基于瞬变电磁反演的浅海掩埋小目标探测方法研究

Limited from detecting means, the detection of small buried objects underwater is a global challenge. The high reverberation interference and multipath effect in underwater environment, especially in very shallow water area, aggravate the difficulty of acoustic detection. However, the application of non-magnetic target makes the detection of magnetic method greatly restricted. Therefore, it is in need of developing an effective method in detection of underwater buried-objects. Transient electromagnetic method (TEM) is a time-domain active electromagnetic induction method, it is based on the difference of electric and magnetic between the target and the sediments around, the change of electric field and magnetic field of the seafloor target can be evaluated by the principle of electromagnetic induction, which can provide more target information than acoustic techniques, such as target conductivity, spatial location, size, etc. In this study, we introduce transient electromagnetic measurement and interpretation technology in the field of geosciences into underwater target detection. Through the combination of theoretical simulation analysis and experimental data processing, the study focuses on the interference suppression of TEM response and 3D inversion technique. The research results of this project can serve as an effective complement to traditional acoustic exploration, which will offer theory basis for the comprehensive underwater detection with multi-physics field in the future.

对水下掩埋小目标的探测一直是全球性的难题。水下环境特别是甚浅水区域的混响及多途干扰等因素加重了声学探测的难度，而目标磁隐身技术的发展使得磁法探测受限，因此亟需发展一种有效的水下掩埋小目标探测新方法。本研究引入地球科学领域中的瞬变电磁方法，它是一种时间域主动电磁探测方法，其基于海底掩埋目标与周围介质之间的电性差异，通过有效的三维反演解释技术能够提供丰富的目标体信息（如电导率、三维空间位置、尺寸等），实现对水下掩埋目标的初步辨识。本研究通过数值仿真与试验验证相结合的方式，在分析水下瞬变电磁场传播规律及目标特性的基础上，重点研究浅海环境条件下瞬变电磁场干扰抑制技术及三维反演解释技术，最终实现浅海掩埋小目标的有效探测。本项目的研究成果能够作为传统声学探测的有效补充，为今后开展多物理场的综合探测研究奠定必要基础。

针对浅海掩埋小目标的探测与识别一直是全球性的难题，准确探测、识别水下掩埋目标对于浅海工程、军事及资源勘探领域具有重要的现实意义。水下环境特别是甚浅水区域的混响及多途干扰等因素加重了声学探测的难度，而目标磁隐身技术的发展使得磁法探测受限。在此背景下，本项目引入地球科学领域中的瞬变电磁方法，在分析水下瞬变电磁场传播规律及目标特性的基础上，开展浅海环境条件下瞬变电磁场干扰抑制技术及反演解释技术研究。.本项目基于三维矢量有限单元法实现海底全空间条件下瞬变电磁响应的三维正演模拟，并在此基础上建立浅海瞬变电磁三维模型，细致分析浅海掩埋小目标的瞬变电磁响应特征及其电磁场传播规律，为探测的最优化设计和数据处理提供了有价值的理论依据。实现了任意发射波形条件下浅海瞬变电磁全时响应模拟，并通过三维正演分析给出浅海瞬变电磁发射波形和系统参数的选取原则。结合仿真与试验数据从发射源姿态响应分析与校正、信号噪声干扰抑制等方面开展研究，提取浅海掩埋小目标瞬变电磁的有效信号。最后，利用不同目标在电导率等特征方面的差异，通过全域视电导率定义与非线性反演技术实现浅海掩埋小目标的有效检测并通过水池试验验证。.本项目研究成果进一步拓展了现有水下目标探测的技术类型，为今后开展多物理场综合探测研究提供了重要的理论依据，对提高水下掩埋目标探测水平于具有重要的科学意义。此外，研究成果在海底工程勘察、水下考古及资源勘探等领域具有重要的应用价值和应用前景。