EXH1316053252

TO: Mr. Jim Thomson, P.E., HNTB Corporation 6o.o_ FROM: Doug Lindquist, P.E., Reda Mikhail, P.E., Michael Bailey, P.E. RE: Third Runway FLAC Analysis of MSE Walls 4978-40 Cn,caoo CC: Mr. Robert Millar, P.E., HNTB Corporation Mr. John Sankey, P.E., RECo Denver This memo presents results of Hart Crowser's analyses using the finite difference model, FLAC, for three proposed mechanically stabilized earth (MSE) retaining walls for the Third Runway project at Seattle-Tacoma International Airport. F_arD4nk$ SUMMARY Results of the analyses presented herein provide an independent verification of acceptable Je,,e_,c,ry performance for the Third Runway MSE walls that are designed in accordance with AASHTO. Four wall sections were selected for analysis to represent various soil conditions, and the Juneau range of wall and slope heights for the three proposed MSE walls. The purpose of the FLAC analyses was to provide additional information to the design team on anticipated wall performance to supplement the AASHTO design analyses. Results of the FLAC analyses are not intended to replace design analyses accomplished in accordance with AASHTO code. Long Beach The FLAC analyses show generally similar wall performance (stresses and displacements) will occur regardless of when liqueiaction occurs relative to the start and end of shaking. Dynamic response varies somewhat with stiffness of the modeled soil elements. This was of particular interest because soils at the site have: 1) varying resistance to liquefaction and 2) portland potential variability in the timing of the onset of liquefaction relative to the start of shaking. The analyses indicated that…

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Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]