This approach allows for the direct underground resource utilization of gangue, and overcomes challenges related to gangue transportation and discharge [13]. However, gangue differs from traditional shotcrete materials, including gravel, in terms of the mechanical properties, so the mix proportions of gangue-based shotcrete materials applied to roadways prepared by replacing original aggregates with gangue exert different influences on the shotcrete materials. Considering this, studying the influence of various mix proportions of the gangue-based shotcrete material on its mechanical properties can help optimize the mix proportions and promote the material's resource utilization. This is significant to realizing the potential of gangue and promoting the material's application. Scholars worldwide have studied the utilization of gangue by transforming it into shotcrete materials. [PERSON] et al. summarized the comprehensive disposal methods of gangue, including ground and underground disposal techniques. Using gangue to prepare building materials is an important method of consuming gangue [16]. [PERSON] et al. proposed using residual solid waste from mines to produce building materials as a method to promote the development of a recycling economy and realize innovation in clean energy. The application of gangue to concrete provides an important reference for the development of the shotcrete materials used in roadways [17]. In the experimental process, [PERSON] et al. explored the crushing of concrete with gangue as aggregates in the compression process, and considered that the compressive strength and grain breakage are similar to those of concrete prepared with natural gravels and sand [18]. [PERSON] et al. provided the optimized mix proportions of non-activated gangue for preparing building concrete [19]. According to [PERSON] et al. [20], the concrete columns made with gangue as coarse aggregates achieve sufficient adhesion to steel reinforcements. However, they do not prevent fracture propagation under high stress. [PERSON] et al. found that the addition of fly ash can enhance the working performance and mechanical properties of gangue-based concrete, as determined through nuclear magnetic resonance and grey correlation analysis [21]. [PERSON] et al. conducted experimental studies on the effects of aggregate (gangue) content and water/cement ratio on shotcrete, and discussed their positive impact on CO\({}_{2}\) emission reduction in the field of environmental protection [22]. [PERSON] et al. used a cement-based paste to coat the surface of gangue aggregates, in order to enhance the mechanical and interfacial properties, and they verified that the CO\({}_{2}\) emissions associated with such concrete are only 73.3% of those arising from the use of conventional concrete of the same label [23]. In other aspects, [PERSON] et al. conducted numerical research into the macroscopic mechanical behaviors and microscopic particle motions of gangue with different sizes under different confining pressures and at different loading rates [24]. [PERSON] et al. adopted particle flow code (PFC) to simulate the influences of different gangue sizes on the compressive deformation of gangue particles [25]. Additionally, gangue, as an industrial waste, is also mainly used for backfill  
Figure 1: Roadway with shotcrete [14; 15]. ing in mines, power generation, road paving, and brickmaking. For instance, [PERSON] et al. summarized the technical framework of coal mining with direct gangue backfilling and gangue grouting as well as filling, and improved the technological system of comprehensive gangue disposal and utilization [26]. [PERSON] et al. conducted triaxial compression tests to verify the feasibility of using gangue to pave road subgrades [27]. Other studies have investigated the effect of a gangue aggregate on basic physical properties, such as the modulus of elasticity and pore structure, of concrete [28; 29].