Frictional mechanisms of hydrated montmorillonite under normal loading

PC Wei and YY Zheng and A Zaoui, COMPUTERS AND GEOTECHNICS, 173, 106568 (2024).

DOI: 10.1016/j.compgeo.2024.106568

The friction behavior of clay particles plays an essential role in controlling its mechanical properties, but remains unclear in microscale. As one of the major clay particles, the nanoscale friction properties of hydrated montmorillonite have been studied using steered molecular dynamics (SMD) simulation method, considering the coupling effect of water content of 0 similar to 30 % and normal load of 1 atm similar to 10 GPa. The SMD friction along the y-direction has been performed to investigate the frictional mechanism of hydrated montmorillonite and its structural properties of interlayer water. The evolution of average friction load with water content, friction coefficients, and the distribution of interlayer water molecules were obtained. Furthermore, the SMD pulling along the z-direction was conducted to study the effect of interlayer water molecules on the interaction between montmorillonite layers. All simulation results showed that more energy and a higher friction load were required to slide at a higher normal load. The friction coefficient of 0.058 similar to 0.17 and internal friction angle of 3.3 degrees similar to 9.6 degrees for hydrated montmorillonite agreed well with previous studies in microscale, showing the weak friction properties. The evolution of friction coefficient with water content was different at different normal loads, where the friction coefficient of 5 % hydrated montmorillonite was the highest at 3 similar to 10 GPa. Moreover, the increasing normal load could change the distribution of interlayer water molecules.

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