固体非均匀混合介质频域介电特性测量理论与方法研究

发布时间：2018-02-02 07:25

本文关键词： 岩石介电常数弛豫极化孔隙度　出处：《长安大学》2014年博士论文　论文类型：学位论文

【摘要】：近年来随着微波检测技术在道路工程领域中的应用，用于道路施工的岩石、沙子等非均匀混合介质介电特性的研究成为热点，非均匀混合介质测量理论也成为介电测量技术发展的一个重要分支。非均匀混合介质介电特性主要受界面极化影响，而界面极化发生频率范围较宽。因此，在不同频段对固体非均匀混合介质介电测量技术的研究具有重要意义。文章对固体非均匀混合介质在低频、射频和高频段的介电测量方法展开讨论。在低频段采用电容法，设计一款新型平板电容器。电容器测量原理是将测量样本看做电容和电导并联的等效集总回路，通过测量回路导纳得到样本介电常数。通过对传统电容器结构和算法的改进，提高电容器的测量精度。在射频段，从分析电极间场分布出发，，根据似稳场理论建立极板间导纳的高阶场函数，通过计算贝萨尔零阶场和高阶场函数得到样本介电常数。此方法有效提高射频段电容器测量精度和测量频率上限，使得对非均匀介质宽频介电谱测量成为可能。在高频段,提出了基于微带线结构的谐振微带环和平行微带线的介电测量方法。微带环采用微扰原理。微带环紧贴测量样本，构成等效回路，样本介电常数差异会影响微带环电场分布，微带环的谐振频率与品质因数发生扰动，通过计算这种变化可得到样本的介电常数；平行微带线利用相位法，通过检测微带线插入样本前后相位的变化来计算样本的介电常数。平行微带线结构不同于传统的微带传输线结构，是将微带线底层的接地板改为与顶层相同的微带线结构，这种结构不仅保持微带线原有传输模式，同时增强边缘电场分布，从而提高测量分辨率和精度。与传统的平行线、同轴线、波导和谐振腔相比，这两种微带线结构的测量方法对样本尺寸加工精度要求低，适合固体材料测量。在较高频段，岩石等混合介质介电常数受其电导率的影响较小，因此，采用不同检测方法分别对沙子含水量，饱水砂岩孔隙度等物理参数进行实验测量，并对实验结果采用经验公式进行验证。在低频至射频段，采用平板电容器分别对用作路基的饱水岩石、油气岩石和泥质岩石的介电谱进行测量与讨论，对多弛豫过程和低频弛豫强度异常增大现象进行分析；对模拟路面结构的两相和三相平板电容模型的介电谱进行解析计算和实验测量，将计算值与测量结果进行比对分析。
[Abstract]:In recent years, with the application of microwave detection technology in the field of road engineering, the study of dielectric properties of non-uniform mixed media such as rock and sand used in road construction has become a hot topic. Non-uniform mixed dielectric measurement theory has also become an important branch of dielectric measurement technology. The dielectric properties of non-uniform mixed media are mainly affected by interface polarization, and the frequency range of interface polarization is wide. It is of great significance to study the dielectric measurement technology of solid heterogeneous mixed medium in different frequency bands. In this paper, the dielectric measurement methods of solid inhomogeneous mixed medium at low frequency, radio frequency and high frequency are discussed. The capacitance method is used in low frequency band. A new type of flat capacitor is designed. The measuring principle of the capacitor is to regard the measurement sample as the equivalent lumped circuit of the capacitance and conductance in parallel. The dielectric constant of the sample is obtained by measuring the admittance of the circuit. The measurement accuracy of the capacitor is improved by improving the structure and algorithm of the traditional capacitor. In the RF section, the field distribution between the electrodes is analyzed. According to the theory of quasi-stable field, the higher-order field function of admittance between polar plates is established. The dielectric constant of the sample is obtained by calculating the zero-order field and high-order field function of Beisal. This method can effectively improve the measurement accuracy and the upper limit of the measurement frequency of the RF capacitor. It is possible to measure the wide frequency dielectric spectrum of non-uniform medium. In the high frequency band, the dielectric measurement method of resonant microstrip ring and parallel microstrip line based on microstrip line structure is proposed. The microstrip ring adopts perturbation principle, and the microstrip ring clings to the measurement sample to form an equivalent circuit. The dielectric constant of the sample will affect the electric field distribution of the microstrip ring. The resonance frequency and quality factor of the microstrip ring will be disturbed. The dielectric constant of the sample can be obtained by calculating the variation. Parallel microstrip lines use the phase method to calculate the dielectric constant of samples by detecting the phase changes before and after the microstrip lines are inserted into the samples. The parallel microstrip line structure is different from the traditional microstrip transmission line structure. The bottom floor of the microstrip line is changed to the same microstrip line structure as the top layer, which not only maintains the original transmission mode of the microstrip line, but also enhances the electric field distribution at the edge. Compared with the traditional parallel line, coaxial line, waveguide and resonator, these two microstrip structure measurement methods require less precision of sample size processing, and are suitable for solid material measurement. In the higher frequency band, the dielectric constant of rock and other mixed media is less affected by its conductivity. Therefore, the physical parameters such as sand water content and saturated sandstone porosity are measured by different testing methods. The experimental results are verified by empirical formula. The dielectric spectra of saturated rock, oil and gas rock and muddy rock used as subgrade are measured and discussed by plate capacitor in low frequency to radio frequency range. The multi-relaxation process and the abnormal increase of low-frequency relaxation intensity are analyzed. The dielectric spectrum of the two-phase and three-phase flat capacitor models of simulated pavement structure is calculated and measured by experiments. The calculated values are compared with the measured results.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM934.3;U416.0

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