塑料排水管道几种典型破裂缺陷的研究

发布时间：2018-06-03 13:55

本文选题：排水管道 + 破裂　；参考：《广东工业大学》2014年硕士论文

【摘要】：城镇排水管道在运行的过程中,常会由于各种原因造成管道破裂。这些破裂缺陷如何影响排水管道承载能力,是排水管道检测和评估中要解决的问题之一。目前国内对排水管道破裂缺陷的研究比较有限,本文主要利用塑料管道作为模型试件,针对排水管道几种典型破裂缺陷进行实验和理论分析研究。结合现行国家标准与实际工程中排水管道缺陷特征,制作一批有缺陷的塑料排水管道试件,并对试件进行环刚度、抗压强度、外压破坏荷载值的测定。根据断裂力学经典理论,对所测的实验结果进行理论分析,验证《城镇排水管道检测与评估技术规程》中对排水管道破裂等级的划分以及分析不同破裂缺陷对塑料排水管道承载能力的影响。结果表明： (1)在塑料排水管道环向方向上,一个破裂的2级叉形缺陷与四个破裂1级叉形缺陷在承载能力上可以认为是等效的,这与《城镇排水管道检测与评估技术规程》中的破裂缺陷打分标准一致；一个破裂的4级圆形缺陷与七个3级的圆形缺陷在承载能力上可以认为是等效的,这与规范中的破裂缺陷打分标准存在较大的差距。 (2)对于塑料排水管道分叉型裂纹,裂纹角度在120度左右对管道的径向承载能力影响最大,管道最危险；主裂纹长度越长,应力强度因子越大,管道的径向抗压能力越差；次裂纹长度越长,应力强度因子越大,管道的径向抗压能力越差,但相比主裂纹,次裂纹对管道的径向承载能力的影响较小。 (3)对于塑料排水管道平行裂纹,经过研究发现,裂纹的交错率对排水管道承载能力的影响受裂纹间距的干扰,两条裂纹间距越大,交错的越多或两条裂纹间距越小,交错的越少,试件的径向承载能力越弱,结构越危险；平行裂纹间距越大,排水塑料管道的径向承载能力越差,结构越危险；平行裂纹深度越大,排水塑料管道的径向承载能力越差,结构越危险。 (4)在缺陷等级和缺陷个数都相同的情况下,缺陷位于管道侧壁比缺陷位于管道顶部对管道破坏的影响更大；在缺陷等级和缺陷个数都相同的情况下,缺陷分布越均匀对称,对管道的破坏影响越大；在缺陷尺寸相同的情况下,管道方形孔洞和圆形孔洞对塑料排水管道的危害性差别不大。
[Abstract]:In the course of operation of urban drainage pipes, they often break down due to various reasons. How these ruptured defects affect the carrying capacity of drainage pipes is one of the problems to be solved in the inspection and evaluation of drainage pipes. At present, the domestic research on rupture defects of drainage pipes is limited. In this paper, plastic pipes are mainly used as model specimens to carry out experimental and theoretical analysis on several typical rupture defects of drainage pipes. Combined with the current national standards and the characteristics of the defects of the drainage pipeline in the actual engineering, a batch of defective plastic drainage pipe specimens were made, and the ring stiffness, compressive strength and external pressure failure load value of the specimens were measured. According to the classical theory of fracture mechanics, the measured experimental results are theoretically analyzed. The paper verifies the classification of rupture grade of drainage pipe and analyzes the influence of different rupture defects on the carrying capacity of plastic drainage pipe in the Technical Specification for Detection and Evaluation of Urban drainage Pipeline. The results show that: 1) in the circumferential direction of plastic drainage pipes, one broken grade 2 fork defect and four rupture grade 1 fork shape defects can be considered as equivalent in carrying capacity, This is in accordance with the standard of rating for rupture defects in the Technical Code for the Detection and Evaluation of Urban drainage pipes; one broken circular defect of grade 4 and seven circular defects of class 3 are considered equivalent in carrying capacity. There is a big gap between this and the standard of scoring the broken defects in the code. (2) for the bifurcation crack of plastic drainage pipeline, the radial bearing capacity of the pipe is most affected by the crack angle about 120 degrees, the pipeline is the most dangerous, and the longer the main crack length, the greater the stress intensity factor, the worse the radial compressive capacity of the pipeline; The longer the secondary crack length, the greater the stress intensity factor and the worse the radial compression resistance of the pipeline, but the smaller the influence of the secondary crack on the radial bearing capacity of the pipeline is compared with the main crack. 3) for the parallel cracks of plastic drainage pipes, it is found that the influence of the staggered rate of cracks on the bearing capacity of the drainage pipes is affected by the crack spacing. The larger the distance between the two cracks, the more the interlaced or the smaller the distance between the two cracks. The less the interlaced, the weaker the radial bearing capacity of the specimen and the more dangerous the structure; the greater the distance between the parallel cracks, the worse the radial bearing capacity of the drainage plastic pipe, the more dangerous the structure, and the greater the depth of the parallel crack. The worse the radial bearing capacity of the drainage plastic pipe, the more dangerous the structure. In the case of the same defect grade and number of defects, the defect on the side wall of the pipeline has more influence on the pipeline failure than the defect on the top of the pipe, and when the defect grade and the number of defects are the same, the more uniform the defect distribution is, the more symmetrical the defect distribution is. When the size of defects is the same, the harm of square and circular holes to plastic drainage pipeline is not different.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU992.23

【参考文献】