Kaiser效应激发验证中的压头尺寸效应研究  

Investigation on indenter size effect in Kaiser effect excitation verification

作　　者：马春德[1,2] 龙珊 胡顺喜 王业顺 MA Chun-de;LONG Shan;HU Shun-xi;WANG Ye-shun(School of Resources and Safety Engineering,Central South University,Changsha 410083,Hunan,China;Center for Advanced Studies,Central South University,Changsha 410083,Hunan,China)

机构地区：[1]中南大学资源与安全工程学院,湖南长沙410083 [2]中南大学高等研究中心,湖南长沙410083

出　　处：《实验力学》2020年第1期91-99,共9页Journal of Experimental Mechanics

基　　金：国家重点研发计划(2016YFC0600706)

摘　　要：针对声发射(AE)法现场测量地应力须选用便捷式小型加载设备来激发岩石声发射信号的实际要求,本文提出以减小压头直径来提高激发应力的解决思路。为此,利用MTS试验机、PCI-II声发射仪等仪器对预设应力的岩石试件开展5组不同直径(5mm、10mm、15mm、20mm和50mm)压头下的Kaiser效应激发显现验证试验。确定激发岩石Kaiser效应的压头直径临界值范围为5~10mm后,再增设4组(6mm、7mm、8mm、9mm)压头直径试验。试验结果表明:采用8mm直径的小压头可以有效激发并准确显现岩石Kaiser效应,压头直径对Kaiser效应的显现特征具有一定的影响作用。与预设应力相比,实测突变点应力出现"滞后显现"或"提前显现"现象。同时,文中还运用FLAC3D软件模拟计算了不同直径压头下大理岩试件的内部应力分布情况。结合声发射试验结果,初步分析解释了端部效应及压头直径对岩石试件Kaiser效应影响的机理。上述研究成果对在现场使用AE法准确测量地应力具有一定的参考意义。In view of practical requirement that the on-site crustal stress measurement by acoustic emission(AE) method should use a small and convenient loading device to excite acoustic emission signal of rock, this paper proposes a solution to increase the excitation stress by reducing the diameter of indenter. For this reason, using MTS testing machine, PCI-II acoustic emission instrument and other instruments, Kaiser effect excitation behavior verification experiments for five groups of prefabricated stress rock specimens with different indenter diameters(5 mm, 10 mm, 15 mm, 20 mm and 50 mm) were carried out, respectively. After determining the critical range of indenter diameter for Kaiser effect of rock to be 5~10 mm, further experiments for four groups of specimen with different indenter diameters(6 mm, 7 mm, 8 mm and 9 mm) were carried out. Experimental results show that the indenter with 8 mm diameter can excite and accurately show the rock Kaiser effect, but the indenter diameter still has a certain effect on Kaiser effect. Compared with prefabricated stress, the phenomenon of "delayed appearance" or "early appearance" occurs in the measured catastrophe point stress. At the same time, the internal stress distribution of marble specimens with different diameters is simulated by FLAC3 D software. Based on results of acoustic emission experiment, the mechanism of end effect and indenter diameter on Kaiser effect of rock specimen is analyzed and explained. Above results have certain guiding significance for accurate on-site measurement of crustal stress by using AE method.

关 键 词：KAISER效应 声发射 尺寸效应 单轴压缩 FLAC3D 

分 类 号：TU45[建筑科学—岩土工程]