土壤含水率探地雷达响应特征研究

发布时间：2018-06-02 12:25

本文选题：土壤含水率 + 探地雷达　；参考：《中国矿业大学》2017年硕士论文

【摘要】：为给农田灌溉技术和沙漠化治理等提供更好的方案依据,探明土壤含水率的分布情况就显得尤为重要。相对其他探测方法,探地雷达(GPR)探测土壤含水率更能突出高分辨率、无损、高效等优点,应用探地雷达检测土壤含水率成为近年来新的研究方向。基于时域有限差分正演模拟了不同含水土壤模型,分析了其对应的雷达信号在时频域中的响应特征。针对雷达不同探测方式对含水土壤的探测效果进行了对比,结果表明,雷达同步法探测效果相对较好;同时,利用雷达波场分析了土壤含水颗粒尺寸大小对含水构造探测效果的影响,分析表明,在一定的尺寸范围内,含水颗粒尺度越大对雷达信号影响就较大。对探地雷达信号频域分析可以发现,在频谱图中,不同含水体在频谱图上具有明显区别;在功率谱分析中,结合经典和现代功率谱分析,可以对含水目标ROI进行提取,最终确定含水体的分布范围和含水率的相对大小;在谱能分析中,将谱能系数和小波分析相结合得到三维谱能分析图,得到的三维含水体土壤谱能图能更直观的解释含水体的附存状态。与此同时,考虑到电磁波在含水土壤传播过程中高频成分衰减较快,致使探地雷达的分辨率会随深度的增加而降低的问题,本文采用了基于S变换的频谱均衡技术给予矫正,且矫正效果良好。为了更好的验证解释方法的有效性,本文对数值模拟中设计的孤立异常体地质模型和异常组合地质模型进行了物理模型实测,解释结果表明利用所提的时频域解释方法能有效的提高实测数据解释效果。通过以上研究,初步得到土壤含水率与探地雷达信号响应关系,但理论和实际应用仍需要进一步开展。
[Abstract]:In order to provide better basis for farmland irrigation technology and desertification control, it is very important to find out the distribution of soil moisture content. Compared with other detection methods, GPR (ground penetrating Radar) for soil moisture content detection has the advantages of high resolution, nondestructive, high efficiency and so on. In recent years, the application of GPR to soil moisture detection has become a new research direction. Based on the finite difference time domain (FDTD) forward modeling, the response characteristics of the corresponding radar signals in time-frequency domain are analyzed. The results show that the detection effect of radar synchronization method is relatively good, and at the same time, The effect of the size of soil water-bearing particles on the detection effect of water-bearing structures is analyzed by using radar wave field. The results show that the larger the size of water-bearing particles is, the greater the effect on radar signals is in a certain range of dimensions. In the frequency domain analysis of ground penetrating radar signal, it is found that different water bodies have obvious differences in the spectrum map, and in power spectrum analysis, the ROI of water-bearing target can be extracted by combining classical and modern power spectrum analysis. Finally, the distribution range of water body and the relative size of water content are determined. In the spectral energy analysis, the spectral energy coefficient and wavelet analysis are combined to obtain the three-dimensional spectral energy analysis map. The three dimensional soil spectral energy map can explain the state of the water body more intuitively. At the same time, considering the high frequency component attenuation of electromagnetic wave in the process of water-bearing soil propagation, the resolution of ground penetrating radar will decrease with the increase of depth. In this paper, a spectrum equalization technique based on S-transform is used to correct the problem. And the correction effect is good. In order to better verify the effectiveness of the interpretation method, the physical model of the isolated anomaly geological model and the anomaly combined geological model designed in the numerical simulation are measured in this paper. The results show that the proposed interpretation method in time and frequency domain can effectively improve the interpretation effect of measured data. The relationship between soil moisture content and ground penetrating radar signal response is preliminarily obtained through the above research, but the theoretical and practical application still needs to be further developed.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152.7

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