Roof stability analyses of “water-preserved and water-stored” coal mining with constructional backfill mining
DU Xianjie1,2 ,FENG Guorui1,2 ,QI Tingye1,2 ,GUO Yuxia1,2 ,WANG Zehua1,2 , ZHANG Yujiang1,2 ,LI Zhen1,2 ,BAI Jinwen1,2
在结构充填开采基本思想的指导下,根据我国西北干旱半干旱地区保水采煤与矿区水资源安全高效存储的实际需求,充分发挥条带式结构充填保护含水层结构与煤矿地下空间再利用的优势,提出条带式结构充填“保水-储水”采煤构想。在分析了条带式结构充填覆岩结构特征基础上,采用弹性地基上的有限长梁模型对“充填条带-直接顶”整体结构进行了力学分析,并结合初始参数法分段解析了直接顶变形方程。同时根据“保水-储水”的功能要求,提出了条带式结构充填“保水-储水”采煤的直接顶控制原则。根据新阳矿区工程地质条件和充填材料性能,通过理论计算得到条带式结构充填的临界充填率为51%,最大充填间距为11.46m。通过FLAC3D数值模拟对新阳矿区条带式结构充填“保水-储水”方案进行了优化设计,结果表明:在保持充填率基本不变的情况下,随着充填间距的减小,直接顶自承载能力逐渐增强,可形成“充填条带-直接顶”结构控制体系,对上覆岩层的控制作用明显提升;充填间距的减小缓解了充填体和直接顶内的应力集中现象,显著减小了充填条带和直接顶内的塑性区范围,有利于充填条带和直接顶的长期稳定,进而实现条带式结构充填“保水-储水”的目的;综合分析得到了新阳矿区条带式结构充填“保水-储水”采煤的最佳充填方案为间隔2m充填2m。
In view of the demand of the water-preserved coal mining and the safe and efficient storage of water resource in arid and semi-arid areas of northwest China,in order to give full play to the advantages of strip constructional back- fill to protect aquifer structure and to reuse underground space in coal mines,the technical conception of “ water-pre- served and water-stored” coal mining with strip constructional backfill is put forward under the guidance of the basic i- dea of constructional backfill mining. Based on the analysis of structural characteristics of overlying strata with strip constructional backfill,the finite length beam model on elastic foundation is used to analyze the “constructional strip- immediate roof” structure,and the deformation equation of immediate roof is piecewise analyzed by combining the ini- tial parameter method. At the same time,the immediate roof control principle of strip constructional backfill is put for- ward according to the functional requirements of “water-preserved and water-stored” coal mining. According to the en- gineering geological conditions of Xinyang mining area and the properties of backfill materials,the critical backfill rate and maximum backfill spacing of strip constructional backfill obtained by theoretical calculation are 51% and 11. 95 m respectively. The backfill scheme of Xinyang mine is optimized through FLAC3D numerical simulation. The results show that when the back rate changes little,with the decrease of backfill space,the self-bearing capacity of the immediate roof gradually increases,a “ constructional strip-immediate roof” structure control system is forming,and the control effect of immediate roof on overlying strata is improved significantly. The decrease of the backfill spacing relieves the stress concentration phenomenon in the backfill strip and immediate roof and reduces the range of plastic zone in back- fill strip and immediate roof significantly,which is conducive to the long-term stability of backfill strip and immediate roof,and realizes the purpose of “ water-preserved and water-stored” coal mining. According to the comprehensive a- nalysis,the optimum scheme of strip constructional backfill in Xinyang mine is spaced 2 m and backfill 2 m.
“water-preserved and water-stored” coal mining;strip constructional backfill;“constructional strip-imme- diate roof” structure;backfill space;self-bearing capacity
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会