Study On The Key Technologies And Mechanical Model Of Gob-Side Retaining Entry

After deeply analysis of domestic and abroad coal mining technology development and related experience, especially those of China in the recent decade, combined with coal mining safety production and environment control in China, non-pillar mining was brought up to change the traditional concept of using the coal pillar to protect roadway and control the surface subsidence. The urgent task now is to innovate the relevant theories by the "Practical mine ground pressure control theory".According to the non-pillar mining, based on the "Practical mine ground pressure control theory", the key technologies and basic engineering principles of gob-side retaining entry has been studied through the combination of various ways, of which are theoretical research, simulation, and comprehensive analysis.(1) The mechanical model formulation and its development rules were studied. According to the "arch structure theory", the spatial morphology of mining stope was divided into "fracture arch" which directly influences the ground pressure manifestation and "stress arch" which does not clearly influence the ground pressure manifestation; four types of "stress arch" morphology were discussed, the influencing factors'effect degree of the spatial morphology of mining stope were determined; the abutment pressure and different strata structure's evolutional laws were analysed, the abutment pressure evolutional characteristics were divided.(2) The mechanics properties of different hardness coal mass under the action of abutment pressure were analyzed; the coal particle density distribution and evolution equation of space scale were established; the abutment pressure distribution range equations with different face forward distance was fixed; the criterion to judge "interior stress field" range whether or not it extends was established.(3) The goaf overburden strata's dynamic laws was studied. Based on the study on gangue characteristics and time dependence during the compression process, the gangue stress-strain curve and bulk factor were analysed; the mining stope stability condition was predicted by Lyapunov index, the relationship between "arch structure" and mining stope's stability was confirmed.(4) The "backfilling the goaf-side entry by presetting distortion technology" which is a new non-pillar mining technology was raised. Based on the study on accidents causes, the mechanical model of surrounding rock structure was built; two types of structure mechanical model which are "given-deformation" and "limit-deformation" and their mechanics parameters were studied;a new type of full grouted prestressed anchor was devised, also its anchor mechanism was studied and analysed.