Ultimate Bearing Capacity of Two Interfering Rough Strip Footings

The ultimate bearing capacity of two interfering strip footings was determined by using the method of stress characteristics. The analysis was performed by choosing two different possible failure mechanisms. The variation of the efficiency factor ( ξγ ) was computed with respect to change in the clear spacing (s) between the two footings. For a given s∕B , the value of ξγ predicted on the basis of Mechanism 1 was always found to be smaller than those on the basis of Mechanism 2. For Mechanism 1, the maximum value of ξγ , which becomes always equal to 2.0, always occurs at s∕B=0 . On the other hand, the Mechanism 2 provides maximum value of ξγ even greater than 2.0, especially with ϕ>20° , corresponding to s∕B= scr ∕B . It was noted that the results from Mechanism 2 compare more closely with the theory of Stuart in 1962 and with the recent upper bound limit analysis solution of the writers.

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