Importance

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Abstract

A method and implementing apparatus for measuring in situ the electrical capacitance and resistance of soils and determining therefrom the density and fabric thereof. The apparatus includes a self-contained probe adapted to be driven into the soil to be measured. The probe has a soil sensor element and a measuring circuit such as a capacitance and resistance bridge. The measuring circuit employs radiofrequency current to enable direct measurement at the probe of the resistance and capacitance of the soil sample and of the pore liquid. A remote indicator and control unit in communication with the probe is provided with indicators such as meters or displays which provide direct readout of measured resistance and capacitance, and which may also enable the bridge in the probe to become balanced. Alternatively, the probe may include a computer for automatically balancing the bridge and calculating critical soil properties. The apparatus can automatically register such engineering properties as density, porosity, friction angle, elastic and secant modulus, coefficient of dynamic settlement, stress ratio required to cause liquefaction, and permeability coefficient. The probe and measuring equipment can, alternatively, be manually balanced and the engineering properties and related properties can be hand calculated. The concept outlined and apparatus can be extended or modified for a wide variety of other uses also.

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First Claim