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浅埋房式采空区下近距离煤层长壁开采覆岩运动规律及控制
Overlying Strata Movement Laws and Ground Control of the Longwall Face Mining in a Shallow Depth Seam in Proximity Beneath a Room Mining Goaf
【作者】 王方田；
【作者基本信息】 中国矿业大学 ， 采矿工程， 2012， 博士
【摘要】 针对神东煤田浅埋房式采空区下近距离煤层长壁开采地质生产条件，综合运用现场调研、数值计算、物理模拟、理论分析及现场试验的研究方法，对房式煤柱稳定性、顶板大面积来压机理及防治技术、房式采空区下近距离煤层开采覆岩运动规律及其控制技术等进行了系统研究，主要研究成果如下：（1）综合运用逐步破坏理论及突变理论对房式煤柱失稳机理进行了分析，建立了煤柱失稳的判别式。基于逐步破坏理论对房式残留煤柱稳定性进行了计算分析，判定了满足煤柱稳定性安全系数1.5以上的煤柱设计尺寸。采用突变理论建立了房式煤柱破坏失稳的尖点突变模型，得到房式煤柱发生突变的必要条件为0.33w<Y<0.43w，即弹性核区宽度大于煤柱宽度的34%时，煤柱将不会发生突变失稳，与现场勘测结果相吻合，揭示了房式残留煤柱失稳机理。（2）建立了浅埋房式采空区下煤层开采覆岩运动结构模型，确定了支架合理工作阻力。基于弹性力学建立了固支梁及悬臂梁结构模型，并对顶板抗拉与抗剪屈服破坏进行了比较分析，理论计算与矿压监测相结合确定了顶板初次及周期来压步距。根据浅埋房式采空区下煤层开采覆岩运动特征，将“载荷层—老顶—房式煤柱—直接顶—支架”系统划分成“载荷层—老顶—房式煤柱”及“房式煤柱—直接顶—支架”两个关联系统，并求得支架合理支护阻力。根据直接顶结构特征进行力学平衡分析，得到了直接顶发生切冒的判据。（3）揭示了深孔预裂爆破强制放顶的机理，防止了顶板大面积来压。建立了大面积顶板来压飓风冲击模型，为因大面积冒顶形成的飓风而损坏综采设备、摧毁巷道设施等现象做出了合理解释。为防止顶板大面积来压，提出采取切眼深孔预裂爆破强制放顶技术，采用LS-DYNA3D程序建立了深孔预裂爆破强制放顶计算模型，在揭示爆破放顶的机理的同时，优化了主要爆破参数。现场采用深孔预裂爆破强制放顶技术取得了良好的效果。（4）提出了以合理控制采高及加快推进速度等措施为主的顶板控制技术，确保了浅埋房式采空区下近距离煤层安全高效开采。依据浅埋房式采空区下近距离煤层开采覆岩运动规律，提出了以合理控制采高、注砂充填采空区、加强支护管理及加快工作面推进速度为主的顶板控制技术体系，现场应用实现了浅埋房式采空区下近距离煤层安全高效开采。
【Abstract】 According to the geological conditions of the longwall face mining in theshallow depth coal seam in proximity beneath a room mining goaf in the ShendongCoal Field, in situ survey, numerical simulation, physical simulation, theoreticalanalysis and field experiment were undertaken to study the stability of the roommining goaf residual coal pillars, the large area roof weighting mechanism and itscontrol technology, overlying strata movement laws and ground control of thelongwall face, the major achivements are as follows:(1) The instability mechanism of the room mining residual coal pillars wasuncovered by the integrate analysis of gradually damage theory and catastrophe theory,and the criterion of pillar instability was also established. The room mining residualcoal pillars instability was calculated with gradually damage theory, and the pillardesign size, which meet the request that safety factor greater than1.5, was judgedaccordingly. The cusp catastrophic model was established through catastrophe theory,and an essential condition to indicate pillar mutation was presented as0.33w<Y<0.43w, i.e. the pillar cannot occur mutation instability if the elastic areawidth greater than34%of the total pillar width, this result is consistent with the in situobservations, thence the instability mechanism of the room mining residual pillarswas uncovered.(2) The overlying strata movement structure model of the longwall face miningin the shallow depth seam beneath a roof mining goaf was set up, and the reasonablesupport working resistance was also confirmed. Based on the theory of ElasticMechanics, a clamped beam and a cantilever beam were built to analyze the roofweighting length, and the tensile yield and shear yield of the mian roof werecompared, then the first roof weighting length and the period weighting length werecalculated and monitored. According to the overlying strata movement characteristicsof the longwall face mining in the shallow depth coal seam in proximity beneath aroom mining goaf, the system of “Loading layer-Main roof-Room mining residualpillar-Immediate roof-Support” can be divided into two linking systems including“Loading layer-Main roof-Room mining residual pillar” and “Room mining residualpillar-Immediate roof-Support”, and then the reasonable support working resistancecan be achieved. Furthermore, the slice-caving criterion of the immediate roof wasrevealed through the mechanical equilibrium analysis of the immediate roof structure. (3) The mechanism of the deep-hole pre-split blasting for controlled roof cavingwas uncovered, and the application avoided the large area roof weighting accidents. Alarge area roof weighting wind blast model was established to explain the wind blastinduced fully mechanized equipment damage and roadway destroy. To prevent largearea roof weighting, a deep-hole pre-split blasting technology carried out at theopen-off cut for controlled roof caving was presented, the software of LS-DYNA3Dwas used to set up a simulation model, then the mechanism was revealed and themajor blasting parameters were also optimized. The field experiment indicated thatthis technology was successfully practiced for controlled roof caving.(4) The roof control technologies including control the reasonable mining heightand increase the mining speed properly, etc. were presented to enable the achievementof safe and highly-efficient mining in the shallow depth seam in proximity beneath aroom mining goaf. According to the overlying strata movement laws of the longwallface mining he shallow depth seam in proximity beneath a room mining goaf, the roofcontrol technologies including control reasonable mining height, sandfilling in theroom mining goaf, enhance the roof control management and increase the miningspeed properly were presented, and the in situ experiments enable the longwall facemining safely and efficiently.
【Key words】 shallow depth coal seam； room mining goaf； close coal seams； overlyingstrata movement law； roof control；