孔洞尺寸效应对岩石单轴压缩力学强度及破坏特征影响试验研究

Experimental Research on Influence of Size Effect on Compression Mechanical Strength and Failure Characteristics of Rock

为了研究孔洞尺寸效应对岩石力学强度的影响,利用岩石伺服压力机对含不同孔洞直径的岩石进行单轴压缩,并通过高速摄像机记录其破坏特征及裂纹扩展过程,从裂纹扩展角度阐述强度弱化机理。研究表明:(1)随着孔洞直径的增大,其抗压强度随之而减小,但降低速率逐渐减小;(2)起裂裂纹类型控制脱落面积,进而影响岩石宏观力学强度;(3)孔洞直径为6 mm、8 mm试样起裂裂纹为反向拉伸裂纹,反向拉伸裂纹扩展很短;孔洞直径为10 mm、12 mm试样起裂裂纹为正向拉伸裂纹,最终贯穿试验边界的均为正向拉伸裂纹。

In order to study the influence of hole size effects on rock strength,rocks with holes of different diameters are tested under uniaxial compression with a servo press, and their failure characteristics and crack propagation process are recorded by a high-speed camera to identify strength weakening mechanism in the light of crack propagation. The results show that（ 1） with the increase of hole diameter,rock compressive strength decreases,but the rate gradually reduces;（ 2） the type of initiative crack controls the area of fall-off,and thus affects the strength of rock;（3） initiative cracks of specimens of hole diameter 6 mm and 8 mm are reverse tensile cracks with very short crack propagation;initiative cracks of specimens of hole diametersare10 mm and12 mm are positive tensile cracks,cracks finally running through boundaries of specimens are all positive tensile cracks.