An experimental study on the influence of pH values of mine waters on the shear strength of resin grout

Resin grouts are widely used in geotechnical and underground engineering. However, they often suffer from damage caused by different mine water solutions. In this study, a series of immersion tests and direct shear tests (DSTs) were conducted to investigate the effects of variations in solution pH values on the resin shear strength and to analyze the degradation mechanisms of the mechanical properties of the resin in different mine water solutions with varying immersion times. The corrosion mechanisms of resin under the action of different mine water solutions were explored using a scanning electron microscope (SEM). The results showed that the pH values of the solutions gradually stabilized with time as they eventually became weakly alkaline. Increasing the acidity or alkalinity of the solutions and lengthening the immersion time led to a gradual decrease in the resin peak shear strength, internal friction angle and cohesion. Moreover, owing to the different types and intensities of mine water action on resin in different mine water environments, the changes in the resin microstructures also varied. A damage indicator was proposed to quantitatively express the degradation of the mechanical parameters of the resin specimens under the action of mine water solutions. Finally, practical engineering countermeasures were proposed for different scenarios where resin grouts are used for roadway support in coal mines.