Analysis of Stress-Strain Relationship of Earthen Soil Based on Molecular Dynamics

The calibration of material mechanical parameters and deformation and failure mechanism of earthen soil have always been difficult problems in the field of cultural relics protection. How to establish a relationship between physical and mechanical properties of soil at macro and micro scales is the focus of the research. The nanostructure model of earthen soil composed of many atoms was established by molecular dynamics (MD) method. The stress-strain relationship of different moisture content was obtained by uniaxial compression simulation. Based on the electron micrograph image (magnification ×500) and the image reconstruction method, a micromodel composed of particles and pores was constructed. Furthermore, using the displacement loading method, we obtained the stress-strain relationship of the earthen soil with different moisture contents. Our results showed that the displacement of the left and right boundaries of the circular pore model is 1.26 times more than that of the polygonal pore model, and the displacement of the polygonal pore model is 1.28 times more than that of the circular pore model. The stress-strain curve simulated by the polygonal pore model is consistent with the experimental results. The results of the numerical analysis are in good agreement with those of the macro test, which indicates that the research ideas and the methods used for earthen soil exploration in this work are feasible. Our present findings provide reference for deterioration research and safety evaluation of cultural relic buildings such as earthen sites.