## 4 The Proposal and Application of Primary Strong Active Support
### The Proposal of Roadway Support Technology
Specifically, the left side under the support of steel welded mesh enters the constant creep stage after 70 days of deceleration creep, whereas the diamond metal mesh experiences accelerated creep after 90 days of roadway excavation. These observations indicate that the steel welded mesh, with its higher stiffness and larger support parameters, is beneficial in controlling the overall deformation of the roadway and suppressing the occurrence of accelerated creep. According to the aforementioned research, the appropriate parameters were selected based on the parameter selection principle of high pre-tightening force and high stiffness protection surface construction. These parameters were used to simulate the control effect of the primary strong active support technology on the creep effect of a soft coal roadway using UDEC software. The parameters involved in the technical scheme include a bolt length of 2600 mm, a pre-tightening force of 60 kN, a spacing of 800 mm, an anchor cable length of 3500 mm/8000 mm, a pre-tightening force of 120 kN, a spacing of 1600 mm, and the selection of Q235 steel mesh for the anchor net with an elastic modulus of 210 GPa, a Poisson's ratio of 0.25, and a diameter of 4 mm. For the remaining parameters used in the simulation, please consult Table 6. Figure 12 depicts the deformation characteristics of the surrounding rock of the roadway under the condition of strong primary active support. Figure 13, on the other hand, presents the cloud diagram of the surrounding rock fracture field over time under the primary strong active support. Figure 12: Deformation characteristics of roadway surrounding rock under primary strong active support: (**a**) Roadway surface deformation; (**b**) Variation curve of the number of surrounding rock cracks. From the deformation characteristics of the roadway surrounding rock under primary strong support and the cloud diagram depicting the changing crack field over time, the following observations can be made:  
1. The distribution range and density of cracks in the surrounding rock decrease under strong primary active support. For example, after 120 days of roadway excavation, there are fewer tensile cracks on the right side of the roadway compared to the left side. The development range of shear cracks on both sides is approximately 2.4 m, which is 57.1% lower than the original support. The number of tensile and shear cracks in the surrounding rock is 399 and 30,494, respectively, representing a reduction of 91.4% and 57% compared to the shed cable support. 2. The rate of fracture development decreases with strong primary active support. This is because strong primary active support increases the confining pressure strength of the roadway and improves the yield strength of the roadway, thereby reducing the occurrence of accelerated creep. The strong primary active support effectively controls the creep of the roadway during the steady-state creep stage. Compared to the roadway supported by shed cables during the same period, the overall rate of fracture development is reduced. 3. The deformation of the surrounding rock decreases under strong primary active support. The overall deformation of the roadway becomes more balanced, and the deformation rate gradually decreases. During the simulated 120 days of roadway excavation, the maximum deformation of 250 mm occurs at the floor position. This is significantly lower compared to the maximum floor heave of 2155 mm under shed cable support. The control effect on the roadway is highly significant, and the deformation in other parts of the roadway under primary strong active support is also lower compared to the original support. In summary, strong primary active support proves to be effective in inhibiting the development and expansion of cracks in the surrounding rock of soft coal roadways, particularly in suppressing the growth of tensile cracks.