Abstract: Regarding the new technique of thermal drainage consolidation method, the finite element model of thermal drainage consolidation method for vertical drain foundation is developed through secondary development on the base of COMSOL. Multiphysics software in which the heat transfer process of U-shaped heat transfer tube in the vertical drains is simulated with the theory of non-isothermal conduit flow, and the effect of temperature on permeability of disturbed and undisturbed zone of the vertical drains is considered. Then, taking the prototype test of thermal drainage and consolidation of soft foundation treatment as an example, the consolidation degree of soft soil foundation is analyzed mainly on the condition of coupling, partial coupling and non-coupling model. It is shown that the rate of consolidation in the partial coupling model decreases in comparison with the non-coupling model used in the traditional drainage consolidation method, because the extra pore pressure induced by the temperature delays the development of consolidation of soil. In case of coupling model, the rate of consolidation is accelerated and consolidation period is shortened because the temperature effectively improves the permeability of soil in vertical drain smear zone, although the extra pore pressure can also be induced by the temperature. The result of computation is in agreement with the test results.

Key words: thermal drainage consolidation, vertical drain foundation, permeability characteristics, non-isothermal conduit flow