Deformation and fracture behavior of strong-weak coupling structure and its application in coal roadway instability prevention

The theoretical work, experiments, and practical application in the field are carried out to investigate the performance of strong-weak coupling structure. Results indicate that the deformation in the weak zone is greater than that in the strong zone before the peak stress. Moreover, the weak zone is crushed while the strong zone remains intact after the peak stress. Hence, the coupling structure could protect the strong zone from damage. Furthermore, the strong-weak coupling structure can effectively transfer the peak stress to the further area from coal roadway and improve the ability of the coal roadway surrounding rock to resist deformation. Finally, in the field tests, the strong-weak structure can significantly improve the stability of coal roadway. It shows that the average subsidence of the roadway roof and the accumulated deformation on the sides of the coal roadway in the strong-weak coupling zone were 55.21% and 61.42% lesser than those in the weak zone, respectively.