## 5 Conclusions  
1. According to the three-stage creep characteristics observed in the deformation of the 11,050 roadways, the CVISC model, which is capable of describing such characteristics, was chosen. Considering the small size, granular nature, and low strength of soft coal, the Coulomb slip unbonded contact joint model was selected. A creep model for soft coal is constructed in UDEC software, and the creep parameters are determined using the least squares method. The triaxial creep characteristics of soft coal are then studied. The results indicate that higher confining pressures lead to lower amounts of creep and lower creep rates in coal. This implies that the initial strength of accelerated creep in coal increases under higher confining pressures.
2. The uniaxial creep crack propagation law of soft coal specimens was determined using the FISH language. During the decay and steady creep stages, the number of cracks increased gradually, with shear cracks being predominant. An important characteristic of soft coal specimens entering the accelerated creep stage is the rapid increase in tensile cracks. Increasing the confining pressure is beneficial for reducing the number and growth rate of tensile cracks in coal, thus avoiding the occurrence of unsteady creep.
3. The creep deformation of coal particles in the surrounding rock of a soft coal roadway, along with the development of meso-cracks between particles and changes in stress state after roadway excavation, contribute to the overall creep failure of the roadway. The low confining pressure provided by the shed cable support results in a continuous increase in the number of cracks in the coal body over time. Furthermore, the inhibitory effect of the support on surrounding rock cracks weakens over time, revealing the underlying mechanism of creep instability in the return air roadway of the 11,000 working faces.
4. According to the characteristics of creep instability in soft coal roadways, a corresponding support principle is proposed. The principle suggests employing high pre-tightening force anchor cable support to enhance the surface and internal confining pressure of the roadway, increase the initial strength of accelerated creep in coal, improve the integrity of the soft coal roadway, enhance the strength of the near-surface surrounding rock, and control the surface deformation of the roadway. Considering the asymmetric deformation of the surrounding rock in the roadway, it is essential to address \"structural compensation\" in specific key areas such as the shoulder socket and bottom angle. This involves dealing with the deformation asymmetry in these areas and inhibiting the development and expansion of tensile and shear cracks at the junction of the roadway floor and the two sides of the coal rock.
5. The primary strong active support technology, comprising high pre-tightening force high-strength bolts and anchor cables, along with a cooperative protection surface using steel mesh and plastic mesh, is proposed for the return airway of the 11,000 working faces. The selection principle of support parameters is clearly defined, and an industrial test is conducted to evaluate its effectiveness. The results demonstrate a remarkable control effect on the roadway, confirming the success of this proposed support technology.  
Conceptualization, F.W.; Methodology, F.W., H.L. and X.Y.; Software, J.Z., P.Y., H.L. and X.Y.; Validation, F.W., H.G., C.L., P.Y. and H.L.; Formal analysis, F.W., J.Z., P.Y. and H.L.; Investigation, C.L. and Y.L.; Resources, C.L.; Writing--original draft, H.G. and J.Z.; Writing--review & editing, H.G.; Visualization, X.C., M.W., Y.J., Y.C. and S.L.; Supervision, X.C., M.W., Y.J., P.W., H.Z. and Z.G.; Project administration, X.C., M.W., Y.J. and P.W. All authors have read and agreed to the published version of the manuscript.  
The work was supported by the National Natural Science Foundation of China (No. 52174138). The authors gratefully acknowledge the financial support of the agencies mentioned above.  
Not applicable.