(a) Sub-bottom profile (3.5-kHz acoustic source) to locate bed- 

 rock, sediment, and layering, and to assess areal uniformity. 



(b) A relatively undisturbed core sample at least as long as the 

 expected depth of anchor penetration to make measurements of 

 undrained shear strength and sensitivity (with a minivane), 

 density, plasticity, grain size, and origin. For most soft 

 cohesive soils, the friction angle can be estimated as 

 35 degrees (from CEL experience) as static short-term capa- 

 city will govern over static long-term capacity. For excep- 

 tions, measure the friction angle and the cohesion of the soil 

 with triaxial tests at the depth of interest. When a long core 

 is not available, analyze a sample of the upper 6 to 8 feet of 

 soil as suggested for a longer core, then extrapolate the data 

 and compare the extrapolation to undrained shear strength 

 data from a Doppler penetrometer or similar device providing 

 comparable data and depths of penetration. 



There will be few cases where cohesionless sediments will be found 

 in deep water. The recommended survey for these cases would have 

 begun with a search of record data followed by: 



(a) Sub-bottom profiling to locate bedrock and layering and 

 assess areal uniformity. 



(b) A Doppler penetrometer test to judge the relative soil 

 strength. 



(c) A sample of even limited depth for grain size and origin 

 determination . 



Determining the friction angle will be difficult, as representative 

 samples cannot be obtained and the penetrometer test will not provide 

 it. However, safe estimates of the friction angle and the submerged 

 density can be made using Table 2-3. 



16 



