低压磨料空气射流破岩能力强、能耗低，是一种解决硬岩掘进效率低、刀具损耗严重最具潜力的技术之一。但采用磨料射流技术进行破岩割缝时，由于评价指标(割缝深度、宽度、体积)单一、普适及通用性差，导致磨料射流在不同工况下的最佳割缝参数难以确定，极大限制了磨料射流技术的推广应用效果。为此，提出一种综合考虑磨料射流割缝深度、宽度和体积等缝槽参数之间定量关系的评价模型。通过对岩石割缝形貌进行三维重构，并进行均值化处理，得到射流割缝缝槽形态分布方程。将缝槽形态曲线方程的均值面积A与分布函数振幅a₁的比值定义为割缝特征宽度b，并将b与a₁的比值定义为宽高比P。利用P对磨料射流割缝效果进行评判，得到如下结论：在P≤0.5时，表示能形成更窄更深的割缝，且当P越小时，割缝窄深特征更明显；当P＞0.5时，表示能够形成更宽更浅的割缝。利用P对不同割缝参数条件下的割缝效果进行表征，得出当需要获得较深的割缝形态时，应控制射流冲击靶距为40 mm，磨料粒径在60～90目(0.16～0.25 mm)，磨料莫氏硬度应控制在7.0以上，采用16 ～32 g/s的磨料质量流量和60°的冲击角度。当获得宽且浅的割缝形态时，可选择磨料粒径大于90目(0.16 mm)，磨料莫氏硬度低于7.0，使磨料质量流量低于8 g/s并控制射流冲击角度超过75°，射流靶距大于40 mm。

Low-pressure abrasive air jet technology is one of the most promising methods for addressing the issues of low efficiency and significant tool wear in hard-rock drilling, owing to its strong rock-breaking capability and low energy consumption. However, the application of this technology faces challenges due to the reliance on single evaluation indices (e.g., slit depth, width, volume), which lack universality and generality, making it difficult to determine the optimal slit parameters under varying working conditions. This limitation significantly hampers the effectiveness of abrasive jet technology. To address this issue, proposes an evaluation model that integrates the quantitative relationships among slit parameters such as depth,width, and volume. A jet slit morphology distribution equation is derived through three-dimensional reconstruction and homogenization of rock slit morphology. The ratio of the mean area (A) of the slit morphology curve to the distribution function parameter (a₁) is defined as the characteristic width of the slit, denoted as b, and the ratio of b to a₁ is defined as the width-to-height ratio P. The effectiveness of the slit is evaluated using P, leading to the following conclusions: when P≤0.5, a narrower and deeper slit is formed; when P > 0.5, a wider and shallower slit is produced. By using P to characterize the slit effect under different parameter conditions, it is determined that when a deeper slit is required, the jet impact target distance should be maintained at 40 mm, the abrasive grain size should range between 60 and 90 mesh (0.16～0.25 mm), the abrasive hardness should exceed 7.0 on the Mohs scale, the mass flow rate of the abrasive should be between 16 g/s and 32 g/s, and an impact angle of 60° should be used. For obtaining a wide and shallow slit, the abrasive grain size should exceed 90 mesh (0.16 mm), the Mohs hardness should be less than 7.0, the abrasive mass flow rate should be lower than 8 g/s, the jet impact angle should be greater than 75°, and the distance between the jet and the target should be greater than 40 mm.