Mechanical Properties of Acid-corroded Sandstone Under Uniaxial Compression

Abstract

Long-term exposure to chemical solutions can change the mineral composition and microstructure and may seriously affect the physical and mechanical properties of rocks. Therefore, to clarify the effects of long-term exposure and types of acids on the mechanical properties of rocks, and to develop the constitutive model of acid-immersed rocks, uniaxial compression tests were carried out on acid-immersed sandstone specimens. The sample weakened, and the brittle failure behavior became more ductile by the acid immersion to the aqueous solution of hydrochloric or sulfuric acids. The duration of the compaction stage of the stress–strain curve increased, that of the elastic stage decreased; the peak stress, elastic modulus, and Poisson's ratio decreased, and the peak point strains increased with the acidity and the immersion duration. The brittle shear failure of the untreated specimen became more axial splitting type failure with acidity. The damage variable of the combined effects of chemical and stress was introduced, and a statistical damage model considering the compaction stage of the stress–strain curve was established based on the damage variable. The model well-simulated the experimentally obtained stress–strain curves of the acid-immersed specimens. Finite element models reflecting the characteristics of the acid-immersed sandstone were established based on CT images.