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Fig. 10 The Delft electric penetrometer tip (a) and the friction sleeve electric penetrometer tip (b).

Symbols: El.l and El.2 respectively.

Fig. 11 The Degebo friction sleeve electric pen etrometer tip.

Symbol: E2.

#4Smm

Fig. 12 The Parez hydraulic penetrometer tip (a) anu the friction sleeve hydraulic penetrometer tip (b).

Symbols: Hl.l and HI.2 respectively.

Fig. 13 There should not be any protruding edge at the screw connections between the rods.

The rods must not screw together or be joined in any way which gives them an ad-ditional degree of freedom as this has been found to increase the parasitical friction between the rods and the tubing. Before and after the test a check will be madę that the inner rods slide very easily in the push-rods, and that the cone and the friction sleeve move easily with respect to the body of the penetrometer tip. For improved accu-racy at Iow values of the resistances, the thrust data registered at the surface should be corrected for the total weight of the inner rods in the case of the cone resist-ance, and for that of the push-rods and inner rods in the case of the total resistance.

11. EXPLANATORY NOTES AND COMMENTS Notę 1: Definitions 2.11

The denominations "continuous" and "discon-tinuous" penetration testing are not ąuite correct, and the denomination "penetration testing with simultaneous pushing, and non-simultaneous pushing of cone and push rods", would be morę adeąuate. However, the denominations "continuous" and "discontinuous" have been maintained, as they are already well established.

Notę 2: Definitions 2.16

The friction ratio Rf, being the ratio of the

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