Molecular dynamics simulation of deformation and failure mechanism of kaolinite at different temperatures

Abstract

Uniaxial tensile simulations were carried out in OA,OB and OC directions of kaolinite at different temperatures by using molecular dynamics simulations.The deformation and failure processes of kaolinite were studied at the atomistic scale.The change of microstructure,deformation mechanism and temperature effect of tensile mechanical properties of kaolinite at different temperatures were also analyzed.This work would be helpful to understand the mechanisms of large deformation and failure of soft rock.The results indicated that the increasing of temperature results in the thermal expansion of kaolinite after relaxation.Once the crack nucleation appears,it propagates very quickly and leads to a sharp decrease in stress along OA and OB loading directions.The layer separation occurs during loading along OC direction,while the structure could fail since the hydrogen bonds are broken.The mechanical properties of kaolinite have a strong dependence on temperature.There is a negative correlation between tensile strength,Young’s modulus and temperature.With the increase of temperature,the tensile ultimate strain and residual strength tend to decrease,and the strength attenuation coefficient tend to increase.In addition,OC direction is the most affected by the temperature,followed by OB direction,and OA direction is the least affected.

Keywords

• kaolinite
• molecular dynamics
• mechanical properties
• deformation mechanism
• temperature effect