New three-dimensional shear strength criterion of discontinuities with different joint wall compressive strengths

• A novel 3D shear strength criterion for discontinuities with different joint wall compressive strengths (DDJCS) is proposed, extending the JRC-JCS model to account for 3D surface morphology. • The Grasselli and Develi directional roughness method accurately predicts shear-induced potential contact zones in DDJCS, validated by experimental contact area measurements. • The proposed criterion reliably predicts peak shear strength for both DDJCS and DIJCS within 16% error, validated against 240 direct shear tests. • The criterion captures the anisotropy of DDJCS peak shear strength, which decreases with increasing normal stress, though further experimental verification is needed.