基于散斑监测的抽采钻孔变形破坏特征试验研究

Experimental study on deformation and failure characteristics of drainage boreholes based on speckle monitoring

为研究钻孔对煤体变形破坏特征的影响规律,开展了完整试样及含钻孔型煤试样单轴压缩试验,分析了试样强度特征、位移场及裂纹演化特征。结果表明:相同试验条件下,与完整试样相比,含孔试样单轴抗压强度由1.19 MPa减小至0.95 MPa,减小幅度为20.17%;完整试样及含孔试样的破坏模式均为拉剪复合破坏,含孔试样破坏形状呈“X”状;结合轴向加载应力-时间曲线,将含孔试样孔周位移演化过程分为快速增长、稳定增长、缓慢增长和极速增长4个阶段,加载过程中测点位移值随着层位的增高而增大。

In order to study the influence of drlling on the deformation and failure characteristics of coal,uniaxial compression tests were carried out for complete samples and briquette samples with drilled holes,and the strength characteristics,displacement field and crack evolution characteristics of the samples were analyzed.The results show that:under the same test conditions,compared with the intact sample,the uniaxial compressive strength of the sample with holes is reduced from 1.19 MPa to 0.95 MPa,and the reduction range is 20.17%;the failure modes of intact samples and samples with holes are tensile shear combined failure,and the failure shape of the samples with holes is"X"shape.Combined with the axial loading stress-time curve,the evolution process of the displacement around the holes of the samples with holes is divided into rapid growth,stable growth,slow growth.During the four stages of rapid growth,the displacement value of the measuring point increases with the increase of the horizon during the uniaxial loading process.