Effects of joint angle and joint space on rock fragmentation efficiency by two TBM disc cutters

Abstract

通过实验研究不同节理倾角和间距对TBM双刃滚刀破岩的影响效果。实验采用预制节理水泥砂浆试件模拟节理岩体,节理面与侵入力方向夹角?分别为0°,30°,60°和90°,节理面间距分别为20,30,40和50 mm,采集整个加载过程中滚刀的侵入深度和侵入力,并采用相机进行实时拍摄,获得试件表面破坏的发展过程以及最终破坏形态。研究结果表明:节理岩体存在3种基本破碎模式,主要与节理倾角有关;相邻滚刀的协同破岩作用导致滚刀间岩体产生贯通裂纹,形成片状岩碴;当节理倾角为60°时,破岩比能耗最小,滚刀破岩效率最高;节理间距对岩碴的形成有较大影响,比能耗随着节理间距增大而增大,破岩效率降低。 Based on laboratory tests, the effects of joint angle and joint space on the penetration of two TBM disc cutters were studied. In the test, concrete jointed specimens were adopted to simulate jointed rock mass. The angle α between joint plane and tunnelling axis were 0°, 30°, 60° and to 90°, and four joint spaces were 20, 30, 40 and 50 mm respectively. Penetration depth and penetration force were collected during the loading process. Shooting with the camera in real time, photographs of the damage of specimen and failure mode of the development process were taken. The results show that there exists three basic modes of rock fragmentation which are mainly related to the joint orientation. The interaction between rock and TBM double disc cutter leads to cracks coalescence and chips formation. The specific energy achieves the minimum at the joint angle α=60° and the fragmentation efficiency of two TBM disc cutters can reach the highest. The joint space has significant impact on the formation of rock chips. Specifically, the specific energy increases with the increase of the joint space, but the fragmentation efficiency presents the opposite trend.