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Gregg In Situ, Inc. SECOR January 14, 1998 SFFB, Stockton, CA 3.0 CONE PENETRATION TEST DATA & INTERPRETATION The cone penetration test data are presented in graphical form in the attached Appendix. Penetration depths are referenced to existing ground surface. The data include CPT logs of measured soil parameters and interpreted soil types along with pore pressure dissipation plots. The stratigraphic interpretation is based on relationships between cone bearing (Qc), sleeve friction (Fs), and penetration pore pressure (Ut). The friction ratio (Rf), which is sleeve friction divided by cone bearing, is a calculated parameter which is used to infer soil behavior type. Generally, cohesive soils (clays) have high friction ratios, low cone bearing and generate large excess pore water pressures, Cohesionless soils (sands) have lower friction ratios, high cone bearing and generate little in the way of excess pore water pressures. Pore Pressure Dissipation Tests (PPDT's) were taken at various intervals in order to measure hydrostatic water pressures and approximate depth to groundwater table. In addition, the PPDT data can be used to estimate the horizontal permeability (ko of the soil. The correlation to permeability is based on the time required for 50 percent of the measured dynamic pore pressure to dissipate (t54). A summary of the PPDT data is provided in Table 2. The PPDT plots and correlation figure are provided in the Appendix. Table 2 Summary of Pore Pressure Dissipation Tests Test Location PPDT Test Depth Time for 50% Dissipation (t5o} CPT-01 44.78 ft 60 sec { 80.54 ft 35 sec l CPT-02 31.82 ft 40 sec 82.51 ft 18 sec CPT-03 42.81 ft 50 sec 47.74 ft 5 sec 91.70 ft 240 sec The interpretation of soils encountered on this project was carried out using recent correlations developed by Robertson and Campanella, 1988. It should be noted that it ( is not always possible to clearly identify a soil type based on Qc, Fs and Ut. In these 5 f