Academy / Dynamic penetration
The continuous dynamic penetration test is a simple methodology consisting of an assessment of the number of blows which is takes to dynamically sink rod sections of 10 or 20 cm (N10, N20, respectively).
The blows are made with a hammer of known weight which is allowed to fall freely from a fixed height. A larger diameter tip is attached to the lower end of the rod which reduces the parasitic drag on the shaft and facilitates its extraction as the tip remains in the soil when the survey is completed.
The survey is suspended when fifty blows are reached for the reading section (refusal). The results are presented as graphs on which the blow (N) is plotted against depth, the type of penetrometer used in each case being noted.
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