Strand Anchors Stabilize Residential Area in a Central Coast Region
In the city of Santa Barbara, a large slope stabilization project was carried out to secure a residential area nestled above Sycamore Canyon Road (Highway 154) and to protect the Highway. The $50 million Sycamore Ranchito Project was divided into seven construction phases to stabilize a sliding hill side.
Seven anchor walls of various heights with integrated drainage systems were constructed. The walls consist of either shotcrete with DCP strand anchors or concrete piles (shear pins) that were tied back with DCP strand anchors spaced at distances of approx. 1.5m (4.9ft). The majority of the strand anchors consisted of nine 0.6" dia. strands and were tested to a load of 1,846kN (415kips) after installation and locked off at a load of 1,388kN (312kips).
The first construction phase included the installation of several hundred DYWIDAG Strand Anchors into an approx. 7.6m (24.9ft) high reinforced shotcrete wall at the top of the slope to arrest the upslope expansion.
The second phase involved the rebuilding of the streets in the upper section. Reinforced Ø 91-122cm (3-4ft) concrete shear pins were anchored at depths of approx. 12-35m (39.4-114.8ft) and tied back using 30.5m- 61.0m (100-200ft) long DYWIDAG Strand Anchors. In the southern section, a reinforced shotcrete retaining wall was built and backfilled to decrease the slope gradient.
Within the scope of the third section, the beginning land slide between two other roads had to be stopped. For this purpose, a row of reinforced concrete shear pins were connected to a horizontal tie-beam and tied back using permanent DCP strand anchors.
The sixth phase, which had to be carried out before the fourth and fifth phase, included the stabilization of an active landslide movement in the upper area. The landslide was successfully stopped by installing another concrete shear pin tieback system.
The same system was used for the fourth and fifth construction phases to protect the lower roads from the active landslide movement. The seventh and last construction phase included the repair and re-opening of the streets in the area as well as landscaping.
Thanks to these measures, the landslide threatening the residential area and the road below was stopped. DSI USA supplied a total of 1,100 permanent 3, 6 and 9 strand DYWIDAG Strand Anchors in lengths of approx. 19.8m - 68.6m (65ft-225ft) as well as the necessary stressing equipment.