Estimation of unfrozen water content of saturated sandstones using nuclear magnetic resonance, mercury intrusion porosimetry, and ultrasonic tests  

作　　者：Fei Liu Shibing Huang Gang Liu Shilin Yu 

机构地区：[1]School of Resources and Environmental Engineering,Wuhan University of Science and Technology,Wuhan,430081,China [2]Hubei Key Laboratory for Efficient Utilization and Agglomeration of Metallurgic Mineral Resources,Wuhan University of Science and Technology,Wuhan,430081,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第9期3465-3484,共20页岩石力学与岩土工程学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.42377191);Hubei Provincial Natural Science Foundation of China(Grant No.2021CFA094);“The 14th Five Year Plan”Hubei Provincial advantaged characteristic disciplines(groups)project of Wuhan University of Science and Technology(Grant No.2023A0303)。

摘　　要：The unfrozenwater content(UWC)is a crucial parameter that affects the strength and thermal properties of rocks in relation to engineering construction and geological disasters in cold regions.In this study,three different methods were employed to test and estimate the UWC of saturated sandstones,including nuclear magnetic resonance(NMR),mercury intrusion porosimetry(MIP),and ultrasonic methods.The NMR method enabled the direct measurement of the UWC of sandstones using the free induction decay(FID).The MIP method was used to analyze the pore structures of sandstones,with the UWC subsequently calculated based on pore ice crystallization.Therefore,the MIP test constituted an indirect measurement method.Furthermore,a correlation was established between the P-wave velocity and the UWC of these sandstones based on the mixture theory,which could be employed to estimate the UWC as an empirical method.All methods demonstrated that the UWC initially exhibited a rapid decrease from 0C to5C and then generally became constant beyond20C.However,these test methods had different characteristics.The NMR method was used to directly and accurately calculate the UWC in the laboratory.However,the cost and complexity of NMR equipment have precluded its use in the field.The UWC can be effectively estimated by the MIP test,but the estimation accuracy is influenced by the ice crystallization process and the pore size distribution.The P-wave velocity has been demonstrated to be a straightforward and practical empirical parameter and was utilized to estimate the UWC based on the mixture theory.This method may be more suitable in the field.All methods confirmed the existence of a hysteresis phenomenon in the freezing-thawing process.The average hysteresis coefficient was approximately 0.538,thus validating the GibbseThomson equation.This study not only presents alternative methodologies for estimating the UWC of saturated sandstones but also contribute to our understanding of the freezing-thawing process of pore water.

关 键 词：Unfrozen water content(UWC) Nuclear magnetic resonance(NMR) Mercury intrusion porosimetry(MIP) Pore structures P-wave velocity SANDSTONE 

分 类 号：TU45[建筑科学—岩土工程]