Evaluating Seismic Stability of Embankment Dams - Multiscale Geomechanics: From Soil to Engineering Projects - page 358

Figure 10.9. Resistance to liquefaction measured by SPT
or CPT (Cone Penetration Test) [YOU 01]
The in situ resistance is measured by the SPT, which has the advantage of being
not only a penetrometer test but also a boring machine. Since the development of
this experimental procedure, new faster and more precise testing procedures have
been studied. Among them we can cite destructive borings with recording of
machine parameters, stato-dynamic penetrometers such as PANDA or the ones with
an electrical cone. The most effective one appears to be the piezocone with an
electrical cone. The penetrometer with an electrical cone permits a soil classification
without boring and a fast investigation of a large zone, therefore being more
economical. The piezocone is not so fast but gives a measurement of the soil
permeability. It requires some pre-borings to bypass zones that are too strong and
additional points to cover up the point breakage.
The safety factor is given by the ratio CRR/CSR; the contours of its value can be
mapped into the foundation. The practice shows that potentially liquefiable zones
are often found. The in situ investigation has to be sufficiently precise in order to
quantify the spreading of these potentially liquefiable zones.