Detection of Density Changes in Soils with Impedance Spectroscopy

Abstract

Measurement of soil parameters, such as moisture, density and density change, can provide important information for evaluating the stability of earthwork structures and for structural health monitoring. To ensure the stability of flood protection dikes, erosion at the contact zones of different soil zones must be avoided. In this work we propose the use of impedance spectroscopy to measure changes in density and volume caused by contact erosion. Erosion leads generally to a volume decrease in the contact zones between soils with different grain sizes and, consequently, to cavities in the dike structure. For this purpose, a proctor mould was developed for emulating contact erosion and the realisation of impedance measurements. Experimental investigations show a correlation between volume change of the soils in the proctor mould and impedance value. For a volume change of soil in the range of approximately 1.5% to 5.3%, an impedance change arises in the range of 17.2% to 29.8%. With several investigations we proof, that it is possible to detect material transport by impedance spectroscopy.