Many important properties of the moist soils and other porous media are conditioned by the content, composition, energy states and bulk distributions of a liquid phase (pore solution). A porous medium saturated with a solution represents a peculiar chemotron, i.e. an electrochemical converter of energy, therefore, of the information. The regularities governing these conversions corresponds to particularities of the liquid phase states, as well as to the structural and surface properties of the medium solid matrix.

The laboratory experiments to study the electroacoustic convertation (EAC) were carried out by the electric exciting of the samples placed between the electrodes at which was applied the time variable voltage in frequency range 1 - 20 kHz. The resulting converted acoustic signal was measured by means of piezotransducer and selective microvolt gauge. A special control of frequency, intensity and shape of exciting and measuring voltages was also realized.

It have been found two kinds of EAC - A1 and A2 corresponding to two different electrokinetic mechanisms of the energy transformation, in a moist porous medium.

EAC-A1 is due to an electric osmosis in the diffusive parts of pore solution double layers, when there is the some through permeability of medium. The acoustic signal A1 is measured at the frequency of exciting electric field and linearly correlated with its intensity.

EAC-A2 is conditioned by the ion migrate displacements in spatially limited domains (cells, islands etc) of saturating pore solution. The acoustic signal A2 is measured at the double frequency relatively an exciting field and nonlinearly correlated with it intensity. The magnitudes A2 increase but A1 decrease with some increasing of the degree of liquid phase bulk distribution discreteness.

The series of the quartz sand samples were saturated with solutions of a number salts with a progressively decreasing eutectic temperature (up to -38 C), and with a various initial concentration in the range 0-1 mole/l. Dependencies of both EAC on the ionic composition and concentration of pore solution as well as on the liquid phase content etc. have been established for thawed and frozen (at 0 - -40 C) media.

Joint study and analysis of the linear and nonlinear EAC variations in moist soils are useful as a new technique to estimate the state (degree of bound and of discreteness) of a liquid phase, to monitor of the moisture content and state changes, during the soil freezing, drying or wetting, as well as the structural transformations in the moist soils.

Prof. Anatoly D. Frolov
Apt.128, Leninsky Prospect 64
Moscow 117296, Russia
Phone: (095)-930-26-34
Fax: (095)-253-11-92
E-mail: kvb@kvb.msk.ru.