Mechanical properties and damage constitutive model of sandstone after acid corrosion and high temperature treatments

Aiming at the problem of temperature-mechanics-chemical (T-M-C) action encountered by rocks in underground engineering, sandstone was selected as the sample for acid corrosion treatment at pH 1, 3, 5 and 7, the acid corrosion treated samples were then subjected to high-temperature experiments at 25, 300, 600, and 900 °C, and triaxial compression experiments were conducted in the laboratory. The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality, wave velocity, porosity and compression failure characteristics of the rock. Based on the Lemaitre strain equivalent hypothesis theory, the damage degree of rock material was described by introducing damage variables, and the spatial mobilized plane (SMP) criterion was adopted. The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process, which verified the rationality and reliability of the model parameters. The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage, which had certain practical significance for rock engineering construction.