隧洞施工不良地质与岩体结构钻孔定向雷达超前探测三维精细成像理论研究

A detailed detection of adverse geology and rock mass structure is crucial for the analysis, early-warning, prevention and control of water and mud inrush, instability and collapse of rocks in tunnel. Thus, a theoretical study of three-dimensional (3D) detailed imaging with directional borehole radar advanced detection is of great importance. However, for single borehole radar at home and abroad, one key problem is ‘unable to obtain the correct azimuth angle of target body and the real image’. Therefore, for borehole radar directional detection and detailed imaging, we propose an idea of ‘emitting directional electromagnetic beam rotationally, calculating azimuth angle by receiving arrays, obtaining 3D image by reverse-time migration’. Through the study of propagation property of electromagnetic wave and directional emitting method, one major breakthrough is the calculation theory of target body azimuth angle based on the difference of the same source signal among receiver antenna arrays. Then we propose a 3D directional borehole radar imaging theory based on full waveform inversion and high-precision reverse-time migration. After systematic numerical simulations, physical model tests and engineering verifications, a directional borehole radar detection theory and method integrated with calculation of azimuth angle, 3D migration imaging is proposed, which provides scientific theory and practical method for detailed detection and accurate imaging of adverse geology and rock mass structure in tunnel.

不良地质和岩体结构的精细探测对于隧洞突水突泥、失稳塌方灾害的分析、预警和防控十分重要，因此开展钻孔定向雷达超前探测三维精细成像理论研究具有重要意义。然而，目前国内外单孔钻孔雷达存在“无法获取目标体方位角与真实成像”的关键难题。为此，提出了“旋转发射定向电磁波束、阵列接收解算方位角、逆时偏移获取三维成像”的钻孔雷达定向探测与精细成像思想。在研究电磁场传播特性及定向发射方法的基础上，重点突破基于阵列接收子天线之间同源信号差异的目标体方位角解算理论，进而提出基于全波形反演与高精度逆时偏移的钻孔定向雷达三维成像理论，通过系统的数值模拟、物理模型试验与工程验证，最终形成集方位角解算和三维偏移成像于一体的钻孔定向雷达探测理论和方法，为隧洞不良地质和岩体结构的精细化探测和较准确成像提供科学理论和实用方法。

不良地质和岩体结构的精细探测对于隧洞突水突泥、失稳塌方灾害的分析、预警和防控十分重要，因此开展钻孔定向雷达超前探测精细成像理论研究具有十分重要的意义。然而，目前国内外单孔钻孔雷达存在“无法获取目标体方位角与真实成像”的关键难题。为此，提出了“旋转发射定向电磁波束、阵列接收解算方位角、逆时偏移获取成像”的钻孔雷达定向探测与精细成像思想。本项目实现了基于柱坐标的FDTD计算方法，研究了钻孔定向雷达三维时间域仿真方法和隧道复杂环境钻孔定向雷达电磁波场传播特征，提出了基于ESPRIT算法的四联阵列天线数据处理方法，完成了基于反射板聚焦的钻孔定向雷达天线设计和基于铁氧体加载的高增益钻孔定向雷达天线设计，进而研究了基于全波形反演与高精度逆时偏移的钻孔定向雷达成像理论，通过系统的数值模拟、物理模型试验与工程验证，最终形成了一套钻孔定向雷达探测理论和方法，为隧洞不良地质和岩体结构的精细化探测和较准确成像提供科学理论和实用方法。