Polarimetric borehole radar measurement at the Mirror Lake test site

摘要

Abstract: In order to understand the potential of polarimetric borehole radar, field measurement was carried out at the Mirror Lake fractured-rock research site (NH, USA), in October 1998. The polarimetric borehole radar system can measure the full- polarimetry in a borehole by changing antenna arrangements. We developed a network analyzer based stepped-frequency radar. The radar penetration depth from the borehole in the reflection measurement was over 10 m, in the frequency range of 2 - 200 MHz. We could observe many clear reflections form fractures in each polarization state. Even in the raw data, we could observe the difference in the radar profile for different polarization states. Polarimetric future for the acquired data is analyzed and it was found that the depolarization effect is different in each fracture. We think this is closely related to the roughness of each fracture, and it is also related to physical properties of the fracture such as water permeability. Cluster analysis was tested for classification of fractures. !6