Research on supporting mechanism and application of new ductile thin spraying technology in coal mine roadway

The safety and stability of the roadway is the fundamental guarantee for safe, green, high-yield and efficient production in coal mines, and the surface support of the roadway surrounding rock is crucial for the stability and effectiveness of the entire roadway support system. However, currently most coal mines use traditional shotcrete technology for surface protection, which has disadvantages such as poor ductileness, easy detachment and cracking, high transportation and labor costs, environmental pollution and high rebound; Only a few mines have adopted the new ductile thin spraying technology, but the support mechanism, applicable conditions, and application effects are still unclear and in the stage of engineering experience. This article first provides a detailed theoretical analysis of the support mechanism of ductile thin spray coatings, including surface protection and cooperative support. Secondly, numerical simulations and comparative analysis were conducted using finite difference software FLAC3D and discrete element software 3DEC to study the effectiveness of new ductile thin spray materials and traditional sprayed concrete materials in roadway support. The simulation results show that ductile thin spray materials are more conducive to improving the stress environment of shallow rock layers in roadway surrounding rock, enhancing the bearing capacity of roadway surrounding rock itself, suppressing the displacement and sliding of loose rock blocks between anchor rods, optimizing the stress state of the entire support system, and greatly ensuring the stability of the roadway support system. They are particularly suitable for application in two types of coal rock roadways: "poor quality+medium hard rock/hard rock" and "general quality+soft rock/medium hard rock". Finally, the new ductile thin spraying technology was industrially tested in the bottom extraction roadway of Changping Coal Mine. The on-site measurement results showed that the technology effectively controlled the overall deformation of the roadway surrounding rock, improved the stress state of the roadway support components, and had good application effects. The research results of this article have good reference and guidance significance for the understanding of the importance of roadway surrounding rock surface support and the promotion and application of new ductile thin spraying technology.