Measurement variability of calibration factor of earth pressure cells with different contact materials

Abstract

The earth pressure cells (EPC) response is highly dependent on the contacting material which is not always a soil, as several other materials are also used in geotechnical engineering. In the present study, 30 nos. of EPCs are calibrated with river sand and geofoam (EPS15) as contacting materials, as these EPCs are being used in the field to investigate suitability of the geofoam inclusion. The variability of individual EPCs with different contacting materials is determined by calculating the coefficient of variation (COV) of the calibration factor. The COV for manufacturer’s calibration factor is 2.61%, which increases significantly to 8.22% for river sand and 7.14% for EPS15 as contacting materials, demonstrating the importance of EPC's proper calibration for reliable measurement of earth pressures. The EPC calibration factor determined in the present study is significantly different from that provided by the manufacturer, which invariably bring significant error in pressure measurement with these EPCs.