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1 <br /> 4"EGG <br /> Gregg in Situ <br /> IleEnvironmental and Geotechnical Site Invests ation Contractors <br /> 1 Gregg In Situ CPT Interpretations as of January 7, 1999 (Release 1 0019) <br /> Gregg In Situ's Interpretation routine should be considered a calculator of current published CPT <br />' correlations and Is subject to change to reflect the current state of practice The Interpreted values are not <br /> considered valid for all sod types The Interpretations are presented only as a guide for geotechnical use <br /> and should be carefully scrutinized for consideration in any geotechnical design Reference to current <br /> literature Is strongly recommended <br /> The CPT interpretations are based on values of tip, sleeve fnction and pore pressure averaged over a <br /> user specified Interval (typically Q 25m) Note that Qt is the recorded tip value, Qc, corrected for pore <br />' pressure effects Since all Gregg In Situ cones have equal end area friction sleeves, pore pressure <br /> corrections to sleeve friction, Fs, are not required <br /> The tip correction is Qt= Qc+ (1-a) a Ud <br />' where Qt is the corrected tip load <br /> Qc is the recorded tip load <br />' Ud is the recorded dynamic pore pressure <br /> a is the Net Area Ratio for the cone(typically 0 85 for Gregg In Situ cones) <br /> Effective vertical overburden stresses are calculated based on a hydrostatic distnbution of equilibrium <br />' pore pressures below the water table or from a user defined equilibrium pore pressure profile (this can be <br /> obtained from CPT dissipation tests) The stress calculations use unit weights assigned to the Soil <br /> Behavior Type zones or from a user defined unit weight profile <br />' • Details regarding the interpretation methods for all of the interpreted parameters is given in table 1 The <br /> appropriate references referred to in table 1 are fisted in table 2 <br />' The estimated Soil Behavior Type is based on the charts developed by Robertson and Campanella shown <br /> in figure 1 <br />' Table 1 CPT Interpretation Methods <br /> interpreted Description Equation Ref <br /> Parameter <br />' Depth mrd layer depth <br /> AvgQt Averaged corrected tip(Qt) <br /> AvgQt <br /> Avgf's � Averaged sleeve friction(Fs) <br /> fI vgFs=i�Fs <br /> n <br /> AvgRf Averaged friction ratio(Rf) Av Fs <br /> I AvgRf-100%• S <br />' I <br /> AvgUd { Averaged dynamic pore pressure(Ud) A vgQt f <br /> If AvgUd=1 Ud <br /> n .� <br /> SBT Soil Behavior Type as defined by Robertson and Campanella � <br /> F <br /> • <br />