Cementation State of Sand Judged by the Stress−Dilatancy Relationship from a Single Drained Triaxial Test

For noncrushable sand, this paper describes the experimental phenomenon of the opposite turning directions of stress–dilatancy curves between sands before and after cementation. Then, based on the thermomechanical framework and Legendre transformation, the stress–dilatancy model is obtained from the dissipation function. This stress–dilatancy model considers the coupled effect of bond breakage and rearrangement energy. This model also incorporates the mechanism that cementation-improved strength leads to the opposite turns of sands before and after cementation. Compared with the other four existing stress–dilatancy models, this paper’s model can depict the opposite turning directions of stress–dilatancy curves between uncemented and cemented sands. This stress–dilatancy model is also verified through five types of cementation: colloidal–silica–cemented sand, (CaCl2+Na2SiO3) cemented sand, naturally bonded sand, microbially induced carbonate precipitation (MICP)–cemented sand, and portland cement–treated sand. The broader application of the model is that it can also be used for crushable sand with particle breakage, as well as artificially cemented sand after freeze–thaw damage.