The allowable bearing capacity of soils were calculated by considering the minimum of bearing capacity which is obtained by shearing and settlement. For sandy soils the well known Vesic' s formula S=(I.q.b.(1-v2)/Es) were used to back calculate the q for different width of foundation. but, for clay soils its more complicated. I want to know how can I derive the ultimate bearing capacity corresponding to consolidation settlement of cohesive soils?
C=qu/2 where c is the cohesion of the clay using UCS test, qu is the maximum stress
Dear Sayed,
The ultimate capacity of foundation on clay is calculated by using the formula..Qu = cNc, where c - shear strength of clay = qu/2 and Nc - bearing capacity factor..the consolidation settlement is calculated using the equation Se = cc/1+eo X H X log (stress increased due to construction = bearing capacity + soil effective overburden pressure/effective overburden pressure). The maximum pressure used to calculate settlement is the bearing capacity of soil. Thus, while calculating the settlement due to the incremental pressure i.e. equal to bearing capacity of clay should be within the permissible limit..ok all the best..
Karthigeyan . S
Ahmed Salih Mohammed
Thank you so much for your cooperations.
Actually I have a problem with finding the maximum pressure that is allowed for settlement. There are two types of settlement: immediate and consolidation settlement for foundations on clay soils ( Se+Sc
Dear Seyed Bearing capacity can be obtained using Terzaghi formula below if it is for square footing
qf=0.4(𝜸BN𝜸)+1.3(CNc)+𝜸DNq (Square footing)
and you can use the table below to find the various parameters
Dear Friend.
Settlement controlled bearing capacity for clay could be computed using the one dimentional consolidation equation by computing the allowable stress increase available for external loading.
Dr. Fawzi gharagheer
You may use Terzaghi Bearing Capacity Theory or modified Hansen Theory. Both are well covered in Bowles (1996).
You may also use the correlation between allowable bearing capacity of clay and the SPT resistance given in page 430 of the book "Soil Mechanics in Engineering Practice" by Terzaghi & Peck (1958).
Raid R Al-Omari
can you please mention the correlation between allowable bearing capacity of clay and SPT resetance give in book ?
thank you
Good morning
Attached is the table of correlation between bearing capacity of clay and SPT.
Regards
An interesting paper on consolidation and desiccation of clay slurries
https://www.researchgate.net/publication/321844141_A_framework_for_coupled_consolidation-desiccation_behaviour_of_clay_slurries
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