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)
See Extra Handout
 Vesic (1973, 1975)

Vesic (1973, 1975) Formulas
qult  cN c sc d cicbc g c   zD N q sq d q iq bq g q  0.5 BN  s d i b g
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
 6.4
 6.5
 6.6
 6.7
 6.8
 6.9

Groundwater Effects
Allowable Bearing Capacity
Selection of Soil Strength Parameters
Local & Punching Shear Cases
Bearing Capacity on Layered Soils
Accuracy of Bearing Capacity Analyses
Bearing Capacity Spreadsheet
Allowable Bearing Capacity
qult
qa 
F

qa

F …. Factor of safety
….. Allowable Bearing Capacity
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, c and  
 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