Drive Mechanism 



The driving mechanism pushes the cone penetrometer into the sea- 

 floor. This mechanism is composed of a 1-hp motor and gearbox on the 

 base, twin drive chains along the sides of the beam, and a guide track 

 and bracing system for the push rods along the front of the beam 

 (Figure 2). The drive chains are connected to a header block at the top 

 of the push rods. The block slides along a track mounted on the front 

 of the beam. The push rods are supported and guided along the track by 

 spacer blocks. When the cone control switch is flipped to DOWN, the 

 motor drives the chains which steadily push the header block and, con- 

 sequently, the cone penetrometer downward. The depth of penetration is 

 measured by a depth encoder on the side of the beam which is gear-driven 

 by one of the drive chains. 



Water- Jetting System 



The water- jetting system on the XSP is a unique feature. The 

 jetting system consists of the jetting nozzle on the upper end of the 

 cone unit, water hoses, and an on-deck water pump. The components are 

 shown in Figure 2. Seawater is pumped through hoses to the header 

 block, where it is directed down through the push rods and out and 

 upward from the jetting nozzle. The purpose of the jetting is to flu- 

 idize the soil adjacent to the push rods to reduce soil friction and 

 ease penetration. If too much water and pressure are used, the jetting 

 can adversely affect the penetration data; this condition will be 

 detected by a difference in the two friction sleeve readings. Experi- 

 ence has shown that 50 gpm at 50 psi does not influence the cone 

 readings in a variety of mixed soils and sands. Jetting is not needed 

 to achieve maximum penetration in most clays. 



EQUIPMENT OPERATION 



To operate the XSP, the equipment must be assembled and the opera- 

 ting mechanisms checked out. After checkout the equipment is laid on 

 the support vessel and transported to the location for the first 

 sounding. The vessel is anchored or otherwise held stationary as the 

 XSP structure is deployed and the cone penetrometer pushed into the soil 

 while the console records the data. The process of inserting the cone 

 penetrometer into the soil is often referred to as a sounding. The 

 deployment, operating, and data acquired by the XSP are described in the 

 following sections. 



Deployment 



The XSP can be deployed in either of two ways: it can be stood up 

 and deployed from the ship's deck with a crane, which depends on deck 

 space and the type of lifting equipment available, or it can be deployed 

 from a hanging position along the side of the vessel. To lay the XSP in 

 the 40-foot mode down on the deck for transit to the test site, a tri- 

 angular space 50 feet long with a 20-foot base must be available, along 



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