基于频率步进原理的TDR研制及在土体含水率测试中的应用
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摘要
基于时域无载频脉冲原理的时域反射法(TDR)能够快速准确测试土体含水率,在岩土工程领域有广泛用途。但是目前TDR测定仪器均为进口,国外对中国实行技术封锁。介绍了一套基于频率步进原理的TDR,利用该原理信号源输出的频率分量能够精确获知,接收信号中的噪声有效被抑制;研制了探针转换器,避免在常态测试区域出现测试盲点,提高测试范围和精度。最后通过水、空气及土体3种介质中含水率测试对比试验,验证了新型TDR测试设备的有效性。
The time-domain reflection method(TDR) based on the time-domain carrier-free pulse principle can test volumetric water content of soils timely and accurately and is widely applied in geotechnical engineering. But all the TDR testing instruments are imported at present, and some foreign countries implement blockade on the techniques. A set of TDR system based on the principle of stepped-frequency is recommended. The output frequency component of the signal source can be accurately known and the noise in the received signal can be effectively restrained. A reasonable probe converter is developed to avoid blind spots in normal testing area and to improve testing range and accuracy. Finally, the effectiveness of the new TDR testing equipment is verified by comparing the volumetric water contents of water, air and soil.
The time-domain reflection method(TDR) based on the time-domain carrier-free pulse principle can test volumetric water content of soils timely and accurately and is widely applied in geotechnical engineering. But all the TDR testing instruments are imported at present, and some foreign countries implement blockade on the techniques. A set of TDR system based on the principle of stepped-frequency is recommended. The output frequency component of the signal source can be accurately known and the noise in the received signal can be effectively restrained. A reasonable probe converter is developed to avoid blind spots in normal testing area and to improve testing range and accuracy. Finally, the effectiveness of the new TDR testing equipment is verified by comparing the volumetric water contents of water, air and soil.
引文
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[14]TOPP G C,YANUKA M,ZEBCHUK W D.Determination of electrical conductivity using time domain reflectometry:soil and water experiments in coaxial lines[J].Water Resources Research,1988,24(7):945-952.
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[19]KRAUS D K.Electromagnetics[M].New York:McGraw-Hill Inc,1984.
[20]ZEGELIN S J,WHITE I,JENKINS D R.Improved field probes for soil water content and electrical conductivity measurement using time domain reflectometry[J].Water Resources Research,1989,25(11):2367-2376.
[21]YANUKA M G,TOPP C C,ZEGELIN S,et al.Multiple reflection and attenuation of time domain reflectometry pulses:theoretical considerations for applications to soil and water[J].Water Resour Res,1988,24:939-944.
[22]许伟.TDR表面反射法土体含水率测试理论及技术[D].杭州:浙江大学,2008.(XU Wei.Theory and technology for measurement soil water content by time domain reflectometry surface reflection[D].Hangzhou:Zhejiang University,2008.(in Chinese))
[23]ASTM D4959.Standard test method for determination of water content of soil by direct heating[S].2000.
[24]王进学.离子污染饱和无黏性土电导率特性及TDR测试技术[D].杭州:浙江大学,2007.(WANG Jin-xue.Electrical conductivities of ionic contaminated saturated sandy soils and TDR measurement[D].Hangzhou:Zhejiang University,2007.(in Chinese))
[2]TOPP G C,DAVIS J L,ANNAN A P.Electromagnetic determination of soil water content:application of TDR to field measurements[C]//Planetary Water,Proceedings of the third Colloquium.New York,1980.
[3]TOPP G C,DAVIS J L.Electromagnetic determination of soil water content:measurements in coaxial transmission lines[J].Water Resources Research,1980,16(3):574-582.
[4]TOPP G C,DAVIS J L.Electromagnetic determination of soil water content and electrical conductivity measurement using time domain reflectometry[J].Water Resources Research,1980,16:574-582.
[5]HEIMOVAARA T J.Comments on time domain reflectometry measurements of water content and electrical conductivity of layered soil columns[J].Soil Science Society of America Journal,1992,56:1657-1658.
[6]陈仁朋,许伟,汤旅军,等.地下水位及电导率TDR测试探头研制与应用[J].岩土工程学报,2009,31(1):77-82.(CHEN Ren-peng,XU Wei,TANG Lü-jun,et al.Development and application of TDR probes to monitor water level and electrical conductivity[J].Chinese Journal of Geotechnical Engineering,2009,31(1):77-82.(in Chinese))
[7]谭捍华,傅鹤林.TDR技术在公路边坡监测中的应用试验[J].岩土力学,2010,31(4):1331-1336.(TAN Han-hua,FUHe-lin.Testing study of application of time domain reflectometry to highway slope monitoring[J].Rock and Soil Mechanics,2010,31(4):1331-1336.(in Chinese))
[8]王华.步进频率连续波探地雷达信号源设计与实现[D].长沙:国防科学技术大学,2009.(WANG Hua.Design and implementation of a frequency synthesizer for SFCW ground penetrating radar[D].Changsha:National University of Defense Technology,2009.(in Chinese))
[9]方广有,佐藤源之.频率步进探地雷达及其在地雷探测中的应用[J].电子学报,2005,33(3):436-439.(FANGGuang-you,SATO M.Stepped-frequency ground penetrating radar and its application for landmine detection[J].Acta Electronica Sinica,2005,33(3):436-439.(in Chinese))
[10]陆明,刘惠斌,王晨光,等.新型TDR土壤水分测定仪SOILTOP-200的开发及应用[J].水利信息化,2017(2):31-37.(LU Ming,LIU Hui-bin,WANG Chen-guang,et al.Development and application of the new TDR soil moisture meter soiltop-200.Water Resources Informatization,2017(2):31-37.(in Chinese))
[11]DEBYE P.Polar molecules[M].New York:Chemical Catalog Company,1929.
[12]SANTAMARINA J C,KLEIN A,FAM M A.Soils and waves:particulate materials behavior,characterization and process monitoring[J].Journal of Soils&Sediments,2001,1(2):130-130.
[13]张鹏.主要因素对土壤介电特性的影响分析研究[D].西安:西北农林科技大学,2013.(ZHANG Peng.Analysis to effects of main factors on dielectric properties of soils[D].Xi'an:Northwest Agricultural and Forestry University of Science and Technology,2013.(in Chinese))
[14]TOPP G C,YANUKA M,ZEBCHUK W D.Determination of electrical conductivity using time domain reflectometry:soil and water experiments in coaxial lines[J].Water Resources Research,1988,24(7):945-952.
[15]TOPP G C,DAVIS J L,ANNAN A P.Electromagnetic determination of soil water content:measurements in coaxial transmission lines[J].Water Resources Research,1980,16(3):574-582.
[16]CHEN Y,WANG H,CHEN R,et al.A newly designed TDRprobe for soils with high electrical conductivities[J].Geotechnical Testing Journal,2014,37(1):20120227.
[17]WANG H,CHEN R,QI S,et al.Long-term performance of pile-supported ballastless track-bed at various water levels[J].Geotech Geoenviron Eng,2018,144(6):04018035.
[18]陈赟,陈伟,陈仁朋,等.TDR联合监测土体含水率和干密度的传感器的设计及应用[J].岩石力学与工程学报2011,30(2):418-426.(CHEN Yun,CHEN Wei,CHENRen-peng,et al.Design of TDR sensor for joint measurement of soil water content and dry density and its application[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(2):418-426.(in Chinese))
[19]KRAUS D K.Electromagnetics[M].New York:McGraw-Hill Inc,1984.
[20]ZEGELIN S J,WHITE I,JENKINS D R.Improved field probes for soil water content and electrical conductivity measurement using time domain reflectometry[J].Water Resources Research,1989,25(11):2367-2376.
[21]YANUKA M G,TOPP C C,ZEGELIN S,et al.Multiple reflection and attenuation of time domain reflectometry pulses:theoretical considerations for applications to soil and water[J].Water Resour Res,1988,24:939-944.
[22]许伟.TDR表面反射法土体含水率测试理论及技术[D].杭州:浙江大学,2008.(XU Wei.Theory and technology for measurement soil water content by time domain reflectometry surface reflection[D].Hangzhou:Zhejiang University,2008.(in Chinese))
[23]ASTM D4959.Standard test method for determination of water content of soil by direct heating[S].2000.
[24]王进学.离子污染饱和无黏性土电导率特性及TDR测试技术[D].杭州:浙江大学,2007.(WANG Jin-xue.Electrical conductivities of ionic contaminated saturated sandy soils and TDR measurement[D].Hangzhou:Zhejiang University,2007.(in Chinese))