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

TABLE 1. ASCE 7-16 MAPPED SEISMIC DESIGN PARAMETERS ASCE 7-1G Parameter Recommended Value Site Class F Shortperiodmapped MC& soectrol response acceleration, Ss (9) 1.2251 Long -period mapped MCEe spectral response acceleration, Sr (g) 0.435' Short period she caefflclenq FA 1.01 Long -period site coefficient, Po L87 holes. 'The project see isclaeaheci as Sue Case F Buts and s, are based on sue does D per the code exception for building Abortion period less Nan 0.5 seconds, 4.2. Liquefaction Potential Liquefaction is a phenomenon where soils experience a rapid loss of internal strength as a consequence of strong ground shaking. Ground settlement, lateral spreading and sand boils may resultfrom liquefaction. In general, the soil that is susceptble to liquefaction include very loose to medium dense, clean to silty sands and some sifts that are below the groundwater level. The structures supported on liquefied soils could suffer foundation settlement, downdrag loads, or lateral movement that could he severely damaging to the structures. The evaluation of liquefaction potential is complex and dependent on numerous parameters, including soil type, grain distribution, soil density, depth to groundwater, in -situ static ground stresses, earthquake- induced ground stresses and excess pore water pressure generated during seismic shaking. We evaluated the liquefaction potential of the site soils at the maximum -considered earthquake (VICE) level ba ced on the previous SPTs (6-4, 6-9, B-19, &23, B-24, DM-6-164, and U6-1) and CPTs (CPT-1/]A and CPT-2 through CPT-4) as shown in Figure 2. Table 2 below presents the seismic input parameters used in our liquefaction analyses, where the magnitude is the mode magnitude from Me deaggregation performed at the peak ground acceleration (PGA) using the 2014 United States Geological Survey (USGS) seismic source characterization (SSC) model; and the PGA was derived from ASCE 7-16 for Site Class D. TABLE 2. SEISMIC INPUT PRAMEEERS FOR LIQUEFACTION EVALUATION Design Earthquake All Pill (10 NICE 7.11 0.578 The simplified Nggering criteria proposed by Iddss and Boulanger (2008) and Youd at al. (2001) were used to evaluate the liquefaction potential of the site soils. An SPT hammer efficiency of 76 percent was assumed and used in our SPTcorrelated simplified liquefaction analyses for the borings B-4, B-9, &19, &23, B-24, and UB-1 that used aut"ammer during the test An SPT hammer efficiency of 60 percent was assumed and used for the boring DM-B-1-64 due to the lack of Information on hammer type. Based on our slmplffled liquefaction analyses, the fill and recent deposits are susceptible to liquefaction. Therefore, the depth of liquefaction is along the top of the glacially consolidated soils, as shown in Figure 4. Liquefaction -Induced tree -geld ground settlement of the potentially liquefiable zones was estimated using The semiempirical approaches proposed by Tokimatsu and Seed (1987), Ishiham and Yoshimine (1992), GEOENGINEEaS 67 Ocroba 3p 2211 2Ow osrPal