Deep mixing treatment of a clayey mine waste: Analysis of load tests on single column

The technique of deep mixing treatment with cement, aimed at improving the mechanical characteristics of a clayey waste underlying a new electric power plant in central Italy, is considered and critically evaluated. The effectiveness of the treatment is evaluated by comparing the results of in-situ and laboratory tests before and after the treatment. Several load tests were carried out in-situ on the treated columns: numerical simulations of such tests, using the finite difference method, are performed in order to obtain by back-analysis the overall stiffness of the treated soil. The parameters relevant to single column are finally compared to the results obtained, at a smaller scale, from laboratory tests on undisturbed samples. The results show that reproducing the load tests is strictly linked to the definition of an appropriate decay of the mechanical properties of the treated soil, simulated by means of a strain-softening constitutive model.