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

为开发适用于大深度硬岩开挖的新系统，开展了水射流钻进和随钻削屑技术的研究。提出了一种新的钻井过程分析方法--三次幂方法，并对水射流在钻井过程中的压力衰减和材料的冲蚀强度进行了评价。通过一个特定的定深切屑实验，提出了由冲蚀强度和入射水射流有效压力定义的切屑潜势来评价钻井时的切屑发生率。从量纲分析出发，考虑了岩石应力的影响，给出了侵蚀强度的计算公式。双轴压缩下的水射流钻进试验验证了该公式的有效性，并发现随着围压的增大，切屑发生率增加，开挖比空载时大。利用普通尺寸的硬岩试件，成功地进行了格构式多点钻进实验，以求取比能量。给出了比能量和最佳钻井间隔，并建立了计算比能量的重复模型。结果表明，连续切割水射流钻进比常规水射流切削具有更高的开挖效率。

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.