大跨径斜拉桥拉索破损断裂性能的研究

A Study on Cable Breakage and Fracture of Long Span Cable-Stayed Bridge

从线弹性断裂力学理论出发,对雅砻江桐子林斜拉桥拉索的病害、索力及破损安全进行了初步分析。通过现场试验得到平行钢丝拉索的恒载索力,全桥39%拉索索力超过设计索力5%,13%拉索索力超过设计索力10%,2-1号拉索索力超设计索力16.5%。采用含半椭圆表面裂纹的圆杆受远场均匀拉伸应力作用裂纹模型,对钢丝的断裂安全评估表明,裂纹应力强度因子KI最大值小于材料断裂韧度KIC,钢丝中的裂纹不会在静态下失稳扩展。PE护套防护作用失效是造成索内钢丝锈蚀的直接原因,钢丝锈蚀是造成拉索断裂的重要原因。

On the basis of the theory of linear flexibility fracture mechanics, the cable disease, power and breakage of Tongzilin Bridge over Yalong River is analyzed. The parallel steel wire cable power under stable load is obtained by fieldwork test. 39% cables power is 5% greater than the designed power, 13% cables power is 10% greater than the designed power, the power of No. 2-1 cable is 16.5% greater than the designed power. The safety of steel wire breakage is evaluated by using semi-elliptical surface cracked pole model which is pulled by far-field even forces. The results show that when the maximum value of stress intensity factor K1 is less than the fracture toughness KIC, the crackle in steel wire will not lose stability and extend under static circumstance. The most important reason of the breakage of cables is the eorrosin of steel wires, while the direct reason of steel wires corrosin is that the PE shield lost effect.