On long-term direct measurement of suction in soft soils

High Capacity Tensiometers (HCTs) have recently received significant interest in laboratory measurements of soil suction mainly due to their fast response time, accurate measurements, and ease of transport and installation in geotechnical apparatuses. An HCT is typically comprised of a strain-gauged diaphragm for pressure measurement, a water reservoir and a high air-entry porous ceramic filter as the interface between the soil and the pressure measurement system. The major drawback of the HCTs is occurrence of cavitation in the water reservoir and the porous ceramic before pressure equalisation. Recent studies on the development of HCTs have focused on identifying experimental procedures for expanding the range and duration of suction measurements. In this work a new HCT is designed and constructed. In this design, a new technique is employed to account for the potential of cavitation occurrence during suction measurement. The functionality of the developed tensiometer is examined through a number of element level tests and it is shown that the newly designed HCTs are capable of providing an improved response, in both range and duration, for suction measurements.