预应力钢筒混凝土管结构性能及耐久性理论研究

发布时间：2018-03-23 06:08

  本文选题：PCCP　切入点：承载机理　出处：《武汉大学》2014年博士论文　论文类型：学位论文

【摘要】：输水管线的安全与耐久是社会发展和人民安居乐业的必要保障。近年来,预应力钢筒混凝土管广泛应用于南水北调等大型输水工程。因此预应力钢筒混凝土管承载机理、破坏形态和安全耐久性能的研究,对保证生产运营的安全顺畅有非常重要的理论与实践意义。本文针对预应力钢筒混凝土管,立足于管道的结构性能分析和耐久性理论研究两方面,主要开展如下研究工作： 一、回顾了PCCP结构设计理论的发展过程,认为目前的PCCP结构计算理论不能反映PCCP作为多层结构沿管壁厚度方向上的应力分布特征。在此基础上,对PCCP的结构计算方法进行了改进,完善了符合PCCP实际服役环境的荷载计算理论和截面应力分析模型。二、建立了反映PCCP截面特性的二维平面有限元模型和反映PCCP钢丝螺旋缠绕和复杂层间关系的三维实体有限元模型,按照PCCP的生产工艺流程,对PCCP从生产制造到最终破坏的全过程进行了模拟,得到了PCCP在各种工况下的受力状态和结构响应,并且通过与理论分析结果和相关试验结果对比验证,证明了有限元模型及分析方法的正确性。通过在模型中合理的考虑砂浆层与管芯、管芯与钢丝之间复杂的相互作用关系,获得了在各种工况下,砂浆层的剥蚀、开裂情况,以及预应力钢丝预应力损失情况。 三、通过分析不同埋深和不同内水压力对PCCP受力性能的影响,研究了不同荷载类型对PCCP结构响应规律的影响,发现PCCP具有两种不同的破坏形态,并且破坏形态与管道埋深有关,深埋时PCCP受外压破坏,浅埋时PCCP受内压破坏。提出现行设计规范仅考虑了PCCP受内压破坏的极限状态。研究了内水压力改变下,PCCP结构受力响应的变化规律,模拟了结构在内水压力作用下的破坏过程,研究了PCCP在内水压力作用下的破坏机理和破坏形态；结合前人进行的PCCP外压破坏试验研究成果,建立了PCCP两种破坏形态下的承载能力极限状态方程,通过算例证明本文提出的承载能力极限状态方程可作为现行设计规范的有益补充。 四、分析了管芯混凝土厚度、砂浆层厚度、钢筒位置、钢筒厚度、钢丝直径和钢丝间距变化对PCCP结构性能的影响,以此提出了砂浆层、预应力钢丝、管芯混凝土和钢筒在PCCP承载过程中分别发挥的功能作用。研究了PCCP结构尺寸变化对结构性能影响的规律,提出了能指导PCCP各结构部件布置和结构设计的重要工程结论,建立了能用于结构优化的反映PCCP关键截面应力与结构尺寸变化关系的分析公式。 五、分析了造成PCCP结构耐久性退化的多种因素,认为氯离子侵蚀对PCCP耐久性危害最大,并提出基于氯离子侵蚀的PCCP寿命评估准则和耐久性设计方法。研究了氯离子侵蚀PCCP的机理,发现氯离子侵蚀PCCP呈二维扩散规律,并且管道截面半径及预应力钢丝和钢筒均对PCCP内部的氯离子浓度分布有显著影响,结合PCCP的截面特征建立了PCCP氯离子扩散理论模型及PCCP剩余使用寿命评估模型。 六、研究了氯盐环境下预应力钢丝的腐蚀特性,提出氯离子侵蚀PCCP将造成三种腐蚀结果：局部预应力损失、局部钢丝锈蚀和钢丝锈断。针对三种腐蚀结果,分别建立PCCP局部预应力损失模型、PCCP局部钢丝锈蚀模型和PCCP钢丝断裂模型,研究预应力钢丝腐蚀损伤对PCCP结构性能的影响,提出预应力钢丝腐蚀将降低PCCP的承载能力,显著影响PCCP的耐久性能。
[Abstract]:Safety and durability of the water pipeline is necessary for social development and people's live and work in peace. In recent years, the prestressed concrete cylinder pipe is widely used in large-scale water diversion project of South to North Water Diversion Project. So the prestressed concrete cylinder pipe bearing mechanism, failure mode and safety of durability, to ensure there is very important theoretical and practical significance of safety the smooth production operation. Based on the prestressed concrete cylinder pipe, two based on pipeline structure durability performance analysis and theoretical research, the main research work carried out as follows:
A review of the development process, the design theory of the structure of PCCP, PCCP believes that the current structure of the theoretical calculation can not reflect the PCCP as a multilayer structure along wall thickness on the stress distribution characteristics. On this basis, the calculating method of the PCCP structure was improved, improve the service environment of the actual loads in accordance with PCCP calculation theory and cross section the stress analysis model. Two, establish a plane finite element model to reflect the PCCP section characteristics and reflect the three-dimensional finite element model of PCCP steel wire spiral winding and complex relations between layers, according to the production process of PCCP, the PCCP was used to simulate the whole process from production to final failure, obtained in a variety of PCCP under the condition of stress response and structure, and through the comparative analysis of test results and relevant test results and theory, to prove the correctness of the finite element model and the analysis method. Through the Considering the complex interaction between the mortar layer and the core and the core and the steel wire, the erosion and cracking of the mortar layer and the prestress loss of the prestressed steel wire under various conditions are obtained.
Three, we analyze the effect of different depth and different water pressure on PCCP mechanical properties, the effects of different load types on the structure of PCCP response, PCCP has found two different failure modes and failure modes and the buried depth of pipeline, buried PCCP under external pressure damage, shallow PCCP under internal pressure damage. Proposed the design specification only consider the limit state PCCP under internal pressure damage. On the internal pressure changes, changes of stress response in PCCP structures, to simulate the failure process of the structure in the water pressure under the action of PCCP, the failure mechanism of the inner water pressure and failure form; the destructive test combined with some previous results of PCCP external pressure, a bearing capacity limit state equation PCCP two kinds of failure mode, it is proved that the bearing capacity limit state equation is proposed in this paper can be used as the current A useful supplement to the design specification.
Four, analysis of the tube core thickness of concrete, mortar layer thickness, the thickness of steel tube, steel tube, influence of wire diameter and wire spacing changes on the PCCP structure performance, this proposed mortar layer, prestressed steel wire, pipe core concrete and steel tube in PCCP bearing function are played in the process. The effect of PCCP the structure size changes on the structure and properties of the law, put forward an important engineering layout and structural design guide PCCP parts can be used to reflect the conclusion, established PCCP critical section structure optimization analysis formula of force and structure size change.
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本文编号：1652213