Pressure profile measurements using Spatial-TDR

Many applications in geotechnical engineering require the knowledge of total pressure distributions. So far, only measurements at individual locations can be carried out with conventional geotechnical devices. A novel approach has been investigated to determine pressure profiles from the time domain reflection data of transmission lines. Mechanical forces change the distance between rubber-insulated conductors which then changes the capacitance and inductance of the transmission line. These variations lead to partial reflections of an incident step pulse, from which physical parameter distributions are reconstructed using an inversion algorithm (Spatial-TDR). Laboratory investigations illustrate the applicability of this approach for the indirect measurement of mechanical pressures.