Effects of thermo-osmosis on hydraulic behaviour of saturated clays

Despite a body of research carried out on thermally coupled processes in soils, understanding of thermo-osmosis phenomenon in clays and its effects on hydromechanical behavior is incomplete. This paper presents an investigation on the effects of thermo-osmosis on hydraulic behavior of saturated clays. A theoretical formulation for hydraulic behavior was developed, incorporating an explicit description of thermo-osmosis effects on coupled hydromechanical behavior. The extended formulation was implemented within a coupled numerical model for thermal, hydraulic, chemical, and mechanical behavior of soils. The model was tested and applied to simulate a soil heating experiment. It is shown that the inclusion of thermo-osmosis in the coupled thermohydraulic simulation of the case study provides a better agreement with the experimental data compared with the case in which only thermal expansion of the soil constituents was considered. A series of numerical simulations are also presented, studying the pore-water pressure development in saturated clay induced by a heating source. It is shown that pore-water pressure evolution can be considerably affected by thermo-osmosis. Under the conditions of the problem considered, it was found that thermo-osmosis changed the pore-water pressure regime in the vicinity of the heater when the value of thermo-osmotic conductivity was larger than 10−12 m2·K−1·s−1. New insights into the hydraulic response of the ground and the pore-pressure evolution due to thermo-osmosis are provided in this paper.