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

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CHAPTER IVDEVELOPMENT OF THE NEW GRAPHS4.1 <strong>Graphs</strong> for Footing on Granular Soils4.1.1 Wall FootingThe AASHTO equation:q 0+ qN s b iult= cNcscbcic+ .5γBNγsγbγiγqqq qwill have: i) c = 0 for granular soil; ii) s c = s q = s γ = 1 for L > 5B; iii) i c = i q = i γ = 1 for verticalload, and iv) b c = b q = b γ = 1 for horizontal base, thus the AASHTO equation will be:qult= γDN+ 0.5γBN= γ= γq[ DN + 0.5NB][ Dx + Bx ]1q2γγwhere x 1 = N q and x 2 = 0.5 N γFigure 4.1 and Table 4.1 show the values of x 1 and x 2 as a function of N 60 . Appendix A-1 showsthe determination of x 1 and x 2 as a function of ϕ.4.1.2 Square FootingThe AASHTO equation:q 0+ qN s b iult= cNcscbcic+ .5γBNγsγbγiγqqq qwill have: i) c = 0 for granular soil; ii) s q = 1 + tan ϕ, s γ = 0.6; iii) i c = i q = i γ = 1 for vertical load,and iv) b c = b q = b γ = 1 for horizontal base, thus the AASHTO equation will be:qultq( 1+tanφ)D( 1+tanφ) N[ Dx + Bx ]= γDN= γ= γ[ + 0.3NB]12+ 0.5γBNqγγ0.6where x 1 = (1 + tan φ) N q and x 2 = 0.3 N γ4-1
90807060Wall Footing on Granular Soilsq ult = γ [D x 1 + B x 2 ] psfq q FSall=ultγ in pcf, D in ft, B in ftx1 and x2 factors504030x 1x 2201000 5 10 15 20 25 30 35 40 45 50Standard Penetration Resistance, blows/ftNote: Settlement was not considered in the graphFig. 4.1x 1 and x 2 factors as a function of N-value for a wall footing4-2
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 and 16: CHAPTER IISOIL PROPERTIES FROM SPT
Page 17 and 18: Fig. 2.1Correlation between frictio
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: TABLE 3.3 AASHTO Expressions for Fo
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

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