Calibrating Moisture Content Measurement of Loess by Time Domain Reflectometry: Influential Factors and Assessment

ZHANG Shi-bin; LI Rong-jian; WANG Lei; XIAO Hui-ping; LIU Jun-ding; ZHU Cai-hui

doi:10.11988/ckyyb.20191161

PDF(1331 KB)

Journal of Changjiang River Scientific Research Institute ›› 2020, Vol. 37 ›› Issue (3) : 155-161. DOI: 10.11988/ckyyb.20191161

THE TENTH NATIONAL YOUTH CONFERENCE ON GEOMECHANICS ANDGEOTECHNICAL ENGINEERING

Calibrating Moisture Content Measurement of Loess by Time Domain Reflectometry: Influential Factors and Assessment

ZHANG Shi-bin¹, LI Rong-jian¹, WANG Lei^{1, 2}, XIAO Hui-ping³, LIU Jun-ding¹, ZHU Cai-hui¹

Author information +

History +

Abstract

Time domain reflectometry (TDR) has been widely used in geotechnical engineering field as a reliable method to measure the volumetric water content of soils. In this study, TDR measuring of moisture content was calibrated. Loess samples from Yan’an New Area and Wuqi County were selected for test. The test error in the TDR measurement was analyzed, and the effects of dry density and plasticity index of loess on the calibration of TDR test were discussed. Results revealed large error of measurement before the TDR moisture sensors were calibrated. Given the same mass moisture content, the volumetric water content of loess measured by TDR moisture sensor was in a linear growth relation with dry density. For loess samples from Yan’an New Area with a plasticity index less than 10, the volumetric moisture content (θ_v) measured by TDR moisture sensor was greater than that (θ_w) measured by drying method, and the results were all below the contour line (θ_w=θ_v). For loess samples from Wuqi County with a plasticity index between 10 and 17, when the mass moisture content w was smaller than 12%, θ_v was greater than θ_w, and the test results were below the contour line (θ_w=θ_v); on the contrary when w was larger than 12%, θ_v was smaller than θ_w, and the test results were above the contour line (θ_w=θ_v). By comparing and analyzing the relations between θ_w and θ_v, a modified formula for TDR moisture measuring results was established. The research results offer reference for the application of TDR to measuring moisture content of loess in the loess area of north Shaanxi Province.

Key words

loess / TDR / moisture measuring / volumetric water content / dry density / plasticity index

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

ZHANG Shi-bin, LI Rong-jian, WANG Lei, XIAO Hui-ping, LIU Jun-ding, ZHU Cai-hui. Calibrating Moisture Content Measurement of Loess by Time Domain Reflectometry: Influential Factors and Assessment[J]. Journal of Changjiang River Scientific Research Institute. 2020, 37(3): 155-161 https://doi.org/10.11988/ckyyb.20191161

References

[1] 吴月茹,王维真,晋锐,等.TDR测定土壤含水率的标定研究.冰川冻土,2009,31(2): 262-267.
[2] 李旺霞,陈彦云.土壤水分及其测量方法的研究进展. 江苏农业科学,2014,42(10): 335-339.
[3] BITTELLI M, SALVATORELLI F, PISA P R. Correction of TDR-based Soil Water Content Measurements in Conductive Soils. Geoderma, 2008, 143(1/2): 133-142.
[4] KAMEYAMA K, MIYAMOTO T, SHIONO T. Influence of Biochar Incorporation on TDR-based Soil Water Content Measurements. European Journal of Soil Science, 2014, 65(1): 105-112.
[5] EVETT S R, TOLK J A, HOWELL T A. Time Domain Reflectometry Laboratory Calibration in Travel Time, Bulk Electrical Conductivity, and Effective Frequency. Vadose Zone Journal, 2005, 4(4): 1020-1029.
[6] 张瑞国,罗强,蒋良潍,等.土体含水率TDR测试技术的影响因素分析.传感器与微系统,2016,35(5): 16-19.
[7] 曹玉鹏,邓永锋,洪振舜.高盐分环境下TDR测试高含水率方法研究.岩土工程学报,2010,32(12):1916-1921.
[8] 吕海波,蒋文宇,赵艳林,等.南宁膨胀土的体积含水率-等效介电常数关系.岩土力学,2016,37(8):2145-2150.
[9] 苏都,红梅,陈有君,等.TDR测定淡栗钙土水分的标定.内蒙古农业大学学报(自然科学版),2012,33(1): 88-92.
[10] 杨静,陈洪松,王升,等.TDR测定喀斯特地区石灰土含水率的标定研究.中国岩溶,2017,36(1): 75-80.
[11] 于永堂,张继文,郑建国,等.驻波比法测定黄土含水率的标定试验研究.岩石力学与工程学报,2015,34(7): 1462-1469.
[12] 于永堂,郑建国,刘争宏,等.基于贯入阻力与含水率联测的黄土填方压实度检测方法.raybet体育在线院报,2018, 35(3):129-134,143.
[13] 王铁行,曹怀长,焦丹,等.电势作用下非饱和黄土水分迁移试验研究.地下空间与工程学报,2018,14(4): 994-998.
[14] TOPP G C, DAVIS J L, ANNAN A P. Electromagnetic Determination of Soil Water Content: Measurements in Coaxial Transmission Lines. Water Resources Research, 1980, 16(3): 574-582.
[15] 吕海波,赵艳林,陈川亮.时域反射法测量膨胀土含水率试验研究.岩石力学与工程学报,2008,27(12): 2568-2574.
[16] CRISTI F, FIERR V, SUÁREZ F, et al. A TDR-waveform Approach to Estimate Soil Water Content in Electrically Conductive Soils. Computers and Electronics in Agriculture, 2016, 121: 160-168.
[17] 冷艳秋,林鸿州,刘聪,等.TDR水分计标定试验分析.工程勘察,2014,42(2): 1-4.
[18] GRECO R, GUIDA A. Field Measurements of Topsoil Moisture Profiles by Vertical TDR Probes. Journal Of Hydrology, 2008, 348(3/4): 442-451.
[19] ZAGOSKII V V, NSETEROV V M, ZAMOTTRINSKAYA E A, et al. Dependence of Dielectric Permittivity of Moist Disperse Materials on the Temperature. Russian Physics Journal, 1982, 25(1): 62-65.
[20] 李道西,彭世彰,丁加丽,等.TDR在测量农田土壤水分中的室内标定.干旱地区农业研究, 2008,26(1):249-252.