Study On The Stability And Grouting Reinforcement Of The Gob-side Entry Retaining With Solid Backfilling

The technology of gangue solid backfilling with mechanized gob-side entry retaining is an important development direction of green mining technology in coal.However,the technology of gob-side entry retaining still has problems such as the mismatch between the mechanical properties of the roadway support and the surrounding rock,and the unclear influence mechanism of the gangue material grouting reinforcement,which leads to high blindness and excessive reliance on experience in the process of gob-side entry retaining.It restricts the application and development of the technology of gob-side entry retaining.In order to deeply study the stability of the roadway support under the stress of the surrounding rock,that the structural characteristics on the roof of gob-side entry retaining under different filling rates,the influencing factors of the stability of the roadway support body,the compaction characteristics of the gangue roadway filling material and the mechanical response under tamping,the influence of the grouting diffusion model of the gangue roadway filling material and the mechanical properties of the cement coal gangue cement body factor was systematically studied by laboratory tests,theoretical analysis,numerical simulation and physical simulation.In order to achieve the purpose of reducing the cost of roadway retention under the premise of ensuring the stability of the roadway support body,it provides guidance for realizing the optimal economic benefits of filling and mining mechanized roadway retention along the goaf.Through the above research,the following results have been achieved:(1)By analyzing the change characteristics of the structure of the overlying rock under different filling rates,the stability model of the roadway support body under the combined action of the roof load and the side pressure of the goaf filling body was established,the relationship between the stability of roadway side support body and the material characteristics of roadway side support was revealed.Determined to improve the stability of the roadway support body by improving the mechanical properties of the roadway support body aggregate and grouting reinforcement to increase the cohesion of the roadway support body.(2)Using a combination of laboratory tests and discrete element simulations,the optimal particle size gradation of the gangue roadway material,namely the Talbol coefficient,is determined to be 0.4.The meso-compaction characteristics of the gangue material with the best particle size gradation were studied and analyzed,and the relationship between the evolution of the meso-force chain structure and the macro-strain response were established.(3)Using the self-designed roadway retention ramming simulation test bench and discrete element software,the lateral compaction characteristics of the support body beside the gangue roadway were studied.and the thrust of the thrust plate and the grouting of the roadway retention at different pressing speeds and unloading steps,The lateral pressure on the side plate,the force state of the gangue particles and the change law of the porosity were obtained.(4)The correctness of the theoretical model was verified by establishing a theoretical model of the two-dimensional penetration grouting diffusion of cement slurry in the support material next to the gangue road,and using the independently developed two-dimensional visual grouting system to test.In addition,the Fluent software was used to simulate the grouting process of the support body in the goaf,and the influence of the spacing of different grouting holes on the degree of grout density were obtained.(5)By the test of mechanical aging characteristics of cement gangue cementation body,the influence of water-cement ratio,coal gangue porosity and curing age on the uniaxial compressive strength,elastic modulus and post-peak load-bearing capacity of cement coal gangue cement were obtained.