scope:

This test method covers the determination of the strength of cylindrical rock specimens in an undrained state under triaxial compression loading. The test provides data useful in determining the strength of rock, namely: shear strengths at various lateral pressures, angle of internal friction (angle of shearing resistance), and cohesion intercept. It should be observed that this method makes no provision for pore pressure measurements. Thus, the strength values determined are in terms of total stress that is not corrected for pore pressures.

The values stated in inch-pound units are to be regarded as the standard.

This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns 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.

The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of R 18 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with R 18 alone does not completely assure reliable results. Reliable results depend on many factors; following the suggestions of R 18 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.