大洋海底富钴结壳厚度声学原位测量算法研究

Manganese crust thickness is an important factor for manganese resource assessment and mining. If core samples of deep seabed shallow strata are drilled with rig, the measurement results will be accurate. But core sampling is time-consuming and inefficient. Measuring manganese crusts thickness with acoustic methods could improve survey efficiency. In this project, manganese crust samples are measured for designing acoustic waveform and analyzing variation law of measurement error changing with incident grazing angle. Based on the characters of acoustic backscatter signal, the thickness estimation algorithm is proposed. Then, variation law of measurement error changing with incident grazing angle is used to improve measurement accuracy of manganese crust thickness. The tank experiments will be implemented to verify the measurement accuracy of manganese crust samples and man-made large crust plate. The proposed method could be implemented at low altitudes using underwater platforms such as Human Occupied Vehicles or Remote Operated Vehicles. It could improve survey accuracy and efficient of manganese crusts. It is of great significance in study on metallogenetic mechanism and distribution on seamount of manganese crusts.

结壳厚度是富钴结壳资源评估的重要参数，对于资源量评估与开采具有重要意义。利用浅钻取样测量结壳厚度的精度高，但取样难度大、效率低；利用声学手段测量结壳厚度可提高富钴结壳资源调查效率。本项目首先利用已有富钴结壳样品开展用于结壳厚度测量的最佳发射声信号形式研究，分析不同入射掠射角的后向散射声信号特征与厚度测量误差规律；基于不同入射掠射角后向散射声信号特征，研究富钴结壳厚度声学原位测量算法；利用不同入射掠射角测量误差规律修正测量结果，提高富钴结壳厚度测量精度。通过水池试验对富钴结壳样品及仿制大板块结壳样品进行测量，验证结壳厚度测量算法。项目研究算法今后可利用载人潜水器或水下遥控机器人近底航行实现结壳厚度原位快速测量，提高富钴结壳资源调查精度与效率，为海山富钴结壳成矿研究以及分布规律研究提供支撑。

结壳厚度是富钴结壳资源评估的重要参数，对于资源量评估与开采具有重要意义。利用浅钻取样测量结壳厚度的精度高，但取样难度大、效率低；利用声学手段测量结壳厚度可提高富钴结壳资源调查效率。本项目利用已有富钴结壳样品开展了富钴结壳声学后向散射特性研究，测量获得了从90kHz~200kHz频段内的富钴结壳后向散射强度，可为多波束及侧扫声纳等基于声学后向散射特性评估结壳覆盖度的方法提供基础参数支撑。同时，本项目开展了富钴结壳厚度测量算法研究，提出了一种基于快速能量中心收敛法的结壳厚度快速计算方法。在实验室利用仿制结壳样品对提出的算法进行了验证，试验结果验证提出的算法可以精确估计出结壳的厚度。研究算法收敛快，适合于利用嵌入式技术实现，为进一步研制便携式富钴结壳厚度测量装置奠定良好的基础。