Unformatted text preview: unit weight of 19 kN/m 3 . The SPT recorded blows were 357 to penetrate the split samplers 18 inches. The water table is 16 feet below the surface. Estimate the angle of internal friction. The raw SPT value is N = 5 + 7 = 12 (that is, only the last two sets of 6” penetrations). Assume the use of a USstyle donut hammer efficiency is E m = 0.45, and the other parameters C B = 1.00, C S = 1.00, C R = 0.75. With these values, the SPT corrected to 70% efficiency can use the table of correlations based on the N’ 70 , ( 29 ( 29 ( 29 ( 29 ( 29 ' 70 0.45 1.00 1.00 0.75 12 6 0.70 0.70 m B S R E C C C N N = = = That corrected SPT N’ 60 is then corrected for depth, ( 29 ( 29 ( 29 ( 29 ( 29 ' 70 70 100 100 6 10 2 19 corrected N N depth effectiveunit weight m= = = The table of correlations suggests that for a mediumdense sand, an angle of internal friction is about 33º....
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 Summer '10
 STAFF
 Geotechnical Engineering, SPT, Geotechnical investigation, Standard penetration test

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