Numerical simulation on effects of embedded crack on rock fragmentation by a tunnel boring machine cutter
来源期刊：中南大学学报(英文版)2014年第8期
论文作者：LIU Jie(刘杰) CAO Ping(曹平) JIANG Zhe(蒋喆) ZHAO Yan-lin(赵延林) CAO Ri-hong(曹日红)
文章页码：3302 - 3308
Key words：numerical simulation; embedded crack; rock fragmentation; breaking efficiency
Abstract: Based on the simplification of cutting process, a series of numerical simulations were conducted using a 2-D discrete element method to explore the effects of embedded cracks with different dip angles on the rock fragmentation process, cutting characteristics and breaking efficiency. The results show that the simulated results are in a good agreement with previous theoretical study. The main crack propagates to the top tip of embedded crack, except when the dip angle is 90°. Side cracks which are more fully developed in the rocks containing embedded cracks tend to propagate towards the free surface. According to the history of vertical cutting force, it is shown that the peak force is decreased by embedded cracks. The study on cutting efficiency was conducted by combining the quantity of crack and cutting energy. And the results show that breaking efficiency can be treated as a decreasing or a increasing function when the dip angle is less or larger than 30°, respectively. Breaking efficiency is higher than that in intact rock when the dip angle is larger than 45°.
LIU Jie(刘杰)1, CAO Ping(曹平)1, JIANG Zhe(蒋喆)1, ZHAO Yan-lin(赵延林)2, CAO Ri-hong(曹日红)1
(1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. School of Energy and Safety Engineering, Hunan University of Science and Technology, Xiangtan 411201, China)
Abstract:Based on the simplification of cutting process, a series of numerical simulations were conducted using a 2-D discrete element method to explore the effects of embedded cracks with different dip angles on the rock fragmentation process, cutting characteristics and breaking efficiency. The results show that the simulated results are in a good agreement with previous theoretical study. The main crack propagates to the top tip of embedded crack, except when the dip angle is 90°. Side cracks which are more fully developed in the rocks containing embedded cracks tend to propagate towards the free surface. According to the history of vertical cutting force, it is shown that the peak force is decreased by embedded cracks. The study on cutting efficiency was conducted by combining the quantity of crack and cutting energy. And the results show that breaking efficiency can be treated as a decreasing or a increasing function when the dip angle is less or larger than 30°, respectively. Breaking efficiency is higher than that in intact rock when the dip angle is larger than 45°.
Key words:numerical simulation; embedded crack; rock fragmentation; breaking efficiency
