Drawing mechanisms for top coal in longwall top coal caving(LTCC):A review of two decades of literature

作     者：Jiachen Wang Shengli Yang Weijie Wei Jinwang Zhang Zhengyang Song Jiachen Wang;Shengli Yang;Weijie Wei;Jinwang Zhang;Zhengyang Song

作者机构：School of Energy and Mining EngineeringChina University of Mining and Technology-BeijingBeijing 100083China Department of Civil EngineeringSchool of Civil and Resource EngineeringUniversity of Science and Technology BeijingBeijing 100083China Coal Industry Engineering Research Center of Top-coal Caving MiningBeijing 100083China 

出 版 物：《International Journal of Coal Science & Technology》 (国际煤炭科学技术学报（英文）)

年 卷 期：2021年第8卷第6期

页      面：1171-1196页

核心收录：

学科分类：081901[工学-采矿工程] 0819[工学-矿业工程] 08[工学] 

基　　金：This work is funded by the National Natural Science Foundation of China(Grant No.51934008,51674264 to Jiachen Wang,Grant No.51974320 to Shengli Yang) Fundamental Research Funds for the Central Universities(Grant No.06500182 to Zhengyang Song) Funds from State Key Laboratory of Coal Resources in Western China(SKLCRKF20-07 to Zhengyang Song) 

主　　题：Longwall top coal caving(LTCC) Top coal drawing Top coal drawbody(TCD) Top coal boundary(TCB) Top coal recovery ratio(TCRR) 

摘      要：This review details the state of the art in research on top coal drawing mechanisms in Longwall top coal caving(LTCC)by examining the relevant literature over the last two *** startswith an introduction of the brief history and basic procedures of *** framework of research on the drawing mechanism,basic concepts,and some theoretical models of LTCC are detailed in *** framework of top coal *** authors note that theTop coal drawbody(TCD),Top coal boundary(TCB)and Top coal recovery ratio(TCRR)are key factors in the ***-boundary-ratio(BBR)research system has been the classic framework for research over the last 20 *** modified Bergmark-Roos model,which considers the effects of the supporting rear canopy,flowing velocity of top coal,and its shape factor,is optimal for characterizing the TCD.A 3Dmodel to describe the TCB that considers the thicknesses of the coal seam and roof strata is *** *** testing and numerical simulation,the physical tests and numerical simulations in the literature are classified for ease of bibliographical review,and classic conclusions regarding the drawing mechanism of top coal are presented and discussedwith elaborate illustrations and *** deflection of the TCDis noted,and is caused by the shape of the rear *** inclined coal seam always induces a largerTCD,and a deflection in theTCDhas also been observed in *** effects of the drawing sequence and drawing interval on the TCRR are reviewed,where a long drawing interval is found to lead to significant loss of top *** flowing behavior and velocity distribution are also *** applications of drawingmechanisms forLTCCmines 4 summarizes over 10 cases where the TCRRof LTCCmines improved due to the guidance of the drawing *** final section provides a summary of the work here and some open *** investigations are highlighted to give researchers guid