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!EGG Gregg In Situ ,. Environmental and Geotechnical Site Investigation Contractors ' Gregg In Situ CPT Interpretations as of'January 7, 9999 (Release 9.00.19) Gregg In Situ's interpretation routine should be considered a calculator of current published CPT correlations-and is subject to change to reflect the current state of practice. The interpreted values are not considered valid for all soil types. The interpretations are presented only as a guide for geotechnical use and should be carefully scrutinized for consideration in any geotechnical design. Reference to current ' literature is strongly recommended. The CPT interpretations are based on values of tip, sleeve friction and pore pressure averaged over a user specified interval (typically 0.25m). Note that Qt is the recorded tip value, Qc, corrected for pore t pressure effects. Since all Gregg In Situ cones have equal end area friction sleeves, pore pressure corrections to sleeve friction, Fs, are not required. ' The tip correction is: Qt= Qc +(1-a) • Ud where: Qt is the corrected tip load Qc is the recorded tip load Ud is the recorded dynamic pore pressure a is the Net Area Ratio for the cone (typically 0.85 for Gregg In Situ cones) Effective vertical overburden stresses are calculated based on a hydrostatic distribution of equilibrium ' pore pressures below the water table or from a user defined equilibrium pore pressure profile (this can be obtained from CPT dissipation tests). The stress calculations use unit weights assigned to the Soil Behavior Type zones or from a user defined unit weight profile. ' Details regarding the interpretation methods for all of the interpreted parameters is given in table 1. The appropriate references referred to in table 1 are listed in table 2. ' The estimated Soil Behavior Type is based on the charts developed by Robertson and Campanella shown in figure 1. ' Table 1 CPT Interpretation Methods interpreted Description Equation Ref" ' Parameter Depth mid layer depth AvgQt Averaged corrected tip(Qt) f - AvgQt=— n AvgFs I Averaged sleeve friction(Fs) 1 AvgFs= n AvgRf Averaged friction ratio(Rf) AvgFs AvgRf=1001/10• AvgQt AvgUd Averaged dynamic pore pressure(Ud) 1 AvgUd=— Ud, n S8T Soil Behavior Type as defined by Robertson and Campanella � I r •