Research On Surrounding Rock Stability Of Gob-side Entry Retaining At Flexible Formwork Fluid Backfilling Mining

Technology of gob-side entry retaining at flexible formwork fluid backfilling minning is used by aeolian sand fluid to fill mined-out area at the same time, by setting the roadway of lateral retaining structure, reserve into the roadway, service for the next working face. It is the part of mining technology without pillar and a major innovation achievements on Chinese coal mining technology, has great technical and economic advantages and worth to promot. Surrounding rock stability research of Gob-side Entry Retaining at flexible formwork fluid backfilling mining is great significance for improving the coal recovery rate and reducing drivage rate of roadway and also inevitable choice for backfilling mining. Taking gob-side entry retaining of fluid backfilling at 2307 in Yuyang coal mine as the background,it based on the theoretical analysis, laboratory test, numerical simulation and other comprehensive research methods and the main conclusions are as follows:(1) Based on the analysis of flexible formwork fluid backfilling mining and procession of gob-side entry retaining, experimental research on the impact of backfilling material components and flexible formwork to physical properties of backfill, the conclusion is that the ratio of fly ash and cement has the greatest effect in strength and elastic modulus of backfill,and mass fraction of fine grained coal gangue has a greater influence on elastic modulus of backfill,at the same time accessories content has a greater influence on the material content on the strength of backfill.(2)Based on the rules of the overlying rock movement of the gob-side entry retaining of fluid backfilling with thick coal seam is that: overburden to entity coal for anchoring,the overlying rock bend sinking slowly, without breaking. The mechanical model of gob-side entry retaining of fluid backfilling is set up and then the analytical solutions of roof subsidence and filling pressure and the subsidence curve of different factors on the roof are obtained respectively. it also obtained the support resistance of bolt under bolting support coal side. At the same time it studies the reasonable width and the effect mechanism of the gateside pack, and determined stability of the control factors to the elastic modulus of filling E0, intensity and the amount owed to meet top U.(3)By 3D numerical modeling of gob-side entry retaining of fluid backfilling and it got stress distribution law of stope and changes of surrounding rock stress and plastic zone with the increase of backfill length. Meanwhile it obtained curve of roadway deformation that impacted by strength of backfill and the rate of supporting pit roof.(4)Combined with 2307 backfill working face at YuYang coal, backfill strength is determined to 4MPa and its Modulus of elasticity is 1.26 GPa for the 28 d and the rate of supporting pit roof is more than 95%, meanwhile, cable anchor supported in mine gateway, so that the stability structure of surrounding rock is well and meet the requirements though on-site monitoring data collation and analysis.