Experimental study of permeability evolution in modified desulfurization gypsum under complete stress-strain process

In the context of low-carbon economy and sustainable development, industrial by-products are being gradually converted into green building materials. The effect of groundwater on the properties of modified desulfurization gypsum must be examined to increase its application in shotcrete supporting structures in underground engineering. In this study, triaxial compression tests with permeability measurements were carried out for modified desulfurization gypsum by simulating underground engineering conditions. The peak strength, permeability-deformation curves, and permeability-stress curves were obtained. The results showed that an increase in pore water pressure promoted internal crack propagation and enhanced the connectivity between cracks. This decreased the specimen strength and increased the initial permeability. As axial deformation and circumferential deformation increased, the variation in the permeability showed five stages: decline, gradual rise, rapid rise, rapid decline, and gradual decline. The permeability was more sensitive to circumferential deformation compared to axial deformation. The critical impermeability strength and abrupt permeability were defined according to the permeability-stress curves. These parameters can be used to evaluate the seepage problems in shotcrete supporting structures in underground engineering.