矿井瞬变电磁法超前探测合成孔径成像研究

在矿井瞬变电磁超前探测数据处理和解释中,为了更好地识别巷道前方含水体电性分界面,利用扩散场与波动场间的函数关系,将矿井瞬变电磁法超前探测中瞬变电磁波场转换为拟地震波场,实现波场转换.同时,为了解决波场转换后信号幅值偏弱,以增加信噪比利于解释,利用雷达的合成孔径方法对波场转换后的拟地震信号进行相关叠加处理.将矿井瞬变电磁法巷道超前探测的同一测点不同探测方向的数据作为孔径数据进行合成孔径成像,以突出弱异常而提高信噪比,结合应用实例验证了方法的效果.研究表明,矿井瞬变电磁法合成孔径成像方法能够提高电性界面信息的信噪比和界面几何分辨率,对矿井瞬变电磁法精细超前探测含水构造具有重要的理论意义和应用价值.

Synthetic aperture imaging in advanced detection of roadway using the mine transient electromagnetic method

During the data processing and interpretation of the mine transient electromagnetic method (MTEM), it is an important goal to improve the identification of the geo-electrical interface between low resistivity abnormal body and surrounding rock in advanced detection. To achieve this end, the transient electromagnetic field is transformed into the pseudo-seismic wave-field based on the function relationship between spreading electromagnetic field and seismic wave-field in whole-space. Meanwhile, the signal of pseudo-seismic after transform is processed with correlative stack to strengthen the amplitude and improve signal-noise-ratio (SNR) using the synthetic aperture imaging(SAI). The data of different detection directions on one surveying point in the MTEM are imaged as aperture data, which would highlight weak anomalies and improve SNR. In addition, the application effect of SAI was testified with the in-site advanced detection in roadway using the MTEM.The results show that the SAI of the MTEM can improve SNR of the electrical interface information and highlight the geometrical resolution to increase exploration accuracy. The technique is significant theoretically and practically in accurate advanced detection of aquifer structure by the MTEM.