TBM滚刀动、静载荷组合破岩数值模拟

Simulation of TBM cutter penetration under static and dynamic coupled loads

在对TBM破岩实际工况的合理简化基础上,采用颗粒流软件建立动、静载荷组合破岩数值模型,从微观裂纹发育与宏观损伤断裂角度出发,研究动、静载荷作用下单滚刀破岩特性。研究结果表明:在不同频率及速度振幅动、静载荷作用下,TBM滚刀切削扩展模型与钝刀切削扩展模型相类似,主要差异体现在密实核与损伤区域面积和宏观裂纹发育之上;在多数情况下,动、静组合加载有利于剪切微裂纹的发育而不利于张拉微裂纹发育;动、静载荷会在一定程度上增大密实核与损伤区域面积;中低频时,中间裂纹长度与频率成正比,而高频时中间裂纹长度与频率成反比,高频不利于中间裂纹发育;当频率小于等于2 Hz时,中间裂纹发育与速度振幅成正比,而当频率高于2 Hz时,利于中间裂纹发育的速度振幅为0.4 mm/s;低频大速度振幅加载有利于侧向裂纹发育,高频大速度振幅加载不利于侧向裂纹发育。

Based on the simplification of practical cutting process of TBM cutters, particle flow code was applied to establish the penetration model of single TBM cutter which was controlled by coupled static and dynamic loads. The development of micro cracks and macro fractures were studied. The results show that the cutting expansion model of coupled static and dynamic load is similar to that of the blunter cutter under static load, and the main differences exist in the areas of crushed core and damaged region and the development of macro cracks. Generally, compared with the static load, the coupled loads are beneficial to the development of micro shear cracks, while the effect of coupled loads on the development of micro tensile cracks is opposite to that on micro shear cracks. Compared with the areas of crushed core and damaged region under static load, the areas under coupled loads are expanded. The length of middle crack increases with the increase of frequency when the frequency is low or medium, while the length decreases when the frequency is high. High frequencies are not beneficial to the development of middle crack. When the frequency is less than 2 Hz, the length of middle crack increases with the increase of the velocity amplitude, and when the frequency is higher than 2 Hz, the optimum velocity amplitude for the development of middle crack is 0.4 mm/s. The load characterized with big amplitude and low frequency is beneficial to the development of lateral cracks, while the load characterized with big amplitude and high frequency is not beneficial to the development of side cracks.