Shear strength of rock joints influenced by compacted infill

• Published in: International journal of rock mechanics and mining sciences (Oxford, England : 1997) Vol. 70; pp. 296 - 307
• Main Authors: Indraratna, Buddhima, Premadasa, Wuditha, Brown, Edwin T., Gens, Antonio, Heitor, Ana
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2014; Elsevier
• Subjects: Applied sciences; Buildings. Public works; Compacted infill; Compacting; Constants; Exact sciences and technology; Geotechnics; Infilled joints; Mathematical models; Measurements. Technique of testing; Planes; Rock; Rock (material); Rock joint; Rock mechanics; Shear strength; Soil investigations. Testing; Soil mechanics. Rocks mechanics; Strength of materials (elasticity, plasticity, buckling, etc.); Structural analysis. Stresses; Unsaturation; Shear strength; Unsaturation; Rock joint; Rock mechanics; Compacted infill; Theoretical study; Slope stability; Compaction; Triaxial test; Experimental study; Rock mass; Modeling; Unsaturated porous medium; Soil water properties; Undrained soil test; Laboratory test; Jointed rock; Filling; Application; Joints
• ISSN: 1365-1609; 1873-4545
• DOI: 10.1016/j.ijrmms.2014.04.019

Discontinuities such as fault planes, joints and bedding planes in a rock mass may be filled with different types of fine-grained material that are either transported or accumulated as gouge due to weathering or joint shearing. Previous laboratory studies have mainly examined the role of saturated infill that exhibits the minimum shear strength. However, in practice, the infill materials are often partially saturated generating matric suction within the joint that can contribute to increased shear strength. To the authors’ knowledge this is the first study to examine the influence of compacted (unsaturated) infill on the joint shear strength. A series of laboratory triaxial tests on idealised model joints and imprinted natural joint profiles was carried out, with constant water contents of the infill being maintained. From the laboratory results, it is observed that the peak shear strength of infilled joints increased with the decrease of degree of saturation from 85% to 35% for both idealised joints and replicated natural joints. Based on the laboratory observations an empirical model for describing the infilled joint shear strength was developed. •A new testing program for infilled joints using a constant water content approach.•A semi-empirical model to quantify the strength contribution of infill suction.•Use of idealised and natural joint profiles to model infill shear strength.•Modelling the shear strength of jointed slopes to evaluate safety factors.