Keywords

retaining wall, swelling soil, measurements, pressure, movement, numerical simulations, design

Abstract

The earth pressure on retaining walls is often considered to be the “active pressure” or the “at rest pressure” and may involve the passive pressure. However, in the case of swelling soils and when the top of the wall is inundated for a long period of time, the pressure can be much higher than the active pressure. In this article, the pressure on retaining walls generated by inundated swelling soils is investigated based on well-documented case histories and numerical simulations using unsaturated soil mechanics principles. Because the swell pressure plays a critical role in this case, the swell pressure prediction methods are briefly evaluated. The results of the case histories analysis and associated numerical simulations include the maximum potential pressure diagram, the influence of the wall movement, and the time-dependent pressure diagram. The inundation time is a major influencing factor, and the concept of the 100-year inundation period is developed as a design inundation time. In the unusual case where the inundation period is sustained for a long period of time, the pressure diagram for swelling soils shows a much higher pressure toward the top of the wall compared to non-swelling soils. In this extreme case, a shallow anchor is suggested to resist the pressure on walls retaining swelling soils; a vertical compressible layer to reduce the pressure between the wall and the soil when it swells is another possible solution.

DOI