My first Magazine dsi-info-23-en | Page 141

Construction—North America—USA—Slope Stabilizations The Elephant Trunk, Highway 1: Stabilization of a Steep Coastline using permanent DYWIDAG Strand Anchors Near the northern border of San Luis Obispo County in southern California, Highway 1 is located in the immediate vicinity of a rocky bluff. Through an area known as the Elephant Trunk along this route, the Pacific coast is characterized by unstable geology. Major landslides and settlements occurred time and again in this area, which is why repair work was required on a regular basis. Photos reprinted courtesy of John Madonna Construction Co., Inc., USA In order to permanently stabilize this area, a soldier pile wall was constructed in this section below the route, and Highway 1 was straightened. The lanes are being widened from 3.35m to 3.65m (11 to 12ft), and an additional 1.2m (4ft) wide hard shoulder is being built. The steel girders of the soldier pile wall were tied back to the stable slope strata using permanent DYWIDAG Strand Anchors. To tie back the retaining wall, DSI Construction USA supplied 259 Type 5-0.6" and 6-0.6" DYWIDAG Strand Anchors. To prevent possible rock falls from the steep coast above the road, a 0.60 to 1.2m (2-4ft) wide catchment area was built for falling debris, and the existing drainage system was optimized and repaired. The DYWIDAG Strand Anchor System was especially suitable for use due to its high degree of flexibility with regards to the required anchor lengths. As construction and storage space was limited, the anchors were supplied to the jobsite on coils, thus minimizing space requirements. The new soldier pile wall has a total length of approximately 305m (1,000ft). On the surface, only a part of the maximum 15m (50ft) high retaining wall is visible. Owner Caltrans (California Department of Transportation), USA General Contractor John Madonna Construction Co., Inc., USA Subcontractor Drill Tech Drilling & Shoring Inc., USA Engineering Caltrans (California Department of Transportation), USA DSI Unit DYWIDAG-Systems International USA Inc., BU Geotechnics, USA DSI Scope Production, supply DYWIDAG Products 259 Type 5-0.6" and 6-0.6" permanent DYWIDAG Strand Anchors 141