Weakening Laws of Mechanical Properties of Sandstone Under the Effect of Chemical Corrosion

The mechanical properties of rocks are significantly affected by chemical corrosion. To explore the influence of chemical corrosion on the weakening laws of sandstone mechanical properties, the porosity and pore size distribution (PSD) of sandstone samples immersed in different chemical solutions was measured by the nuclear magnetic resonance (NMR) technique. The damage variable based on the change of porosity was proposed to analyse the chemical damage to the sandstone samples. Moreover, both compressive and Brazilian tensile tests under static and dynamic conditions were carried out using a conventional servo-controlled testing machine and a split Hopkinson pressure bar (SHPB) system. The results showed that the porosity and proportion of macropores of the sandstone increase after chemical corrosion. The weakening laws of compressive and tensile strength of the sandstone under static and dynamic states are similar, and the relations among them and the damage variable are exponential. The dynamic tensile strength is most sensitive to the effects of chemical corrosion. The order of the degree of damage of chemical solutions on mechanical properties of sandstone is: DH2SO4 > DNaOH > DDistilledwater. Based on the experimental data, the relationships between the mechanical properties and chemical damage variable can be described as exponential equations. Additionally, the variations of dynamic increase factors versus chemical damage variable, the relationship between PSD and the strength of the chemically corroded sandstone, and the corrosion mechanism are also investigated.