<p>Due to an unclear understanding of the crack initiation mechanism during the process of splitting grouting at the top of the Ordovician limestone, there is a lack of a theoretical basis for the selection of key parameters such as grouting pressure, slurry water–cement ratio, and borehole azimuth. This study explored those problems using indoor physical model tests of the real triaxial and numerical analysis, considering factors such as the slurry water–cement ratio, in situ stress level, and crack inclinations and openings. The results of the real, triaxial, physical, similar- material model test were compared with a numerical simulation calculation of splitting grouting. The results show that in the process of splitting grouting, the fracture initiation pressure at the top of the Ordovician limestone decreased with increases in the water–cement ratio, and the secondary fracture initiation pressure was greater than that of initial fracture initiation. The crack initiation pressure increased with increases in the crack opening and the angle between the crack and the maximum principal stress (PS). When the maximum PS, intermediate PS, slurry water–cement ratio, and angle between the crack and maximum PS were fixed, the initiation pressure and secondary initiation pressure decreasd with increases in the difference between the maximum and minimum PSes. However, the decrease in secondary initiation pressure was greater than that of the initiation pressure. Under various slurry water–cement ratios, stress levels, and angles between the crack and maximum PS, the crack started at the tip and showed a characteristic trend of extending parallel to the direction of maximum PS.</p>