This standard specifies the in-situ method for conducting a uniaxial jacking test to determine the modulus of deformation of a rock mass. The results are essential for the design of foundations for heavy civil engineering structures like dams, large bridges, and underground powerhouses.
Code of practice for uniaxial jacking test for deformation modulus of rock
Quick Reference Values
Minimum loaded area0.1 m²
Recommended plate side length30 to 75 cm
Accuracy of deformation measurement0.002 mm
Maximum test pressure2 to 3 times design bearing pressure
Distance of reaction supports from test> 3 times plate width
Key Formulas
E = [ (Δp) / (Δs) ] * a * (1 - v²)
Practical Notes
Test results are highly sensitive to the preparation of the test surface; it must be perfectly smooth, flat, and perpendicular to the loading axis.
The modulus value obtained is for the rock mass under the specific loading conditions of the test and may need adjustment for scale effects when applying to a larger rock mass.
Ensure the reaction system is sufficiently rigid and located far enough away (at least 3 times the plate width) to not influence the measurement zone.