单轴压缩下含孔洞裂隙砂岩力学特性试验分析

EXPERIMENTAL ANALYSIS OF MECHANICAL BEHAVIOR OF SANDSTONE CONTAINING HOLE AND FISSURE UNDER UNIAXIAL COMPRESSION

利用岩石力学伺服试验机与岩石声发射仪,对含孔洞裂隙砂岩(尺寸为60 mm×120 mm×30 mm)的力学特性进行单轴压缩试验。基于试验结果,首先分析含孔洞裂隙砂岩岩样的强度和变形特性,结果表明,含孔洞裂隙砂岩岩样的力学参数均显著低于完整岩样,但降低幅度与孔洞直径及缺陷对称分布密切相关,随着孔洞直径的增加,含单孔洞砂岩的峰值强度与峰值应变均呈衰减趋势,而不对称分布的孔洞裂隙砂岩岩样的力学参数均低于对称分布;然后基于含孔洞裂隙砂岩加载过程中的声发射特征,揭示声发射分布显著受孔洞裂隙等缺陷分布的影响,这主要是由于含不同孔洞裂隙砂岩中裂纹扩展模式存在着显著差异;最后通过照相量测技术,探讨含不同孔洞裂隙砂岩的裂纹扩展特征,分析含缺陷砂岩裂纹扩展过程及其对宏观应力–应变曲线的影响规律。

By using rock mechanics testing system and acoustic emission（AE） equipment,the mechanical behavior of sandstone（the size is 60 mm×120 mm×30 mm） containing a single hole and fissure are tested by uniaxial compression test.Based on the experimental results,the strength and deformation behavior of fractured sandstone are first analyzed.The results show that the mechanical parameters of fractured sandstone are significantly lower than that of intact sample,and the reducing extent depends on hole diameter and symmetrical distribution of flaws.With the increase of hole diameter,the peak strength and peak strain of sandstone containing a single hole decreases gradually.The mechanical parameters of samples with asymmetrical flaw geometry are lower than that of samples with symmetrical flaw geometry.And then,on the basis of AE behavior of sandstone samples containing a single hole and fissure during loading,the AE distribution is significantly affected by flaw geometry,which is mainly due to significant differences of crack coalescence modes of sample containing different holes and fissures.Finally,by photographic measurement techniques,the failure modes of sandstone containing different holes and fissures are analyzed,and the crack coalescence process of sample containing a single hole and fissure and its effect on microscopic stress-strain curve are also investigated.