Passive earth pressure of overconsolidated collapsible soil subjected to inundation

ABSTRACT

Backfills behind retaining walls are often made of collapsible soils, which are subjected to wetting by surface running water or by rising the groundwater table. Collapsible soil shows considerable strength when it is dry or at a relatively low degree of saturation and experiences excessive and sudden settlement when it is inundated. This paper presents an experimental investigation on walls retaining overconsolidated collapsible soil subjected to passive earth pressure. A prototype model of a vertical wall, retaining horizontal backfill was developed. Collapsible soil was prepared in the laboratory by mixing kaolin clay with fine sand. The model was instrumented to measure the total passive earth force on the wall, the passive earth pressure at strategic locations on the wall, and the overconsolidation ratio of the soil in the testing tank. The state of passive pressure was developed by pushing the wall horizontally toward the backfill without any rotation. Tests were conducted on walls retaining overconsolidated collapsible soil at the dry and at full saturation conditions. Results showed that for the dry state, the passive earth pressure increases with the increase of the collapse potential and overconsolidation ratio, and was significantly dropped at full saturation.

KEYWORDS:

• Retaining walls
• passive earth pressure
• collapsible soils
• collapse potential
• over consolidation ratio
• backfills
• inundation
• experimental investigation

Acknowledgments

The financial support received from the Natural Science and Engineering Research Council of Canada (NSERC) and Concordia University are acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Natural Sciences and Engineering Research Council of Canada [N00049].