###### Abstract  
The mining of the part of the inclined one body below a goal is crucial for improving resource extraction and safe production. In this study, the cementation properties of crushed stone during the mining of the inclined ore body were investigated by means of laboratory experiments, theoretical analysis, and numerical simulation. Additionally, orthogonal experiments were performed to assess how factors like water-cement ratio, crushed-stone particle size, and cement-sand ratio affect the strength of the growing concretion body (GCB). Furthermore, the fluidity of the slurry under different ratios was also measured. Considering both the fluidity of the slurry and the strength of the GCB, the optimal ratios of the slurry were determined to be a water-cement ratio of 2.5:1 and a cement-sand ratio of 1:4. This ratio was then used for crushed-stone cementing under the poorest crushed-stone particle size conditions, based on which mechanical parameters were obtained from experiments. Theoretical analysis equated the problem of the grouting range to the width of the plastic zone of surrounding rock, and a conclusion was reached that the width of the GCB should be at least 29 m. The numerical simulation results reveal that among 30 mining rooms formed below the GCB, 24 mining rooms are in a stable state and 6 mining rooms are partially damaged on a small scale. As a whole, the GCB formed by grout filling into the goaf manages to effectively support the stope below, and it is verified that the theoretical calculation method of the width of the GCB is feasible. goaf; grouting concretion body; stope stability analysis; orthogonal experiment; numerical simulation +
Footnote †: journal: Medical  
When the ore body is located directly below the goaf, this method contributes to forming a false roof for the mining of the ore body. Such a false roof can support the load from the overlying rock and meanwhile prevent crushed stone from entering into the mining space, thus ensuring the safety of workers below [4; 5; 6; 7]. In the case where structures are built above the goaf, this method can effectively fill voids within the goaf and enhance the deformation resistance of crushed stone, thereby reducing the residual surface deformation and protecting the structures on the surface [8; 9; 10; 11]. The strength of the GCB is directly related to the effect of engineering application. Scholars have extensively researched this topic for the purpose of solving problems such as the strength design of the GCB, the ratio and optimization of grouting materials, and the reduction of costs. Since different working conditions pose varying requirements for the strength of the GCB, the design of the strength of the GCB should incorporate the actual working conditions. [PERSON] [12] proposed an empirical formula for designing half-cubic parabolic strength based on the statistical analysis on strength design values and filling heights from 31 mines all over the world. [PERSON] et al. [13] analyzed the target strengths of the filling body in three stress states (supporting surrounding rock, laterally exposed while self-supporting, and supporting equipment), compared the vertical stress reduction ratios of the filling body before and after the introduction of the arch effect, and proposed that the transformation of the vertical stress brought by the arch effect should be taken into account in the design of the target strength of a narrow and long GCB. After determining the target strength of the GCB, another critical point is to achieve the required strength in engineering. Some scholars have successfully improved the mechanical properties of the GCB by changing the cementing materials and ratios [10; 14; 15; 16]. Other scholars have effectively enhanced the strength of the GCB by adding fiber materials into the slurry [17; 18; 19]. Meanwhile, the costs should be considered on the premise of satisfying the requirement for the strength of the GCB.