节理特征对TBM盘形滚刀破岩特性的影响

Influence of joint characteristics on rock fragmentation induced by TBM disc cutter

为了研究节理特征对全断面岩石掘进机(TBM)盘形滚刀破岩机制的影响,从岩体细观尺度出发,基于颗粒离散元法建立不同节理强度、间距和倾角特征下盘形滚刀破碎中分化灰岩的数值模型,模拟TBM滚刀切削岩石时岩石裂纹生成、扩展和碎块形成的全过程,以及滚刀受力和岩石应力分布状态。研究结果表明:岩体中的节理面能改变裂纹扩展方式,阻隔损伤向节理面下的岩石传播,且低强度节理面阻隔损伤的能力较强;节理间距对岩碴的块状大小有较大影响,当节理间距减小时破岩效率升高;节理岩体存在3种基本的破碎模式,主要与节理倾角有关;当节理倾角为60°时,破岩比能耗最小,滚刀破岩效率达到最高值。

In order to study the effects of joint characteristics on rock fragmentation modes, from the meso-level structure of rock mass, the jointed rock indentation by a single TBM disc cutter was simulated by using the particle discrete element method, and rock fragmentation process was highlighted. A series of two-dimensional numerical modeling in jointed rock mass were performed to explore the influence of joint strength, spacing and orientation on rock fragmentation by disc cutter. Finally the load of disc cutter and the stress distribution of rock were analyzed. The results show that the joints in the rock mass can change the crack propagation pattern and obstruct the damage spread into the rocks under the joints. For the low strength joint in the rock mass, the ability of obstructing damage spread is better. The joint spacing has significant impact on the size of rock debris and the penetration rate increases with the decrease of the joint spacing. There exists three basic modes of rock fragmentation which are mainly related to the joint orientation. The specific energy achieves the minimum value at the joint dip angle a=60° and the penetration efficiency of disc cutter can reach the highest.