Obtaining high-quality undisturbed sand samples remains a challenge. In this paper, a ground freezing for sampling campaign is presented in detail. The campaign, was performed at a sandy–silty research site, known as Øysand, near Trondheim, Norway. The site was thoroughly characterized using state-of-the-art techniques; ground freezing for sampling was designed and then successfully implemented in the field. Monitoring data, from pressure cells and thermistor strings, during ground freezing are presented in the light of sample disturbance. An overview of the samples obtained and lessons learned from the field campaign are discussed, together with a rigorous qualitative assessment of the frozen sand sample quality, which was carried out in the laboratory using microcomputed tomography (μCT). Based on the μCT-scans, we concluded that there are no signs of ice lenses, nor rotation of particles around the cored edges, and no cracks formed within the frozen mass. The sand samples obtained are believed to be of the highest quality. Finally, quantitative image analysis of the three-dimensional CT scans comparing the void ratio distributions of a ground-frozen sample and a conventionally sampled counterpart substantiates the hypothesis that ground freezing was able to recover minimally disturbed, representative high-quality sand samples. This study expands on previous experience of the few well-documented cases where ground freezing for sampling was successfully used.
Quinteros et al. (Sat,) studied this question.