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353 Main Street Apartments <br />Redwood City, California <br />May 1, 2018 <br />(Originol Report Dated November 78,2076) <br />where CRRz.s is the cyclic resistance ratio for a magnitude 7.5 earthquake and MSF is the <br />magnitude scaling factor. The soil layer is considered to be potentially liquefiable if the CRR and <br />CSR established for the soil stratum at a given depth produce a factor of safety against <br />liquefaction, CRR/CSR, less than the selected factor of safety for the project. A general guideline <br />in selecting an appropriate factor of safety for a project is shown in the table below (SCEC, 1999): <br />Consequence of Liquefaction (Nrloo (clean sand)Factor of Safety <br />Settlement <br /><15 <br />>30 <br />T,L <br />1.0 <br />Surface Manifestation <br /><15 <br />>30 <br />1.2 <br />1.0 <br />Lateral Spreading <br /><15 <br />>30 <br />1.3 <br />1.0 <br />The variables discussed in the above text are used to develop a profile of the soil, and an in-house <br />developed computer spreadsheet analysis is carried out to assess liquefaction triggering, <br />liq uefaction induced settlement, and seism ically ind uced settlement. <br />CPT Liquefaction Analvsis Methodolosv <br />Additional analyses were carried out on CPT soundings Cl through C4. The CPT liquefaction <br />analysis at the subject site was evaluated using the NCEER (L998) procedure with the help of CLiq <br />computer program. <br />The CPT friction ratio (sleeve resistance divided by cone tip resistance) generally increases with <br />increasing fines content and plasticity. The appropriate grain characteristics, such as <br />approximate soil type and a rough estimate of the fines content, termed as apparent fine <br />content, is estimated directly from CPT data using the relationships recommended by Robertson <br />and Wride. The radius of each circle, defining the boundaries between different soil behavior <br />types, 1., was calculated using the following equation: <br />ls = [(3.47-logQ)2 + (1.22+logF)z1o's <br />Where: Q= [(q.-ouo)/P.][(P,/o'uo)n] and F = [fr/(qco"o)]x100% <br />ln general, if the calculated value of lc was greater than 2.6, the soil was classified as clayey and <br />was considered too clay-rich to liquefy and if the calculated lc was less than 2.6, the soil was <br />classified as granular in nature and susceptible to liquefaction. <br />9301842-001 1610-038.SER.REV2 <br />7.B. - Page 67