Study of the Moisture Equilibrium of Highway Expansive Soil Embankments

Abstract

To investigate the moisture equilibrium of expansive soil embankments, a series of stress-dependent soil-water characteristic curve (SWCC) tests, one-year field monitoring on a trial covered expansive soil embankment, and numerical simulations of the process of moisture equilibrium of a covered expansive soil embankment under atmospheric effects over a period of ten years are conducted. The results show that (1) The effect of the stress state on the equilibrium moisture of expansive soil is clearly in the suction range of 0–3 MPa; (2) In the first year of service, the moisture content of the core of an expansive soil embankment increases gradually, the extent of moisture content fluctuation increases with increasing proximity to the slope side, and the differential settlement of the embankment is observed; (3) The moisture content of the core reaches a steady state, i.e., the moisture equilibrium state, on the sixth year of service; (4) The optimum moisture content of an expansive soil compacted in accordance with wet heavy compaction standard is close to the equilibrium moisture content, and it is better to use this standard to control field compaction of an expansive soil embankment in moist and hot areas in southern China.