Laserfiche WebLink
ECS Gregg in Situ <br /> 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 <br /> not considered valid for all soil types The interpretations are presented only as a guide for geotechnical <br /> use and should be carefully scrutinized for consideration in any geotechnical design Reference to <br /> current 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+(t,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 <br /> shown in figure 1. <br /> Table 1 CPT Interpretation Methods <br /> Interpreted Description Equation Ref <br /> Parameter <br /> Depth mid 1Mw depth <br /> AvgQt �. Averaged corrected tip(Gtt) �--.—�-- ;�____---— ---- <br /> AvgQt=—±Qt, <br /> AvgFs FSS <br /> AvgRf � -Averaged friction ratio 04 ry .� AvgRJ 10 <br /> AvgFs <br /> = 0%'A t _ <br /> AvgUd - Averaged�pore p (Ud) Avg Ud 1±Ud, <br /> SBT -^ Sod Behavior Type as defined by Robertson and Campanella----- - - - - _ ___ — _ - ;_-- <br />