Retaining Wall

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Retaining Wall

Serial Information: Civil Engineering—ASCE, 1984, Vol. 54, Issue 7, Pg. 54-55

Document Type: Feature article

Abstract:

The foundation of this off-ramp in Manchester, New Hampshire is made up of end-bearing piles and sloping rock anchors�an innovation that is unique to the United States. End bearing piles were driven vertically to refusal, along with rock anchors installed at 45� through the footing to resist horizontal forces. Construction innovations included using a section of salvaged grid-bridge deck as a platform mounted on soldier piles to support the earth-anchor drilling rig; using prefabricated, adjustable steel frames to support the wall's cantilevered deck forms that were anchored to the wall stem by bolting them into threaded inserts in the concrete stems; constructing a temporary bridge ramp at the north end of the project to maintain access during excavation of the footings. Approximately 350 steel H-piles, up to 340 kips design load, were driven vertically 11 to 32 feet to the underlying bedrock. By using pile foundations, the height of the walls were reduced by 15% to 50% and dewatering problems were avoided. Sixty five rock anchors, from 260 to 480 kips, were installed through sleeves precast in the combined wall/pile cap. The 70 to 80 ft. long anchors consist of 8 to l3 strands of 270 ksi stranded wire.

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