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GREGG C i EGG GGG IN SITU �■■ Environmental and Geotechnical Site Investigation Contractors • GREGG IN SITU CPT Interpretations as of July 31, 2002 (Release 1.20c) GREGG IN SITU's interpretation routine provides a tabular output of geotechnical parameters based on 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 sod 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 GREGG IN SITU, Inc and GREGG DRILLING &TESTING Inc do not warranty the correctness or the applicability of any of the geotechnical parameters interpreted by the program and can not assume liability for any use of the results in any design or review Representative hand calculations should be made for any parameter that is enticai for design purposes The end user of the interpreted output should also be fully aware of the techniques and the limitations of any method used in this program The purpose of this document is to inform the user as to which methods were used and what the appropriate papers and/or publications are for further reference The CPT interpretations are based on values of tip, sleeve friction and pore pressure averaged over a user specified interval (e g 0 20m) Note that q,is the recorded tip value, q, corrected for pore pressure effects Since all GREGG IN SITU cones have equal end area fnction sleeves, pore pressure corrections to sleeve fiction, Fs, are not required The tip correction is qi=qc+(1-a) .u2 where qt is the corrected tip resistance q,is the recorded tip resistance U2 is the recorded dynamic pore pressure behind the by(u2 position) a is the Net Area Ratio for the cone (typically 0 85 for GREGG IN SITU cones) The total stress calculations are based on sod unit weights that have been assigned to the Sod Behavior Type zones, from a user defined unit weight profile or by using a single value throughout the profile Effective vertical overburden stresses are calculated based on a hydrostatic distrbution of equilibnum pore pressures below the water table or from a user defined equilibrium pore pressure profile(this can be obtained from CPT dissipation tests) For over water projects the effects of the column of water have been taken in to account as has the appropriate unit weight of water How this is done depends on where the instruments were zeroed(i a on deck or at mud line) Details regarding the interpretation methods for all of the interpreted parameters are provided in Table 1 The appropriate references cued in Table 1 are listed in Table 2 Where methods are based on charts or techniques that are too complex to descnbe in this summary the user should reference to the cited references The estimated Sod Behavior Types(normalized and non-normalized)are based on the charts developed by Robertson and Campanella shown in Figures 1 and 2 Where the results of a calculation/interpretation are declared `rnvalid'the value will be represented by the text strings 4-9999°or"-9999 0" Invalid results will occur because of(and not limited to) one ora combination of i I 1 Invalid or undefined CPT data (e g dnlled out section or data gap) 2 Where the interpretation method is inappropnate, for example,drained parameters in an undrained material (and vice versa) 3 Where interpretation input values are beyond the range of the referenced charts or speed limitations of the interpretation method 4 Where pre-requisite or intermediate interpretation calculations are invalid