岩石冻融过程未冻水含量演化特征及对力学特性影响研究  

Evolution characteristics of unfrozen water content and its influence on mechanical properties of rock during freeze-thaw process

作　　者：宋勇军[1] 卢云龙 王双龙 谢丽君 操警辉 安旭晨 SONG Yong-jun;LU Yun-long;WANG Shuang-long;XIE Li-jun;CAO Jing-hui;AN Xu-chen(College of Architecture and Civil Engineering,Xi’an University of Science and Technology,Xi’an,Shaanxi 710054,China;China Metallurgical Group Northwest Geotechnical Engineering Co.,Ltd.,Xi’an,Shaanxi 710061,China)

机构地区：[1]西安科技大学建筑与土木工程学院,陕西西安710054 [2]中冶地集团西北岩土工程有限公司,陕西西安710061

出　　处：《岩土力学》2025年第4期1049-1059,1121,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.42277182,No.11972283)。

摘　　要：冻融过程岩石孔隙内未冻水含量变化是影响其力学特性的关键因素之一。以砂岩为研究对象,采用低场核磁共振系统(nuclear magnetic resonance,NMR)对岩石冻融过程(20、0、-2、-4、-6、-10、-15、-10、-6、-4、-2、0、20℃)孔隙水含量进行监测,分析未冻水含量随温度的演化规律,并探讨岩石冻融过程未冻水含量演化对其力学特性的影响。研究结果表明:(1)冻融过程岩石中孔隙水受温度影响显著,共经过5个阶段,即过冷段、快速冻结阶段、缓慢冻结阶段、缓慢融化阶段和融化加速阶段。(2)岩石在解冻过程中有明显的滞后现象。在相同温度下,岩样冻结过程未冻水含量明显高于解冻过程。与之对应,解冻过程的峰值强度和弹性模量相对于冻结阶段显著提高。(3)冻融过程的单轴抗压强度以及岩石弹性模量与未冻水含量的关系可由指数函数表示。冻结初期,岩石力学参数的变化主要受孔隙冰含量的增长及孔隙冰对岩石颗粒的胶结作用影响,随温度进一步降低,吸附水膜厚度下降,吸附能力增强,使孔隙冰与对岩石颗粒之间的整体性增强,岩石力学参数进一步发生改变。The change of unfrozen water content in pores of rock during freeze-thaw process is one of the key factors affecting its mechanical properties.In this paper,the sandstone is taken as the research object,and the pore water content of rock during freeze-thaw process(20,0,−2,−4,−6,−10,−15,−10,−6,−4,−2,0,20℃)is monitored by low-field nuclear magnetic resonance system(NMR),and the evolution law of unfrozen water content with temperature is analyzed.The influence of the evolution of unfrozen water content on the mechanical properties of rock during freeze-thaw process is also discussed.The research findings show that the pore water in rocks during the freezing-thawing process is significantly influenced by temperature,passing through five stages:supercooling,rapid freezing,slow freezing,slow melting,and accelerated melting.A distinct hysteresis phenomenon is observed in the rock during thawing.At identical temperatures,the unfrozen water content during freezing is notably higher than during thawing.Consequently,the peak intensity and elastic modulus during thawing are significantly greater than during freezing.The relationship between uniaxial compressive strength,rock elastic modulus,and unfrozen water content in freeze-thaw process can be expressed by exponential function.At the beginning of freezing,the change of rock mechanical parameters is mainly affected by the increase of pore ice content and the cementation effect of pore ice on rock particles.With the further decrease of temperature,the thickness of adsorbed water film decreases,and the adsorption capacity increases,so that the integrity between pore ice and rock particles is enhanced,and rock mechanical parameters further change.

关 键 词：核磁共振 冻融回滞 未冻水含量 力学特性 

分 类 号：TU452[建筑科学—岩土工程]