高压水刀辅助TBM滚刀破岩效率室内模型试验

研究不同工况条件下高压水刀辅助TBM滚刀破岩效率,对于进一步优化该新兴技术,实现高强度高磨蚀性地层TBM高效安全掘进具有重要意义。为此,基于室内滚刀贯入模型试验,对不同低围压作用(围压p₀=0,1.25,2.5 MPa)以及不同高压水刀预切割竖向裂缝几何参数(切缝深度H=10,20 mm,预切缝-刀具轴线间距L=0,20,40 mm)条件下高磨蚀性硬岩试样滚刀贯入破碎过程及破岩效率影响规律展开研究。试验结果表明:低围压且无预切缝条件下,随着围压的增大,岩样峰值贯入荷载增大,贯入荷载-贯入度曲线跃进跌落次数增多,试样破坏特征从脆性破坏向延性破坏转化,无围压条件下高强度高磨蚀性地层TBM掘进难度高于常规强度地层和高强度磨蚀性地层;低围压且有预切缝条件下,预切缝-刀具轴线间距L=0时,岩样发生劈裂模式破坏,无围压条件下,L=0时,其峰值贯入荷载显著小于L≠0情况,有围压条件下,L=0时,岩样达到峰值贯入荷载所对应的贯入度显著大于L≠0情况;有预切缝条件下,预切缝-刀具轴线间距L≠0时,预切缝深度H越大,破岩效率越高,较大的高压水刀切割深度H能够降低高强度高磨蚀地层TBM掘进中滚刀的磨损率;有预切缝条件下,当预切缝深度H一定时,不同L值下的岩样峰值贯入荷载及对应的贯入度都随着围压增大而增大,而当L值较大时,一定程度上需提高掘进推力才能够实现高效破岩。

Model Test Study on Rock Breaking Efficiency by TBM Cutter Assisted with High Pressure Water Jet

Study on the rock-breaking efficiency of TBM cutter assisted by a high-pressure water jet under different working conditions is significant to further optimization of this new technology,hence to achieve efficient and safe TBM digging in high-strength and high-abrasion strata.In this study,the cutter penetration,crushing process,and rock-breaking efficiency of the high-abrasive hard rock samples under different confining pressures (p₀=0,1.25,and 2.5 MPa) and pre-cutting vertical crack geometric parameters (depth H=10 mm,pre-cutting crack=20 mm,and cutter axis distance L=0,20,and 40 mm) were investigated using TBM cutter penetration model tests.The principal conclusions are as follows:Although no vertical crack is pre-cut in the upper surface of the rock samples,the peak penetration load increases with an increase in confining pressure,and the penetration load-depth curve undergoes many stress drops at the post-peak stage,reflecting a transition from brittle to ductile failure.The difficulty of TBM tunneling in high-strength and high-abrasion strata is considerably higher than that in a conventional stratum.While a vertical crack is pre-cut in the upper surface of the rock samples,a splitting mode failure of the rock sample occurs when L=0.Under the condition of no confining pressure,the peak penetration load when L=0 is significantly smaller than that of L≠0.Under the condition of confining pressure,when L=0,the penetration corresponding to the peak penetration load of rock samples is significantly higher than that of L≠0.When the distance between the pre-cutting crack and cutter axis is not zero,the larger the pre-cutting crack depth H,the higher is the rock-breaking efficiency,and the larger the pre-cutting crack depth H,the lower is the cutter wear rate in the TBM tunnelling of high-strength and high-abrasion strata.When the pre-cutting depth H is constant,the peak penetration load and corresponding penetration of the rock samples under different L values increase with an increase in the confining pressure.For a relatively large L value,a high-efficiency rock breaking can be achieved by increasing the driving thrust to a certain extent.