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AARON- Gregg In Situ <br />' Offloomm Environmental and Geotechnical Site Investigation Contractors <br />' Gregg In Situ CPT Interpretations as of January 7, 1999 (Release 1 00.19) <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 soil 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 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 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) AvgQ t— 1 .,Qt I -- <br /> 1 <br /> AvgFs I Averaged sleeve friction (Fs) 1 <br /> AvgFs=—i Fs. <br /> n •I <br /> AvgRf Averaged friction ratio(Rf) AvgFs <br /> AvgRf=100%• <br />' { <br /> AvgUd Averaged dynamic pare pressure{Ud} AvgQt <br /> AvgUd— 1 Ud _ 1 <br /> n - <br />' SBT Sod Behavior Type as defined by Robertson and Campanella t <br /> 1 <br />