复杂应力状态下TBM刀盘裂纹应力强度因子分析

摘要

为了预测全断面岩石掘进机(tunnel boring machine,TBM)刀盘的疲劳寿命,本文对其裂纹尖端的应力强度因子进行了研究.以某水利工程的刀盘为研究对象,采用基于子模型技术的有限元法分析复杂应力状态下刀盘裂纹的应力强度因子,并给出了不同裂纹参数对应力强度因子的影响规律,为刀盘裂纹扩展寿命的预测提供输入条件.分析表明,当裂纹位置角为45°或135°时,裂纹尖端的等效应力强度因子最大,对结构损伤最严重;形状比对KI值影响最显著,形状比越大,尖端KI值相差越大,在深度方向的扩展趋势也越强;KI、KII及KIII值均随裂纹深度的增加而增大,裂纹尖端最深处以张开型扩展形式为主,而表面点则是3种开裂形式并存.%We studied the stress intensity factors of the crack tip of a tunnel boring machine (TBM) cutter head to predict the fatigue life of the TBM.A TBM cutter head in a water tunnel project was studied,and the finite element method based on submodeling technology was used to analyze the stress intensity factors of the cutter head crack under complex stress conditions.The influences of various crack parameters on stress intensity factors were illustrated to provide input conditions for cutter head life prediction.The analysis showed that equivalent stress intensity factors at the crack tip were the largest when the crack position angle was 45° or 135° and it caused the most serious damage to the structure.In addition,the crack shape ratio had the greatest influence on KI and a larger shape ratio meant a larger KI difference at the crack tip.This led to an obvious expansion trend in the depth direction.Furthermore,KI,KII,and KIII increased with increasing crack depth.The crack tip was dominated by an opening mode crack,whereas the surface points comprised three types of cracks.