Effect of various storage times for a block sample. Experiences with sample tubes coated with a low friction polymer and a new piston sampler, all on Onsøy clay

Abstract

This report contains the results of four CAUC triaxial tests, two being performed on block samples and two on 72 mm tube samples. The tests were all performed on plastic clay from Onsøy. The purpose with the block samples was to see if there is any significant improvement in sample quality whether the sample is mounted into the triaxial in the field compared to when it is transported to the laboratory and mounted into the triaxial cell several days later. However, no improvement was observed in sample quality for the test on the sample being mounted in the field. One of the two tube samples was sampled with the ordinary NGI 72 mm piston sampler, but the sample tube was smeared on the inside and the outside with a low friction polymer. However, again, no improvement in sample quality. The other tube (72 mm) sample was sampled with a new piston sampler for a remote operated drilling system (Santos et al, 2015). However, during removal of the sample tube from the sampler a suction was created that spoiled the sample so no conclusion can be drawn regarding this sampler in this case