ASTM D8359-21

5.1?The dilatometer test is usually performed in vertical boreholes. It can be used in inclined or horizontal holes, but the probe would drag along the borehole wall.

5.2?Deformation modulus of rock, creep characteristics, rebound, and permanent set data is obtained and is useful for engineering designs.

5.3?The rock mass discontinuities, in situ stresses, geologic history, crystallography, texture, fabric, and other factors will determine the rock mass properties that laboratory size tests alone may not be able to measure and that the dilatometer test may be better able to measure.

5.4?Determination of rock mass deformability yields a critical parameter in the design of foundations of dams, support of underground excavations, piers, caissons, and stability of rock slopes.

5.5?In situ tests such as this one provides general information regarding rock mass behavior. Dilatometer tests are advised when designing and constructing specific structures.

5.6?Dilatometer tests can be performed at a reasonable cost and effort. Dilatometer tests are also less expensive and time-consuming compared to other deformability tests like radial jack or flexible plate tests that require underground excavation and access too.

5.7?Dilatometer modulus can be correlated with the moduli obtained by other methods (for example, the plate loading or radial jacking methods). The correlated dilatometer modulus can then be used instead of other more expensive in situ modulus tests.

5.8?Dilatometer tests can provide a qualitative evaluation of a rock mass deformability before performing a large scale deformability test such as a radial jack test.

5.9?Dilatometers are valuable for rapid index logging of boreholes in jointed rocks that yield poor core recovery and inadequate specimens for laboratory testing.

5.10?Pressurization and depressurization of the dilatable membrane in this standard are unique. This is done immediately upstream of the dilatable membrane by a dual-action piston actuated from a manual pump at the surface. This configuration allows the use of the dilatometer at substantial depths and eliminates the parasitic expansion of the tubing and pumping system and forces the membrane to collapse completely regardless of if the drill hole column has fluid or not.

5.11?The results of dilatometer tests may be used to check against the serviceability limit state of spread foundations on rocks through a deformation analysis.

5.12?When performing a deformation analysis the Young's modulus, E, may be taken equal to E_d on the assumption that the rock is linearly elastic and isotropic.

1.3?Purpose, Application, Range of Uses, and Limitations:?

1.4?UnitsThe values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.

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

1.6?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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7?This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.