Fig. 4From: Triaxial testing and hydraulic–mechanical modeling of sandstone reservoir rock in the Upper Rhine GrabenExemplary differential stress–strain curves for PfSst and TenSst with a confining pressure of 50 MPa, showing the deformation of the two samples. The non-linear behavior for low stresses (strain up to ~ 0.007) is related to limitations of the testing device and the application of the confining pressureBack to article page