Experiment research on unfrozen water content and pore characteristic of cement improved soil under freeze-thaw cycle
), Abstract
Grouting with cementitious materials is a commonly-recognized measure to control the freezing and thawing deformation of artificial freezing strata. This study investigated the unfrozen water content of silty clay with different cement content under freeze-thaw condition, as well as the pore characteristics of the silty clay before and after freeze-thaw cycle based on nuclear magnetic resonance. It analyzed pore characteristics variation patterns of cement improved soil before and after freeze-thaw cycle and the micro-mechanism of freeze-thaw damage through scanning electron microscopy and mercury intrusion porosimetry. Results showed that: ①With the same water content, the increase of cement content would lead to the initial increase and subsequent decrease in the sensitivity to temperature of water molecule magnetization in the pores. ②When the cement content is between 0%~10% and at the same temperature during thawing process, the increase of cement content would lead to the initial decrease and subsequent increase of the unfrozen water content in the frozen soil. ③Compared with the silty clay without cement, cement improved silty clay shows little changes in its pores before and after the freeze-thaw cycle. The pore characteristics and microstructure of improved silty clay with cement content of 5% are less affected by freeze-thaw cycle. This research can provide references for the study of freeze-thaw resistance of improved soil and the stability control of strata frost heave and thaw settlement in artificial frozen engineering.
Keywords
References
Chen Xiangsheng. Several key points of artificial ground freezing method and its latest application in China[J]. Tunnel Construction, 2015, 35(12): 1243-1251.
Dai Huadong, Wang Qingcheng. Experimental study on mechanical properties of frozen soil in deep soil of Wanfu coal mine[J]. Journal of Mining Science and Technology, 2019, 4(2): 120-126.
Li Shuangyang, Zhang Mingyi, Gao Zhihua, et al. Thermal and mechanical analysis of the artificial freezing method applied to a subway tunnel in Guangzhou[J]. Journal of Glaciology and Geocryology, 2006, 28(6): 823-832.
Tan Long, Wei Changfu, Tian Huihui, et al. Experimental study of unfrozen water content of frozen soils by low-field nuclear magnetic resonance[J]. Rock and Soil Mechanics, 2015, 36(6): 1566-1572.
Tian H H, Wei C F, Lai Y M, et al. Quantification of water content during freeze-thaw cycles: a nuclear magnetic resonance based method[J]. Vadose Zone Journal, 2018, 17(1): 1-12.
Liu Bo, Li Dongyang, Liao Jianjun. The effect of earth pressure on ground settlement after frozen soil thawing in connect aisle construction of metro engineering[J]. Journal of China Coal Society, 2011, 36(4): 551-555.
Liu B, Ma Y J, Liu N, et al. Investigation of pore structure changes in Mesozoic water-rich sandstone induced by freeze-thaw process under different confining pressures using digital rock technology[J]. Cold Regions Science and Technology, 2019, 161: 137-149.
Liu B, He Y Q, Han Y H, et al. An improved model assessing variation characteristics of pore structure of sandy soil thawing from extremely low temperature using NMR technique[J]. Cold Regions Science and Technology, 2023, 205: 103717.
Li Tao, Liu Bo, Li Yan, et al. The void ratio of saturated red clay calculated from a micro-structure model[J]. Journal of China University of Mining & Technology, 2011, 40(5): 720-725.
Liu Bo, Li Dongyang, Liu Lulu, et al. CT scanning and images analysis during frozen soil thawing[J]. Journal of China Coal Society, 2012, 37(12): 2014-2019.
Liu B, Li D Y. A simple test method to measure unfrozen water content in clay-water systems[J]. Cold Regions Science and Technology, 2012, 78: 97-106.
Li Dongyang, Liu Bo, Liu Nian, et al. A method to save the determining time of unfrozen water within frozen soil by nuclear magnetic resonance[J]. Journal of Glaciology and Geocryology, 2014, 36(6): 1502-1507.
Zhang Lixin, Xu Xuezu, Zhang Zhaoxiang, et al. Experimental study of the relationship between the unfrozen water content of frozen soil and pressure[J]. Journal of Glaciolgy and Geocryology, 1998, 20(2): 124-127.
Wang Dayan, Zhu Yuanlin, Ma Wei, et al. Testing study on relationship between ultrasonic wave velocities and physico-mechanical property of frozen soils[J]. Chinese Journal of Rock Mechanics and Engineering, 2003, 22(11): 1837-1840.
Yin Zhenhua, Zhang Jianming, Zhang Hu, et al. Microcosmic pore characteristics evolution of the cement improved frozen soil after thawing compression[J]. Hydrogeology & Engineering Geology, 2021, 48(2): 97-105.
Liu Z, Yu X B. Physically based equation for phase composition curve of frozen soils[J]. Transportation Research Record: Journal of the Transportation Research Board, 2013, 2349(1): 93-99.
Wang C, Lai Y, Zhang M Y. Estimating soil freezing characteristic curve based on pore-size distribution[J]. Applied Thermal Engineering, 2017, 124: 1049-1060.
Zhang Xiangdong, Hu Xiaofei. Experimental study on dynamic parameters of modified aeolian sand with lime-fly ash at negative temperature[J]. Bulletin of the Chinese Ceramic Society, 2017, 36(5): 1728-1734.
Huang Jianhua, Yan Gengming, Yang Luming. Analysis of freezing temperature field in connecting passage of cement improved soil layer[J]. China Civil Engineering Journal, 2021, 54(5): 108-116.
Wang Tianliang, Liu Jiankun, Tian Yahu. Dynamic properties of cement-and lime-improved soil subjected to freeze-thaw cycles[J]. Chinese Journal of Geotechnical Engineering, 2010, 32(11): 1733-1737.
Cui Honghuan, He Jingyun, Zhang Zhenhuan, et al. A freeze-thaw damage model of cement-solidified soil in seasonal frozen soil zones[J]. Industrial Construction, 2021, 51(5): 158-163.
Zhang Xiangdong, Ren Kun, Li Jun. Study on frost resistance of EPS particles modified soil as subgrade filler in cold regions[J]. Journal of Glaciology and Geocryology, 2017, 39(6): 1273-1280.
Ren Kun, Yu Zening, Wang Haitao. Experimental study on cumulative deformation characteristics of cement cinder improved soil under freeze-thaw cycles[J]. Journal of the China Railway Society, 2022, 44(10): 123-130.
Li Z Y, Yang G S, Liu H. The influence of regional freeze-thaw cycles on loess landslides: analysis of strength deterioration of loess with changes in pore structure[J]. Water, 2020, 12(11): 3047.
Li T G, Kong L W, Liu B H. The California bearing ratio and pore structure characteristics of weakly expansive soil in frozen areas[J]. Applied Sciences, 2020, 10(21): 7576.
An R, Zhang X W, Kong L W, et al. Artificial ground freezing impact on shear strength and microstructure of granite residual soil under an extremely low temperature[J]. Frontiers in Earth Science, 2021, 9: 772459.
Jin W D, Wang Z, Ai Y M, et al. Analysis of influencing factors and mechanism of strength of cement-modified silty sand[J]. Geofluids, 2021, 2021: 1-10.
Jaeger F, Rudolph N, Lang F, et al. Effects of soil solution's constituents on proton NMR relaxometry of soil samples[J]. Soil Science Society of America Journal, 2008, 72(6): 1694-1707.
Kruse A M, Darrow M M, Akagawa S. Improvements in measuring unfrozen water in frozen soils using the pulsed nuclear magnetic resonance method[J]. Journal of Cold Regions Engineering, 2018, 32(1): 04017016.
Bai R Q, Lai Y M, Zhang M Y, et al. Theory and application of a novel soil freezing characteristic curve[J]. Applied Thermal Engineering, 2018, 129: 1106-1114.
Du Xiaofang. Characteristics of freeze-thaw damage evolution of pore structure in backfill material based on NMR technology[J]. Safety in Coal Mines, 2019, 50(9): 75-78.
Liu Y W, Wang Q, Liu S W, et al. Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling[J]. Cold Regions Science and Technology, 2019, 161: 32-42.
Watanabe K, Mizoguchi M. Amount of unfrozen water in frozen porous media saturated with solution[J]. Cold Regions Science and Technology, 2002, 34(2): 103-110.
Peyron M, Pierens G K, Lucas A J, et al. The modified stretched-exponential model for characterization of NMR relaxation in porous media[J]. Journal of Magnetic Resonance, Series A, 1996, 118(2): 214-220.
Jia Hailiang, Chen Weihang, Wang Ting, et al. Experimental study on the thawing and softening laws of frozen soil under microwave irradiation[J]. Chinese Journal of Rock Mechanics and Engineering, 2020, 39(S2): 3636-3644.
Mangold N, Allemand P, Duval P, et al. Experimental and theoretical deformation of ice-rock mixtures: implications on rheology and ice content of Martian permafrost[J]. Planetary and Space Science, 2002, 50(4): 385-401.
京公网安备11010802044758号