Study On Gob Retaining Technology Of Soft Bottom Of Thick Coal Seam In Fully-mechanized Caving Face Of GuCheng Coal Mine

Current along the empty left lane is the chief object of full-mechanized caving mining face roadway,along the bottom for loose and broken of coal seam,supporting hard top-coal face,to achieve full mining,along the top left lane is required,the surrounding rock control for the soft bottom along the problem is one of the bottlenecks restricting the coal recovery rate,so the need for thick coal seam of full-mechanized caving mining face soft bottom left lane technology research,guarantee for success.Taking N1303 gob-side entry retention in Gucheng Coal Mine as the background,this paper makes a systematic study on the surrounding rock control technology of gob-side entry retention at soft bottom of thick coal seam in fully mechanized caving face by comprehensively applying the methods of field investigation,laboratory experiment,mechanical model,mathematical calculation,numerical simulation and industrial application.The main research results are as follows:(1)The deformation and failure characteristics of gob-side entrapment at soft bottom of thick coal seam in Gucheng Coal Mine are investigated,the structure of surrounding rock and the mechanical properties of coal and rock are analyzed,and the law of mine pressure in working face is summarized.(2)The mechanical model of the interaction between the filling body and the roof and the stability of the filling body was established,the calculation formula of the normal stress of the cross section of the filling body was given,and the factors affecting the stability of the filling body was analyzed.According to the influence of the basic roof breaking position on the filling body,the feasibility criterion of retaining the roadway along the gob was given.The law of floor heave deformation in goaf entry was analyzed and the theoretical calculation formula of floor heave was deduced.(3)A numerical calculation model is established to simulate the backfill parameters(backfill strength and backfill width)of gob-side entry retention,and the reasonable entry retention parameters are determined by the stress transfer,surface displacement and plastic zone distribution law of the roadway.(4)Analyzed the thick seam soft bottom of full-mechanized caving mining face along the roof,coal for help,filling,the deformation and failure of reason,put forward the "top,limited help,let the bottom" of the roadway surrounding rock deformation control principle,according to the special conditions of coal floor is loose bottom,put forward the reinforcement scheme and advanced casting mould filling body itself base of bottom control scheme.(5)The above research results have been applied to goaf entry retention in Gucheng Coal Mine N1303,and the monitoring results show that the deformation control effect of surrounding rock is good.The paper has 88 pictures,21 tables,and 80 references.