基于核磁共振技术的砂岩孔隙结构冻融损伤演化规律试验研究  

Experimental Study on the Evolution Law of Freeze-thaw Damage of Sandstone Pore Structure Based on Nuclear Magnetic Resonance Technology

作　　者：王文通 郭沙 李治兴 李治国 刘传举 WANG Wentong;GUO Sha;LI Zhixing;LI Zhiguo;LIU Chuanju(School of Environment and Resource,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China)

机构地区：[1]西南科技大学环境与资源学院,四川绵阳621010

出　　处：《黄金科学技术》2025年第1期114-126,共13页Gold Science and Technology

基　　金：国家自然科学基金青年科学基金项目“冻融循环—冲击载荷作用下岩石断裂裂纹扩展机理”(编号:52204156);四川省自然科学基金项目“冻融—疲劳荷载交互下川西高寒冻融区岩石冲击疲劳断裂机理”(编号:2025ZNSFSC0419)联合资助。

摘　　要：为研究寒区受冻融影响砂岩的细观和微观孔隙结构损伤特性,以砂岩作为研究对象,基于核磁共振试验,获得了砂岩在不同冻融循环次数下的岩石质量、孔隙度和T_(2)谱曲线分布特征;结合分形理论与Coats渗透率模型,讨论了冻融作用下岩石孔隙和孔喉变化规律,建立了不同孔隙结构、孔隙分形维数、渗透率及孔隙度之间的相互作用关系,揭示了对冻融损伤影响最大的孔隙类型。结果表明:砂岩孔径呈三峰分布,随着冻融循环次数的增加,岩石质量、孔隙度和T_(2)谱峰值增大;小孔(T_(2)<3,ms)体积维持动态稳定,中孔(3<T_(2)<33,ms)和大孔(T_(2)>33,ms)体积呈线性增长;分形维数与循环次数呈负相关关系;大孔分形维数(D_(b))与孔隙度、渗透率均呈线性递减;大孔隙及与之连接的孔喉扩展,孔隙结构复杂程度降低,连通性增强,试样孔隙结构损伤加剧。To investigate the damage characteristics of the mesoscopic and microscopic pore structures of sandstone subjected to freeze-thaw cycles in cold regions,and to offer theoretical support for construction projects in these areas,the authors selected sandstone with a pronounced freeze-thaw response as the experimental subject.Utilizing nuclear magnetic resonance(NMR)technology,the study obtained porosity data and T2 distribution curve characteristics of sandstone across varying freeze-thaw cycles.This study examines the alterations in mass of rocks subjected to freezing and thawing cycles,focusing on changes in rock porosity,pore structure,and aperture distribution.Additionally,it investigates the freeze-thaw responses of various pore content types.Utilizing fractal theory and the Coats permeability model,the authors quantitatively characterize the pore structure of rocks affected by freeze-thaw processes.The research establishes the interrelationships among different pore structures,pore fractal dimensions,permeability,and porosity,ultimately identifying the pore types most significantly influencing freeze-thaw damage.The findings indicate that the rock mass exhibits a non-linear increase in response to the number of freeze-thaw cycles,with trends associated with macro disruptions.The T2 distribution curve reveals that the pore size of the sandstone follows a three-peak distribution.Furthermore,both the porosity and the peak value of the T2 distribution increase as the number of freeze-thaw cycles rises.However,the inconsistency between the freeze-thaw cycles and the changes in peak area and peak value can be attributed to the imbalance between the rate of pore initiation and the rate of pore expansion within the rock,in which the volume of small pores(T2<3 ms)exhibited dynamic stability,whereas the volumes of medium pores(3 ms<T2<33 ms)and macropores(T2>33 ms)increased linearly.Notably,the expansion rate from small to medium pores exceeded that from medium to large pores.To comprehensively characterize the evoluti

关 键 词：冻融循环 核磁共振(NMR) 孔隙特征 分形维数 孔喉 渗透率 砂岩孔隙结构 

分 类 号：TD325[矿业工程—矿井建设]