Study on the Time Effect Model of Physical Damage to Andesite Under Chemical Erosion

ABSTRACT When assessing the stability of open‐pit mining slopes, the development of physical damage in rock masses during prolonged chemical erosion is crucial. The research object for this study was andesite from a particular open‐pit mine. To examine the time‐dependent evolution of physical damage in andesite under the influence of solutions with varying pH values (pH = 3, 7, and 9), the study systematically used correlation analysis, regression fitting, and Weibull statistical distribution methods in conjunction with indoor soak tests, uniaxial compression tests, and microscopic structural analysis. According to the trials, alkaline solutions had comparatively modest erosive effects, neutral solutions mainly impacted the cementing material's binding, and acidic solutions considerably degraded the andesite's surface mineral components. The mass loss rate of the rock samples increased in a decreasing trend as the soak period increased, and the secondary porosity formed according to an allometric function pattern. After being exposed to the pH = 3 solution for 60 days, the uniaxial compressive strength and elastic modulus declined drastically, with a strength loss of 72.9%. A time effect model that took into account both mechanical and chemical damage was developed using the Weibull statistical distribution and damage mechanics theory. The model predicts outcomes that are in good agreement with experimental evidence. The study's conclusions provide a theoretical framework for evaluating the long‐term stability of open‐pit mining slopes.