Moisture migration in frozen silt under different moisture content and negative temperature gradient
Article Text (Baidu Translation)
-
摘要: 为研究初始含水率及负温梯度对粉土冻结过程中水分迁移演变的影响，应用多物理场仿真软件COMSOL Multiphysics 6.0开展了5组不排水条件下的粉土冻结数值试验，重点分析了冻结全过程内冻深发展、温度场演化、未冻水分布、水分迁移通量及冻胀变形的动态响应规律，揭示了二者对冻结水分迁移机制的综合影响。研究结果表明：粉土冻结过程具有明显的阶段特征，即冻结深度随时间呈先快速增长, 后逐渐趋于稳定的变化趋势；负温梯度对冻结进程具有显著调控作用，增大负温梯度能够明显加快冻结锋面的推进速度，并使得最终稳定后的最大冻结深度显著增加，当负温梯度从12.5 ℃·m-1提高至22.5 ℃·m-1时，最大冻结深度增长约63%；冻结前后粉土含水率竖向分布发生显著变化，增大初始含水率和负温梯度导致未冻结区内发生更强烈的水分迁移现象，且峰值含水率随负温梯度增大发生更明显的向下偏移；冻结前期冻结锋面处水分不断得到来自下部未冻区的水分补给，是导致冻胀量快速增长的主要原因，随着冻结进程推进，水分迁移通量因温度场趋于稳定及未冻水含量降低而逐渐减弱，冻胀发展速率也随之下降，最终达到相对稳定的冻胀量。研究所得冻结土体水分迁移特性，结合当前共玉高速公路防排水处治措施的潜在局限，明确了阻断路基内部水分向上迁移对变形控制的重要性。Abstract: To investigate the effects of initial moisture content and negative temperature gradient on water migration during the freezing process of silt, five numerical experiments under undrained conditions were conducted using the simulation software COMSOL Multiphysics 6.0. The study focused on analyzing the dynamic response of freezing depth development, temperature field evolution, unfrozen water distribution, water migration flux, and frost heave deformation throughout the freezing process. This analysis revealed the combined influence of the two factors on the water migration mechanism. The results show that the freezing process of silt exhibits distinct stages, characterized by a rapid initial increase in freezing depth followed by a gradual stabilization. The negative temperature gradient plays a significant regulatory role in the freezing process. Increasing the negative temperature gradient notably accelerates the advancement of the freezing front and leads to a substantial increase in the final stabilized maximum freezing depth. When the negative temperature gradient rises from 12.5 ℃·m-1 to 22.5 ℃·m-1, the maximum freezing depth increases by approximately 63%. The vertical distribution of moisture content changes significantly before and after freezing. Higher initial moisture content and a steeper negative temperature gradient induce more pronounced water migration in the unfrozen zone, with the peak moisture content shifting downward as the negative temperature gradient increases. In the early freezing stage, continuous water supply from the underlying unfrozen zone to the freezing front is the primary cause of rapid frost heave. As freezing progresses, the water migration flux gradually weakens due to the stabilization of the temperature field and the reduction in unfrozen water content. Consequently, the rate of frost heave development decreases, eventually reaching a relatively stable magnitude. Based on the moisture migration characteristics of frozen silt identified in this study and considering the potential limitations of current drainage measures on the Gongyu Expressway, the importance of blocking upward water migration within the subgrade for deformation control is further emphasized.
-
图 1 粉土水分迁移模型的试验和模拟结果
Figure 1. Test and modeling results of the silt moisture migration model
图 5 五等分点处温度随时间的变化
Figure 5. Variation of temperature with time at the five equal points
图 6 五等分点处降温速率随时间的变化
Figure 6. Variation of cooling rate with time at the five equal points
图 7 不同负温梯度下粉土温度场的动态分布情况
Figure 7. Temperature field distribution of silt under different negative temperature gradients
图 8 不同初始含水率和负温梯度下深度6 cm处粉土温度变化
Figure 8. Temperature change of silt at a depth of 6 cm under different initial water content and negative temperature gradient
图 10 五等分点处未冻水含量随时间的变化
Figure 10. Variation of unfrozen water content with time at five equal points
图 11 模拟结束时土中含水量分布
Figure 11. Distribution of moisture content at the end of the simulation
图 12 水分迁移量与初始含水率和负温梯度间的关系
Figure 12. Relationship between moisture migration, initial moisture content and negative temperature gradient
表 1 粉土水力学参数
Table 1. Material hydraulic parameters of the silt
材料 本构参数 残余含水量/% 饱和含水量/% 饱和渗透系数/(m·s-1) a0 m l 粉土 2.5 0.5 0.5 0.05 0.38(文献[25]) 0.41(本模型) 2×10-5 
下载: 导出CSV
表 2 粉土及冰水热力学参数
Table 2. Thermodynamic parameters of the silt, ice and water
材料 密度/(kg·m-3) 导热系数/(W·m-1·℃-1) 比热容/(kJ·kg-1·℃-1) 土质参数 冻结温度/℃ 粉土 1 600 1.67 2.74 0.47 -0.24 水 1 000 0.63 4.20 冰 918 2.31 -2.10
下载: 导出CSV
表 3 粉土冻结模拟方案
Table 3. Simulation scheme for frozen silt
编号 初始含水率/% 冷端温度/℃ 温度梯度/(℃·m-1) A1 10 -2.5 17.5 A2 15 -2.5 17.5 A3 20 -2.5 17.5 A4 15 -1.5 12.5 A5 15 -3.5 22.5
下载: 导出CSV
-
[1] HAO J W, CUI X Z, QI H, et al. Dynamic behavior of thawed saturated saline silt subjected to freeze-thaw cycles[J]. Cold Regions Science and Technology, 2022, 194(1): 103464. [2] 马玲, 彭丽云, 刘德欣, 等. 石灰改良粉土的冻胀特性试验研究[J]. 冰川冻土, 2023, 45(1): 212-221.MA Ling, PENG Li-yun, LIU De-xin, et al. Experimental study on the frost-heaving characteristics of lime-modified silt[J]. Journal of Glaciology and Geocryology, 2023, 45(1): 212-221. [3] 孟祥传, 周家作, 韦昌富, 等. 盐分对土的冻结温度及未冻水含量的影响研究[J]. 岩土力学, 2020, 41(3): 952-960.MENG Xiang-chuan, ZHOU Jia-zuo, WEI Chang-fu, et al. Effects of salinity on soil freezing temperature and unfrozen water content[J]. Rock and Soil Mechanics, 2020, 41(3): 952-960. [4] ZHANG X N, CUI X Z, DING L Q, et al. Effects of a novel hybrid polymer material on the hydro-mechanical behavior of subgrade silts considering freeze-thaw cycles[J]. Cold Regions Science and Technology, 2023, 205(2): 103698. [5] 李金平, 张娟, 陈建兵, 等. 高寒冻土区路基变形演化规律与破坏特征[J]. 交通运输工程学报, 2016, 16(4): 78-87. doi: 10.19818/j.cnki.1671-1637.2016.04.008 LI Jin-ping, ZHANG Juan, CHEN Jian-bing, et al. Evolution laws and failure characteristics of subgrade deformation in alpine permafrost region[J]. Journal of Traffic and Trans-portation Engineering, 2016, 16(4): 78-87. doi: 10.19818/j.cnki.1671-1637.2016.04.008 [6] 刘宇航, 李东庆, 明锋. 冰透镜体形成过程中的土体破裂驱动力研究综述[J]. 冰川冻土, 2019, 41(3): 657-668.LIU Yu-hang, LI Dong-qing, MING Feng. Review on driving forces of soil fracture during ice lens formation process[J]. Journal of Glaciology and Geocryology, 2019, 41(3): 657-668. [7] 王自力, 李金峰, 滕继东, 等. 基于未冻水膜压力判据的冻土水热力耦合冻胀模型研究[J]. 岩土工程学报, 2023, 45(5): 997-1007.WANG Zi-li, LI Jin-feng, TENG Ji-dong, et al. THM coupled model for simulating frost heave based on a new water film pressure criterion[J]. Chinese Journal of Geotech-nical Engineering, 2023, 45(5): 997-1007. [8] 郝小云, 冯文杰, 马巍, 等. 补水压力对土体冻胀的影响[J]. 冰川冻土, 2022, 44(2): 708-716.HAO Xiao-yun, FENG Wen-jie, MA Wei, et al. Experi-mental study on the effect of boundary hydraulic pressure on frost heaving of soil[J]. Journal of Glaciology and Geocryo-logy, 2022, 44(2): 708-716. [9] 魏厚振, 周家作, 韦昌富, 等. 饱和粉土冻结过程中的水分迁移试验研究[J]. 岩土力学, 2016, 37(9): 2547-2552, 2560.WEI Hou-zhen, ZHOU Jia-zuo, WEI Chang-fu, et al. Experimental study of water migration in saturated freezing silty soil[J]. Rock and Soil Mechanics, 2016, 37(9): 2547-2552, 2560. [10] 张莲海, 马巍, 石亚军, 等. 不同成冰机制下冻结锋面附近水分积聚模式及其工程环境意义[J]. 冰川冻土, 2023, 45(1): 31-41.ZHANG Lian-hai, MA Wei, SHI Ya-jun, et al. The modes and its implications of water accumulation near the freezing front during soil freezing with considering ice segregation[J]. Journal of Glaciology and Geocryology, 2023, 9(1): 31-41. [11] WANG H, WU Y K, WANG M, et al. Influence of fines content and degree of saturation on the freezing deformation characteristics of unsaturated soils[J]. Cold Regions Science and Technology, 2022, 201(9): 103610. [12] LU X F, ZHANG F, QIN W J, et al. Experimental inves-tigation on frost heave characteristics of saturated clay soil under different stress levels and temperature gradients[J]. Cold Regions Science and Technology, 2021, 192(12): 103379. [13] LI A Y, NIU F J, ZHENG H, et al. Experimental measure-ment and numerical simulation of frost heave in saturated coarse-grained soil[J]. Cold Regions Science and Techno-logy, 2017, 137(5): 68-74. [14] 周志军, 杨海峰, 耿楠, 等. 冻结速度对冻融黄土物理力学性质的影响[J]. 交通运输工程学报, 2013, 13(4): 16-21. doi: 10.19818/j.cnki.1671-1637.2013.04.003ZHOU Zhi-jun, YANG Hai-feng, GENG Nan, et al. Influence of freezing speed on physical and mechanical properties of freezing-thawing loess[J]. Journal of Traffic and Transportation Engineering, 2013, 13(4): 16-21. doi: 10.19818/j.cnki.1671-1637.2013.04.003 [15] 宋宏芳, 岳祖润, 李佰林, 等. 季节冻土区高速铁路防冻胀路基保温强化特性研究[J]. 岩土力学, 2019, 40(10): 4041-4048.SONG Hong-fang, YUE Zu-run, LI Bai-lin, et al. Thermal insulation and strengthening properties of anti-frost heaving subgrade structure of the high-speed railway in seasonally frozen soil region[J]. Rock and Soil Mechanics, 2019, 40(10): 4041-4048. [16] 李双洋, 张明义, 黄志军, 等. 地铁双线隧道施工人工冻结水热力数值分析[J]. 交通运输工程学报, 2009, 9(1): 67-72, 82. doi: 10.19818/j.cnki.1671-1637.2009.01.014 LI Shuang-yang, ZHANG Ming-yi, HUANG Zhi-jun, et al. Numerical analysis of moisture, thermal and mechanical states for subway double-line tunnel constructed by artificial freezing method[J]. Journal of Traffic and Transportation Engineering, 2009, 9(1): 67-72, 82. doi: 10.19818/j.cnki.1671-1637.2009.01.014 [17] 孙哲, 赵林, 胡国杰, 等. 下边界条件对多年冻土温度场变化数值模拟的影响[J]. 冰川冻土, 2021, 43(2): 357-369.SUN Zhe, ZHAO Lin, HU Guo-jie, et al. Influence of lower boundary conditions on the numerical simulation of perma-frost temperature field changes[J]. Journal of Glaciology and Geocryology, 2021, 43(2): 357-369. [18] 张明礼, 温智, 董建华, 等. 降雨增加对多年冻土区铁路路基水热影响研究[J]. 岩石力学与工程学报, 2017, 36(10): 2580-2590.ZHANG Ming-li, WEN Zhi, DONG Jian-hua, et al. The influence of rainfall increasing on thermal-moisture dynamics of railway embankment in cold regions[J]. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(10): 2580-2590. [19] GRENIER C, ANBERGEN H, BENSE V, et al. Ground-water flow and heat transport for systems undergoing freeze-thaw: Intercomparison of numerical simulators for 2D test cases[J]. Advances in water resources, 2018, 114(4): 196-218. [20] 胡田飞, 王天亮, 常键, 等. 基于有限体积法的冻土水热耦合程序开发及验证[J]. 岩土力学, 2020, 41(5): 1781-1789.HU Tian-fei, WANG Tian-liang, CHANG Jian, et al. Code development and verification for coupled process of water migration and heat transfer of frozen soil based on finite volume method[J]. Rock and Soil Mechanics, 2020, 41(5): 1781-1789. [21] 罗崇亮, 余云燕, 张璟, 等. 硫酸盐渍土热-质迁移试验与耦合模型[J]. 西南交通大学学报, 2023, 58(2): 470-478.LUO Chong-liang, YU Yun-yan, ZHANG Jing, et al. Heat-mass transfer test and coupling model of sulfate saline soil[J]. Journal of Southwest Jiaotong University, 2023, 58(2): 470-478. [22] GENUCHTEN M T. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J]. Soil Science Society of America Journal, 1980, 44(5): 892-898. doi: 10.2136/sssaj1980.03615995004400050002x [23] 邓青松, 曾超, 何先志, 等. 季冻区公路路基水热场阴阳坡差异与防冻胀模拟[J]. 中南大学学报(自然科学版), 2022, 53(8): 3113-3128.DENG Qing-song, ZENG Chao, HE Xian-zhi, et al. Simulation of hydrothermal field difference and anti-frost heaving of highway subgrade with sunny-shady slopes in seasonally frozen regions[J]. Journal of Central South University (Science and Technology), 2022, 53(8): 3113-3128. [24] TAI B W, LIU J K, WANG T F, et al. Numerical modelling of anti-frost heave measures of high-speed railway subgrade in cold regions[J]. Cold Regions Science and Technology, 2017, 141(9): 28-35. [25] ZHANG X Y, ZHANG M Y, PEI W S, et al. Experimental study of the hydro-thermal characteristics and frost heave behavior of a saturated silt within a closed freezing system[J]. Applied Thermal Engineering, 2018, 129(1): 1447-1454. [26] 徐学祖, 邓友生. 冻土中水分迁移的实验研究[M]. 北京: 科学出版社, 1991.XU Xue-zu, DENG You-sheng. Experimental study on water migration in frozen soil Physics of frozen soils[M]. Beijing: Science Press, 1991. [27] LU N, LIKOS W J. Unsaturated Soil Mechanics[M]. New York: Wiley, 2004. [28] 徐安花. 多年冻土区公路病害对冻土地温和含冰类型的敏感性分析[J]. 冰川冻土, 2014, 36(3): 622-625.XU An-hua. Analysis of the sensitivity of highway diseases in permafrost regions to ground temperatures and ice contents[J]. Journal of Glaciology and Geocryology, 2014, 36(3): 622-625. [29] 吕志涛, 夏才初, 李强, 等. 单向冻结时开放条件下饱和砂岩冻胀试验及THM耦合冻胀模型[J]. 岩土工程学报, 2019, 41(8): 1435-1444.LÜ Zhi-tao, XIA Cai-chu, LI Qiang, et al. Frost heave experiments on saturated sandstone under unidirectional freezing conditions in an open system and coupled THM frost heave model[J]. Chinese Journal of Geotechnical Engi-neering, 2019, 41(8): 1435-1444. [30] 刘倩倩, 蔡国庆, 秦宇腾, 等. 单向冻结条件下粗颗粒级配土的水热分布及冻胀特性研究[J]. 岩石力学与工程学报, 2023, 42(9): 2329-2340.LIU Qian-qian, CAI Guo-qing, QIN Yu-teng, et al. Experi-mental study on hydrothermal distribution and frost heave characteristics of coarse-grained graded soil under unidirec-tional freezing condition[J]. Chinese Journal of Rock Mechanics and Engineering, 2023, 42(9): 2329-2340. [31] 张建勋, 毛雪松, 刘飞飞, 等. 单向冻结条件下非饱和土水分迁移规律研究[J]. 冰川冻土, 2023, 45(3): 1080-1091.ZHANG Jian-xun, MAO Xue-song, LIU Fei-fei, et al. Study on water migration behavior of unsaturated soil under unidirectional freezing condition[J]. Journal of Glaciology and Geocryology, 2023, 45(3): 1080-1091. [32] 包卫星, 刘亚伦, 毛雪松, 等. 高海拔多年冻土区砂石路面公路的路基温度场特征[J]. 交通运输工程学报, 2023, 23(4): 60-74.BAO Wei-xing, LIU Ya-lun, MAO Xue-song, et al. Charac-teristics of subgrade temperature field of gravel road in high altitude permafrost region[J]. Journal of Traffic and Trans-portation Engineering, 2023, 23(4): 60-74. -
图(13) / 表(3)
计量
- 文章访问数: 13
- HTML全文浏览量: 4
- PDF下载量: 3
- 被引次数: 0
