ASTM International

Standard Test Methods for Creep of Rock Core Under Constant Stress and Temperature
 N D7070

Annotation

These test methods cover the creep behavior of intact weak and hard rock core in fixed states of stress at ambient (room) or elevated temperatures. For creep behavior at lower temperatures refer to Test Method D5520. The methods specify the apparatus, instrumentation, and procedures necessary to determine the strain as a function of time under sustained load at constant temperature and when applicable, constant humidity.

Hard rocks are considered those with a maximum axial strain at failure of less than 2 %.Weak rocks include such materials as salt, potash, shale, and weathered rock, which often exhibit very large strain at failure.

This standard consists of three methods that cover the creep capacity of core specimens.

Method A—Creep of Hard Rock Core Specimens in Uniaxial Compression at Ambient or Elevated Temperature.

Method B—Creep of Weak Rock Core Specimens in Uniaxial Compression at Ambient or Elevated Temperature.

Method C—Creep of Rock Core Specimens in Triaxial Compression at Ambient or Elevated Temperature.

All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.

The procedures used to specify how data are collected/ recorded and calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining data, special purpose studies, or any considerations for the user’s objectives; and it is common practice to increase or reduce significant digits of reported data to commensurate with these considerations. It is beyond the scope of these test methods to consider significant digits used in analysis methods for engineering design.