A slightly different technique was followed for the field tests. It may 

 be explained by considering first that a relationship similar to Equation 2 holds 

 for the bearing capacity of partially embedded objects;^° 



6 1.0 + 0.2 ^ (3) 



AS V ■ ■ B, 



where P = maximum downward force the object is capable of supporting 

 before bearing capacity failure 



This equation suggests an in-situ test for measuring the undrained 

 shear strength, S. If an estimate of the buoyant unit weight of the soil is 

 made and the geometry terms A, D, and B are known, the soil strength can 

 be determined by measuring the bearing capacity force, P. 



The object placement phases of the NCEL field tests can be considered 

 as in-situ tests of this type. Very heavy objects were used, and considerable 

 object penetration occurred during each placement operation. It is indicated 

 that the soil bearing capacity was exceeded at the soil— water interface and 

 that the objects penetrated until the soil strength was adequate to support 

 the object weights. It can be assumed, therefore, that the bearing capacity, 

 P, is equal to the object buoyant weight, W,^, less any line force, Fg^, applied 

 during the waiting period. 



Equation 3 can be rewritten as 



AS \ ■ ■ B 



^ = 6(1.0.0.2 f) (4) 



where F„ = Wk - Fp,., - W, 



force carried by soil during waiting period prior to breakout 

 loading 



The field test data were correlated by plotting the experimentally 

 determined term, F,jj/Fq, versus D/B. This plot is presented in Figure 2. 



16 



