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

Abstract

In order to study the influence of drilling 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.

Keywords

• gas drainage borehole
• crack evolution
• speckle monitoring
• destruction form
• compressive strength