超大口径PCCP内断丝对其承载能力影响研究

Study on impact from wire-breaking inside of super-large diameter PCCP on its bearing capacity

以南水北调中线工程为背景,进行PCCP断丝原型试验,基于试验结果,利用杆单元模拟钢丝,采用等效降温法施加钢丝预应力,建立PCCP承载数值计算分析模型,基于非线性有限元理论,选取混凝土塑性损伤模型,对超大口径PCCP断丝问题进行承载能力和受力状态分析。计算结果表明:PCCP管芯混凝土损伤开裂位置为断丝对应区域,断丝数增加加剧了管芯混凝土的开裂破坏;断丝数增加急剧降低了PCCP的承载性能;当断丝数达到一定根数时,管芯混凝土更易开裂,在有内水压力作用时,将加剧钢筒和钢丝层的腐蚀,影响PCCP长久运行。

Taking the Mid-route of the South-to-North Water Transfer Project as the background, a prototype test on the wire- breaking inside of PCCP （Pre-stressed Concrete Cylinder Pipe） is made. Based on the test result, a numerical model for analysis on the bearing capacity of PCCP is established by means of simulating the steel wire with bar element, i.e. applying pre-stress to the steel wire by method of equivalent cooling ; and then, the concrete damaged plastic model is selected for analyzing the bearing capacity and stress status for the problem of wire-breaking inside of PCCP with the non-linear finite element theory concerned. The calculation shows that the cracking location of the damaged core concrete of PCCP is just the corresponding area of the broken wire. The increase of the number of the broken wires would aggravate the cracking damage, while the beating performance of PC- CP could be fast lowered by the increase of the number of the broken wires. Therefore, the core concrete of PCCP would be more easily to be broken, when the number of the broken wires reaches to a certain amount. Under this circumstance, the erosion of the steel cylinder and wire layer of PCCP is to be exacerbated, if the inner water pressure is therein, which would impact the lonz-term operation of PCCP.