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"EGG Gregg In Situ <br />' Environmental and Geotechnical Site Investigation Contractors <br />' Gregg In Situ CPT Interpretations as of January 7, 1999(Release 100.19) <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 friction and pore pressure averaged over a <br /> user specified Interval (typically 0 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) .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 distribution 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 Sod <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 listed in table 2 <br />' The estimated Sod 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 mid layer depth <br /> AvgQt Averaged corrected tip(Qt) 1 <br /> AvgQt=n�Qt, <br />' AvgFs I Averaged sleeve friction(Fs) 1 <br /> A vgFs=n�Fs <br /> AvgRf Averaged friction ratio(Rf) n AvgFs <br /> AvgRf=100/o• Av <br /> gQt <br /> AvgtldI Averaged dynamic pore pressure(Ud) I AvgUd— I r Jd, <br /> n <br /> tSBT Soil Behavior Type as defined by Robertson and Campanella t <br /> 1 <br /> 1 <br />