基于核磁共振技术的冻融板岩损伤特性试验研究  

Experimental Study on Damage Characteristics of Freeze-thaw Slate Based on Nuclear Magnetic Resonance Technology

作　　者：卢汉青 包卫星[1] 陈锐 郭强 尹严 Lu Hanqing;Bao Weixing;Chen Rui;Guo Qiang;Yin Yan(School of Highway,Chang'an University,Xi'an 710064,P.R.China;Xinjiang Transportation and Construction Administration Bureau,Urumqi 830049,P.R.China)

机构地区：[1]长安大学公路学院,西安710064 [2]新疆交通建设管理局,乌鲁木齐830049

出　　处：《地下空间与工程学报》2025年第1期78-86,99,共10页Chinese Journal of Underground Space and Engineering

基　　金：新疆重大科技专项(2020A03003-7);陕西省自然科学基础研究计划面上项目(2021JM-180);中央高校基本科研业务费资助项目(领军人才计划)(300102211302)。

摘　　要：为探究风化炭质板岩在冻融循环作用下微观孔隙结构演化规律及宏观损伤特征,选取青藏高原喀喇昆仑山在建隧道围岩中风化程度不同的炭质板岩,开展了不同冻融循环次数后的核磁共振测试,定量分析了冻融板岩孔隙结构演化规律。结果表明:(1)风化板岩饱和质量、体积呈现先缓慢增加后快速降低的趋势,在出现宏观损伤后,其损伤扩展速度加快,质密、强度高的中风化板岩相较于强风化板岩需经历更频繁的冻融循环作用才会出现宏观损伤;(2)风化板岩核磁共振T2谱主要呈现2个谱峰,间断性地出现表征特大孔隙的第3峰,在冻融循环作用下,孔隙孔径逐渐扩大,孔隙增多,中、大孔径孔隙连通性增强,大孔径孔隙比例显著增长;(3)板岩冻融损伤时孔隙率会达到临界值,中风化板岩和强风化板岩冻融致损孔隙率临界值分别为15.36%和17.16%,当孔隙结构扩展使得局部孔隙率增大接近临界值,便出现岩块脱落的局部宏观损伤,从临界孔隙率角度分析了板岩冻融损伤机制。研究成果可对寒区不同风化程度岩体工程防冻设计施工具有参考价值。In order to investigate the evolution law of microscopic pore structure and macroscopic damage characteristics of weathered carbonaceous slate under freeze-thaw cycles,nuclear magnetic resonance testing was conducted on carbonaceous slate with different degrees of weathering in the surrounding rock of tunnels under construction in the Karakoram Mountains of the Qinghai Tibet Plateau after different freeze-thaw cycles.The evolution law of pore structure of freeze-thaw slate was quantitatively analyzed.Research shows that:(1)The saturated mass and volume of weathered slate show a trend of slowly increasing and then rapidly decreasing.After the occurrence of macroscopic damage,its damage propagation speed accelerates.Compared to strongly weathered slate,moderately weathered slate with dense and high strength needs to undergo more frequent freeze-thaw cycles to undergo macroscopic damage;(2)The nuclear magnetic resonance T2 spectrum of weathered slate mainly presents two peaks,with a discontinuous third peak representing extremely large pores.Under the freeze-thaw cycle,the pore size gradually expands,the pores increase,the connectivity between medium and large pore sizes is enhanced,and the proportion of large pore sizes significantly increases;(3)Research has found that the porosity of slate will reach a critical value when subjected to freeze-thaw damage.The critical values of freeze-thaw damage porosity for moderately weathered slate and strongly weathered slate are 15.36%and 17.16%,respectively.When the pore structure expands and the local porosity increases close to the critical value,local macroscopic damage of rock block detachment occurs.The mechanism of slate freeze-thaw damage is analyzed from the perspective of critical porosity.The research results have strong reference value for the antifreeze design and construction of rock mass engineering with different degrees of weathering in cold regions.

关 键 词：冻融循环 炭质板岩 核磁共振技术 微观孔隙变化 临界孔隙率 

分 类 号：TU45[建筑科学—岩土工程]