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CONE EC <br /> ®nel'ec <br /> Geotechnical and Environmental Site investigation Contractors <br /> ConeTec CPT interpretations as of January 7, 1999 (Release 1 00 19) <br /> ConeTec's interpretation routine should be considered a calculator of current published CPT correlations <br /> 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 ConeTec 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 ConeTec 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 /> Behaviour 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 Soil Behaviour Type is based on the charts developed by Robertson and Campanella <br /> shown 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 /> ,4 vgOt=-10 <br /> n <br /> Avg Fs Averaged sleeves faction(Fs) 1 <br /> A vgFs=—�Fs. <br /> n• <br /> AvgRfAveraged friction ratio(Rf) Av Fs <br /> 11 AvgRf=100%o vg <br /> Fs <br /> Av201 <br /> AvgUd Averaged dynamic pore pressure(Ud) I <br /> ] <br /> ,4 vg ud=-I Ud, <br /> n - <br /> SBT Soil Behavior Type as defined by Robertson and Campanella 1 <br />