School of Civil Engineering, Xi’an University of Architecture and Technology
Shaanxi Key Laboratory of Geotechnical and UndergroundSpace Engineering, Xi’an University of Architecture and Technology
State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences

To study the effect of area-to-volume ratio on the dissolution and deterioration characteristics of sandstone inthe static acid-rock reaction system, the HCl and H2SO4 solutions with pH=2 and 5 are selected as corrosion environments,and the different area-to-volume ratios are set by changing surface areas of sandstone. The effects of area-to-volume ratios on the physicochemical and mechanical properties of sandstone are studied. According to the acid-rock reaction theory, theeffect of the area-to-volume ratio on the diffusion-dissolution mechanism during sandstone corrosion is analyzed. The resultsshow that the sandstone mass loss rate and amount of substance of total cations are all related to the corrosion time asa power function. The area-to-volume is positively correlated with the dissolution rate constant and has little effect on thereaction order. The reaction order is less than one in different environments, indicating that the sandstone corrosion ratedecreases gradually with soaking time. In the pH=2、5 HCl solution and PH=2 H2SO4 solution, the amount of substance ofcation shows N(Ca2+) > N(Na+) > N(Mg2+) > N(K+), and in the pH=5 H2SO4 solution, it is N(Na+) > N(Ca2+) > N(Mg2+) ≈N(K+). The acid-rock reaction can be summarized as two mechanisms: diffusion control and chemical reaction control.The two control parameters are negatively correlated with the area-to-volume ratio and positively with the pH value ofsolutions. The parameter values in the H2SO4 solutions are slightly larger than the corresponding values in the HCl solutions.The interaction between sandstone and acid in different conditions is dominated by the chemical reaction. The areato-volume ratio significantly influences diffusion more than the chemical reaction. The mechanical properties of sandstoneare weakened after acid corrosion. The damage of sandstone under uniaxial compression can be divided into fourstages: compaction, elastic deformation, plastic yielding and post-peak. The peak strength and elastic modulus decrease,the peak strain increases, the brittleness declines, and the ductility is enhanced. The larger the area-to-volume ratio, themore severe the sandstone deterioration is. Overall, the smaller the pH value of solutions, the more prominent the effectsof the area-to-volume ratio on the dissolution characteristics and mechanical properties of sandstone are, which is more obviousin the HCl solutions than in the H2SO4 solutions. The finding can provide theoretical references for the safety assessmentand disaster prevention of rock mass engineering under an acidic environment.

国家自然科学基金资助项目(41172237，52178393)；冻土国家重点实验室开放基金资助项目(SKLFE202107)

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LIANG Yanling，HUO Runke，SONG Zhanping，et al. Influence of area-to-volume ratios on dissolution characteristics and mechanical properties of acid-corroded sandstone[J]. Journal of China Coal Society，2023，48(4)：1527−1537