State of the Art of Undisturbed Sampling of Cohesionless Soils
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
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An important phase of any major site investigation is the obtaining of high-quality undisturbed samples of the subsurface materials. This report describes the current state of the art in obtaining undisturbed samples of cohesionless material--specifically, sands, silts, gravels, and mixtures-- primarily as it is reflected in the experience of the Waterways Experiment Station WES and of others on the North American continent. The report discusses general considerations in planning an undisturbed sampling program methods of access to the soil materials for sampling, testing, or observation and methods of sampling cohesionless soil. It is concluded that a high- quality, undisturbed samples of many sands can be obtained with a fixed-piston sampler and drilling mud, with proper care and attention to details of sampling, handling, and transportation this sampling process yields very good samples of medium dense sands, but tends to densify loose sands and loosen dense sands b the use of radiographs is recommended as a nondestructive method of evaluating sample disturbance c in gravels, the only proven means of recovering undisturbed samples is by hand-carving block samples and d recent studies indicate that freezing in situ, followed by coring, offers a promise for obtaining undisturbed samples of much higher quality than is presently possible.
- Soil Mechanics
- Civil Engineering