临空面对TBM楔刀贯入破岩效果影响试验研究

Experimental study on effect of free surface on rock breaking by wedge cutter penetration

为提高深部地下高地应力硬岩掘进效率,对有、无中间临空面的板状花岗岩试样进行了楔刀垂直贯入破岩试验,以探究临空面辅助作用下不同围压、不同楔刀与临空面的距离、不同临空面深度等对楔刀破岩效果的影响。试验结果表明:临空面辅助破岩可大幅降低破岩比能耗;在临空面辅助作用下,楔刀下主裂纹向下延伸后朝向临空面发展贯通,形成三角形大粒径块体岩渣,减小了岩屑的产生;围压对破岩效率具有重要影响,在最优围压时破岩比能耗最低;主裂纹贯通至临空面底部时,伴随楔刀与临空面的距离增大,破岩比能耗呈现非线性增长;临空面深度控制主裂纹朝向临空面发展贯穿,从而影响破岩比能耗。研究结果为TBM高效破岩提供了新思路。

To improve the boring efficiency of hard rock with high geostress in deep ground,vertical penetration test by wedge cutter was carried out on plate granite samples with and without intermediate free surface.The influences of confining pressure,the distance between wedge cutter and free surface,and the depth of free surface on rock breaking by wedge cutter were studied respectively.The results showed that the specific energy consumption of rock breaking was greatly reduced with the assistance of the free surface.The main crack under the wedge cutter extended downward and tended to penetrate to the free surface,forming a large-sized triangular rock chip with little rock fragments.The specific energy consumption of rock breaking was greatly affected by confining pressure,and reached the lowest at the optimal confining pressure.When the main crack penetrated to the bottom of the free surface,the specific energy consumption of rock breaking showed a non-linear increase with the distance from the free surface.The depth of the free surface controlled the development of the main crack toward the free surface,which affected the specific energy consumption of rock breaking.The results provide a new idea for efficient rock breaking of TBM.