Experimental investigation on the relevance of mechanical properties and porosity of sandstone after hydrochemical erosion

Abstract

Under the effect of chemical etching, the macroscopic mechanical properties, mesoscopic structure, mineral content, and porosity of rocks undergo significant changes, which can lead to the geological disasters; thus, an understanding of changes in the microscopic and macroscopic structure of rocks after chemical etching is crucial. In this study, uniaxial mechanical tests and nuclear magnetic resonance (NMR) spectroscopy were carried out on sandstone samples that had been previously subjected to chemical erosion under different pH values. The aim was to study changes in properties and mechanical characteristics, including deformation and strength characteristics, of the rock, and microscopic pore variation characteristics, and to perform preliminary studies of the chemical corrosion mechanism. Results show that different chemical solutions have a significant influence on the uniaxial compressive strength, the axial strain corresponding to the peak axial stress, elastic modulus, etc. With the passage of time, porosity increases gradually with exposure to different chemical solutions, and exposure to chemical solutions results in large changes in the NMR T2 curve and T2 spectrum area. Sandstone exposed to different chemical solutions exhibits different corrosion mechanisms; the root cause is the change of mineral.