Accession Number:

ADA207302

Title:

Investigations of Dielectric Properties of Some Frozen Materials Using Cross-Borehole Radiowave Pulse Transmissions

Descriptive Note:

Corporate Author:

COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH

Personal Author(s):

Report Date:

1989-03-01

Pagination or Media Count:

26.0

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 dBm, 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.

Subject Categories:

  • Soil Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE