Event Date
1450 Bayhill Drive is the location of one of YouTube’s (Google’s) planned office structures, also known as “Building 3”. The Building 3 structure is located behind YouTube’s existing headquarters and is up to four above-grade stories in height with below-grade parking facilities extending 70 feet below grade. The building footprint is approximately 550 feet long and 125 feet wide. Just to the east of the building footprint is the San Francisco Public Utility Commission (SFPUC) easement within which the two water transmission lines that serve San Mateo County and the City of San Francisco. These water lines are 60- and 66- inches in diameter and as close as 30 feet to the building footprint. Immediately to the west of the building footprint, and rising above the excavation, is a Caltrans embankment supporting the I-280/I-380 interchange. Due to proximity to existing improvements, the parking garage required a large temporary shoring system. An internally braced system was originally contemplated due to the SFPUC and Caltrans constraints. The selected shoring system was a combination of soil nails with upper cantilever along the east and south sides of the excavation and tiebacks and soldier piles along the west and north sides. During the excavation, ENGEO observed and tested up to 5 rows of tie-backs and 12 rows of soil nails. ENGEO also developed and oversaw a robust and near-real-time monitoring program in conjunction with 2D finite-element modeling (FEM) and calibration to predict future movements of the structure and SFPUC pipelines. Construction of the final basement required erection of two tower cranes between the east shoring wall and the SFPUC pipelines. ENGEO performed additional FEM analysis to understand loading and deformation of the shoring wall and SFPUC pipes based on a micropile foundation solution, provided construction and final design recommendations, created a logistics plan, and observed construction and testing of the micropiles. Ultimately, Google saved $1.5M by moving from an internally braced system to a tieback and soil-nail system. The Caltrans embankment and the SFPUC pipelines remained fully operational throughout construction. Construction is now complete.
Biographies
Pedro Espinoza
Pedro is a Principal geotechnical engineer with over 19 years of high-level geotechnical engineering design experience and is a recognized technical leader in the industry. He specializes in current building code parameters and interpretation, seismic design, earthquake engineering, and seismic retrofit evaluations for transportation, infrastructure, high-rise
construction, ground improvement, waterfront, and deep foundation projects. Pedro’s technical leadership in the area of geotechnical numerical analysis, including finite element modeling and soil structure interaction, is of utmost importance during evaluations of structures within highly seismic regions. He has led the geotechnical engineering on many high-profile projects, including serving as the lead geotechnical engineer for ENGEO’s work at Treasure Island in San Francisco and the Lucas Museum in Los Angeles, among many other projects.
Jeff Fipin
Jeff graduated with a B.S. in Civil Engineering from UC Davis in 1995. Jeff has been practicing Geotechnical Engineering since 1997 and joined ENGEO in 2002. He coordinates complex field investigations, provides design recommendations, and communicates with various stakeholders in providing geotechnical services to both public and private sector clients. His experience includes waterfront and marine engineering, hydraulic structures, industrial facilities, transportation and infrastructure improvements, and residential and commercial developments. Jeff has significant experience in soil structure interaction, foundation design, earthwork construction, and structural construction. This experience includes analysis of levee embankments for seepage and stability, design of shallow and deep foundations, pavement design including subgrade improvement, seismic site evaluation including liquefaction, retaining structure design and ground response, and earthwork recommendations. Jeff has performed services for projects in the San Francisco Bay, California North Coast, Sacramento, Central Valley, Southern California, and Northern Nevada areas.