Load Settlement Relative Density of Sand, Dr Relative Depth of Foundation D/B^ 0 A. General Shear Settlement Load Ultimate Load B. Local Shear Settlement Load 0 0.2 0.4 1 Local Shear 2 1.0 General Shear Punching Shear 3 4 B^ = B for a Square or Circular Footing. B^ = 2BL/(B+L) for a Rectangular Footing. Surface Test Modes of Failure of Model Footings in Chattahoochee Sand (20,76) C. Punching Shear Modes of Bearing Capacity Failure (76) Adapted from Vesic (1973) JSMFD, ASCE, 99(SMI) Dense Very Dense 140 0 130 10 N 120 20 110 30 100 40 90 50 80 60 Nr 70 60 Standard Penetration Resistance N, blows/ft Very loose Loose Medium Bearing Capacity Factors, Nr and Nq 0.8 5 Test at Greater Depth Nq 50 40 30 20 10 0 28 0.6 30 32 34 36 38 40 42 44 Angle of Internal Friction, �, degrees Curves showing the relationship between bearing-capacity factors and �, as determined by theory, and rough empirical relationship between bearing capacity factors or � and values of standard penetration resistance N. Adapted from Peck, Hanson & Thornburn (1974) Vertical Stress, �v̀o (kg/cm2) 0 0 SPT N Value (Blows/30cm) 40 60 20 80 100 Dr = 80% 1 2 Dr = 40% 3 Gibbs & Holtz (1957) Peck & Bazaraa (1969) Marcuson & Bieganousky (1976) Schultze & Melzer (1965) Fig. 47. Empirical correlations between standard penetration resistance and relative density for cohesionless soils. Adapted from Ladd et al. (1977) 9th ICFMFE Effective Overburden Pressure, Kips/Square Foot 0 0 40 N, Blows/Foot 80 120 160 200 2 4 DR = 100 % (Gibbs and Holtz) DR = 100 % (Bazaraa) 6 Points omitted in this area 8 Dry Cohesionless Soil Submerged Coarse Cohesionless Soil 10 Results of Standard Penetration Tests for Very Dense Sands Adapted from Peck & Bazarra (1969) Angle of Internal Friction Vs Density (For Coarse Grained Soils) Angle of Internal Friction �`(Degrees) 45 �` Obtained from effective stress failure envelopes approximate correlation is for cohesionless materials without plastic fines 40 t Rela 75% GP 50% SW d SP SM an Material Type 25% nge in this ra 30 100% GW 35 ML sity en ive D 0 25 20 75 80 90 100 110 120 130 140 Dry Unit Weight (� ), PCF D 1.2 1.1 1.0 0.9 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 150 (G = 2.68) 0.35 0.3 0.25 0.2 0.15 Void Ratio, e 0.55 0.5 0.45 0.4 0.35 Porosity, n 0.3 0.25 0.2 0.15 Correlations Of Strength Characteristics For Granular Soils Adapted from NAVFAC DM-7.1 (5/82) p 7.1 - 149

III-4 Shallow Foundations on Sand: Bearing Capacity

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