A multistory building is to be built on a level ground at a seismically
active site. The SPT is performed during the subsoil exploration phase.
A safety hammer is used, and the outside diameter of the modified
California sampler used is 3 inches. The peak ground horizontal accel-
eration that was recorded in the seismic history in this area is 0.2 g,
and the design earthquake magnitude is 6.5. The mat foundation is
designed to be 8 m below ground where the fine content is 15%. At
8 m depth, the soil sample is retrieved by the sampler. The blow counts
at the first, second, and third six-inch penetrations are 8, 9, and 8,
respectively. The boring log indicates the following subsurface profile.
Assess the liquefaction hazard at the footing of the building at this site
(Figure 9.31).