| At present,coal resources in many major coal-producing areas in China have also begun to enter deep development,and the dynamic pressure display of ultra-thick coal seam face is particularly obvious.At present,the problem of dynamic pressure display can be effectively solved mainly by small coal pillar roadway protection technology.But the extra thick coal seam has certain particularity and there are many problems in the research of its support technology.In this paper,by means of indoor test and theoretical analysis,numerical simulation,and other research methods,analysis of working face mining process,the different coal pillar width and surrounding rock stress and roadway displacement variation characteristics,such as to determine the reasonable width of coal pillar,further gives special thick seam pressure support scheme of roadway of fully mechanized working face and the pressure relief measures,the industrial test was carried on.The main research results of this paper are as follows:(1)Through field investigation and laboratory test,the failure characteristics of roadway surrounding rock roof structure and mechanical parameters of coal and rock were studied,which provided a basis for simulating dynamic pressure roadway support design of extra-thick coal seam.(2)Theoretical analysis of special thick seam fully mechanized working face structure characteristics of surrounding rock stability of coal pillar and section concrete performance,combined with masonry beam theory,the key strata theory,obtains 39204 strata of full-mechanized caving mining face is brokeback symmetric structure of "T" type,and in two side goaf under the influence of key strata fracture,mining dynamic pressure appear obvious,stress concentration factor is higher.The influence factors of coal pillar stability are analyzed,and the principle of coal pillar determination is given.The width range of coal pillar is 5～10m according to various theoretical calculations.(3)FLAC3D numerical simulation was used to study the distribution of surrounding rock stress,displacement and plastic zone during the mining process when the coal pillar size varied from 5m to 10 m.Finally,the reasonable size of coal pillar is determined to be 7m,which can ensure that the internal stress of coal pillar is close to the original rock stress and improve the stability of roadway.(4)Combined with the supporting theory of bolt and cable and the results of numerical simulation,the roof classification supporting principle is put forward,and the supporting scheme of small coal pillar roadway in extra-thick coal seam is given according to the supporting principle,and the reasonable pressure relief scheme of drilling hole is determined.(5)The industrial test of the above research results shows that the roadway has good stability and no obvious large deformation damage,which can fully ensure that the roadway keeps good safety during mining.There are 83 figures,15 tables and 84 references in this thesis. |
