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cM=4 ONc ConeTec Geotechnical and Environmental Site Investigation Contractors ConeTec CPT Interpretations as of January T, 1999 (Release 1.00.19) ConeTec'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 pressure effects. Since all ConeTec cones have equal end area friction sleeves, pore pressure corrections to sleeve .� friction, Ps, 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 ConeTec cones) Effective vertfcaf 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 +..r obtained from CPT dissipation tests). The stress calculations use unit weights assigned to the Soil Behaviour Type zones or from a user defined unit weight profile. w 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 Behaviour 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) 1 AvgQt L. AvgFs Averaged sleeve friction(Fs) 1 AvgFs=—RFS, n AvgRf Averaged friction ratio(Rf) .4vgF's - � I ,4vgRf=100°/fl• - rlvgQt AvgUd Averaged dynamic pore pressure(Ud) 1 AvgUd Ud, SBT Soil Behavior Type as defined by Robertson and Campanella 1 V W