采动应力下急倾斜煤层顶板砂岩的力学及渗透特性

发布时间：2018-05-13 20:13

本文选题：采动应力 + 急倾斜　；参考：《煤炭学报》2017年S1期

【摘要】：针对煤矿开采过程中垂直应力集中及水平应力卸载所引起的岩体变形破坏和渗透特性等问题,运用自主研制的含瓦斯煤热流固耦合三轴伺服渗流试验装置,以急倾斜煤层顶板砂岩为研究对象,开展不同静水压力条件下,砂岩定轴压卸围压瓦斯三轴渗流试验,研究应力集中状态对砂岩卸围压破坏过程中变形规律及渗流特性的影响。得出的主要结论有:岩样屈服阶段存在一点,为岩样卸荷由张拉破坏向压剪破坏的转折点,且卸荷点越接近屈服强度,岩样卸荷破坏越突然和剧烈,岩体破碎度越高;初始围压(轴压)相同时,砂岩的峰值强度随初始轴压(围压)增大而有所提高;砂岩卸荷破坏卸荷量百分比随轴压增大而减小,随初始围压增大而增大;砂岩卸荷破坏后,峰值瓦斯流量与体积应变之间存在指数函数关系;砂岩卸荷破坏形态主要表现为沿层理方向的张剪混合裂缝,且微裂缝十分发育,岩样的渗透性与裂缝的发育程度具有较好的相关性。岩体渗透性与其所处的应力状态密切相关,开展采动应力下煤系砂岩的变形破坏规律及瓦斯流动特征研究对指导急倾斜煤层开采中瓦斯抽采钻孔的合理布设、提高瓦斯抽采效率具有重要的理论及现实意义。
[Abstract]:Aiming at the problems of rock mass deformation, failure and permeability caused by vertical stress concentration and horizontal stress unloading during coal mining, the self-developed triaxial servo seepage test device for gas-bearing coal heat fluid-solid coupling is used. Taking the roof sandstone of steeply inclined coal seam as the research object, the triaxial percolation test of sandstone under different hydrostatic pressure conditions was carried out to study the influence of stress concentration state on the deformation law and seepage characteristics of sandstone during unloading confining pressure failure. The main conclusions are as follows: there is a point in the yield stage of rock sample, which is the turning point of unloading rock sample from tensile failure to compression shear failure, and the closer the unloading point is to yield strength, the more sudden and violent the unloading failure of rock sample is, and the higher the degree of rock mass fragmentation is; When the initial confining pressure (axial pressure) is the same, the peak strength of sandstone increases with the increase of initial axial pressure (confining pressure), and the percentage of unloading damage of sandstone decreases with the increase of axial pressure and increases with the increase of initial confining pressure. There is an exponential function relationship between peak gas discharge and volume strain, and the failure form of sandstone unloading is mainly composed of tensile and shear mixed fractures along the bedding direction, and the micro-fractures are well developed. There is a good correlation between the permeability of rock samples and the degree of fracture development. The permeability of rock mass is closely related to the stress state in which the rock mass is located. The study of deformation and failure law and gas flow characteristics of coal-bearing sandstone under mining dynamic stress can guide the reasonable arrangement of gas drainage boreholes in steep coal seam mining. It is of great theoretical and practical significance to improve the efficiency of gas drainage.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点实验室;重庆大学资源及环境科学学院;
【基金】：国家自然科学基金应急管理资助项目(51474258);国家自然科学基金重点资助项目(51434003)
【分类号】：TD313;TD712

【相似文献】