围压条件下不同脆性岩石滚刀侵入破岩机制研究

Rock Breaking Mechanism of TBM Cutters for Rocks with Different Brittleness Indexes under Confining Pressure Condition

在TBM(全断面隧道掘进机)掘进过程中,岩石性质和围压是影响滚刀破岩机制的重要因素,因此研究这两种因素共同作用下的侵入破岩规律对于TBM选型、刀盘优化布置有着重要意义。文章基于3-D离散单元法,利用三维离散元软件MatDEM建立了数值模拟模型,综合考虑岩石物理力学性质和围压条件的影响,研究了岩石破碎模式和滚刀侵入破岩效率的变化规律。结果表明,当围压水平较低时,岩石脆性指标对破岩效率影响明显,破岩效率随岩石脆性指标的增大而减小;但当围压超过一定值时,脆性指标对破岩效率的影响幅度变小。对于脆性不同的岩石,破岩效率随围压增大整体呈下降趋势,但对于脆性大于18的岩石,破岩效率在围压为5 MPa时达到最高;当围压水平较低时,岩石破坏模式均以张拉破坏模式为主,随着围压的增大,破坏模式逐渐向拉剪综合破坏模式转变。

In the process of TBM excavation,the properties of rock mass and confining pressure are key factors affecting the rock breaking mechanism of the TBM cutters.Study on the rock breaking mechanism under the combined action of these two factors is of great value for the TBM selection and the optimal arrangement of the cutterhead.Based on the 3-D discrete element method,a numerical simulation model is established by using the three-dimensional discrete element software MatDEM.Considering the influence of rock mass physical and mechanical properties and confining pressure conditions,the variation law of rock fracture mode and rock breaking efficiency is studied.The results show that when the confining pressure is low,the rock brittleness index has obvious influence on rock breaking efficiency,and the rock breaking efficiency decreases with the increase of rock brittleness index.However,when the confining pressure exceeds a certain value,the influence of rick brittleness on rock breaking efficiency is smaller.The influence of rock brittleness index on rock breaking efficiency becomes smaller.For rocks with different brittleness,the rock-breaking efficiency decreases with the increase of confining pressure,but for rocks with brittleness greater than 18,the rock-breaking efficiency reaches the highest value when the confining pressure is 5 MPa.When the confining pressure level is low,the rock failure mode is dominated by the tensile failure mode.With the increase of confining pressure,the failure mode gradually changes to the shear tensile failure mode.