含孔洞大理岩破坏特性的颗粒流分析  

Particle flow analysis of fracture characteristics of marble with a single hole

作　　者：黎崇金 李夕兵[1] 李地元[1] 

机构地区：[1]中南大学资源与安全工程学院,长沙410083

出　　处：《工程科学学报》2017年第12期1791-1801,共11页Chinese Journal of Engineering

基　　金：国家自然科学基金资助项目(11472311;41630642);中南大学中央高校基本科研业务费专项资金资助项目(2017zzts538)

摘　　要：基于室内单轴压缩试验结果,利用颗粒流程序PFC2D,模拟含预制孔洞大理岩在单轴和双轴压缩条件下的破坏过程,分析预制孔洞形状、围压大小以及岩石非均质性对大理岩力学特性和裂纹扩展的影响.数值结果表明:与完整大理岩试样相比,含孔洞试样的峰值强度显著降低,降低程度与孔洞形状有关;围压对含孔洞大理岩试样的力学特性和裂纹扩展有显著影响,含孔洞试样的峰值强度随围压的增加而增加,但偏应力峰值随围压的增加呈先增大后减小的变化趋势;试样的破坏模式与孔洞形状相关,含圆形孔洞试样为类X型剪切破坏,含矩形孔洞或马蹄形孔洞试样为对角剪切破坏;岩石内部的矿物结核影响了裂纹的扩展路径,从而改变试样的宏观破坏模式.微观机理分析表明:孔洞周边裂纹的萌生与扩展过程伴随着应力集中区的释放与转移;含孔洞试样的宏观裂纹有3种模式:孔壁剥落、拉伸裂纹和压剪裂纹.Based on uniaxial compression laboratory results,the failure process of marble with a single hole was simulated using the particle flow code PFC2 D under uniaxial and biaxial compressions. The influence of the pre-existing hole shape,confining pressure and the rock heterogeneity on the mechanical properties of marble and the coalescence of cracks was analyzed. Numerical results show that compared to an intact marble specimen,the peak strength of a specimen containing a single hole reduces significantly,and the extent of reduction is related to the hole shape. The confining pressure has a significant effect on the mechanical properties of marble and the coalescence of cracks. The peak strength increases with the increase of confining pressure,while the peak deviator stress increases first and then decreases with the confining pressure increasing. Specimens containing circular holes exhibit X-type shear failure,while specimens containing rectangular or U-shaped holes exhibit diagonal shear failure. The mineral nodules in the rock specimen significantly affect the propagation of cracks leading to a change in the failure mode of marble specimen. Analysis results of the microscopic mechanisms show that the initiation and propagation of cracks around the hole is always accompanied by the release and transfer of stress from a concentrated zone. Three types of macroscopic cracks can be classified in specimen containing a single hole as hole surface spalling,tensile crack,and compressive shear crack.

关 键 词：颗粒流程序 孔洞试样 裂纹扩展 岩石非均质性 双轴压缩 

分 类 号：TU452[建筑科学—岩土工程]