[S-CG48] Petrology, Mineralogy & Resource Geology

[SCG48-P11] Evolution of the disintegration breakage of weakly expansive red-bed mudstone under acidic environment based on Weibull model from Hubei Province, China

*Guodong Zhang¹, Xiyong Wu¹, Sixiang Ling¹, Zhuowu Xie¹ (1.Faculty of Geoscience and Environmental Engineering, Southwest Jiaotong University)

Keywords:Red-bed mudstone, Acid rain, Fractal dimension, Weibull model, Quantitative disintegration

The disintegration of red-bed mudstone is prone to be affected by the environment. The acid rain can significantly influence the disintegrating process, while the corresponding mechanism remains to be studied. This paper was implemented to characterize the disintegration breakage evolution of red-bed mudstone through the static disintegration experiment with pHs from 1.0 to 7.0, over 10 dry-wet cycles. Characteristics of particle disintegration evolution in different acidic environments were expounded by monitoring six disintegration indexes, i.e. decay ratio, fractal dimension, particle gradation, grading entropy, disintegration ratio, and relative breakage. Moreover, the evolution model of the disintegration breakage of red-bed mudstone was used by the Weibull model with the shape (m) and slope (n) of particle size distribution curve. The grading entropy was used to quantitatively characterize the disintegration evolution of particles. It was found as the number of dry-wet cycles and the acidity of solution increased, the grading entropy of the disintegration breakage showed a downward trend. The disintegration ratio was applied to quantify the particle size distribution, then which was amended by replacing the initial gradation curve with the Weibull evolution model. Similar to the grading entropy, the disintegration ratio was negatively correlated with both the number of cycles and the acidity of solution. Finally, the rock relative breakage was proposed to describe the extent of rock disintegration between different dry-wet cycles. The relative breakage was positively correlated with cycles and the acidity. The applicability of the Weibull model was verified by the comparison of the fractal model and the Weibull model, a three–segment fitting method was proposed to better improve the fitting coefficients of the fractal model. The relative breakage and the fractal dimension were negatively correlated with the relative basic entropy, but the disintegration ratio was positively correlated with the relative basic entropy.