摘要
对取自重庆地区的不同粒度的砂岩进行单轴压缩条件下的声发射试验,并以时间为参考变量,得到力学与声发射参数之间的耦合关系,对其进行分析研究,以研究粒度对砂岩在单轴压缩破坏过程的影响规律,并以此进一步揭示岩石破坏的微观机制,结果表明:(1)粒度越大,砂岩的抗压强度越大,弹性模量越大,峰值应变越小。表明粒度越大,砂岩的抗压和抗变形能力越强。(2)砂岩的声发射现象可以分为三个阶段:初始压密期、平静期和爆发期。粒度对砂岩的声发射初始压密期和平静期影响不明显,但对爆发期有显著影响,粒度越大,砂岩在破坏阶段的声发射越剧烈。(3)从砂岩声发射RA值可以看出,砂岩破坏时的裂纹为张剪混合裂纹,以剪切裂纹为主,粒度越大,张拉裂纹越多。并且砂岩声发射RA值在破裂发生前都有突然增大,并达到峰值的现象,预示着破裂即将发生,因此可以将声发射RA值的突然增加作为砂岩破裂前兆信息。。
In order to study the effect of grain size on the failure process of sandstone under uniaxial compression condition and reveal the microscopic mechanism of rock failure,the corresponding acoustic emission experiments were conducted on the sandstones with different grain sizes which were sampled from Chongqing basin. With time as the reference variable,coupling relation between mechanics and AE parameters was obtained and further analyzed. The results showed that:( 1) Compressive strength and elastic modulus of sandstone increased with the increase of grain size. Meanwhile,peak strain decreased with the increase of grain size. This indicates compression and deformation resistances of sandstone increase with the grain size increases.( 2) Acoustic emission phenomenon of sandstone can be divided into three stages: initial compaction period,quiet period and outbreak period. The effect of grain size on the initial compaction and quiet period was not obvious,but the grain size had great influence on outbreak period. The acoustic emission signal of outbreak period was enhanced with the increase of grain size.( 3) It can be seen from the acoustic emission RA value that the crack during sandstone failure was combination of tensile and shearing crack and most of crack was shearing crack. The number of tensile crack increased with the increase of grain size. Moreover,the RA value before the sandstone failure suddenly increased and reached to the peak value,indicating that the main rupture is about to happen. Therefore,it can take the increase of RA value as the precursor information of sandstone rupture.
出处
《地下空间与工程学报》
CSCD
北大核心
2017年第S2期705-714,共10页
Chinese Journal of Underground Space and Engineering
基金
国家自然科学基金青年基金(51204128)
煤矿灾害动力学与控制国家重点实验室自主研究资助项目(2011DA105287-MS201303)
关键词
岩石力学
砂岩
单轴压缩
声发射
粒度
rock mechanics
sandstone
uniaxial compression
acoustic emission
grain size
