Trunk Highway 67 slope repair, Yellow Medicine County, MN

摘要

A 175 foot long section of Minnesota Trunk Highway 67 embankment experienced a slope stability failure in 2010; while there was existing distress at the site, it is likely that heavy September rainfall accelerated existing distress or promoted new adjacent instability. This highway section was along Hazel Creek, approximately 4 miles south of Granite Falls. A rapid response was needed to restore the slope and highway embankment prior to winter. Use of a column supported embankment (CSE) was considered the best option to provide strength and base support for a new roadway embankment. This approach was designed and specified as an "Aggregate Column Supported Embankment Stabilization System" (ACSESS). MnDOT also designed a Reinforced Soil Slope (RSS) with drainage and base riprap to complete the embankment repair and slope protection. Ground Improvement Engineering (GIE) designed the ACSESS system to increase the composite shear resistance and control settlement beneath the RSS. This was the first application of the Rammed Aggregate Pier® system by the Minnesota Department of Transportation (MnDOT).The paper describes the geotechnical investigations at the slide area, the stability issues, and the ACSESS and RSS repair designs as well as long term performance monitoring at the site.