Numerical thermo-hydro-mechanical modeling of buffer material in mock-up test for deep geological disposal

Bufffer material is the last artificial engineered barriers for the repository in deep geological disposal of high-level radioactive waste.It is necessary to demonstrate the long term properties of the buffer material under coupled thermo-hydro-mechanical conditions after the repository closed.A numerical study of the test is conducted in this paper.The principal THM characteristics of the bentonite are present at first.A THM model is then present to tackle the complex coupling behaviors encountered in the bentonite.A detailed formulation coupling heat,moisture in unsaturated soil is given.The formulation of Alonso-Gens mechanical model for unsaturated soil is incorporated to reproduce the mechanical behavior of the bentonite.Finally,with the proposed model,numerical simulations of the mock-up test are carried out by using the code of LAGAMINE.The time variations associated with the temperature,degree of saturation,suction and swelling pressure of the compacted bentonite are studied.The results suggest that the proposed model is able to reproduce the mechanical behavior of the bentonite,and to predict heat,moisture motion under coupled THM conditions.