Pile Drivability . Drivability of piles has been correlated to cone 

 pressure. One correlation was developed by DeRuiter and Beringen (1979) 

 and is given in Appendix. 



APPROACH 



After the decision to develop a platform for performing penetration 

 tests was set, the operational requirements were set at 40 feet of 

 penetration into uncemented sands, silts, and soft- to-medium clays at a 

 maximum water depth of 200 feet. Forty feet of penetration in these 

 soils was chosen because it was sufficient for designing the common 

 shallow piles used in Navy operations (e.g., ELCAS) and would satisfy 

 most of the requirements in propel 1 ant-embedded anchor work. The 

 200-foot water depth represented the design depth limit of many NCEL- 

 developed shallow water systems, such as the Offshore Bulk Fuel System 

 (OBFS), and therefore seemed to be a logical depth limit for this 

 experimental device. Also, within this depth limit, difficulties in 

 transmitting data and providing power to the device were minimized. 

 Another requirement in the project was that the tool be operable from 

 the type of Navy-owned vessel typically available. This vessel is 

 usually a small barge with a deck-mounted crane. Also, this constraint 

 in effect limited the weight of the tool to about 10,000 pounds. 



The first step in developing this tool was to generate a conceptual 

 design conforming to these operational limits. Woodward-Clyde Consul- 

 tants (1980) was contracted to do the design. Their first thought was 

 simply to extend the capabilities of an already developed cone penetrom- 

 eter. However, it was apparent that the reaction required to push a 

 cone 40 feet into sand would be about 30,000 pounds. This posed two 

 problems. First, to provide the reaction by self-weight would violate a 

 design provision; weight was limited to 10,000 pounds. Second, the rod 

 used to push the cone would be susceptible to buckling under such loads. 

 As alternatives to pure mechanical insertion of the cone, vibration and 

 water- jet-assisted mechanical insertion were studied. Vibration was 

 eliminated because of concern that the 40- foot penetration would not be 

 obtained and that the cone's sensors would be damaged. The water- jet- 

 assisted penetration appeared promising because there was experience in 

 water jet penetrations to the necessary depth. 



This concept was further developed by analyzing the hydraulics of 

 jetting and the cone rod design. The configuration believed to be most 

 viable was a vibracorer-type frame with a remotely controlled chain- 

 driven, water- jet-assisted cone penetrometer (Figure 1). 



The conceptual design of the device was moved to final design and 

 fabrication by Fugro-Gulf, Inc. (1981). This device, called the XSP 

 (for experimental static penetrometer), is the subject of this report. 

 It is described in detail, operational procedures are presented, and the 

 results of its evaluation are given. Procedures for interpreting CPT 

 data and using it with geotechnical designs are given in the Appendix. 



