【作者】 熊欢；

【导师】 李庆斌；

【作者基本信息】 清华大学 ， 水利工程， 2010， 博士

【摘要】 本文结合南水北调中线输水工程的实际问题,从合理考虑钢丝刚度贡献及其行为特性的基本思想出发,建立了模拟分析PCCP管道预应力施加的缠丝模型,并对南水北调中线用4m内径超大口径埋置式PCCP管道进行了原型管试验,然后以原型管试验所发现的断丝响应规律为基础建立了PCCP管道的断丝模型,最后对管道进行了结构分析与承载力评价。论文的主要研究工作和创新点包括:一、从施工仿真的角度建立了超大口径埋置式PCCP管道预应力施加模拟分析的缠丝模型。模型实现了预应力钢丝缠丝过程的动态仿真模拟,合理考虑了钢丝与混凝土管芯之间的相互作用机理,以及钢丝刚度对管道整体刚度的贡献,钢丝自身的应力变形能够得到正确计算。然后,将缠丝模型应用于南水北调中线超大口径埋置式PCCP管道进行预应力场的施加模拟分析,并将计算结果与现有方法给出的结果进行对比分析,验证了缠丝模型的合理性。二、首次对南水北调中线超大口径埋置式PCCP管道进行现场原型管试验,包括抗裂外压试验、抗裂内压试验和断丝试验。获得了PCCP管道在压力作用下的受载响应规律;研究了钢丝断裂后,对旁侧未断钢丝及其自身受力状态的影响,发现了新的断丝响应规律,定义出了失锚长度的概念,用以描述钢丝断丝后与砂浆保护层重新建立起锚固所需的长度。三、以原型管试验所发现的断丝响应规律为基础,从过程仿真的角度建立了超大口径埋置式PCCP管道预应力丧失模拟分析的断丝模型。模型对失锚长度进行了定量化描述,得到了失锚长度内钢丝应力与握裹力分布,真实反映了钢丝断丝后的作用机理与响应规律,实现了断丝过程数值模拟。然后,将断丝模型应用于南水北调中线超大口径埋置式PCCP管道进行断丝过程数值模拟分析,并将计算结果与原型管试验结果进行了对比分析,验证了断丝模型的合理性。四、应用本文所建立的缠丝与断丝模型,对南水北调中线超大口径埋置式PCCP完好与断丝管道进行了抗裂外压和内压数值模拟分析,研究了管道的受载响应规律,评价了管道结构的承载能力,并提出了PCCP管道爆管的内外载影响机制等重要的工程结论。更多还原

【Abstract】 Under the background of the Mid-route of South-to-North Water Diversion (MSNWD) project in China, some research works are done for the consideration of the stiffness and behavior of the wire of a PCCP. A new finite element model, called wire-wrapping model, is proposed to simulate the prestressing of a PCCP. Some prototype tests on the embedded PCCP with an ultra-diameter of 4m used in the MSNWD project are conducted. On the basis of the response patterns of the PCCP found in the prototype tests mention above, a new model, called wire-breaking model, is proposed to simulate the process of breaking wire. The analysis of the pipe structure and the evaluation of the load-bearing capacity of the embedded PCCP are performed. The main contents and the innovative points are summarized as follows.1. A wire-wrapping model is proposed to simulate the process of wrapping wire for the prestressing of an embedded PCCP with an ultra-diameter. The wire-concrete core interaction and the contribution of the wire stiffness are taken into account in this model. The stress and deformation of the wire could be calculated correctly. The wire-wrapping model is applied to simulate the prestressing of an ultra-diameter embedded PCCP used in the MSNWD project. The results obtained using the wire-wrapping model are analyzed and compared with those obtained using current methods for its verification.2. Some prototype tests on the ultra-diameter embedded PCCP used in the MSNWD project are conducted for the first time. The load-bearing response patterns of the PCCP under loads are obtained. The new wire-breaking response patterns are also found, which exhibite the effects of breaking wire on the stress states of the unbroken wire and broken wire itself. A new concept called bonding-lost length is presented, which describes a certain length to develop again the bonding effect with the mortar when a wire breaks.3. On the basis of the response patterns of the PCCP found in the prototype tests mention above, a wire-breaking model is proposed to simulate the process of breaking wire for the un-prestressing of an embedded PCCP with an ultra-diameter. The bonding-lost length could be determined quantitatively in this model. The distribution of wire stress and gripping power are obtained. The mechanism the response when a wire breaks can be reflected by the wire-breaking model. The wire-breaking model is applied to simulate the process of breaking wire of an ultra-diameter embedded PCCP used in the MSNWD project. The results obtained using the wire-breaking model are analyzed and compared with those obtained from prototype tests for its verification.4. The wire-wrapping model and the wire-breaking model proposed in this dissertation are applied to simulate and analyze the processes of three-edge bearing tests and hydrostatic pressure tests of the ultra-diameter embedded PCCP used in the MSNWD project. Here, two kinds of PCCP are considered: the PCCP with and without broken wires. The load-bearing resoponses of PCCP are analyzed and the load-bearing capacity of PCCP is evaluated in this part. Finally, some significant engineering conclusions about the mechanism of pipe rupture are presented.更多还原