to barge 





height indicator 



potentiometers 



instrument mounting 

 stand 



pile no. 21 



(8-5/8-in. OD) 



3/4-in.-diameter 

 wire rope" 



existing peg-top chain to 

 be removed from pile 



^L 



four-part line 



tload 

 cell 



. pile no. 1 

 (24-in. OD) 



pile no. 15 j^ 

 (24-in. OD) ! 



Figure 21. Pop-Up Site pile load test. (After Sutton, 1969.) 



St. Andrews Bay Model Studies. In 1961, Keller (1964 and 1969) 

 placed three concrete blocks on the shallow seafloor (water depth averaged 

 1 7 feet) to study the bearing capacity of spread footing foundations. Two 

 test sites in St. Andrews Bay, Florida, were used during the investigation. 



The concrete blocks were rectangular, square, and circular in plan 

 (Figure 23). Each weighed approximately 2,100 pounds in water. Applied 

 pressures ranged from 164to246psf. The soil at each site was sampled and 

 evaluated. It varied from a silty clay to a silty sand classification and, in all 

 cases, would be considered a weak and compressible cohesive soil. Results 

 of the laboratory study were then used to estimate the bearing capacity at 

 various levels of object penetration. 



Laboratory data indicated that the undisturbed strength of the soil 

 could not support the blocks at the soil surface; thus, a bearing capacity 

 failure was expected. The extent of block penetration was predicted by 

 determining the depth at which the bearing capacity, based upon undis- 

 turbed soil strength, had increased enough (assuming soil strength increased 

 with depth) to support the block. However, the blocks penetrated beyond 

 the estimated depths. Subsequent analysis of the data has shown that use of 



36 



