A case study of reinforced soil slopes in Ontario

ABSTRACT: This paper presents a case study of reinforced soil slopes (RSS) along Bathurst Street in the Region of York, Ontario. Six RSSs were designed to be up to 10 m in height and reinforced with geogrids at vertical spacings of 0.6 m for the roadway embankments over three culverts. The slope angle was 70o and slope face units consisted of vegetated geocells. Two years after the RSS construction, the face units of one RSS collapsed after a significant rain event. Field investigation and global stability analysis were carried out. It was found that the possible failure mechanisms of the RSS were the infiltration rate of surface water exceeded the drainage capacity of the RSS and the buildup of hydrostatic pressure exceeded the sliding resistance between the geocells. The failed face units were then reinstalled using the same geocells with the installation of a vertical drainage layer behind the geocells. Following the reinstallation of the face units of the RSS, ground movement monitoring was conducted for all RSSs over the culverts. Field inspection was carried out one year after the reinstallation of the face units. It was found that all RSSs were globally stable and reinstalled face units were stable. However, localized soil erosions and geocell displacements were observed at the face units of remained five RSSs. Improvements for the design and construction of the RSS are recommended.