Submergence Rescue Vehicle) into cohesive soil at either the reservoir or test 

 bin sites. The objects were allowed to remain in place for varying times and 

 then broken out either by rapidly increasing the uplift force until the occur- 

 rence of breakout or by applying a smaller force and measuring the time 

 required for breakout. The results were presented in the form of regression 

 equations relating breakout force to object embedment depth. These were 

 given for different object shapes and in-situ times. No attempt was made to 

 derive general equations which could be extrapolated to situations other than 

 those investigated. It was concluded, however, that embedment depth is a 

 significant parameter in determining the required breakout force.^ 



Marine Salvage and Offshore Petroleum Industry Operations. 



Documented evidence relative to the problem of freeing objects from the 

 seafloor is limited. A "mud suction" force is often mentioned in the litera- 

 ture of marine salvage operations, but no measurements of such forces seem 

 to have been made. In the offshore petroleum industry, it is often necessary 

 to extract large mat foundations from the seafloor soils. In some cases, the 

 forces required have been measured, but these are difficult to analyze because 

 the mat embedment depth is generally not known and the lifting process is 

 usually accompanied by water jetting beneath the mat. A good review of the 

 breakout problems associated with marine salvage and offshore petroleum 

 industry operations is provided by two NCEL reports.^- ^ 



Objectives 



The objectives of this report are: 



1 . To present the results of NCEL breakout tests. 



2. To provide an analysis of these data. 



3. To recommend practical techniques for use by field 

 engineers in estimating the effort required to break out 

 partially embedded objects from seafloor soils. 



TEST PROGRAM AND RESULTS 



As discussed in the Background section, NCEL has conducted five 

 series of tests to investigate the unaided breakout of partially embedded 

 objects. They are: 



1. FY-66 Seal Beach field tests 



2. FY-67 San Francisco Bay field tests 



