Sampling of Saturated and Unsaturated Sands by Freezing
A 600-mm-long, 100-mm-wide, and 20-mm-thick steel plate containing a wavey groove carrying chilled ethanol at -40°C was used successfully to obtain undisturbed frozen samples of saturated clean sand. The freezing probe was also used in an unsaturated sand dune to obtain samples at a depth of 3.0 m. For sands above the groundwater level, an imbibition test is, however, required prior to freezing in order to increase the in situ water content and bond the sand particles as freezing proceeds. The prismatic freezing probe is very efficient and produced frozen sand masses having an outside diameter of 26 cm after 4 h of freezing. Pushing the probe into the ground resulted in a disturbed zone of about 3 to 5 times its thickness.