A soft-rock model for cement-improved clays

Soil improvement techniques commonly result on soft clays mixed “in situ” with cement. Engineering practice has usually dealt with the treated soil bodies using simplistic constitutive models (e.g. elastic perfectly plastic Mohr Coulomb). A more refined bonded elasto-plastic model is here applied, emphasizing ease of calibration. Empirical studies have identified the ratio of cement content to the cured mixture void ratio as a controlling variable for mechanical response. This observation is elaborated upon to show that measuring porosity and unconfined compressive strength is enough to initialize the state variables of a bonded elasto-plastic model. The model is shown to predict the brittle behaviour of Bangkok clay-cement mixtures in oedoemeter tests. The relations here explored facilitate the use of more realistic soil models in the design of clay-cement structures.