Nanomechanical behavior and failure mechanisms of hydrated montmorillonite: Insights from molecular dynamics simulations

Abstract

Montmorillonite, a typical clay mineral, significantly influences the macroscopic deformation and fracture of soft rocks through water absorption-induced swelling and mechanical behavior at the atomic scale. Molecular dynamics (MD) simulations were employed to investigate the microscopic mechanical behavior of montmorillonite systems with varying hydration levels under compressive conditions. The effects of water content and loading direction on the crystal structure, mechanical properties, failure modes, and bond evolution were analyzed, and the elastic constants and fracture toughness of the systems were determined. The results demonstrate that the increase of hydration decreases the mechanical properties of the montmorillonite crystal while facilitating the initiation and propagation of cracks within the crystal. The failure mode of the crystal demonstrates significant anisotropy, and the bond evolution shows a strong correlation with the stress-strain curve.