A Flat Dilatometer to Operate in Glacial Tills

Abstract

The Marchetti flat dilatometer is a simple to operate in-situ testing device that was designed for use in clays, silts, and sands. A new dilatometer has been developed for use in a greater variety of soil types, in particular glacial tills. This probe is more robust than the Marchetti dilatometer because it uses a rigid piston instead of a flexible membrane to load the soil. The new dilatometer is also a research dilatometer incorporating a displacement transducer and pressure transducer. This allows an applied pressure displacement curve to be produced. Tests have been carried out at several sites to compare results from the two dilatometers, check the robustness of the new dilatometer, and produce data to establish new correlations.

Marchetti Flat Dilatometer Tests in a Virtual Calibration Chamber

“…However, instead of a flexible membrane, a rigid piston with diameter of 60 mm was introduced. This alternative design has previously been implemented in several research DMT (Akbar andClarke 2001, Colcott andLehane 2012). Work with those apparatus shows that the piston solution allows larger displacements in the expansion phase.…”

“…The electromechanical principle underlying standard DMT measurements offers robustness and repeatability, but with just two pressure values, relatively little information is obtained from the test. Modified dilatometers, usually built for research purposes (Campanella and Robertson 1991, Fretti, Lo Presti, and Salgado 1992, Akbar and Clarke 2001, Stetson, Benoit, and Carter 2003, Colcott and Lehane 2012, are able to register the complete load-displacement curve of the membrane. Frequently these research dilatometers also acquire other measurements, like pore pressure on the blade or resistance to DMT blade penetration, q d .…”