An experiment performed in the city of Yakutsk using vertical electrical sounding (VES) and ground penetrating radar (GPR) methods has provided more insight into the petrophysics of frozen rocks in the zone of interaction with engineering structures down to the bedrock of the Lena River valley. The variation coefficients indicate that the basic electrophysical property (electrical resistivity) and the resulting radiophysical property (attenuation of electromagnetic waves) are sensitive to lateral and vertical variations in texture, condition and properties of the permafrost material, while propagation velocity exhibits no significant response. The cluster and correlation analyses have shown a statistical relationship between the group average values of resistivity and attenuation which are theoretically related in cause and effect. This relationship is adequately described by the power function equation with a high level of determination. The same equation describes the equally strong correlation between attenuation and velocity. Therefore, the inverse regression equations can be used to obtain additional information on the radiophysical properties of frozen rocks and vice versa from VES and ERT data. In other words, permafrost resistivities can be derived with the GPR method. The maximum error of such transformations is low even without grouping the initial data, being 8,7% for attenuation, 13,7% for velocity, and 17,5% for resistivity. This level of accuracy is sufficient for approximate solution of geotechnical tasks at the initial stages of engineering site investigations in Yakutsk and its vicinity.

Neradovskii Leonid Georgievich, Doc. Sc. (Eng.), Senior Research Scientist, Laboratory of Engineering Geocryology, Melnikov Permafrost Institute SB RAS, 677010, Yakutsk, Permafrost streed, 36. E-mail: leoner@mpi.ysn.ru.

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