预应力钢筒混凝土管（PCCP）运行过程中的数值仿真

发布时间：2018-05-28 16:41

本文选题：预应力钢筒混凝土管 + 有限元　；参考：《郑州大学》2017年硕士论文

【摘要】：预应力钢筒混凝土管(Prestressed Concrete Cylinder Pipe,简称PCCP)因其能承受内外高压、抗渗耐腐蚀、通水能力强及安装便利,良好的实用性和经济性,广泛应用于市政、电力和水利工程中,尤其是国家重大工程——南水北调工程,关系国计民生。因此,管道运行过程中的安全性与稳定性尤为重要,根据工程实际合理地建立PCCP仿真模型,分析管道应力分布,裂缝产生及破坏工况,从而为实际工程提供参照,很有意义也很有必要。本文总结了PCCP国内外发展历程及其设计原理和标准,介绍了PCCP加工工艺和关键要点。根据研究现状和南水北调中线实际工程选用埋置式预应力钢筒混凝土管(PCCP-E),利用ANSYS建立数值仿真模型,模型中合理地考虑了各层之间的连接关系,采用降温法模拟预应力,分析缠丝完成、自重、静水压力、不同内水压力和重型车载作用等不同工况下管道内外层管芯混凝土、钢筒和预应力钢丝的应力变化规律。主要结论如下:(1)缠丝完成时,内外层管芯混凝土和钢筒均会出现轴向应力、径向应力和环向应力,其中径向应力很小,对裂缝没有影响,可忽略不计,主要为轴向应力和环向应力,但相比混凝土和钢筒抗拉和抗压强度都很小,不会引起裂缝。(2)管道正常运行工况(内水压力从静水压力至设计内压0.84MPa)下,管道各部位受力正常,不会出现裂缝。(3)在极限内压(内水压力为1.2MPa)作用下,管道以环向拉应力为主。内层管芯混凝土最大环向拉应力为2.65MPa,超过C50混凝土抗拉强度标准值(2.64MPa),持续作用时内层管芯混凝土沿环向出现裂缝,水流沿裂缝涌出,引起破坏;钢筒和预应力钢丝的强度足以满足承载力要求,不会出现屈服。与此同时,在长期使用中,混凝土的徐变,氯离子的侵蚀,预应力钢丝的松弛以及地面移动荷载的作用都会引起管道破坏,多种因素叠加将加速管道破坏。(4)重型车载作用下,即当管顶中部区域应力超过2MPa时,对于内层管芯混凝土,轴向最大拉应力出现于管底中部,为2.4MPa,很接近C50混凝土抗拉强度标准值(2.64MPa),很易出现轴向裂缝;环向最大拉应力也出现于管底中部,为3.06MPa,超过C50混凝土抗拉强度标准值(2.64MPa),内层管芯混凝土沿环向出现裂缝,若同时有内水压力作用,将加速裂缝延展,引起管道破坏,对行车构成危险。为此,实际工程中,若能加强管道运行监测,发现破坏及时采取措施,从而减少损失,很有必要。
[Abstract]:Prestressed Concrete Cylinder Pipe, is widely used in municipal, electric and hydraulic engineering because of its high pressure, high permeability and corrosion resistance, good water capacity and convenient installation. In particular, the national major project-South-North Water transfer Project, the national economy and people's livelihood. Therefore, the safety and stability of pipeline operation process is particularly important. According to the engineering practice, the PCCP simulation model is established reasonably, and the stress distribution, crack generation and failure condition of pipeline are analyzed, so as to provide a reference for practical engineering. It's meaningful and necessary. This paper summarizes the development of PCCP at home and abroad and its design principles and standards, and introduces the processing technology and key points of PCCP. According to the present research situation and the actual project of the South-to-North Water transfer Project, the buried prestressed steel cylinder concrete pipe PCCP-E is selected, and the numerical simulation model is established by using ANSYS. In the model, the connection between each layer is reasonably considered, and the prestressing force is simulated by using the cooling method. The stress variation law of outer pipe core concrete, steel cylinder and prestressed steel wire under different working conditions, such as wire winding, deadweight, hydrostatic pressure, different internal water pressure and heavy truck action, is analyzed. The main conclusions are as follows: (1) when the wire winding is finished, the axial stress, radial stress and circumferential stress will appear in both inner and outer layer pipe core concrete and steel cylinder, in which the radial stress is very small and has no effect on the crack, so it can be ignored. It is mainly axial stress and circumferential stress, but compared with concrete and steel cylinder, the tensile and compressive strength is very small and will not cause cracks. 2) under normal operating conditions (from hydrostatic pressure to design internal pressure 0.84MPa), all parts of the pipeline are subjected to normal loading. Under the action of limit internal pressure (1.2MPa), the main stress of pipeline is circumferential tensile stress. The maximum circumferential tensile stress of inner pipe core concrete is 2.65 MPA, which exceeds the standard value of C50 concrete tensile strength (2.64 MPA / a). When the concrete is acting continuously, cracks appear along the circumferential direction, and the water flows out along the crack, causing damage. The strength of the steel cylinder and prestressed steel wire is sufficient to meet the bearing capacity requirement and will not yield. At the same time, the creep of concrete, the erosion of chloride ion, the relaxation of prestressed steel wire and the action of moving load on the ground will all cause pipeline failure in a long period of time. That is, when the stress in the middle part of the pipe top exceeds 2MPa, the axial maximum tensile stress appears in the middle of the pipe bottom, which is 2.4MPa, which is very close to the standard value of tensile strength of C50 concrete (2.64MPa / a), and it is easy to appear axial cracks. The maximum tensile stress in the circumferential direction also appears in the middle of the pipe bottom, which is 3.06 MPA, which exceeds the standard value of the tensile strength of C50 concrete (2.64 MPA / a). Cracks appear in the inner tube core concrete along the circumferential direction. If there is internal water pressure at the same time, the crack extension will be accelerated and the pipeline will be destroyed. Pose a danger to driving. Therefore, it is necessary to strengthen the monitoring of pipeline operation and find that the damage can be taken in time to reduce the loss in practical engineering.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV672.2

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