Block sampling and test sample preparation of locked sands

After a long period of neglect there has been increasing interest in the sand/sandstone borderline materials, especially concerning the fabric components of their structure (Barton, 1993; Cuccovillo & Coop, 1997; Cuccovillo & Coop, 1999). An interlocked fabric in sands cannot be produced artificially, and investigations have to be carried out on intact samples of these materials. Progress has been delayed by the problem of sampling sands that owe their strength solely to fabric and have little or no bonding. They are extremely friable but resist cutting, owing to the dilation that occurs on disturbance. Locked sands are cut or reduced in size by a process of grain plucking, which can be achieved by abrasion or a scraping action. This paper describes advances made in cutting the samples out of the ground and manipulating them to the shape required for a test specimen. Although the saws were developed for locked sands they have been found useful for other materials such as clayey silts.