Seismic Response and Extended Life Analysis of the Deepest Top-Down Soil Nail Wall in the U.S.

Typically, temporary shoring support systems are not required to provide for design level earthquake occurrences consistent with the building or structure being constructed inside the excavation. This paper evaluates the seismic response of the deepest soil nailed walled constructed in the U.S. at the time of construction, for a Mw 6.8 earthquake in the Puget Sound Region in Washington State. In addition, an extended life analysis was required when the project was stopped in the middle of an economic downturn. The construction was stopped at a depth of 86.5 feet with the basement slab in place and no lateral support from the eight levels of planned reinforced concrete parking slabs. Project start up is not expected for 2 to 4 years; therefore, the life of the temporary soil nails had to be evaluated for their ability to support the cut for the interim time period. The construction design life was initially set for one year.