低透气性煤层群煤与瓦斯共采中的高位环形裂隙体

摘要

以顾桥煤矿1115(1)工作面为试验点,运用国际先进的岩层应力、位移、孔隙流压等实时监测手段,围岩变形与水、气耦合的COSFLOW数值模拟技术以及研究采动区流场特征的CFD模拟技术,系统研究并基本掌握了11号煤层深部煤层开采过程中的围岩应力场、裂隙场以及瓦斯流动场之间的动态变化规律.研究表明,采动支承压力影响范围可达300 m,覆岩运动和采动裂隙发育范围在工作面后方170 m以内,170 m以后采动裂隙基本压实,采动裂隙发育高度以及孔隙流压明显降低的高度可达145 m.在此基础上判别了1115(1)工作面上覆煤层群瓦斯高效抽采范围,并初步建立了低透气性煤层群瓦斯高效抽采的高位环形裂隙体及其判别方法,为煤与瓦斯共采理论发展以及工程实践提供了一套新的科学研究方法和工程设计手段.%Presented key results from a recent comprehensive research programme based on integrated field monitoring of mining induced overburden displacement,stress and pore pressure changes at the longwall panel 1115 (1) of the Guqiao Coal Mine,and coupled modelling of strata and fluid behaviours using COSFLOW software,and gas flow simulations at the longwall panel with CFD software. Studied and got the complex dynamics of the interaction between mining induced strata stress changes,fractures,gas flow patterns. The results show that effective range of abutment pressure by mining can reach near 300 m, the range of overburden strata movement and mining-induced fractures area is within 170 m after working face, and beyond the range the fractures are generally compacted, development height for mining-induced fractures of overburden rock and the height of crack zone with flowing pressure dropping remarkablely both can reach 145 m. Based on these, methane drainage scope with high efficiency in overlying coal seam group of working face 1115 (1)were obtained, and a new concept that a circular overlying zone existed at the longwall panel for efficient methane capture, and a practical method that helped define the geometry and boundary of this zone. The outputs of the research programme provide a unique methodology and a set of engineering priciples of planning for optimal co-extraction of coal and methane.