Transmission And Substation Foundations - Technical Design Manual (TD06088E)

TABLE 4-10. EMPIRICAL VALUES FOR DR, FRICTION ANGLE AND UNITWEIGHT VS SPT (AS- SUMING A 20 FT (6 M) DEPTHOF OVERBURDEN AND 70% ROD EFFICIENCY ON HAMMER) Description Very Loose Loose Medium Dense Very Dense Relative Density (D r ) (%) 0 15 35 65 85

Fine

1-2

3-6

7-15

16-30

?

Medium

2-3

4-6

8-20

21-40

40+

SPT (N 70 )

Coarse

3-6

5-9

10-25

26-45

45+

Fine

26-28

28-30

30-33

33-38

38+

Friction Angle (f)

Medium 27-29

29-32

32-36

36-42

50+

Coarse

28-30

30-34

34-40

40-50

50+

Total Unit Weight (g wet ) (PCF) 130-150 Additional test results from 24 different sands were compiled by Kulhawy and Mayne (1990) who pro- posed the following expression: φ ’ = 17.70 + 11.0 log (q t1 ) Equation 4-28 where: (q t1 ) = (q t / σ atm )/( σ ’ vo / σ atm ) 0.5 σ atm = atmospheric pressure (1 atm = 1 bar = 100 kPa = 1tsf = 14.7 psi) 70-100 90-115 110-130 110-140

TABLE 5-11. REPORTED CORRELATIONS BETWEEN SPT N-VALUE AND Φ ’ FOR COARSE-GRAINED SOILS Correlation Reference φ ’ = (0.3N) 0.5 + 27 0 Peck et al. (1953) φ ’ = (10N)/35 + 27 0 Meyerhof (1956) φ ’ = (20N) 0.5 + 15 0 Kishida (1967) φ ’ = (N/s’ vo ) 0.5 +26.9 0 (s’ vo in MN/m 2 ) Parry (1977) φ ’ = (15N) 0.5 +15 0 Shioi & Fukui (1982) φ ’ = (15.4(N 1 ) 60 ) 0.5 + 20 0 Hatanaka & Uchida (1996)

DESIGN METHODOLOGY

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