ABSTRACT

Geotechnical centrifuges of various sizes have been used to obtain the hydraulic properties and model the behaviour of unsaturated soils. Centrifuges that are capable of taking inflight and real time pressure and flow measurements tend to be large, complex and expensive to operate. Whereas smaller centrifuges are simpler and have much smaller preparation and testing times, but have little to no real time or inflight measuring systems because of space and weight restrictions. In this study, a Beckman Coulter J6-M1 centrifuge with a diameter of 280 mm and a swinging bucket assembly was modified so that the pore water pressure in unsaturated soil samples could be measured and recorded inflight. Miniature pore pressure transducers were embedded into the soil sample and were also connected to an on board power source and wireless data acquisition system. Battery powered wireless cameras were mounted onto the specimen holder so that the sample could be visually monitored in real time. Results are presented to demonstrate the ability of the system to monitor dynamic moisture changes in the soil and show how these vary with initial degree of saturation. The advantages and limitations of small centrifuges for these studies are discussed.