Abstract
There have been marked improvements during the past 20 years in overall soil exploration practices in North America. Much of the improvement is the result of the stringent requirements associated with subsurface investigations of nuclear power plant sites. The improved practice includes block sampling in both cohesive and noncohesive deposits, the use of rotary drilling with mud in conjunction with a fixed-piston sampler, and the freezing of undisturbed samples of granular soil after they have been drained to minimize sample disturbance during shipment or handling. In-situ freezing of granular deposits as a means of stabilizing the soil, before sampling is a promising new concept, and X-radiography has proven to be a powerful tool in studies of soil structure and sample disturbance.