Abstract
The San Francisco-Oakland Bay Bridge is one of the most heavily travelled bridges in the world. The east span of the bridge will be replaced due to seismic safety concerns. The new bridge will be founded mostly on large 1.8 to 2.5-metre diameter, approximately 60- to 100-metre long pile foundations. Pile foundations will experience tension loads of up to approximately 90 MN and compression loads of approximately up to 140 MN during the design earthquake. This paper discusses the geotechnical design approach and techniques followed to evaluate the soil-pile-setup with time and the axial capacity of large diameter impact driven pipe piles for the project.
Highlights
The San Francisco-Oakland Bay Bridge (SFOBB) is the primary link between the cities of San Francisco and Oakland and carries 10 lanes of traffic across San Francisco Bay in California, USA
The new bridge will consist of 5 segments: (1) an approximately 460-metre-long transition structure extending from the Yerba Buena Island (YBI) Tunnel to the eastern tip of YBI, (2) main-span signature structure extending offshore from the tip of YBI with an approximately 625-metre-long, singletower that rises 164-metre above the water and asymmetrical, self-anchored suspension (SAS) cable, (3) an approximately 2.1-kilometre-long, four-frame Skyway structure extending from the signature structure eastward to the Oakland Shore Approach, (4) an Oakland Shore Approach structure extending about 700 metres from the Skyway structure to the north side of the Oakland Mole, and (5) an earthen fill transition from the Oakland Shore Approach structure to the roadways leading to and from the existing bridge
The observed blow counts and soil resistance to driving (SRD) spikes at penetration depths of about 45 and 70m were as a result of soil pile setup that occurred during driving delays such as splicing and welding of pile sections
Summary
The San Francisco-Oakland Bay Bridge (SFOBB) is the primary link between the cities of San Francisco and Oakland and carries 10 lanes of traffic across San Francisco Bay in California, USA. The existing east span bridge is a 3.5-km-long, double-decked structure that was constructed in the 1930s. The proposed east span bridge will be constructed along a parallel alignment to the north of the existing bridge. The SAS-East Piers and the Skyway and Oakland Shore approach portions of the bridge piers are underlain by over 85 to 135 metres of marine and alluvial sediments. Each pile will experience tension loads of up to approximately 9 to 30 MN and compression loads of up to approximately 18 to 42 MN during the design earthquake Each of these piers will be supported by a retangular or square pilecap with 8 to 9 piles. A cofferdam will be constructed at each pier location (except Piers 2 through 6), the pilecap footing box will be placed inside and the piles will be driven through the footing box with the use of a 1700 kilo-joule Menck MHU-1700 hydraulic impact hammer
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