Pertemuan 06 Daya Dukung Tanah Matakuliah : S2094 / Rekayasa Pondasi Tahun : 2005 Versi : 1.1 Pertemuan 06 Daya Dukung Tanah

Further Developments Skempton (1951) Meyerhof (1953) Brinch Hansen (1961) De Beer and Ladanyi (1961) Meyerhof (1963) Brinch Hansen (1970) Vesic (1973, 1975) See Extra Handout

Vesic (1973, 1975) Formulas Shape factors….… Eq. 6.14, 6.15 and 6.16 Depth Factors ……. Eq. 6.17, 6.18 and 6.19 Load Inclination Factors …. Eq. 6.20, 6.21 and 6.22 Base Inclinations factors .. Eq. 6.25 and 6.26 Ground Inclination Factors…. Eq. 6.27 and 6.28 Bearing Capacity Factors …. Eq. 6.29, 6.30 and 6.31

Bearing Capacity of Shallow Foundations 6.3 Groundwater Effects 6.4 Allowable Bearing Capacity 6.5 Selection of Soil Strength Parameters 6.6 Local & Punching Shear Cases 6.7 Bearing Capacity on Layered Soils 6.8 Accuracy of Bearing Capacity Analyses 6.9 Bearing Capacity Spreadsheet

Allowable Bearing Capacity F …. Factor of safety

Factor of Safety Depends on: Type of soil Level of Uncertainty in Soil Strength Importance of structure and consequences of failure Likelihood of design load occurrence

Minimum Factor of Safety

Selection of Soil Strength Parameters Use Saturated Strength Parameters Use Undrained Strength in clays (Su) Use Drained Strength in sands, Intermediate soils that where partially drained conditions exist, engineers have varying opinions; Undrained Strength can be used but it will be conservative!

Accuracy of Bearing Capacity Analysis In Clays …..Within 10% of true value (Bishop and Bjerrum, 1960) Smaller footings in Sands…. Bearing capacity calculated were too conservative – but conservatism did not affect construction cost much Large footings in Sands … Bearing capacity estimates were reasonable but design was controlled by settlement

Accuracy; Bearing Capacity Analysis