soil model data question!?

Posted by: YB

soil model data question!? - 02/18/09 09:16 PM

Everybody:
This is the soil model data submitted by engineering company, The value of the undrained shear strength may have a problem. See details in the following:
Coefficient of friction, 0.35
Soil density, 00.0024(kg./cu.cm)
Buried depth, 1600(mm)
Angle of internal friction 35(deg)
undrained shear strength 1000(kpa)
Overburden compaction multiplier: 6
Yield Displacement Factor 0.015
Thermal expansion Coefficient 11.214(L/L/dec C)
Temperature Change 50(dec C)

Please advise:
1, Whether choose one enter between Coefficient of friction and the Undrained Shear Strength or not? If enter the two value at the same time, how will it affect the calculation of the results?
2, what value is the undrained shear strength of general soil?

THANKS!
Posted by: Dave Diehl

Re: soil model data question!? - 02/19/09 01:52 PM

For cohesive soils (clay):
Specify Undrained Shear Strength (Su). Friction Angle should be 0 and Coefficient of Friction should remain blank.

For granular soils (e.g. sand):
Specify Coefficient of Friction and Friction Angle (25-45deg). Undrained Shear Strength should remain blank.

If no Coefficient of Friction is specified, the axial load limit will be based, instead, on Su/600psf.

If Su is specified, the transverse load limit will be factored by Su/250psf.

Regarding values for Undrained Shear Strength - I have a paper here that suggests a very soft clay at 10kPa and a stiff clay at 100kPa.