Development of a High-Speed Rock Excavation System using Water Jet

为开发适用于大深度硬岩掘进的新系统，开展了水射流钻孔及随钻削技术的研究。提出了一种新的分析方案--三次幂法，并对水射流在钻孔过程中的压力衰减和材料的冲蚀强度进行了分析。通过一个特定深度的切削实验，提出了由冲蚀强度和入射水射流的有效压力定义的切削势，以评估钻井时的切削发生率。从量纲分析出发，考虑岩石应力的影响，提出了岩石抗蚀强度的计算公式。双轴压缩条件下的水射流钻孔实验成功地证实了该公式的有效性，并且随着围压的增加，崩落的发生率增加，导致开挖大于空载条件下。利用小尺寸硬岩试件成功地进行了网格式多点钻孔实验，并对比能进行了评价。给出了比能和最佳钻距，沿着建立了计算比能的重复模型。已经得出结论，水射流钻孔时的连续切削导致比常规水射流切割更高的挖掘效率。

Study on water jet drilling and chipping upon drilling was performed to develop a new system available for hard rock excavation at a great depth. A new scheme named the Third Power Method was proposed for the drilling process analysis, and the pressure attenuation of water jet upon drilling was evaluated as well as the erosion strength of materials. The chipping potential defined by the erosion strength and the effective pressure of incident water jet was presented to evaluate the incidence of chipping upon drilling, from a specific fixed depth chipping experiment. A formulation of the erosion strength was presented from the dimensional analysis, including the effect of rock stresses. The validity of the formulation was successfully confirmed by the water jet drilling experiment under a biaxial compression, and the incidence of chipping was shown to increase with increasing of the confining pressure, resulting in an excavation larger than that in no-load condition. A latticed multi-point drilling experiment was successfully conducted using the fun-size specimen of hard rock, to evaluate the specific energy. The specific energy and the optimum drilling interval was given along with the repetition model to calculate the specific energy. It has been concluded that the continuous chipping upon water jet drilling results in an excavation of higher efficiency than the conventional water jet cutting.