Updating Bearing Capacity – SPT Graphs - Maryland State Highway ...

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2.3 Friction Angle of Granular SoilsThe SPT can be used to estimate the in-situ angle of internal friction φ for granular soils.The SPT test is commonly used to estimate the properties of cohesionless soils due to thedifficulty in obtaining undisturbed samples. It should be stated that the SPT number may bemisleading if large-size gravel is wedged into the split spoon sampler, resulting in apparentlyhigh N-values.The angle of friction of granular soils, ϕ, has been correlated to the standard penetrationnumber. Peck, Hanson, and Thornburn (1953) gave a correlation between N and ϕ in a graphicalform, Fig 2.1, which can be approximated as (Wolff, 1989)2ϕ ° = 27.1+0.3N − 0.00054N(2.1)In Japan the “Road Bridge Specifications” (Shioi and Fukui 1982) suggests for N > 5,( 15 ) 1 2 + 15ϕ = N(2.2)and the “Design Standards for Structures” (Shioi and Fukui, 1982):ϕ = 0.3N+ 27°(2.3)Table 2.1 shows the values of ϕ as a function of the SPT N-value. The values from equation 2.3,are very close to the values of equation 2.1. Thus, equation 2.3 is recommended in this study asa good linear approximation of the relationship between the angle ϕ and the blow count N.2-2
Fig. 2.1Correlation between friction angle and SPT N-value (from Peck, Hanson, andThornburn, 1953)2-3
Page 1: UPDATING BEARING CAPACITY - SPT GRA
Page 4 and 5: SUMMARYThe graphs used by the Maryl
Page 6: 90x1 and x2 factors x1 and x2 facto
Page 9 and 10: LIST OF TABLESTablePage2.1 Angle of
Page 11 and 12: CHAPTER IINTRODUCTION1.1 General Ov
Page 13 and 14: Fig. 1.2Maryland SHA graphs for cla
Page 15: CHAPTER IISOIL PROPERTIES FROM SPT
Page 19 and 20: The Japanese “Road Bridge Specifi
Page 21 and 22: Fig. 2.3Relationship between SPT N-
Page 23 and 24: CHAPTER IIIAVAILABLE BEARING CAPACI
Page 25 and 26: q ult(AASHTO 4.4.7.1-1)= cNc+ 0.5γ
Page 27 and 28: TABLE 3.3 AASHTO Expressions for Fo
Page 29 and 30: 90807060Wall Footing on Granular So
Page 31 and 32: x1 and x2 factors180160140120100806
Page 33 and 34: q ult= γ 1x 1D + γ 2x 2Bwhere γ
Page 35 and 36: Presumptive Ultimate Bearing Capaci
Page 37 and 38: = 466N psfFigure 4.5 and Table 4.4
Page 39 and 40: CHAPTER VAPPLICATIONS OF CURRENT AN
Page 41 and 42: Fig. 5.1 Comparison between the cur
Page 43 and 44: Fig. 5.2 Comparison between the cur
Page 45 and 46: REFERENCESMcGregor, J.A. and Duncan
Page 47 and 48: A.1. x 1 and x 2 factors as a funct
Page 49: APPENDIX BShear Strength vs. SPT-va

Updating Bearing Capacity – SPT Graphs - Maryland State Highway ...

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