漏失发生在管道接口等局部薄弱位置,采用外包式管件可以对管道局部漏失进行报警及自修复,可以在较低的成本下大幅降低管网漏失率,节约水资源。
[Abstract]:With the rapid development of economy in China, the total length of urban water supply network is also growing rapidly, but the leakage rate of water supply is always high, which not only results in a great waste of water resources and water supply energy. It also has a great influence on the ecological environment around the missing point. Pipeline leakage is mainly due to the low residual strength in the weak position of the pipeline, which causes the high pressure water in the pipe to leak out from the notch because of the failure and failure of the pipeline under the larger water pressure inside the pipe. Therefore, it is necessary to understand the distribution of stress and strain in the weak position of pipeline and to study the corresponding reinforcement method. The typical weak position of feed water pipeline, flange interface and local corrosion zone, is selected and simulated by finite element software ANSYS. For the corrosion defects, the stress and strain distribution of the corrosion defects under three kinds of geometric dimensions (axial length, circumferential width and corrosion depth) is simulated by taking the cylindrical groove defect as the simulation object. It is concluded that the axial length of the defect is the main factor restricting the residual strength of the corrosion zone. The distribution of equivalent stress around the defect varies greatly under different axial lengths, followed by the corrosion depth, and the circumferential width of the defect. The change of its size has little effect on the residual strength around the defect. For flange joints, the stress distribution of flanges and bolts and the deformation characteristics of gaskets are simulated under the pretightening force of bolts and different hydraulic pressures, taking the plain welded steel flanges as the simulation object. The simulation results show that with the increase of the water pressure in the pipe, the bolt and flange are always at low stress level, and the deformation of the gasket varies greatly in different positions, and the deformation of the underside of the screw hole near the inner part of the gasket is the least. The deformation of the outer edge of the gasket between the adjacent holes is the largest, and the leakage is likely to occur near the screw hole. Based on the simulation results, the outsourced pipe fittings used to reinforce the local weak position of the pipeline are designed, and the concept of "active repair" is put forward, and the absorbent expansion rubber is applied to the field of water supply pipeline repair for the first time. Combined with relevant tests, the leakage alarm and self-repair of pipe fittings were studied. By filling the tube cavity with absorbent expansion rubber and installing strain gauges, two functions of self-repair and leakage monitoring are realized. In order to verify the application effect of the outsourced pipe fittings, the "static pressure" and "dynamic water opening" tests were carried out with the outer pipe fittings made of organic glass and carbon steel, respectively. In the "static pressure" test, the outer tube is made of plexiglass, the strain sensor is attached to the inner side of the ear plate of the tube, and the outer tube can detect the leakage signal within a few hours after the leakage occurs. The leakage rate was reduced by more than 90% in 72 hours. In the "dynamic water opening" test, the tube is made of carbon steel, and the strain sensor is attached to the surface of the vulcanized expanded rubber, and the obvious leakage signal can be detected within half an hour after the leakage occurs. The leakage rate decreased by more than 90% in 72 hours. Most of the leakage of urban water supply network occurs in the local weak position such as pipeline interface. The outsourced pipe fittings can alarm and self-repair the local leakage of the pipeline, which can greatly reduce the leakage rate of the pipe network and save water resources at lower cost.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU991.36

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