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Gregg CFT interpretation Software 1.1.. 2007 <br />- Cone Penetration Test (CPT) Interpretation <br />Gregg has recently updated their CPT interpretation and plotting software (2007). The <br />software takes the CPT data and performs basic interpretation in terms of soil behavior <br />type (SBT) and various geotechnical parameters using current published empirical <br />correlations based on the comprehensive review by Lunne, Robertson and Powell (1997). <br />The interpretation is presented in tabular format using MS Excel. The interpretations are <br />presented only as a guide for geotechnical use and should be carefully reviewed. Gregg <br />does not warranty the correctness or the applicability of any of the geotechnical <br />parameters interpreted by the software and does not assume any liability for any use of <br />the results in any design or review. The user should be fully aware of the techniques and <br />limitations ofany method used in the software. <br />The following provides a summary of the methods used for the interpretation. Many of <br />the empirical correlations to estimate geotechnical parameters have constants that have a <br />range of values depending on soil type, geologic origin and other factors. The software <br />uses 'default' values that have been selected to provide, in general, conservatively low <br />estimates of the various geotechnical parameters. <br />Input: <br />1 Units for display (Imperial or metric) (atm. pressure, pa = 0.96 tsf or 0.1 MPa) <br />2 Depth interval to average results,( ft or m). Data are collected at either 0.02 or <br />0.05m and can be averaged every 1,3 or 5 intervals. <br />3 Elevation of ground surface (ft or m) <br />4 Depth to water table, zw (ft or m) - input required <br />5 Net area ratio for cone, a (default to 0.80) <br />6 Relative Density constant, Cc)r (default to 350) <br />7 Young's modulus number for sands, a (default to 5) <br />8 Small strain shear modulus number <br />a. for sands, So (default to 180 for SBTn 5,6,7) <br />b. for clays, Co (default to 50 for SBA 1,2,3 &4) <br />9 Undrained shear strength cone factor for clays, Nkt (default to 15) <br />10 Over Consolidation ratio number, kocr (default to 0.3) <br />11 Unit weight of water, (default to yw = 62.4 lb/fP or 9.81 kN/mb <br />Column <br />1 Depth, z, (m) - CPT data is collected in meters <br />2 Depth (ft) <br />3 Cone resistance, qc (tsf or MPa) <br />4 Sleeve friction, fs (tsf or MPa) <br />5 Penetration pore pressure, u (psi or MPa), measured behind the cone (i.e. UD <br />6 Other - any additional data, if collected, e.g. electrical resistivity or UVIF <br />7 Total cone resistance, qt (tsfor MPa)qt = qc + u (1-a) <br />Gregg Page I of4 8./28/2007 <br />SL Rvcd 2019.01.21