层状灰岩各向异性力学特征及声发射演化试验分析

Experimental Analysis of Anisotropic Mechanical Characteristics and Acoustic Emission Evolution of Layered Limestone

为研究层状岩体力学强度的各向异性特征,室内钻取7种不同层理倾角灰岩样,进行单轴压缩试验,并辅以声发射监测。试验结果表明:随着层理倾角增加,灰岩单轴抗压强度呈现先减小后增大的“V”形特征,在层理倾角为45°时达到最小值;以45°为界,45°以前,声发射能量累计曲线有两个明显台阶,在0.3σp(σp为峰值强度)与0.7σp两个点存在激增现象,45°及以后,声发射能量累计曲线呈锯齿状增加,无明显台阶;声发射b值以45°为界,45°以前整体呈下降趋势,在中间存在升高并保持一段台阶,45°及以后,呈“V”形,最低点出现在0.6σp度左右。

In order to study the anisotropy characteristics of the mechanical strength of layered rock masses,seven kinds of limestone samples with different bedding dip angles were drilled indoors,and uniaxial compression tests were carried out,supplemented by acoustic emission monitoring.The test results show that:As the bedding dip angle increases,the uniaxial compressive strength of the limestone presents a“V”-shaped characteristic that first decreases and then increases,and reaches the minimum value when the bedding dip angle is 45°.Taking 45°as the boundary,before 45°,the acoustic emission energy accumulation curve has two obvious steps.There is a sharp increase at the two points of 0.3σp(σp is the peak intensity)and 0.7σp.The acoustic emission energy accumulation curve is at 45°and beyond.It increases in a zigzag shape,without obvious steps.The b value of acoustic emission is bounded by 45°.Before 45°,the overall trend is downward,and there is a step in the middle that rises and maintains a step.After 45°,it is in a“V”shape,The lowest point appears at about 0.6σp degrees.