Investigations of Dielectric Properties of Some Frozen Materials Using Cross-Borehole Radiowave Pulse Transmissions
Abstract
Pulsed radiowaves have been transmitted between boreholes at specially prepared sites in central Alaska to determine physical properties of the intervening material. The boreholes were drilled 12-25 m deep in both ice- rich silt and frozen alluvium materials commonly found in the Alaskan interior. The pulse spectra were centered near 100 MHz and were analyzed to obtain the ground dielectric constant epsilon and the attenuation rate beta, which were then correlated with material type, water content and temperature. The ice-rich silt, which had volumetric ice contents between 47 and 70%, gave epsilon values between 4 and 7 and beta values between 2 and 4 dB/m, thus limiting the use of our commercial equipment to borehole spacings of less than 20 m. For this material, epsilon correlated well with volumetric ice content but not with temperature. In a deep section (25m), dielectric contrasts were seen between ice-rich silt, massive ice and frozen gravel. Keywords: Alaska; Dielectric properties; Frozen soils; Radiowaves; Site surveys.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1989
- Accession Number
- ADA207302
Entities
People
- Allan J. Delaney
- Steven A. Arcone
Organizations
- Cold Regions Research and Engineering Laboratory