Interstate 40 Emergency Rock Remediation, Haywood County, North Carolina

摘要

On Saturday morning, October 25, 2009 at 02:30 a massive rockslide occurred on Interstate 40 in North Carolina at Mile Marker 2.6 near the border with Tennessee. The volume of material that fell was roughly 80,000 cubic yards and some of the rock blocks were the size of city busses. Phillips and Jordan of Knoxville Tennessee were called under an emergency contract to remove slide material from the roadway and find a specialty subcontractor to address remediation of the remaining rock slope. Noel Philippon of Janod Contractors arrived on site Monday October 26th to assess the slope condition and develop a work plan with Phillips and Jordan, and Janod commenced initial scaling of the slide mass and scarp on October 28th. Initial scaling and material removal operations were closely monitored for movement as the slide was considered potentially still active. Jody Khune, a geological engineer with North Carolina Department of Transportation (NCDOT), completed geologic mapping of the slide mass and scarp and concluded that the slope consisted of several potential wedge failures and further rockfalls could be expected from the failure plane. An initial plan was developed to remove the slide debris and the remaining wedge structure extending up to 900 feet above the roadway where the joint planes daylighted. When wedge removal proved to be too expensive, NCDOT short listed contractors to bid on installing 50,000 linear feet of post-tensioned rock anchors up to 130 feet long in 60 days to stabilize the wedge structure. The team of Phillips and Jordan and Janod were the successful bidders on the project and the contract work started on December 28, 2009. There were several challenges on the project that became exponentially more complicated due to the fact that the work was to be performed during the worst weather of the year for that area and in one of the most severe winters in the last 30 years. Due to the time restraints in designing such a complicated project there were several changes to the design that were proposed by Janod. We discuss in detail the design and construction challenges that were met and innovative construction methods used that exceeded expectations.