## 4 High Strength Prestressed Anchor Cable Truss Support System
### Truss Anchor Cable Numerical Simulation and Support Scheme  
(1) Model building  
The length of the anchor cable is set at 9.4 m. The inclined part of the anchor cable is set to 8 m, and the horizontal part is set to 2.1 m. The preload force on the anchor cable is set to 200 kN. We are simulating the upper boundary stress of the 1409 airway by excavating the model. The roadway has a width of 4.2 m and a height of 2.8 m. The model consists of 15 layers of rock strata arranged from top to bottom. We will be using the Mohr-Coulomb intrinsic structure model and assigning material characteristics to each rock layer. The initial equilibrium will be calculated using the numerical model. The numerical model of the roadway support structure is shown in Figure 15.  
Figure 14: Schematic diagram of neutral axis moving. Figure 15: Numerical model of roadway support structure. (**a**) Model dimensions and boundary conditions (**b**) Support structure model. Analysis of the anchor cable pre-stress field  
Characteristics of prestress distribution of HSCTS support system and ordinary anchor cable are shown in Figure 16. Based on the simulation results, the truss prestressing anchor system in the top slab's rock layer produced a larger prestressing belt. The prestressing value gradually decreases from the center to the outside, forming a ring structure with left and right symmetry. This structure ensures the stability of the support in the deep rock layer of the top slab and reduces deformation caused by tensile stress. In the direction of the roadway, a strong prestressing layer is formed in the middle of the roof plate due to the connections between each prestressing zone. The prestressing zone is formed by the single-ring structure of the monolithic anchor cable. However, due to the formation of a narrow prestress belt, there is almost no prestress in the deep roof rock on both sides, resulting in high stress on the composite roof roadway. This makes the top plate susceptible to significant off-layer deformation and even sudden roof collapse. (3) Simulation of the support scheme analysis  
Through numerical simulations, we conducted a comparative analysis between the traditional anchor cable support system and the HSCTS support system. The purpose of the analysis was to understand the stress distribution characteristics of the surrounding rock in the roadway, the expansion characteristics of the plastic zone, the stress state of the anchor cables, and the deformation patterns of the surrounding rock. Based on the analysis of Figure 17a,b, we observed that regardless of the type of support system, the deformation of the surrounding rock gradually decreases as the roadway depth increases. However, the HSCTS support system showed a more uniform  
Figure 16: Characteristics of prestress distribution of HSCTS support system and ordinary anchor cable. (a) Roof with a single, massive anchor cable; (b) Support structure for the HSCTS support system. and symmetrical stress distribution in the roof and floor rock layers compared to the conventional support system. This suggests that the HSCTS support system has a significant impact on the stress distribution in the excavated roadway, resulting in symmetric and evenly distributed stress without concentration, which is beneficial for ensuring the stability of the surrounding rock. Figure 17: Comparative effect of simulation of support scheme. (**a**) Simulation effect of ordinary anchor cable support scheme; (**b**) Simulated effect of HSCTS support scheme. Moreover, after implementing the HSCTS support system with dual-anchor truss support for the roof, we observed a more uniform stress distribution as a whole. The deformation of the roof was significantly reduced under the combined action of the HSCTS support system, achieving overall control of the surrounding rock in the roadway.