Study On The Feature Of Pressure Behavior And Top Coal Cavibility On Fully Mechanized Caving Of Extremely Thick Coal In Chenjiagou Coal Mine

Thick coal seam reserves and production accounted for 40% to 46% of the country’s coal reserves and production in China.Economic development and the mining technology is becoming mature, and the level of equipment manufacturing developed, thick seam mining theory and technology has made considerable development. In recent years, with the continuous progress and improvement of fully mechanized caving mining technology improving,mechanized caving mining has become one of the high productivity and efficienc main ways in China’s coal mine system.Shanxi, Shaanxi, Inner Mongolia, Gansu and others commonly exist special thick seam which thickness exceeds 8m, Large Deformation of extraction opening,support crushing and others often occur. Therefore, special thick seam mining technology and research is extremely important.Chenjiagou Coal mining NO.8 area currently mainly is mining layer 5, in which seam thickness is 13.32 ~ 54.49 m, the average thickness of 26 m, coalseam dip angle 3 ° ~ 10 °, average of 6 °. layer 5 is medium hard coal seam, and it uses the low Caving mining method in the nearly horizontal stratification which’s thickness is 11.92 m. At the same time, the structure of coal seam occurrence behave differently: the area in a relatively simple structure-seam partings, the number of dirt band generally are 2 to 5, total thickness is 0.2 ~3.25 m, average thickness is 0.75m; in complex region, the number of dirt band are beyond 20, average number is 0.75 m, total thickness is 0.2 ~ 4.16 m,average thickness is 1.49m;The main part of Dirt band is carbonaceous mudstone, and it includes boom clay, sandy mustone, siltstone and others.The project background is Chenjiagou eight Mine Mining Area First Coal Face 8512, using field measurement, theoretical analysis and numerical simulation methods, it studys fully mechanized coal caving face overlying rock breakage characteristics, the height of two belts, surrounding rock and support’s Force status, pressure distribution of seam with dirt band and top coal caving characteristics, mainly as follows:(1) It analysises the overlying rock breakage characteristics and the height of two belts: using field measurement, theoretical analysis,it get the failure span of the Overlying key stratum; using theoretical analysis,it sum up to the feature of Overlying failure-stone and the evolution of the height of two belts.The height of caving zone is 42.5m, The height of water flowing fractured zone is102.5m.(2) The mechanical model of immediate roof combination of cantileverbeam is established.The reasonable support working resistance is 9528 k N.The data of mining pressure indicates that the model ZF10000/20/32 H of support is reasonable,and that the mechanical model also is correct.(3) Analysising stress field, displacement field, faliure stone field and Force status of support with FLAC2 D,the strata behavior of 8512 Face;The average cycle weighting interval of 8512 Face is 13.3m,the average working resistance is 4789.5k N, the average dynamic load coefficient is 1.2.(4) Gives the ultimate in top coal thickness formula partings at uniform load and linear loads, boom length limit formula, and then get the top Chenjiagou Mine Coal carbonaceous shale partings and broken top coal caving characteristics; the use of numerical simulation software 3DEC get partings layer position to influence top coal caving characteristics, mainly in lower position partings less impact on the top coal caving of risk, while the median partings easy to form class arch structure of top coal caving greatest impact.(5) Giving the problem of poor coal cavibility, The method of blasting top coal is taken in Chen Jiagou mining coal. Blasthole is arranged along the Face direction, The main blasting parameters includes the following: ① Sealing length exceeds 1.0m; ② borehole depth is 6m; ③ weight of each hole is 3.7Kg.