Cohesion and overburden stress
Cohesion and overburden stress
(OP)
hi all
How do i take into account the cohesion of clay when calculating overburden stress.
the overburden stress is just the wet density x the height of the material -( the density of water x the height of the water)
how do i take into account the cohesion of the clay?
thanks
How do i take into account the cohesion of clay when calculating overburden stress.
the overburden stress is just the wet density x the height of the material -( the density of water x the height of the water)
how do i take into account the cohesion of the clay?
thanks





RE: Cohesion and overburden stress
RE: Cohesion and overburden stress
Now you may be really asking about undrained shear strength. Undrained shear strength does very with confinement. In normally-consolidated soils taht variation may be at 20% of the overburden pressure. Don't rely on that value though. As you may already know, geotechnical laboratories are a much better resource.
f-d
¡papá gordo ain’t no madre flaca!
RE: Cohesion and overburden stress
thank you
RE: Cohesion and overburden stress
What information do you have? Do you only have boring logs? Is there any Atterberg limits to contrast to natural water contents?
All we know is somewhere there's a site and an engineer is concerned about soil strength. Your original post was focused on effective (drained, long-term) strength. Your subsequent post seems to be now focused on short-term, undrained strength. To me they're both relavent.
f-d
¡papá gordo ain’t no madre flaca!
RE: Cohesion and overburden stress
Im trying to calculate the overburden pressure at point 12m bgl where a horizontal borehole for installation of an electrical conduit will be drilled.I have logs and some PI values.
Ive taken standard density values for the strata and calculated my effective overburden stress at that point. There are clay layers and i was told that i need to take into account undrained shear strength.
...?
RE: Cohesion and overburden stress
Unless there is some other aspect involved in the design of the electrical conduit and Su is a necessary variable which does not govern overburden stress though.
RE: Cohesion and overburden stress
Hinted like a 2x4 to the forehead!
RE: Cohesion and overburden stress
RE: Cohesion and overburden stress
RE: Cohesion and overburden stress
f-d
¡papá gordo ain’t no madre flaca!
RE: Cohesion and overburden stress
RE: Cohesion and overburden stress
yes - getting a bit confused as im told when calculating the overburden stress i have to take into account the undrained strength, and that means multiplying by a passive pressure resistance coefficient.
RE: Cohesion and overburden stress