Apparatus for measuring the permeability of ground and more particularly formations with very low permeability, of the double ring type

摘要

The present invention relates to an apparatus for measuring the permeability of ground and more particularly formations with very low permeability, comprising two cylindrical coaxial annular rings driven into the ground and containing respectively a central level of water contained in the inner ring and an annular level of water contained in the space between the two rings. This apparatus comprises, at the upper part of the inner ring 2, a proximity sensor 7 which forms part of an oscillating circuit, associated with a float 8 floating on the surface of the central level of water and carrying an element which alters the resonant frequency of the oscillating circuit as a function of its distance with respect to the sensor, and a frequency measurer 9 connected to the proximity sensor in order to determine the resonant frequency of the oscillating circuit and in order to provide, from this measurement, an indication of the coefficient of permeability of the ground. IMAGE