## 5 Simulation of Synergistic Support Effect of Bolt-Cable Support
### Supporting Effect Simulation Results and Analysis
In summary, through numerical simulation analysis, it can be concluded that the optimal spacing of anchor bolts in the roof of 1331 (1) track roadway in Zhuijdong Mine should be 800 mm and the length should be 2800 mm. (2) Optimization of bolt spacing and length on both sides of the roadway  
When the length of bolt on both sides of the roadway is 2400 mm, the distribution of the horizontal stress field of the surrounding rock with different spacings is shown in Figure 11.  
Figure 10: Stress-field diagram of roof bolt at 2900 mm. When the length of bolt on both sides of the roadway is 2500 mm, the distribution of the horizontal stress field of the surrounding rock with different spacings is shown in Figure 12.  
When the length of bolt on both sides of the roadway is 2600 mm, the distribution of the horizontal stress field of the surrounding rock with different spacings is shown in Figure 13.  
As can be seen from the above figures, when both sides of the roadway are supported only, without the influence of ground stress, the distribution characteristics of stress field formed by the anchor bolt on both sides of the roadway are similar to those of anchor bolt in the roof. The prestress diffuses from both sides of the roadway to the surrounding rock, forming a crescent-shaped stress zone. As the stress on both sides of the crescent gradually decreases until it approaches zero, a stress superposition zone is formed at the side of the anchor bolt, providing effective support for the surrounding rock of the roadway. Figure 11: Stress-field diagram of side bolt at 2400 mm. Figure 12: Stress-field diagram of side bolt at 2500 mm. Under the same length of anchor bolts, the effective compressive stress area formed by the superposition of anchor bolts decreases as the spacing of the anchor bolts increases. The reduced position of the superimposed stress area starts from the heads of adjacent anchor rods and diffuses to both sides, resulting in the anchor bolts being unable to form an effective support compressive stress field when the spacing of the anchor bolts is too large. When the spacing is expanded to 900 mm, the compressive stress between two adjacent anchor bolts is small, and an effective stress bearing area cannot be formed, resulting in a significant reduction in the active support effect of the anchor bolts. It can be concluded that the spacing of the anchor bolts on both sides of the roadway should be less than 900 mm. When the spacing is 800 mm, the number of anchor bolts is less than that of 700 mm, but the difference in effective compressive stress formed by the spacing of 700 mm is not large. Based on the above analysis, the reasonable spacing of anchor bolts on both sides of the roadway is 800 mm. Under the same spacing of anchor bolts, as the length of the anchor bolts increases, the area of the bearing compressive stress area formed by the anchor bolts will also increase, but the degree of stress diffusion will decrease with the increase in the diffusion distance. When the length of the anchor bolt is too large, the compressive stress at the head of the anchor bolts is too small, and the stress distribution is discontinuous, which affects the support effect. The stress distribution characteristics of the roof and both sides of the roadway are similar. In order to ensure that the stress can be fully diffused and that the compressive stress distribution will not separate at the head of the anchor rod, the length of anchor bolts is 2500 mm. Effective stress superposition can form a greater bearing effect, so that a larger area of surrounding rock in the sides can be actively supported. Therefore, the reasonable length of the anchor bolts on both sides of the roadway is 2500 mm. In summary, as the length of the anchor bolts increases, the additional stress-field area will also increase, and the stress diffusion effect will decrease with the increase in the diffusion distance.