TBM刀盘裂纹分析及止裂方案研究

TBM cutter-head crack analysis and crack stopping scheme research

针对TBM刀盘在破岩过程中出现表面裂纹而造成刀盘疲劳失效,从而引发施工风险和经济损失的问题,以辽宁大伙房水库输水隧洞所用MB264-311-8030mm型号TBM刀盘为研究对象,利用Abaqus进行有限元仿真,得到刀盘应力分布状况。基于Paris公式建立TBM刀盘的裂纹扩展模型,利用扩展有限单元法(XFEM)模拟裂纹的开裂过程,分析开裂路径和开裂时所需载荷的循环次数。提出通过安装筋板进行刀盘裂纹止裂的方案,并从筋板的安装位置、厚度、高度和宽度4个结构参数分别设置实验组,以未安装止裂筋板的刀盘作为对照组进行对照实验,计算不同结构参数下止裂板的止裂系数、裂纹长度和裂纹深度变化,评估不同实验组的止裂效果。研究结果表明:止裂筋板的结构参数明显影响了TBM刀盘表面裂纹的扩展速率,进而影响刀盘疲劳裂纹扩展寿命,合理地设计止裂筋板参数可有效延长疲劳裂纹扩展寿命,反之则会加速裂纹的扩展。经过多组对照后,采用安装位置距裂纹中心为5 mm,厚度为4 mm,高度为12 mm,宽度为6 mm的止裂板可将裂纹宽度和深度方向的止裂系数分别提升28.42%和27.86%,其中影响最显著的是距裂纹中心的安装位置和止裂板高度2个参数。研究可为实际隧道工程中TBM刀盘的止裂方案的设计与制定提供一定参考。

The TBM cutter-head appeared in the process of rock breaking can result from the cutter-head fatigue surface crack, which causes the construction risk and economic loss problem. MB264-311-8030mm TBM cutter head used in the water tunnel of Dahuofang Reservoir in Liaoning Province was taken as the research object. The stress distribution of cutter head was obtained by finite element simulation using Abaqus. The crack propagation model of TBM cutter head was established based on Paris formula. The crack propagation process was simulated by extended finite element method(XFEM), and the crack path with the cycles of load required for cracking were analyzed. A scheme of using stiffened plate to stop the crack of cutter-head was put forward. The control experiments were set up from four aspects of location, thickness, height and width. The crack stopping coefficient and effect of different structural parameters were calculated. The results show that the structural parameters of the crack-stopping stiffened plate can affect the fatigue crack growth life of the cutter-head, and the reasonable design of the crack-stopping stiffener parameters can improve the fatigue crack growth life. Otherwise, it will accelerate the crack growth. After multiple groups of control, the crack stopping coefficient of crack width and depth direction can be increased by 28.42% and 27.86% respectively by using crack stop plate with 5 mm, 4 mm thickness, 12 mm height and 6mm width from the crack center. The most significant influence is on the location from the crack center and the height of crack stop plate. This study can provide a reference for the design of cutter-head crack stopping in tunnel construction.