含孔试样渐进性破坏的表面变形特征

发布时间：2018-05-01 12:24

  本文选题：裂纹扩展 + 数字散斑　； 参考：《煤炭学报》2017年10期

【摘要】：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。
[Abstract]:It is one of the main reasons that the gas leakage in the hole in the hole of the gas extraction drilling is one of the main reasons for the failure of the extraction. The expansion of the fracture of the hole in the process of the failure of the coal body shows birth, the steady expansion and the rapid expansion of the 3 stages. The plaster and water are mixed with water with the mass ratio of 7 to 3 to make a square specimen with holes in the soft coal. A single axial compression test and a digital speckle correlation method (DSCM) are used to obtain the total field deformation of the surface of the specimen. Based on this, a method of determining the stress threshold by the DSCM system is proposed and used in the progressive failure of the bore specimen. The failure process of the specimen can be divided into 5 stages by the stress threshold value determined by this method. By extracting and calculating the total field deformation data on the surface of the specimen, the relative displacement of the specimen surface and the displacement of the hole in different stages are obtained. The results show that the relative displacement of the sample surface develops through the development of the specimen surface. Slow reduction, acceleration reduction and rapid reduction of 3 stages, in which the accelerated and rapid reduction stages correspond to the steady crack propagation of the stress strain curve and the acceleration of the crack. In the compression process, the Kong Zhou symmetry movement causes the Kong Zhou surface tension and the compression dislocation, and finally the main tensile crack and the normal shear are formed on the surface. Crackle.

【作者单位】： 西安科技大学理学院;西安科技大学安全科学与工程学院;
【基金】：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)
【分类号】：TD712.6
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本文编号：1829356