01551276

Component

The National Park Service (NPS) staff first reported the beginnings of landslide movement at Mile Post (MP) 270.3 on the Blue Ridge Parkway in Wilkes County, North Carolina in the early 1970s. The landslide may have been active prior to this date. The Blue Ridge Parkway is a 469-mile (755-km) long National Scenic By-Way that began construction in 1935 and completed in 1987. A 340-foot (104-meter) long and 160-foot (49-meter) high section of the Parkway embankment began to settle, creating cracks in the asphalt concrete (AC) paved road. Initial corrective measures consisted mainly of AC overlays to bring the roadway back up to grade. Previous slide corrective measures, consisting mainly of installing horizontal and vertical drains and shallow excavation, were performed in 1978, 1981 and 1992 after observations of new slide movement and roadway settlement. The slide was reactivated in 1995 with observations of 5 inches (125 mm) new settlement. Eastern Federal Lands Highway Division (EFLHD) Geotechnical Engineers listed four (4) repair options and recommended tensioned anchors with anchor blocks as the preferred option. A Value Analysis/Engineering (VA/VE) Study sponsored by NPS was performed, identifying the preferred option of tensioned anchors and concrete anchor blocks. This was based on a number of factors that included resource disturbance, aesthetics, cost effectiveness, constructability and long-term performance. A subsurface soil, rock and water investigation was performed, consisting of test borings, rock coring and geophysical surveys. Data from earlier subsurface investigations were collected and evaluated with the new subsurface data. Subsurface materials consisted mainly of sand and silt (with some mica) fill over loose colluvium over sandstone and mica schist bedrock at depths ranging from 25 to 65 feet (7.5 to 20 meters). Slope stability and anchor design analysis were performed for optimal anchor distribution that met stability requirements. Construction of the anchor and block system was successfully completed in 2009 with few problems. No new slide movement has been observed since completion of construction.

Alternate title: Final Cost-effective and Context-Sensitive Design for Stabilization of 40-Year-Old Landslide on Blue Ridge Parkway, North Carolina. This paper was sponsored by TRB committee AFP10 Engineering Geology.

01550057

15-1804

English

14p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Anchorages; Concrete blocks; Context sensitive design; Cost effectiveness; Geological surveying; Geotechnical engineering; Landslides; Slope stability; Soil stabilization

Blue Ridge Parkway

North Carolina

Design; Geotechnology; Highways; I20: Design and Planning of Transport Infrastructure; I42: Soil Mechanics

Transportation Research Board Annual Meeting 2015 Paper #15-1804

TRIS, TRB, ATRI

Dec 30 2014 12:39PM