ASTM D4971-16 PDF Download

ASTM D4971-16 is a standard test method used to determine the in situ modulus of deformation of rock using a diametrically loaded 76-mm (3-in.) borehole jack. The results obtained from this test are used to predict displacements in a rock mass caused by loads from structures or underground construction. This test method can also provide an estimate of the anisotropy of the rock.

The analysis of the test data involves recording the applied hydraulic pressure versus the borehole diameter change and requires knowledge of the rock's Poisson's ratio. However, it should be noted that the original theoretical formula used in this test method has sometimes resulted in computing a material modulus that is too low. Therefore, caution must be exercised when analyzing the data.

This test method assumes that the rock mass is linearly elastic, isotropic, and homogeneous, which allows it to provide useful data for rock masses where equivalent continuous properties cannot be determined or estimated. However, it is important to consider that the precision of this test method depends on the competence of the personnel performing it and the suitability of the equipment and facilities used. Compliance with ASTM practice D3740 does not guarantee reliable testing, as many factors contribute to reliable testing.