Although many intact rock types can be very strong, a critical confining pressure eventually reached in triaxial testing, such that the Mohr shear strength envelope becomes horizontal. This state has recently been better defined, and correct curvature or deviation from linear Mohr–Coulomb (M-C) finally found. Standard testing procedures for joints, using multiple of same sample, case insufficient samples, shown to exaggerate apparent cohesion. Even rough joints do not have any cohesion, but...

The joint roughness coefficient (JRC), introduced in Barton (1973) represented a new method rock mechanics and engineering to deal with problems related shear strength estimation. It has the advantages of its simple form, easy estimation, explicit consideration scale effects, which make it most widely accepted parameter for quantification since was proposed. As result, JRC attracted attention many scholars who have developed JRC-related methods areas, such as geological engineering,...

Accurate measurement of the evolution rock joint void geometry is essential for comprehending distribution characteristics asperities responsible shear and seepage behaviors. However, existing techniques often require specialized equipment skilled operators, posing practical challenges. In this study, a cost-effective photogrammetric approach proposed. Particularly, local coordinate systems are established to facilitate alignment precise quantification relative position between two halves...

A practical method for estimating the shear strength of rockfill is developed. The peak drained friction angle π(prime) found to be closely related that rock joints. In both cases values are dependent on sample size, stress level, surface roughness, and uniaxial compression rock. Friction angles therefore higher smaller samples, very high where stresses low, as at toe or near face a dam. Test data reviewed shows value can quantified by equivalent roughness (R), an particle (S). (R) depends...

The authors investigate the failure modes surrounding over-stressed tunnels in rock. Three lines of investigation are employed: three-dimensional (3D) models bored under 3D stress, two-dimensional (2D) numerical simulations 1000 m and 2000 deep using FRACOD, both intact rock masses with one or two joint sets, finally, observations TBM (tunnel boring machine) hard medium massive rocks. reason for 'stress-induced' to initiate, when assumed maximum tangential stress is approximately (0.4–0.5)σc...

In this paper, the Mohr-Coulomb shear strength criterion is modified by mobilising cohesion and internal friction angle with normal stress, in order to capture nonlinearity critical state concept for intact rocks reported literature. The mathematical expression same as classical form, but terms of depend on stress now, leading a nonlinear relationship between stress. It covers both tension compression regions different expressions angle. strengths from two join continuously at transition...