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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 user <br /> specified interval (typically 0 25m) Note that Qt is the recorded tip value,Qc,corrected for pore pressure <br /> effects Since all Gregg In Situ cones have equal end area friction sleeves, pore pressure corrections to <br /> sleeve f vbon, Fs, are not required <br /> The tip correction is Qt= Qc+(9-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 pore <br /> 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 Behavior <br /> 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 i CPT Interpretation Methods <br /> Interpreted Descnptton Equation Ref <br /> Parameter <br /> Depth mid la�w depth <br /> AVQt Averaged corrected tip(Qt) A ngQt— 1 , <br /> n -� <br /> AvgFs Averaged sleeve fnctton(Fs) AvgFs=1 Fs, <br /> AvgRf Averaged fnction ratio(Rf) AvgRf=100%• AvgFs <br /> AvgQ! <br /> AvgUd Averaged dynam pore pressure(Ud) <br /> Avg Ud=1 Ud, <br /> n <br /> SBT Sal Behavior Type as defined by Robertson and Campanella <br />