Huge thick conglomerate movement induced by full thick longwall mining huge thick coal seam

International Joumal of Mining Science and Technology 22(2012)399-404Contents lists available at SciVerse Science DirectInternational Journal of Mining Science and TechnologyELSEVIERjournalhomepagewww.eisevier.com/locate/iimstHuge thick conglomerate movement induced by full thick longwall mininghuge thick coal seamMa Liqiang. D, *, Qju Xiaoxiang Dong Tao. b, Zhang Jixiong a Huang Yanlia b"China Yongcheng Cool and Eiectric Power Group Corporation Ltd, Yongcheng 476600. ChinaARTICLEINFOA BSTRACTness of conglomerate layer in a full thick seamReceived 10 October 2011ilable online 22 May 2012next i afer reaching t em axtmum ca eity die to pw aoth the botte of the plaster telinear fit between the height of the plasticHuge thick coal seamSeparationRock bests theccurrence of rock burst induced by face as the major factor in the accident. This research revealsmeeasures to provide a theoretical basis and implementatiD 2012 Published by Elsevier B.V. on behalf of China University of Mining Technologyin the work face [3-5] Jiang et al. proved that the collapse of hugMine collapsing from top todue to owconglomerate. The overlying huge thick coal seam affects the dislo. Jing analyzed the characteristics of fracation of overburden and appearance of the rock burst when the when overburdened conglomerate rock and coal seam are extion of huge thick from Huafeng coal. He pointed that separation of stratum in roofme and abroad. and crevice is the main reason of connection of water betweers examinations focused on the surface subsidence. water-bearing strata and water entering work face[8ittle examination ontivity rhythm. Guo et al. reportYima coal and xinwen coafect of the moving compounds in the basic roof, and中国煤化工 norphology which Is forrock is the main reason for abnormal pressure and stronCNMHgmain determinant fonding author TeL: +86 13645201296the work face and the movement ofE-mail address: ckmadcumt eduan(L Ma)ck promote each other. The extraction2095-2686/s- see front matter o 2012 Published by Elsevier BV. on behalf of China University of Mining Technologyttp //xdoiorg/10.1016/jijmst 2011 1200140L Ma et aL/intemational Journal of Mining Saence and Technology 22(2012)399-404of full-thickness seam is the reason of the movement of stratum right and bottom boundaries are fixed and their top boundariesd thection of thehe lower work face. The laws of motion fthe numerical simulations for both strike modelingstratum under the influence of extraction and theeling measuring 2000 m x 700 m and 1380 mactivity rhythm of huge thick con- tom boundarsesnd displacemeectively, and a dip angle of 12.Weythm of stress distribution under influence of huge thick corwe used Mohr-Coulumb modeling to setharacteristic for the collapse of huge thick conglomermechanics by considering the real mechanics of rock in21and how collap3. 2. Mining method and date processing2. Geological conditions of coal miningAstrike modelited the 21101 and 21121tinitillustrates the face layout of 21 districts in Qianqiu Coal thickness extraction of the huge thick coal seam.in second level is located in the west of 21 mining districts. A4. Strike activity law of huge thick cord ispart. AtIn pace with expansion and advancement ofworkave been completed. The geological construction of 21141 workerage depth of work face is 665 m, the strike length is 1298 m;ining work. The engenders separation with the rock formation which is below thecline length is 130 m and the dip angle is 10-14.Fig 3 shows the maximum separation between two huge thick3. Element modelingspace reaches 300 m, After the exploitationthe perpendicular displacement in the botton3. 1. Model numerical simulation modelingglomerate stratum grow rapidly and theat the collapse of the conglomof mining districts was simulated using dip. Models of the left, There is a caving area which halock"form at theand load from the top soil after separationconglomerate stratum and the next stratum coming into being1121 work faceThe caving area at the bottom of conglomerate rock increasespidly and the boby seam after exploitation space reaching 310 m. The bottom of21161 work facen space advancing to 40 m. Fig, 4 shows growing form21201 work faceThe plastic zone in the huge thick cohe increasing exploitation space. Fig. 5 shows that the relationshipFig. 1. Face Layout of 21 districts in Qianqiu Coal Mine.between the length of the plastic zone and face advancement isYH中国煤化工CNMHGL Ma er al/international Joumal of Mining Sdence and Technol gy 22(2012)3994×10’c05× 1( Epipedon250x02.2x10' Clay25×0 Mudstone2.7×103 Fine stouL002.7x 10 Fine sandstone80×10 Conglomerate3.253.754254.755255756256.75(102Flg. 3. Caving of overlying strata and deformation conditions when the 211413253.75425475525575625(103a)work face advance 300 m5,50Fig 6 shows the changes of vertical displacement in the hugconglomerate stratum from top to bottom during the advanc2.2×103The collapsing of the bottom of thecement at the top of conglomerate rock shows that the top ofhuge thick conglomerate rock presents bending deflection5, Incline activity law for huge thick conglomerate stratum325375425475525575625675(10)(b) Work face advance 310 mwork ae i epi huge thick conglomerate stratum before 211415. 1. Activity lawIn pace with stratum between coal seam and the collapsing hugelomerate stratum after exploitation of the 21101, 21121, 21181132m22×103Cay2.5×103and the length of the separation is about 240 mre comprising of only steadwastes, The coals in the front-endback-end and unexploited 21141, 21161 work faces bear the2.25The maximum vertical and normal stresses in the 21 141 work303540455055606570(10)face before being exploited are 34.98 and 1.85 MPa, respectively.(c) Work face advance 350 m21121 work faces develop upward because of the effect of roof cut- layer on the strilFig. 4. Plastic zone development patterns at the bottom of the thick coronglomerate stratum above 21181 and 21201 work faces is small. Firstly, a large acreage caving of the huge thick conglomerateglomerate stratum above coal which creates gliding revolution of. the separation disappears. Fig 10 shows the distribution of plasticep of the huge thick congoerate stratum above the gob is developing seam by seam and huconglomerate stratum above the exploited work face produces athick conglomerate stratum above coal is breaking and中国煤化工 a sharp seam by seam caving in the52. Law of movement of huge thick conglomerate stratumexploitation of the work faceCNMHGdes of huge thick conglomerate strture is dynamihuge thick conglincreased from 3 to 11. m hugetical displacement of huge thick conglomerate The structure of the huge thick conglomerate stratum is adverse tostratum increased from 1.5 to 2.5 mroof control of the last 21 161 work face in the 21 mining districts.L Me er al/Intemational Joumal of Mining Science and Technology 22(2012)399-404y=0.002x2+2294x-261036R2=0987y1165+82100R2=0.988Fig-5. Plastic zone size and face advancement distance fittingFig. 11 shows changes of vertical stress in the hugetum gathers and acts on surrounding rock of gob area, espe-cially on 21161 workvertical stress in the strata transfers to the bottom of coal inress zone and theient of support stress reaches 2.5 whereas the1.95 MPa. The rock above the gob area on both sides of 21161ne compact, and then the verticalstress recover to form the rock stress, The 21161 work face thene-At yield surfacex-Ytelded in pastcovery zone above the work face because of the plastic deformTensile failuretion and articulation of the block structure in the both sideswork face. The conglomerate stratum from work face 250 m abovFig& Plastic zone distribution of overburden before 21141 coalface mininghis make a impair tegra ata nt hot t nssf that umbehaviors. The adoptedBy Mayratum, which provides necessary condition for productionsafety drive in the 21141 work face and coal producer was 8Mt6. Effect of industry testThe research results play a lea135Mmm图pc50mes selling profton of coal is 286 RMB while the selling profitspreventing impulsion pressure and analyzing the lta achieved 382 million RMB2004006008001000120014001600180020040060080010001200140016001800中国煤化工/=她mCNMHG -Advance / m(a) Bottom of the huge thick conglomerate seam(b)Top of the huge thick conglomerate seamg 6. Thick conglomerate'layer of vertical displacementL Ma et al/Intermational Joumal of Mining Science and Technology 22(2012)399-404x (m)1000120014002515LDsm been exploited21141 working face2040080010002001400(a)Vertical displacemen(b)Horizontal displacementFig 9. Coal and conglomerate layer vertical stress curve of 21141 coalface before and after its mining.(2)The mwork faces advances to 350 m(3) Before the 21141 work face isFig. 10. Plastic zone distrbution of overburden after 21141 coalface mining.(4)The weight of the huge thick conglomerate stratum and theimpact load of the next stratum is the main force source ofrock burs45the huge thick conglomerateAcknowledgmentsis ceal f immediateFinancial support for this work, provided by the National Natu-and Technology Research of the Ministry of Education of China(NO. 306008), are gratefullyReferencesIll Qian MGSPG. Rock pressure and strata controL Xuzhou; Industry Publishingse;2003.8001000120014002 Qian MG, Miao xⅪJeta.Ke[3] Guo w, Kong LH, Chen Sl, et al.Coal and conglomerate layer vertical stress curve.15] Lu GB. Zhu JM. Shi Lw. Research on Huafeng coal mine rock burst, Ground7. Conclusions6] Jiang Fu x Yang SH, Cheng YH, et al A study on microseismic monitoring of(1)There is a cav中国煤化工如m口mmthe bottom of conontrollingCN MHGT sy dy of mechanism of stog water iMech Eng20092822306-1and length of the adEng Group Inc.. Universal distinct element code usersp between height of the plastic zonede. Minneapolis: Insulting Group Inc: 2003.and the advancing length is quadratic function.of voussoir96:557L Ma et aL/fatermarional Faunal af Mining Science and Technalogy 22(2012)399-404Numerical simulation of coal20061c知m201267dmh1cmunder relatively2007:173}301-5H中国煤化工CNMHG