2. If the soil is cohesionless (sand), breakout will not be a 

 problem. Breakout can be accomplished by applying a 

 line force equal to the buoyant weight of the object. A 

 short time may elapse before the object breaks free. 



3. If the soil is cohesive (clay), the soil will provide at least 

 some resistance to breakout, as indicated by the relation- 

 ships of this report. 



D. Estimate the buoyant unit weight of the soil, 75. 



1 . This can be obtained accurately from a bulk wet density 

 test on a core sample. 



2. If core samples are not available, the buoyant unit weight 

 can be taken as 30 pcf , a typical value for seaf loor soils. 



E. Determine, if possible, how the object became embedded. 



1. If the object was sinking slowly (less than or equal to 2 fps) 

 when it collided with the seafloor, and the present relative 

 embedment depth, D/B is greater than 0.25, it is not neces- 

 sary to measure or estimate the soil strength. Instead, the 

 following procedure should be used: 



a. Calculate Fq = W^ - W^, where W^ = 7^ V^. 



b. Refer to Figure 3 (or insert D/B into Equation 5) 

 and obtain the quantity Fjj^/Fq. 



c. Multiply F[(j/Fq by F^ to obtain F^^, the portion 

 of the immediate breakout force which will be car- 

 ried by the soil. 



2. If the object penetrated the seafloor with a velocity greater 

 than 2 fps, or if the present relative embedment depth, D/B, 

 is less than 0.25, it is necessary to estimate the undrained 

 shear strength of the soil. 



a. This can be accomplished by in-situ vane tests near 

 the object, laboratory vane tests on core samples, or, 

 if neither of these courses can be followed, by refer- 

 ence to Figure 7. This figure presents a typical 

 strength profile for a cohesive seafloor soil. 



b. Once the shear strength profile is known, it is 

 necessary to select a representative shear strength. 

 This can be done by averaging the strength from a 

 sediment depth of to D + B. 



26 



