急倾斜煤层不同覆岩结构导水裂隙演化规律

Evolution Law of Water Flowing Fractures with Different Structures of Overlying Strata in Steep Seam

基于龙湖煤矿南二采区急倾斜煤层的赋存和水文地质条件,采用离散元数值计算方法,分析了覆岩结构组合对急倾斜煤层开采导水裂隙演化规律的影响。结果表明:急倾斜煤层采场上覆岩层无关键层及覆岩结构组合为隔水-结构关键层时,导水裂隙分布呈"耳型"特征;采场上覆岩层存在结构关键层,直接顶为坚硬岩层和软弱的隔水关键层时,导水裂隙以平行于层面的离层裂隙为主;急倾斜煤层开采不同覆岩结构组合,导水裂隙发育高度均随煤层采厚的增加呈增大趋势,裂采比呈降低趋势。现场依据导水裂隙分布特征,设计了合理的防水煤柱尺寸和矸石充填注浆胶结顶板控制技术,确保了水体下急倾斜煤层的安全回采。

Based on the occurrence conditions of steep seam and,the hydrological and geological conditions in south No.2 mining district of Longhu coalmine,the dispersed element numerical calculation method was used in this paper to analyze the influence of structural combination of overlying strata on water flowing fractures in steep seam.The results indicated that water flowing fracture presented ＂ear style＂ distribution with the water-resisting structural key bed in structural combination of overlying strata and without key bed in overlying strata of coalface;water flowing fracture mainly produced bed separation fractures parallel to the bedding face while there was key bed in overlying strata with hard immediate roof and soft water-resisting key bed;water flowing fracture height increased and ratio of the fractured zone height to the mining height decreased with the increase of seam mining height in steep seam.According to water flowing fracture distribution characteristics,the reasonable waterproof pillar sizes are determined and the control technology for roof cementing by grouting in gangue stowing mining is designed,ensuring the safe mining under water body in steep seam.