###### Abstract  
Static crushing agent (SCA) offers advantages such as good safety, no harmful gases, and minimal vibration, making SCA ideal for rock crushing in mines or underground engineering. To scientifically implement the section expansion of mine roadway, the rock mechanical parameters, SCA expansion properties, and cracking behavior of surrounding rock were investigated using laboratory tests, numerical simulations, and field experiments. Results indicate that the smaller hole spacing of SCA improves the fracturing effect on rock mass, reduces the required fracture initiation stress and penetration stress, and the presence of a free surface aids in fracture development in the rock mass. Optimal borehole design parameters and spacing distributions of the SCA were determined, and corresponding construction techniques of roadway expansion were proposed. Field tests demonstrate that static crushing technology, under multi-row drilling conditions, is highly effective for rock roadway expansion projects. These findings provide valuable guidance for non-explosive expansion and other roof breaking treatment projects. static crushing agent; rock fracturing; drilling arrangement; numerical simulation; construction process +
Footnote †: journal: Medical  
have shown that the water-cement ratio significantly affects the volume expansion rate of SCA, which decreases at a certain extent as the water-cement ratio increases [9; 11]. Tests have also found that the mixing water temperature has a significant impact on the reaction rate of the static crushing agent but has a smaller effect on the volume expansion rate of SCA, while the environmental temperature has a certain effect on the volume expansion rate of SCA and does not significantly affect the reaction rate [12]. Experiments indicate the water-cement ratio affects both the expansion pressure and the reaction rate; a higher water-cement ratio results in a slower reaction rate and produces lower expansion pressure [13]. Research on the composition proportion of SCA has found that the proportion of CaO, bentonite, and cement affects the expansion pressure of SCA, so different types and proportions of SCA have different expansion effects [14]. Because the reaction process of SCA is relatively mild, there exists many advantages for rock fracturing, such as no open flame, no dust, no explosive shock, no flying stones, and no noise. Currently, SCA has been widely applied in demolition projects of ground concrete, rock structures, and buildings [15]. The drilling depth, hole diameter, and hole spacing of SCA application are key parameters that affect the fracturing effect of the static cracking agent. [PERSON] et al. [16] have shown that the greater the hole depth, the better the fracturing effect, but the drilling depth should not be too large, generally controlled between 1.5 and 1.8 m. [PERSON] and [PERSON] et al. [17; 18] found that a larger hole diameter produces greater expansion stress; however, if the hole diameter is too large, it may lead to blowouts. Due to varying rock hardness, different required fracturing stresses exist. The selection of borehole spacing can significantly influence the fracturing effect of the static cracking agent, smaller spacing yields better fracturing results, while larger spacing yields poorer results [19; 20; 21]. Generally, the application of SCA in coal mines still requires further research. In rock fracture projects, the use of explosives is restricted, and breaking hard rocks using machine equipment is also difficult. Therefore, investigating coal-rock fracture mechanisms and the application technology of SCA is significant to improving the safety and efficiency of mine production. In this paper, a static crushing technology is adopted in the roadway expansion of a mine. To obtain an efficient construction effect of roadway expansion, the static cracking mechanism of rock roadway expansion is investigated using laboratory tests and numerical simulations.