1. College of Science,Xi’an University of Science and Technology,Xi’an　 710054,China; 2. College of Safety Science and Engineering,Xi’an University of Science and Technology,Xi’an　 710054,China

瓦斯抽采钻孔孔周裂隙漏气是抽采失效的主要原因之一,孔周裂隙扩展在煤体破坏的过程中表现孕育、稳定扩展及迅速扩展3个阶段。为探究孔周裂纹在松软煤体不同破坏阶段的发展特征,开展含孔试样渐进性破坏过程中的孔周裂纹扩展规律研究。将石膏与水以质量比7∶3混合制成类软煤含孔方形试样,进行单轴压缩试验并采用数字散斑相关测量方法(DSCM)获取试样表面全场变形。基于此,提出了利用DSCM系统确定应力门槛值的方法,并将其用于含孔试样渐进性破坏过程的孔周变形精细化分析,利用该方法所确定的应力门槛值可将试样的破坏过程划分为5个阶段,通过提取与计算分析试样表面全场变形数据,得到在不同阶段内试样表面相对位移、以及孔周位移。结果表明:试样表面相对位移发展历经缓慢降低,加速降低以及迅速降低3个阶段,其中加速降低和迅速降低阶段与应力-应变曲线的裂纹稳定扩展和裂纹加速扩展对应;在压缩过程中,由于孔周对称移动造成孔周表面拉伸和压缩错动,最终在表面形成主拉伸裂纹和法向剪切裂纹。

The leak around the gas drilling borehole is one of the major reasons causing the drainage failure,and three stages (crack initiation stage,stable growth stage and unstable cracking stage) of the crack propagation around the gas drilling borehole are performed under the failure of coal. In order to find out the characteristics of crack propagation at different stages,a study on the crack propagation around the gas drilling borehole during the progressive failure was carried out. Plaster and water are blended in a mass ratio of 7 ∶ 3 to make soft coal like blocks,and uniaxial compres-sion tests were performed with digital speckle correlation method ( DSCM) getting the surface deformation of speci-mens. Based on this,a method determining the stress threshold by DSCM was proposed,and the deformation around the hole in the specimens’ progressive failure was analyzed though this method. The sample failure process was divided in-to five stages by the stress threshold determined by this method,then the full-field deformation data were calculated to obtain the surface relative displacement,displacement around the hole and crack mouth opening displacement. The re-sults show that the development of the surface relative displacement can be divided into the gradually decrease stage,the aggravated decrease stage and the rapidly decrease stage,among that the aggravated decrease stage and the rapidly decrease stage are corresponded with the stable growth stage and unstable cracking stage which are found in stress-stain curve. As the symmetrical movement around the hole,tensile and compression state are formed which finally re-sults in the tensile crack and the normal shear crack formed on the surface.

国家自然科学基金资助项目(51374168,51504189)；国家自然科学基金科学仪器基础研究专项资助项目(51327007)；

ZHANG Tianjum,ZHANG Lei,LI Shugang,et al. Characteristics of the surface deformation of specimens with a hole during the progressive failure[J]. Journal of China Coal Society,2017,42(10):2623-2630.