含瓦斯煤多级式卸围压变形破坏及渗透率演化规律实验

摘要

以重庆松藻煤电有限责任公司的典型煤与瓦斯突出矿井——打通一矿7号煤层为研究对象,利用自行研制的＂含瓦斯煤热流固耦合三轴伺服渗流试验装置＂,进行了不同初始围压和不同瓦斯压力组合条件下,含瓦斯煤多级式卸围压变形破坏及渗透率演化规律实验研究。研究结果表明：开始卸围压后,煤岩并不是立即被破坏失稳,而是维持在σ1u一段时间,经历n级卸围压作用后才会失稳;在煤样失稳前,每一级卸围压过程中煤样的变形和渗透率变化速度都是不一样的,均呈加速增大的趋势;在每一级围压恒定阶段,随着围压的降低,煤岩的蠕变速度和渗透率也均是加速增大的;卸围压阶段比围压恒定阶段变形和渗透率增大速度快得多;无论是卸围压过程还是恒定围压阶段,围压降低引起的横向变形的变化速度均大于轴向变形的变化速度。%Focusing on the No.7 coal seam of Datong mine,Chongqing Songzao C ＆ E Co.,Ltd.,by using self-made ＂thermo-fluid-solid coupling with triaxial servo-controlled seepage equipment of gas-containing coal＂,an experiment was carried out to investigate the deformation failure and permeability evolution law of multi-stage unloading confining pressure of gas-containing coal under different initial confining pressures and various gas pressures.The research results show that the coal is not immediately destroyed and out of stability after the unloading process begins,but maintains over σu1 for some time,and coal is out of stability after n stages of unloading confining pressure.Before coal instability occuring,the variable speed of deformation and permeability of coal is not the same during each stage of unloading confining pressure,and shows a trend of increasing speed.At each stage of constant confining pressure,with the lower confining pressure,creep speed and permeability of coal also are increasingly accelerated.The deformation and permeability in unloading confining pressure stage increases faster than inconstant confining pressure stage.Whether it is the process of unloading confining pressure or constant confining pressure stage,the confining pressure to reduce the transverse deformation caused by change speed is greater than the axial deformation change speed.