## 3 Full Anchor Cable Support Mechanism for the Immediate Roof of a Thick Soft Rock Mass Roadway
### Supporting Effect Numerical Simulation Analysis
#### 3.2.1 Numerical Simulation Calculation Model  
(1) Model  
The numerical model was established with the No. 3606 panel of Chaili Coal Mine as the background. The model's overall length, width, and height were 200 m, 200 m, and 59 m, respectively. The model had a total of 546,480 blocks and 574,912 nodes. The simulation used brick elements to construct the model. The model, from top to bottom, included medium sandstone (36.8 m), sandy mudstone (2.7 m), mudstone (0.5 m), coal seam (9.5 m), sandy mudstone (3.0 m), and medium sandstone (6.5 m). The dip angle of each rock layer was 0\({}^{\circ}\). The working face was parallel to the \(x\)-axis direction and advanced along the \(y\)-axis direction. [PERSON] used TENSO software ([[https://www.tensosoftware.com/](https://www.tensosoftware.com/)]([https://www.tensosoftware.com/](https://www.tensosoftware.com/)), accessed on 10 April 2023), which includes modules for simulating finite element cable and beam models [25; 26].The structural element of cables was used to construct the bolt and cable system. The structural element of cables in FLAC3D was used to construct the bolt and cable system in this paper. The numerical calculation model is shown in Figure 4.  
This numerical simulation was computed using the Mohr-Coulomb constitutive model. The mechanical parameters of the simulated coal-rock layer were determined based on the geological report of the No. 3606 panel and coal-rock mechanics tests. The mechanical parameters of coal and rock are shown in Table 1. The boundary conditions of the model were as follows: the upper part of the model in the z direction was a free surface, and a vertical load was applied to simulate the self-weight load of the overlying  
Figure 4: Numerical calculation model. strata. The bottom of the model in the z direction was limited in vertical displacement, while the horizontal displacement in both sides of the model was constrained. In order to eliminate the boundary effect, the distance between the roadway and the boundary was set to 50 m. The model was buried 60 m deep, and the average bulk density of the overlying rock was 26 KN/m\({}^{3}\). Therefore, an equivalent load of 1.56 MPa needed to be applied to the top of the model, and a lateral pressure coefficient of 0.5 was taken, i.e., a horizontal stress of 0.78 MPa was applied in the x and y directions of the model. To ensure that the most realistic results were obtained, the numerical simulation was carried out in the sequence of working face preparation and recovery. First, the stress state of the original rock was simulated, and the displacement was reset to zero after the simulation. Then, the excavation of the roadway was simulated, and the bolts or anchor cables were installed after the roadway was excavated. The solution was then performed. Finally, the excavation of the working face was simulated. The working face was excavated starting from the cutting hole, 10 m at a time, and the solution was performed after each excavation. The simulation ended after a total excavation of 80 m along the working face. After the simulation, the surrounding rock stress, displacement, and plastic zone of the two simulations were studied, and the support effects of the two schemes were compared. (2) Simulation program  
To verify whether the roof full anchor cable support method has a better support effect, it was compared with the roof bolt-anchor cable support method. In order to ensure that the support parameters of the roadway are realistic, the support parameters of the roof and two ribs were designed by referencing the mining roadway support scheme adjacent to the 3606 track roadway. To ensure a fair comparison, the specifications of the anchor rods and anchor cables were kept the same for both schemes, and the spacing, row spacing, and preload applied by the anchor cables were also kept the same. To meet the aforementioned requirements, the combined roof bolt-anchor cable support scheme (Figure 5A) and the roof full anchor cable support scheme (Figure 5B) were designed.