**7.3 Biaxial testing**

In biaxial testing of an overcore section, with no additional instrumentation besides the strain gauges already glued to the inside of the Pilot hole. Measurements can be conducted in the field, in direct unification with overcoring (**Figure 32**). Only radial (biaxial) compression loading is applied to the sample, and there are no restrictions regarding the orientation of the symmetry plane of the rock sample [16]. The biaxial test is exceptionally critical because it establishes the elastic properties of the system, including core, epoxy, and cell, that unlock in situ stress from the over coring strains (**Table 14**). Plots of strain-versus-pressure are shown in **Figure 33**. The calculated elastic properties, namely, Young's modulus and Poisson's ratio are given in **Table 15**.
