Influence of water content on the failure modes and macro-micromechanical properties of sulfate rocks: Insights from experimental and DEM simulations

Abstract

The initial water content significantly affects rock mechanics, especially with swelling minerals. However, the effects of initial water content on the mechanical properties and failure mode of sulfate rocks remain unclear. This study explores these effects by conducting unconfined compressive strength (UCS) experiments and discrete element method simulations on sulfate rocks. The results indicate that as the initial water content increased from 0 to 9%, the Young’s modulus and Poisson’s ratio of sulfate rock exponentially decreased by 48.9% and 290%, respectively. Additionally, the crack initiation stress ($\sigma _{ci}$), crack damage stress ($\sigma _{cd}$), and UCS decreased by 62.4%, 51.5%, and 53.3%, respectively. The stress responses to initial water content follow linear functions. Notable decreases were also observed in the normal and shear stiffness parameters ($k_n$ and $k_s$ of contact, diminishing by 46.53% and 46.54%, respectively; peak cohesion decreased by 69.70%; peak friction angle by 17.39%; peak tensile strength by 124%. Rising initial water content leads to increased damage and softening of sulfate rock, causing decreased mechanical properties. It can be observed that as the initial water content increases, the proportion of micro-tensile fractures in the total number of fractures increases, and the dominant failure mode of sulfate rock gradually transitions from shear to tensile failure.

Keywords

Sulfate rock / Anhydrite / Initial water content / Failure model / 3DEC-GBM

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

CRediT authorship contribution statement

Li Yu: Writing - original draft, Formal analysis, Methodology, Investigation. Youlin Qin: Methodology, Investigation, Writing - review & editing, Formal analysis. Hualao Wang: Funding acquisition, Formal analysis, Writing - review & editing. Mingnian Wang: Supervision, Methodology, Writing - review & editing. Zhaohui Chen: Software, Investigation. Mingyang Yu: Writing - review & editing, Visualization, Data curation. Hong Jin: Writing - original draft, Investigation.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This work was supported by the Special Science and Technology Innovation fund of Research Institute of Highway, Ministry of Transport of the People's Republic of China (Grant No. 2019-C505).

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