bearing capacity from cpt data
DESCRIPTION
basic knowledge how to use cone penetration test data for define a bearing capacity of shallow foundationTRANSCRIPT
FROM CONE PENETRATION DATA ( CPT TEST )
BEARING CAPACITY OF SOIL
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WARNING!!!!
Meyerhof (1956) suggest for foundation on the sand soil :
Rectangular or square footing for width B ≤ 1,2 m :
Rectangular or square footing for width B ≥ 1,2 m :
where : Allowable bearing capacity for settlement of 2,54 cm (1”)
Conus penetration(qc ) taking on average of qc from 0 level to B depth of foundation.
230 cmkgqq c
a
2
230,050 cm
kgB
Bqq ca
aq
Result of investigation data from SPT test have shows a relation with :
for B ≤ 1,2 m :
for B ≥ 1,2 m :
where : Kd = 1+0,33Df/B ,maks. Kd = 1,33
Nqc 4
220 cmkgKqq d
ca
2
230,033 cm
kgB
Bqq ca
Sanglerat (1972) suggest the relationship between undrained shear strength (cu ) with conus penetration
on cohesive (=0)
For normal consolidated :
For over consolidated :
220cm
kgqc 1518cc
uqtoqc
225cm
kgqc 2226cc
uqtoqc
Example problem :
Average of conus penetration under the foundation is :
235cm
kgqc
Take of width B = 1,5 m ,so using a formula for B > 1,2 m :
230,050
B
Bqq ca
2
2
01,15,130,05,1
50 cmkgqq c
a