本文關(guān)鍵詞： 熱脈沖技術(shù) Thermo-TDR技術(shù) 土壤耕作層 熱容量 比熱 熱導(dǎo)率 模型 容重　出處：《中國農(nóng)業(yè)大學(xué)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：土壤容重是土壤學(xué)、生態(tài)學(xué)、農(nóng)學(xué)以及工程建設(shè)中一個不可或缺的物理參數(shù)。農(nóng)田土壤作為一種復(fù)雜的三相系統(tǒng),結(jié)構(gòu)呈現(xiàn)很強的時空變異特征,其容重的原位觀測是土壤學(xué)的一個難點。熱脈沖-時域反射(Thermo-Time Domain Reflectometry, Thermo-TDR)技術(shù)基于土壤熱容量和含水量的線性關(guān)系,通過在同體積土壤上同時測定熱容量和含水量,實現(xiàn)田間土壤容重的定位觀測。但熱脈沖技術(shù)測定土壤熱容量易受到探針間距變化以及探針自身有限特性等誤差的影響。本研究基于熱脈沖技術(shù)測定土壤熱特性的誤差分析,對多因子影響的熱導(dǎo)率曲線進(jìn)行定量化研究和模擬,建立和發(fā)展了基于熱導(dǎo)率獲取土壤容重的方法,并在室內(nèi)和田間進(jìn)行了驗證和評估。主要研究結(jié)論如下：第一,有效改進(jìn)了熱脈沖技術(shù)測定土壤熱特性的計算方法,降低了由于探針自身有限特性導(dǎo)致的熱特性估計誤差。我們基于熱傳導(dǎo)方程,利用無限長線性熱脈沖理論(1ulsed infinite line source theory)擬合熱脈沖方法測得的溫度變化曲線的后時段數(shù)據(jù)(late-time data),得到三個土壤熱特性參數(shù),即熱容量(C)、熱擴散率(K)和熱導(dǎo)率(λ),有效地降低了土壤熱特性的測定誤差,并通過三個獨立的熱特性實驗進(jìn)行了驗證。首先,在烘干土上同時利用熱脈沖方法和掃描示差量熱法(DSC)測定了土壤固體的比熱。結(jié)果表明,相比于傳統(tǒng)擬合方法,后時段數(shù)據(jù)方法估計得到的比熱值更為精確,其相對誤差從16.6%降低到3.2%以內(nèi)；其次,在中低含水量下,后時段數(shù)據(jù)方法可以有效降低熱脈沖技術(shù)對土壤含水量的高估誤差；最后,利用一維熱傳導(dǎo)穩(wěn)態(tài)實驗,對干砂土上得到的熱特性進(jìn)行對比表明,后時段數(shù)據(jù)方法估計得到的熱導(dǎo)率和穩(wěn)態(tài)下熱通量板方法得到的最為接近;與完美柱狀熱導(dǎo)體理論解(identical-cylindrical-perfect-conductors theory)比較,在干砂土上,由于探針有限特性產(chǎn)生的C,K和λ的相對誤差分別為6.9%,13.5%和6.0%,與數(shù)值擬合方法得到的誤差值接近。因此,利用后時段數(shù)據(jù)方法可以得到可靠的土壤熱特性數(shù)值,降低了探針本身的有限特性和土壤-探針之間的接觸熱阻導(dǎo)致C的高估以及K和λ的低估誤差。第二,建立了一個基于土壤含水量、容重和質(zhì)地的土壤熱導(dǎo)率新模型,并利用七種土壤的熱導(dǎo)率曲線進(jìn)行了標(biāo)定。新模型為指數(shù)形式,含有兩個參數(shù),分別為砂粒含量、容重以及粘粒含量的函數(shù)。利用填裝土柱實驗數(shù)據(jù)以及文獻(xiàn)熱導(dǎo)率數(shù)據(jù)的驗證結(jié)果表明,新模型可估計得到準(zhǔn)確的土壤熱導(dǎo)率數(shù)值,在變?nèi)葜貤l件下,其預(yù)測熱導(dǎo)率的均方根誤差(RMSE)在0.15 W m-1K-1以內(nèi),偏差在0.10 W m-1K-1以內(nèi)。該模型形式簡單,具有一定的物理意義,在一定容重范圍內(nèi)可以較為準(zhǔn)確地定量化質(zhì)地、含水量和容重因子對熱導(dǎo)率的共同影響。第三,提出了一種原位測定土壤容重的新方法,即利用Thermo-TDR技術(shù)定位測定的熱導(dǎo)率和含水量,結(jié)合本研究提出的熱導(dǎo)率經(jīng)驗?zāi)Ｐ?反推求出土壤容重。在室內(nèi)不同質(zhì)地填裝土壤上的驗證結(jié)果表明,新方法在五種質(zhì)地土壤上給出了較為可靠的容重估計值,其預(yù)測容重的RMSE小于0.17 gcm-3,而且在細(xì)質(zhì)地土壤上結(jié)果較好,在粗質(zhì)地土壤上易受土壤石英含量不確定性對λ的影響。在田間不同耕作處理的定位驗證結(jié)果顯示,該方法得到的土壤容重的相對誤差在10%以內(nèi)。第四,在田間條件下,利用'hermo-TDR技術(shù)監(jiān)測了自然降雨、土壤干濕交替過程中土壤容重和熱特性的時空變異特征以及耕層土壤沉降的動態(tài)過程。利用沉降尺測得了耕層土壤沉降過程中表面高度的動態(tài)變化,同時利用環(huán)刀法和Thermo-TDR方法測定了不同層次土壤容重的動態(tài)變化。結(jié)果表明,降雨對耕層土壤結(jié)構(gòu)影響較大,隨著降雨和干濕交替,土層厚度發(fā)生動態(tài)變化,對環(huán)刀法采樣層次有很大影響；Thermo-TDR方法獲得的耕層容重與環(huán)刀法基本一致,隨時間呈逐步上升趨勢。本研究結(jié)果有利于深入認(rèn)識土壤容重和熱特性之間的互作關(guān)系,對研究土壤水分運動、溶質(zhì)運移、水熱耦合以及其它土壤物理過程具有重要的理論意義和應(yīng)用價值。
[Abstract]:The bulk density of soil is soil science, ecology, an indispensable physical parameters of agriculture and engineering construction. Soil as a complex three-phase system, the spatial and temporal variation characteristics of strong structure, the in situ observation density is a difficult problem in soil science. The heat pulse time domain reflectometry (Thermo-Time Domain Reflectometry, Thermo-TDR) technology linear relationship between soil thermal capacity and water content in soil by the same volume based on the determination of heat capacity and moisture content, bulk density of soil to achieve positioning observation. But the heat pulse to determine the heat capacity of soil technology is easily affected by probe spacing changes and characteristics of the probe itself limited error based on the error analysis technology. Determination of soil thermal characteristics of heat pulse, thermal effects on multi factor curve quantitative analysis and simulation, the establishment and development of the thermal conductivity of soil based on acquisition Methods the soil bulk density, and the validation and evaluation in laboratory and field. The main conclusions are as follows: first, improve the heat pulse calculation methods for the determination of soil thermal properties, reduces the thermal characteristics of the probe itself leads to the estimation error. We limited characteristics based on the heat conduction equation, the infinite linear heat pulse theory (1ulsed infinite line source theory) after the time temperature curve fitting the data measured by the heat pulse method (late-time data), obtained three soil thermal parameters, namely heat capacity (C), thermal diffusivity (K) and thermal conductivity (lambda), effectively reduce the measurement error of soil thermal properties, which is validated by three independent experimental thermal characteristics. First, in the soil and drying by heat pulse method and differential scanning calorimetry (DSC) specific soil solids were determined. The results show that, compared with the traditional fitting Methods after time data obtained specific estimation method is more accurate, the relative error is reduced from 16.6% to less than 3.2%; secondly, in the low water content, after time data method can effectively reduce the heat pulse technique to overestimate the error of soil moisture; finally, using one dimensional steady state heat conduction experiment on dry thermal characteristics on the sand are compared after that time data estimation method in method of thermal conductivity and heat flux obtained under steady state is most close; with perfect columnar heat conductor theory solution (identical-cylindrical-perfect-conductors theory), in the dry sand, due to limited probe characteristics of C, the relative error for K and 2 6.9% respectively, 13.5% and 6%, and the error value close to the numerical fitting method. Therefore, the time data can be obtained numerically reliable soil thermal properties, reduce the probe The contact resistance between the soil properties and the finite probe leads to C and K and a underestimate overestimate error. Second, set up a soil moisture based on the new model, thermal conductivity of the soil texture and bulk density, and rate curve was calibrated with thermal conductivity of seven kinds of soil. A new model for exponential form there are two parameters, respectively, sand content, soil bulk density and clay content. The filling function of soil column experiment data and verified the thermal conductivity data. The results show that the new model can estimate the numerical rate of soil thermal conductivity accurately, in changing bulk density conditions, the root mean square error of prediction of the thermal conductivity (RMSE) within 0.15 W of m-1K-1, the deviation within 0.10 of the W m-1K-1. This model is simple and has a physical meaning, in a certain density range can be accurately quantified texture, water content and bulk density on the thermal conductivity of the common factor . third, this paper puts forward a new method for in situ determination of soil bulk density, namely the use of Thermo-TDR technology positioning determination of thermal conductivity and water content, combined with the thermal conductivity rate the proposed empirical model, inverse derived soil bulk density. In the soil of different texture fills the interior verification results show that the new method is given in the five soil textures more reliable estimates of the predictive density, bulk density RMSE less than 0.17 gcm-3, and in fine textured soils on results in coarse textured soils susceptible to soil content of quartz is the effect of uncertainty on the lambda. In the fields with the positioning cultivation processing results show that the relative error of the method of soil bulk density get in less than 10%. Fourth, in field conditions, natural rainfall monitoring using'hermo-TDR technology, spatial and temporal variability of soil bulk density and thermal characteristics in the process of soil and soil wetting The dynamic process of soil subsidence. The dynamic change of surface height measured soil settlement rule of the settlement process, and the dynamic changes of different levels of soil bulk density was measured using the ring method and Thermo-TDR method. The results show that the rainfall has great influence on the soil structure, with rainfall and dry wet alternation dynamic changes of soil thickness. The blade has a great influence on sampling level; soil bulk density and ring method obtained by Thermo-TDR method are basically the same, showing a gradual upward trend with time. The results of this study is conducive to in-depth understanding of the interaction between soil bulk density and thermal characteristics, study on soil water movement, solute transport, water heat coupling and other soil physical process has important the theoretical significance and application value.

【學(xué)位授予單位】：中國農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S152.5

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 付永威;盧奕麗;任圖生;;探針有限特性對熱脈沖技術(shù)測定土壤熱特性的影響[J];農(nóng)業(yè)工程學(xué)報;2014年19期

2 任圖生,邵明安,巨兆強;利用熱脈沖時域反射技術(shù)測定土壤水熱動態(tài)和物理參數(shù)Ⅱ.應(yīng)用[J];土壤學(xué)報;2004年04期

3 任圖生,邵明安,巨兆強,Horton Robert;利用熱脈沖-時域反射技術(shù)測定土壤水熱動態(tài)和物理參數(shù) Ⅰ.原理[J];土壤學(xué)報;2004年02期

，

本文編號：1505444