SR99 Bored Tunnel-Assessment of Settlement Impacts ... - SCATnow

uildings. Existing foundation systems for these buildings include rubble,conventional concrete spread footings, mat foundation systems, and pile foundationsystems, including timber, precast concrete, augercast concrete, and drilled caissons.Along the length of the tunnel there have been identified 158 building structures thatmay be impacted by the tunneling operations. Possible effects of the proposed SR99 bored tunnel alternative construction on the existing buildings, utilizing theassumed settlement trough provided by Shannon & Wilson, are discussed. Thisreport also describes the approach to structural analyses based on the methodologydiscussed in Boscardin and Cording [1989], and provides guidelines from whichbuilding protection and monitoring can be established.Based on the results of the structural analyses, anticipated damage to the buildingsfrom tunnel construction is classified on a scale ranging from “Negligible” to“Severe to Very Severe” based upon damage classifications described by Boscardinand Cording (see Table 2 in the report). The range of damage is highly variable dueto many factors including, but not limited to, 1) soil conditions along the path of thetunnel, 2) relative location of the building along the alignment of the tunnel, 3) dateof the original construction of the buildings, 4) existing condition of the buildings, 5)modifications to the original building structure, 6) foundation system(s) utilized forthe buildings, 7) structural systems utilized for the buildings, 8) unknown orconcealed conditions, and 9) architectural detailing of the buildings. Based upon theevaluation described in this report, a number of the buildings are anticipated, withoutmitigation, to have significant damage. These are as outlined in Table 1 below withdamage classification S-VS representing “Severe to Very Severe” damage and M-Srepresenting “Moderate to Severe” damage.Table 1. Buildings with Anticipated Damage of Moderate and AboveIDPROPERTYADDRESSAPPROX. TUNNELSTATIONDAMAGECLASSIFICATIONT252 619 Western Ave 214+72 S-VST251 61 Columbia Street 215+74 S-VSA161 809 Western Ave 217+75 M-SA159 815 Western Ave 218+64 M-ST223 1201 1 st Ave 230+85 M-ST55 605 Thomas 287+04 M-SThe Alaskan Way Viaduct & Seawall Replacement Program March 2010Proposed SR 99 Bored Tunnel - Assessment of Settlement Impacts to Buildings 2Public Disclosure Request 11-0123 for Elizabeth Campbell - 2nd installment