Microscopic damage and dynamic mechanical properties of rock under freeze-thaw environment  

冻融作用下岩石的微观损伤及动态力学特性（英文）

作　　者：周科平[1,2] 李斌[1,2] 李杰林[1,2] 邓红卫[1,2] 宾峰[1,2] 

机构地区：[1]中南大学资源与安全工程学院,长沙410083 [2]中南大学高海拔寒区采矿工程技术研究中心,长沙410083

出　　处：《Transactions of Nonferrous Metals Society of China》2015年第4期1254-1261,共8页中国有色金属学报（英文版）

基　　金：Project(2013YQ17046310)supported by the National Key Scientific Instrument and Equipment Development Project of China;Project(2013M542138)supported by China Postdoctoral Science Foundation;Projects(20130162110010,20130162120012)supported by Specialized Research Fund for the Doctoral Program of Higher Education of China

摘　　要：For understanding the rock microscopic damage and dynamic mechanical properties subjected to recurrent freeze-thaw cycles, experiments for five groups of homogeneous sandstone under different freeze-thaw cycles were conducted. After freezethaw, nuclear magnetic resonance(NMR) tests and impact loading tests were carried out, from which microscopic damage characteristics of sandstone and dynamic mechanical parameters were obtained. The results indicate that the porosity increases with the increase of cycle number, the rate of porosity growth descends at the beginning of freeze-thaw, yet accelerates after a certain number of cycles. The proportion of pores with different sizes changes dynamically and the multi-scale distribution of pores tends to develop on pore structure with the continuing impact of freeze-thaw and thawing. Dynamic compressive stress-strain curve of sandstone undergoing freeze-thaw can be divided into four phases, and the phase of compaction is inconspicuous compared with the static curve. Elastic modulus and dynamic peak intensity of sandstone gradually decrease with freeze-thaw cycles, while peak strain increases. The higher the porosity is, the more serious the degradation of dynamic intensity is. The porosity is of a polynomial relationship with the dynamic peak intensity.为研究冻融循环作用下岩石的微观损伤及动态力学特性,对5组均质砂岩进行不同冻融循环次数的冻融试验,并对冻融后的砂岩进行核磁共振测试以及冲击荷载试验,获得冻融作用下砂岩的微观损伤特征及动态力学参数。结果表明:孔隙度随冻融循环次数的增加而增大,冻融初期的孔隙度增长率趋缓,在达到一定冻融循环次数后孔隙扩展加快;不同尺寸的孔隙比例随冻融循环次数呈动态变化,且孔隙结构总体趋向多尺寸分布发展;冻融砂岩的动态压缩应力-应变曲线可以分为4个阶段,相比静态曲线其压密阶段不明显;随着冻融次数的增加,砂岩的弹性模量和动态峰值强度逐渐减小,而峰值应变则有所增大;砂岩孔隙度越大,动态峰值强度越小,且拟合曲线呈多项式分布。

关 键 词：ROCK freeze-thaw cycle nuclear magnetic resonance(NMR) pore structure dynamic mechanical property dynamic compression stress-strain curve 

分 类 号：TU45[建筑科学—岩土工程]