TBM刀座焊缝疲劳可靠性分析

Analysis of Fatigue Reliability of Cutter Saddle Weld for TBM

刀座焊接处是全断面岩石隧道掘进机(Full face rock tunnel boring machine,TBM)刀盘上最易发生疲劳破坏的部分。基于线弹性断裂力学,以裂纹疲劳寿命为基本变量,建立裂纹扩展可靠性模型,通过JC法计算刀座正面焊缝在不同滚刀实验载荷下的疲劳可靠性,并分析了不同因素对失效概率的影响。结果显示:中心滚刀刀座焊缝的失效概率比正滚刀小,正滚刀的失效概率随着安装半径的增大而减小;刀座焊缝失效概率随着初始裂纹深度的增大而显著增大,而临界裂纹深度的变化对失效概率的影响不大;裂纹形状比越大,刀座焊缝的失效概率越小。

Cutter saddle welding is the part in TBM(Full face rock tunnel boring machine)cutterhead where fatigue damage most likely occurred.A model for cracks extension reliability based on the linear elastic fracture mechanics was built with crack fatigue life as basic variable,and JC method was used to calculate the fatigue reliability of cutter saddle weld under different cutter loads obtained experimentally and analyze the influence of the different factors on the failure probability.The results show that the failure probability of center cutter saddle weld is smaller than that of normal cutter,and the failure probability of normal cutter decreases with increasing of installation radius;the failure probability of cutter saddle weld increases dramatically with the increasing of initial crack depth,but the change of critical crack depth has slight effect on the failure probability;the larger the crack shape ratio is,the smaller the failure probability of cutter saddle weld is.