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