920 MILLWRIGHT LOOP S BASE FILE Geotech Report 2023-12-29

and Idnss and Boulanger (2008) at the MCE level using both SPTs and CPTs. Our analyses indicate that Me site (under existing conditions) could experience liquefactioninducedfree field ground settlement on the order of 3 to 28 inches during an MCE seismic event, as shown In Figure 5. The average liquefaction - induced settlements are anticipated to be 14 inches for Parcel A17; and the differentialliquefaction - intlucetl settlements are anticipated to be on the order of 1 inch over horizontal distance of 50 feet. 4.3. Lateral Spreading and Kinematic Loads Lateral spreading involves lateral displacements of large volumes of liquefied soil. Lateral spreading can occur on near level ground as blocks of surface soils are displaced release W adjacent blocks. Lateral spreading also occurs as blocks of surface soils are displaced towards a nearby slope or free -face by movement of underlying liquefied soil. In the case of this pmjem site, lateral spreading could occur during earthquakes resulting in the movement of soil or Sediment onto belowwaterstructures and kinematic load that should be considered In the structural design. 4.3.1 Earthquake -induced Lateral Ground Deformations Earthquakeinducedlateral ground Deformations were evaluated by performing slope stability analyses and simplified Newmark analyses for the Cascadia Subduction Zone (CSZ) Intraslab source since the Intraslab source has the highest percent contribution per deaggregation. 43.11 Slope Stability Analysis Slope stability analyses were completed on Cross Section A -A' using Limit Equilibrium Method (LEM) with a commercial software, Slope/W, developed by GEOSLOPE International, Ltd. The bulkhead structures (i.e., sheet pile and tiebacks) were included in our slope stability models. The slope stability was evaluated under static, seismic, and post -earthquake conditions. 4.33.2. Soil Proporan The soil properties that were used in the slope stability analyses are listed In Table 3, where static strengths were used in static condition for all sail units. We assumed that liquefaction occurs during the earthquake; therefore, in seismic and postearthquake conditions, residual fiction angles were used in the liquefied soils (below groundwater table and above liquefaction depth); 80 percent of static strengths were used In The soils above groundwater table; and full static strengths were used in the sails (non -liquefiable) below liquefaction depth. TABLE 3. SOIL PROPERTIES IN SLOPE/W ANALYSIS Unit Friction Residual Residual Weigh Angle Friction Angle Strength, Sr Sall bad (Pat) (deg) (deg) (Palo Marine Area Fill' 110 28 ] 139 Fille 120 30 9 112 Recent Deposds(Very Loose to Medium Dense)° 125 30 4 146 Glacially Consolidated Sousa 130 42 - - Notes: 'The non Vormfies for marine area fill were assumed. time ar l Trani for All, recentdepsslts, am inaciallr consolidated mes were eaumated booed on mecomelmone on sera and Cara W-poumceroubinfootdeg'degree:pat-poundsperwuaref t GEOENGINEEaS 67 Daam 20 202 rupeeoarre