Effect of grout on mechanical properties and cracking behavior of rock-like specimens containing a single flaw under uniaxial compression

To investigate the influence of the geometry of a fracture and grouting on failure behaviors and mechanical properties of rock masses, uniaxial compressive tests were conducted on rock-like specimens containing single unfilled and grout-infilled flaws having different geometries. The compressive strength, deformation behaviors, and failure modes were studied and compared among the said specimens. Grouting improves the strength of grouted specimens through the following two mechanisms: (1) by increasing the shear-strength parameter values of the interface between the grout and model material and (2) by reducing the stress concentration at the flaw tips. Seven and eight crack types identified based on the crack geometry and crack-propagation mechanisms were used to analyze the failure modes of the specimens with the unfilled flaws and the grout-infilled flaws, respectively. An equivalent strength theory is introduced to predict the strength and the range of the flaw inclination angle of the grouted specimens for which the damage occurs along the interface between the grout and model material.