基于菲涅尔带理论的无线电波层析正则化方法研究

发布时间：2018-12-14 22:05

【摘要】：无线电波透视法是常用的工作面地质构造探测方法之一,目前煤矿上多采用基于射线理论的联合代数重建(SIRT)层析方法反演介质电磁波衰减系数.由于发射的电磁波频率范围在几百千至几兆赫兹,基于高频近似的射线理论在模拟电磁波传播时存在局限性,而SIRT方法本身受矿井观测方式的限制,在垂直测线方向反演分辨率不高.本文研究基于菲涅尔带理论的正演方法,电磁波频率越高其第一菲涅尔带半径越小,即越接近射线条件;采用约束正则化方法进行层析成像,推导了Tikhonov正则化的最小化问题表达式,说明了正则参数的作用和意义,利用迭代反演法求最优折衷解.对不同异常模型及实际资料进行了层析成像实验,结果表明对于低频电磁波菲涅尔带理论分辨率优于射线理论,正则化方法具有更好的分辨率,识别出的异常构造基本吻合已知疑似构造位置,说明了其在实际应用中的可行性.
[Abstract]:Radio wave perspective method is one of the commonly used methods to detect geological structure in coal face. At present, the combined algebraic reconstruction (SIRT) tomography method based on ray theory is used to retrieve the attenuation coefficient of electromagnetic wave in coal mine. Because the frequency range of electromagnetic wave is from several hundred to several megahertz, the ray theory based on high frequency approximation has limitations in simulating electromagnetic wave propagation, but the SIRT method itself is limited by mine observation mode. The resolution of inversion in vertical line direction is not high. In this paper, the forward modeling method based on Fresnel band theory is studied. The higher the frequency of electromagnetic wave is, the smaller the radius of the first Fresnel band is, that is, the closer the ray condition is. In this paper, the constrained regularization method is used for tomography, and the minimization problem expression of Tikhonov regularization is derived. The function and significance of the regularization parameters are explained, and the optimal compromise solution is obtained by iterative inversion method. Experiments on different anomalous models and actual data show that the theoretical resolution of Fresnel band of low-frequency electromagnetic wave is better than that of ray theory, and the regularization method has better resolution. The identified anomaly structure is basically consistent with the known suspected structure location, which shows its feasibility in practical application.
【作者单位】：国土资源部海底矿产资源重点实验室;中国地质调查局广州海洋地质调查局;中国地质大学(北京);
【基金】：国家自然科学基金(40804024) 海西(平潭-湄洲湾)海岸带综合地质调查(GZH201400211)联合资助
【分类号】：TD163.1;P631.3

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