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T形焊接结构是盾构机刀盘的关键结构之一,焊接处裂纹在亚临界的扩展是其疲劳失效的关键因素.文章在考虑载荷流泄情况下,基于概率断裂力学的一次二阶矩方法提出了一种新的结构疲劳可靠性分析方法.将该方法应用到某盾构机T形焊接结构,给出了考虑与不考虑载荷流泄两种情况下结构疲劳可靠性计算结果,并用Monte Carlo方法验证了文章方法的有效性;利用最小二乘法拟合出了载荷流泄系数对该T形焊接结构疲劳可靠性的影响曲线,将该曲线划分了三个区域:高、中、低疲劳失效区,实际工程在盾构机T形焊接结构疲劳可靠性设计时,将T形焊接结构的厚度作为一个设计变量,而低失效区可以作为一个可靠度约束条件.结果表明在考虑和不考虑载荷流泄时,T形焊接结构的疲劳失效概率分别是8.2644×10-5和3.4314×10-4,即载荷流泄提高了结构的疲劳可靠度;研究成果对实际工程上盾构机刀盘的维修、检验计划和设计都有一定的理论指导意义.
The T-shaped welded structure is one of the key structures of the cutterhead of the shield machine.The crack growth in the weld at the subcritical site is the key factor of its fatigue failure.According to the stress-fracture mechanics, A new fatigue reliability analysis method is proposed, which is applied to the T-shaped welded structure of a shield machine. The calculation results of the fatigue reliability of the structure with or without load shedding are given and used together Monte Carlo method is used to verify the validity of the proposed method. The curve of load-flow coefficient on the fatigue reliability of T-shaped welded structure is fitted by least square method. The curve is divided into three regions: high, medium and low Fatigue failure zone, actual engineering In the fatigue reliability design of the T-shaped welded structure of the shield machine, the thickness of the T-shaped welded structure is taken as a design variable, and the low failure area can be used as a reliability constraint. The results show that in considering and not The fatigue failure probability of T-shaped welded structure is 8.2644 × 10-5 and 3.4314 × 10-4, respectively, considering the flow of load. That is to say, the load leakage increases the fatigue reliability of the structure. The shield machine cutter maintenance, inspection planning and design theory has a certain significance.