偏载作用下三孔洞砂岩的力学特性及声发射特征

Mechanical properties and acoustic emission characteristics behind three-holes sandstone under bias loading

为研究偏载作用下缺陷煤岩局部变形和整体破坏规律,采用TYJ-500电液伺服岩石剪切流变试验机,对不同形态三孔洞砂岩进行偏载试验,并借助声发射技术监测分析砂岩试样损伤演化过程中的力学特性和声发射特征。试验结果表明:孔洞空间布置形态对砂岩抗压强度和弹性模量有一定影响,斜三孔洞对力学特性的劣化作用最为显著;除斜三孔外,塑性屈服阶段应力-应变曲线均具有波动特征,说明处于非优势破裂面孔洞形态首先发生局部破坏;通过分析裂纹分布形态可知,偏载对横三孔与竖三孔主裂纹发育影响较大,而斜三孔与面三孔主裂纹分布受控于孔洞空间形态;竖向空间布置三孔洞声发射特征参数较其他三种孔洞布置方式弱化效果显著。

This paper aims to study local deformation and overall damage law behind the defective coal rock under bias loading.The study includes performing the bias load test on three-holes sandstone with different morphology by using TYJ-500 electro-hydraulic servo rock shear rheology tester,monitoring and analyzing the mechanical properties and acoustic emission characteristics in the process of sandstone specimen damage evolution by means of acoustic emission technology.The test results show that the spatial distributon of holes affects the compressive strength and elastic modulus of sandstone,and the deterioration effect of oblique three holes on mechanical properties is evident;Beyond the oblique three holes,the stress-strain curves of the plastic yielding stage have fluctuating characteristics,which indicates that the holes at the non-dominant rupture surface have localized damage firstly;By analyzing the distribution pattern of the cracks,the eccentric load has a greater influence on the main crack development of horizontal and vertical three holes,while the main crack distribution of oblique and face three holes is controlled by hole space pattern;and the acoustic emission characteristic parameters of vertical space distribution of three holes have weakened effect compared with the distribution of other three holes.