Significance and Use
Disturbance imparted to sediments after sampling can significantly affect some geotechnical properties. Careful practices need to be followed to minimize soil fabric changes caused from handling, storing, and preparing sediment specimens for testing.
Note 1—The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D 3740
The practices presented in this document should be used with soil that has a very soft or soft shear strength (undrained shear strength less than 25 kPa (3.6 psi)) consistency.
Note 2—Some soils that are obtained at or just below the seafloor quickly deform under their own weight if left unsupported. This type of behavior presents special problems for some types of testing. Special handling and preparation procedures are required under those circumstances. Test are sometimes performed at sea to minimize the effect of storage time and handling on soil properties. An undrained shear strength of less than 25 kPa was selected based on Terzaghi and Peck. They defined a very soft saturated clay as having undrained shear strength less than 25 kPa.
These practices shall apply to specimens of naturally formed marine soil (that may or may not be fragile or highly sensitive) that will be used for density determination, consolidation, permeability testing or shear strength testing with or without stress-strain properties and volume change measurements (see Note 3). In addition, dynamic and cyclic testing can also be performed on the sample.
Note 3—To help evaluate disturbance, X-Ray Radiography has proven helpful, refer to Methods D 4452
These practices apply to fine-grained soils that do not allow the rapid drainage of pore water. Although many of the procedures can apply to coarser-grained soils, drainage may occur rapidly enough to warrant special handling procedures not covered in these practices.
These practices apply primarily to soil specimens that are obtained in thin-walled or similar coring devices that produce high-quality cores or that are obtained by pushing a thin-walled tube into cores taken with another sampling device.
These practices can be used in conjunction with soils containing gas, however, more specialized procedures and equipment that are not covered in these practices have been developed for use with such materials.
Note 4—For information on handling gas charged sediments, the reader is referred to papers by Johns, et al., and Lee.
1.1 These practices cover methods for project/cruise reporting, and handling, transporting and storing soft cohesive intact marine soil. Procedures for preparing soil specimens for triaxial strength, and consolidation testing are also presented.
1.2 These practices may include the handling and transporting of sediment specimens contaminated with hazardous materials and samples subject to quarantine regulations.
1.3 These practices offer a set of instructions for performing one or more specific operations. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of the document means only that the document has been approved through the ASTM consensus process.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Sections 1, 2 and 7.
1.5 The values in acceptable SI units are to be regarded as the standard. The values given in parentheses are for information only.