DETERMINATION OF SOIL-WATER CHARACTERISTIC CURVE VARIABLES BASED ON VG MODEL
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摘要: 土水特征曲线基本参数(进气值、残余吸力值和反弯点的斜率等)在非饱和土的强度理论、渗流理论以及体变特性等方面都是非常重要的参数，常常通过传统画图法来确定，其精确度难以保证。以洛川标准剖面4层原状黄土为研究对象，基于VG模型提出单峰和双峰SWCC基本参数的确定方法；采用滤纸法测得SWCC数据点，基于VG模型进行最优化拟合，获取拟合参数，利用单峰和双峰SWCC数据点验证该方法的可行性；进行自然状态下的水分蒸发试验，根据质量含水率与蒸发时间的关系确定蒸发残余饱和度Srzf，依据Sr1、Sr2(Sr1和Sr2分别由确定残余状态的两种方法得到)与Srzf的相对误差值，比较了两种确定残余状态的方法。结果表明：对于单峰和双峰SWCC曲线，该方法都可以得到合理的基本参数并有效地确定其残余状态。Abstract: The variables of the soil-water characteristic curve(air-entry value, residual suction and slope at the inflection point) are very critical parameters in the strength theory, percolation theory and volume change behavior of unsaturated soil. It is often obtained by conventional graphical method, which is subjective and inaccurate. This study presents the methods for determining the variables of unimodal and bimodal SWCC based on VG model using the measured SWCC data of the four layers of undisturbed loess in Luochuan standard section. SWCC data were measured by filter paper method and best fitted using Van Genuchten's equation. Consequently the best fitting parameters were obtained, and the proposed methods were validated using the measured unimodal and bimodal SWCC data. The water evaporation test in the natural state was carried out. Then the evaporation residual saturation Srzf was determined according to the relationship between the mass moisture content and the evaporation time. According to the relative errors between Sr1, Sr2 and Srzf(Sr1 and Sr2 were acquired from the two methods for determining the residual state, respectively), the comparison was made between the two methods for determining the residual state. The results suggest that the proposed methods can produce reasonable variables and determine the residual state effectively related to the unimodal and bimodal SWCC.
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Key words:
- Soil-water characteristic curve /
- VG model /
- Air-entry value /
- Residual state
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图 2 不同的反弯点会产生不同的进气值
Figure 2. Different inflection points will lead to different air-entry values
图 4 基于本文方法确定单峰SWCC的基本参数
a. L6；b. L7；c. L13
Figure 4. The variables of unimodal SWCC are determined based on the method in this paper
图 6 基于本文方法确定双峰SWCC的基本参数
Figure 6. The variables of bimodal SWCC are determined based on the method in this paper
表 1 洛川原状黄土的基本物理性质
Table 1. Properties of Luochuan undisturbed loess
层号 埋深
/m含水量
/%孔隙比 干密度
/g·cm-3比重 饱和
含水率ω液限
/%塑限
/%塑性
指数颗粒组成/% 细砂粒 粉粒 黏粒 L6 43 12.10 0.81 1.50 2.72 32.5 29.0 16.5 12.5 9.17 78.54 12.29 L7 48 14.40 0.75 1.54 2.72 30.1 30.1 19.6 11.2 1.32 72.83 25.85 L13 72 9.76 0.74 1.55 2.72 29.4 31.0 19.4 11.6 5.05 81.75 13.20 
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表 2 单峰土水特征曲线的拟合参数和基本参数
Table 2. Best fitting parameters and variables of the unimodal SWCCs
试验
黄土拟合参数 R2 SWCC基本参数 a n m ψaev I(ψi, Si) Ki R1(ψr1，Sr1) R2(ψr2，Sr2) L6 0.047 1.326 0.246 0.973 9.41 (61.29, 0.671) -0.404 (1002, 0.179) (1136, 0.156) L7 0.034 1.230 0.187 0.973 13.60 (114.96, 0.708) -0.316 (1346, 0.370) (3167, 0.255) L13 0.024 1.232 0.188 0.989 19.30 (161.57, 0.707) -0.318 (1627, 0.390) (3509, 0.284)
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表 3 双峰土水特征曲线的拟合参数
Table 3. Bimodal SWCC best fitting parameters
L1 拟合参数 R2 a/kPa-1 n m 10-1~ψd段 0.161 1.283 0.221 0.964 ψd~106段 3E-4 1.436 0.304 0.991
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表 4 双峰土水特征曲线的基本参数
Table 4. Bimodal SWCC variables
10-1~ψd段 ψaev/kPa I(ψi，Si) Ki R(ψr，Sr) — 2.79 (20，0.686) -0.366 (144.5，0.376) — ψd~106段 ψ′aev I′(ψi，Si) K′i R1(ψr1，Sr1) R2(ψr2，Sr2) 1344 (7096，0.239) -0.184 (29847，0.125) (50938，0.083)
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表 5 Srzf值以及Sr1、Sr2与Srzf的相对误差计算结果
Table 5. Srzf values and the relative errors between Sr1、Sr2 and Srzf
土层 临残时间
tr/h残余含水率
ωr/%残余饱和度
Srzf相对误差
e1/%相对误差
e2/%L1 33 4.52 0.111 12.8 25.1 L6 33 6.91 0.232 22.9 32.8 L7 33 7.22 0.262 41.3 2.6 L13 33 5.49 0.202 93.3 40.7
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表 6 试验黄土的主要矿物成分和含量
Table 6. The main mineral composition and content of the loess
矿物 L1 L6 L7 L13 石英 51.1 55.5 48.7 58.4 方解石 15.2 12.3 15.4 13.1 斜长石 7.7 11.8 19.0 10.4 绿泥石 9.0 7.0 6.0 7.0 伊利石 8.5 8.0 6.5 7.5
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Bates S, Jonaitis D, Nail S. 2013. Sucrose lyophiles: A semi-quantitative study of residual water content by total X-ray diffraction analysis[J]. European Journal of Pharmaceutics & Biopharmaceutics, 85(2): 184-188. http://cn.bing.com/academic/profile?id=a72e99edb282b7b251958a364e8493f6&encoded=0&v=paper_preview&mkt=zh-cn Bishop A W. 1959. The principle of effective stress[J]. Teknisk Ukeblad, 39: 859-863. http://d.old.wanfangdata.com.cn/Periodical/ytlx201801015 Burdine N T. 1953. Relative permeability calculations from pore size distribution data[J]. Journal of Petroleum Technology, 5 : 71-78. doi: 10.2118/225-G Burton G, Sheng D, Campbell C. 2014. Bimodal pore size distribution of a high-plasticity compacted clay[J]. Géotechnique Letters, 4 : 88-93. doi: 10.1680/geolett.14.00003 Childs E C, Collis-George N. 1950. The permeability of porous materials[J]. Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, 201 : 392-405. http://d.old.wanfangdata.com.cn/OAPaper/oai_arXiv.org_1211.6885 Cook F J. 1991. Calculation of hydraulic conductivity from suction permeameter measurements[J]. Soil Science, 152(5): 321-325. doi: 10.1097/00010694-199111000-00002 D18 Committee. 2016. Standard test method for measurement of soil potential(suction) using filter paper (ASTM D5298-16)[S]. West Conshohocken, PA. Fleureau J M, Kheirbeksaoud S, Soemitro R, et al. 1993. Behavior of clayey soils on drying-wetting paths[J]. Canadian Geotechnical Journal, 30(2): 287-296. doi: 10.1139/t93-024 Fredlund D G. 2006. Unsaturated soil mechanics in engineering practice[J]. Journal of Geotechnical and Geoenvironmental Engineering, 132(3): 286-321. doi: 10.1061/(ASCE)1090-0241(2006)132:3(286) Gao Y, Sun D A. 2017. Determination of basic parameters of unimodal and bimodal soil water characteristic curves[J]. Chinese Journal of Geotechnical Engineering, 39(10): 1884-1891. http://d.old.wanfangdata.com.cn/Periodical/ytgcxb201710017 Genuchten M T V. 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J]. Soil Science Society of America Journal, 44(44): 892-898. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ce45a331f64792c4e74d5a74039efdf6 Jia B X, Wang H, Zhou L L, et al. 2018. Experimental study on soil-water characteristic curve of aeolian soil roadbed in western Liaoning Province[J]. Journal of Engineering Geology, 26(3): 633-638. http://d.old.wanfangdata.com.cn/Periodical/gcdzxb201803010 Li T L, Fan J W, Xi Y, et al. 2019. Analysis for effect of microstructure on SWCC of compacted loess[J]. Journal of Engineering Geology, 27(5): 1019-1026. http://d.old.wanfangdata.com.cn/Periodical/gcdzxb201905010 Li X, Li J H, Zhang L M. 2014. Predicting bimodal soil-water characteristic curves and permeability functions using physically based parameters[J]. Computers & Geotechnics, 57(4): 85-96. http://d.old.wanfangdata.com.cn/NSTLQK/NSTL_QKJJ0232634239/ Li Y F. 1994. Research on the relationships between permeability and porosity for loess[M]. Beijing: Geological Publishing House. Mualem Y. 1976. A new model for predicting hydraulic conductivity of unsaturated porous media[J]. Water Resources Research, 12(3): 513-522. doi: 10.1029/WR012i003p00513 Rao H R H, Venkataramana K V, Singh D N S N. 2011. Studies on the determination of swelling properties of soils from suction measurements[J]. Revue Canadienne De Géotechnique, 48(3): 375-387. doi: 10.1139/T10-076 Shi Z M, Liu W R, Peng M, et al. 2018. Experimental study on soil-water characteristic curve of reticulate red clay and its application in slope stability evaluation[J]. Journal of Engineering Geology, 26(1): 164-171. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=gcdzxb201801019 Sillers W S, Fredlund D G. 2001. Statistical assessment of soil-water characteristic curve models for geotechnical engineering[J]. Canadian Geotechnical Journal, 38(6): 1297-1313. doi: 10.1139/t01-066 Sillers W S, Fredlund D G, Zakerzadeh N. 2001. Mathematical attributes of some soil-water characteristic curve models[M]. Springer Netherlands. Soltani A, Azimi M, An D, et al. 2017. A simplified method for determination of the soil-water characteristic curve variables[J]. International Journal of Geotechnical Engineering, (3): 1-10. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=10.1080/19386362.2017.1344450 Tang C S, Shi B, Gu K. 2011. Experimental investigation on evaporation process of water in soil during drying[J]. Journal of Engineering Geology, 19(6): 875-881. http://cn.bing.com/academic/profile?id=2332a210d55ec12bbc15dbcd2bab3b21&encoded=0&v=paper_preview&mkt=zh-cn Tao G L, Li J, Zhuang X S, et al. 2018. Determination of the residual water content of SWCC based on the soil moisture evaporation properties and micro pore characteristics[J]. Rock and Soil Mechanics, 39(4): 1256-1262. http://d.old.wanfangdata.com.cn/Periodical/ytlx201804014 Vanapalli S K, Fredlund D G, Pufahl D E, et al. 1996. Model for the prediction of shear strength with respect to soil suction[J]. Canadian Geotechnical Journal, 33(3): 379-392. doi: 10.1139/t96-060 Wang T H, Li Y L, Su L J. 2014. Types and boundaries of bound water on loess particle surface[J]. Chinese Journal of Geotechnical Engineering, 36(5): 942-948. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytgcxb201405026 Yuan Z H, Ni W K, Liu R, et al. 2015. Study of shear strength of unsaturated and undisturbed loess based on suction stress[J]. Journal of Hefei University of Technology(Natural Science), 38(5): 648-653. http://www.en.cnki.com.cn/Article_en/CJFDTotal-HEFE201505016.htm Zhai Q, Rahardjo H. 2012. Determination of soil-water characteristic curve variables[J]. Computers & Geotechnics, 42(42): 37-43. http://cn.bing.com/academic/profile?id=33353e9f45f463f1fe973fa5ead0e98b&encoded=0&v=paper_preview&mkt=zh-cn 高游, 孙德安. 2017.单峰和双峰土水特征曲线基本参数的确定[J].岩土工程学报, 39(10): 1884-1891. doi: 10.11779/CJGE201710017 贾宝新, 王荷, 周琳力, 等. 2018.辽西风积土路基土水特征曲线试验研究[J].工程地质学报, 26(3): 633-638. doi: 10.13544/j.cnki.jeg.2017-264 李同录, 范江文, 习羽, 等. 2019.击实黄土孔隙结构对土水特征的影响分析[J].工程地质学报, 27(5): 1019-1026. doi: 10.13544/j.cnki.jeg.2019045 李云峰. 1994.黄土渗透性与空隙性关系的研究[M].北京:地质出版社. 石振明, 刘巍然, 彭铭, 等. 2018.网纹红土土水特征曲线试验研究及其在边坡稳定性评价中的应用[J].工程地质学报, 26(1): 164-171. doi: 10.13544/j.cnki.jeg.2018.01.018 唐朝生, 施斌, 顾凯. 2011.土中水分的蒸发过程试验研究[J].工程地质学报, 19(6): 875-881. doi: 10.3969/j.issn.1004-9665.2011.06.012 陶高梁, 李进, 庄心善, 等. 2018.利用土中水分蒸发特性和微观孔隙分布规律确定SWCC残余含水率[J].岩土力学, 39(4): 1256-1262. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytlx201804014 王铁行, 李彦龙, 苏立君. 2014.黄土表面吸附结合水的类型和界限划分[J].岩土工程学报, 36(5): 942-948. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytgcxb201405026 袁志辉, 倪万魁, 刘茹, 等. 2015.基于吸应力的非饱和黄土抗剪强度研究[J].合肥工业大学学报(自然科学版), 38 (5): 648-653. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=hfgydxxb201505016 -
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