Experimental Investigation on Permeability Evolution of Granite Samples Containing a Grout Infilled Fracture under Triaxial Compression

Abstract

Grouting has been widely used in rock engineering to improve the stability and strength of fractured rock mass, as well as to decrease the permeability of fractured rock mass. Fractures infilled with grout may endure different in-situ stress conditions during the construction and operation life of tunnels and other underground spaces in fractured rocks. To study the stress induced changes in permeability of fractures infilled with grout, we carried out triaxial compression tests on the fractured rock samples infilled with grout, during which the permeability of fractured rock samples was measured. Both planar and rough fractures with different apertures were tested. The results showed that the permeability of infilled fracture samples increases with increasing grout width, but the strength of infilled fracture samples decreases with increasing grout width. The evolution of permeability is highly related with the volumetric strain. The permeability decreases slightly with increasing deviatoric stress from 0 to crack damage stress, followed by drastic enhancement in permeability with further increasing deviatoric stress. The sample’s permeability is enhanced by about 5~10 times at the peak deviatoric stress compared with the initial value at 5MPa deviatoric stress.