The electronics and electrical systems have performed well with the 

 exception of the jetting sleeve. It failed several times during 

 testing, and its use was eventually discontinued. Its purpose was to 

 help evaluate the effect of the water jet on the data from the cone and 

 friction sleeve as a sounding is in progress. The evaluation was done 

 by performing side-by-side soundings with and without jetting and com- 

 paring the data. 



The jetting did aid penetration. At the soundings near Port 

 Hueneme full penetration was achieved when jetting was used (Figure 11). 

 When it was not (Figure 10), refusal was met at a dense sand layer at 

 25 feet of penetration. At Coronado there was no significant difference 

 in penetration with or without jetting (Figure 24). Refusal in all 

 tests was essentially met at the cobble layer. However, with jetting, 

 on the average, there was modest additional penetration. The jet was 

 not used in Norton Sound or in San Francisco Bay. 



The stratigraphies developed from the Port Hueneme (Figure 18) and 

 the Coronado soundings (Figures 18 and 24, respectively) show that 

 jetting does not influence the cone or friction sleeve data. In a 

 highly layered seafloor at the Port Hueneme site, the stratigraphies 

 developed with and without the jetting are in good agreement. For the 

 Coronado sites, jetting and nonjetting stratigraphies are nearly 

 identical . 



Stratigraphies developed from the XSP data have been compared to 

 historical core records and cores taken at the test sites. There are 

 too many profiles from Norton Sound to present in this report, but in 

 general the XSP stratigraphy compared well to the core stratigraphy. 

 The data at Port Hueneme show good agreement to core records 

 (Figure 19). No core was taken at the San Francisco Bay site, but the 

 geology of the test area has been well-defined (Corps of Engineers, 

 1963). The test area was in young bay mud; the XSP identified the soil 

 as a silty-clay to clayey silt. For this site, the data indicate an 

 undrained shear strength of nearly zero at the soil surface, increasing 

 to about 3 psi at a soil depth of 38 feet. Undrained shear strengths of 

 these values are very indicative of young bay mud. At Coronado, no 

 cores were taken, but the soil profile was determined with jet probings 

 at the XSP sounding locations. The general agreement between the jet 

 probe stratigraphy and the XSP stratigraphy is good (Figure 25). 



The data acquired from replicate soundings showed good agreement, 

 which is a recognized advantage of cone penetration testing. 



CONCLUSIONS 



1. The XSP cone penetrometer is a reliable piece of equipment for 

 gathering in-situ soil data at subbottom depth of 40 feet in up to 

 200 feet of water. 



2. The water- jet system aids penetration but does not allow pene- 

 tration through very dense sands or cobble layers. 



3. The water jet, when used as described in this report, does not 

 affect the penetrometer data. 



38 



