Transmission And Substation Foundations - Technical Design Manual

SECTION 4: DESIGN METHODOLOGY

Evaluating Soil Properties for Design

SPT Correlation for Relative Density

100

90

80

Reid-Bedford*

Platte River*

70

Standard Concrete*

30 Relative Density, D R (%) 40 50 60

Field Sites (Skempton ‘86) Fine (Gibbs & Holtz ‘57) Coarse (Gibbs & Holtz ‘57)

Terzaghi & Peck ‘48

*Marcuson & Bieganowsky 77

20

) 60 /60

D R = 100 (N 1

10

0

70

80

0

10

20

30

40

50

60

Normalized Resistance, (N 1 ) 60

Relative Density of Clean Sands from SPT Resistance Figure 4-12

1000 800 600 400

Chapman & Donald (1981) Holden (1976) Veismanis (1974) Baldi et al. (1981) Parkin et al. (1980) Villet & Mitchell (1981)

200

β = -15 0 Bearing capacity number N q = q c / σ’ vo ( k 0 = 1.0) ( k 0 = sinφ’) 100 80 60 40 20 10 8 6 4

Durgunoglu & Mitchell (1975)

Increasing compressibility

Proposed correlation by Robertson and Campanella (1983)

β = 0 0

β = +15 0

q

β

2

Janbu & Senneset (1974)

φ’30 0 32 0 34 0 36 0 38 0 40 0 42 0 44 0 46 0

48 0

1 0.0 0.2 0.4

Tangent φ’ 0.6

0.8

1.0 1.2

Relationship between Bearing Capacity Number and Friction Angle from Normalized CPT Tip Resistance [Robertson and Campanella (1983)] Figure 4-13

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