Determination of hydraulic normal stiffness of fractures in hard rock from well testing

This technical note aims at determining the joint normal stiffness of fracture planes by two kinds of hydraulic field tests and coupled hydromechanical numerical modelling. The initial hydraulic aperture of the fracture is determined from a pressure pulse injection test. Thereafter, a step pressure test (hydraulic jacking) is conducted from which the normal stiffness of the fracture plane is back-calculated by numerical modelling. The test procedure is applied to six sub-horizontal joints located in crystalline rock at depths of between 80 and 417 m.

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