Journal of the Japan Society of Erosion Control Engineering, Vol.59,No.2,2006
Experimental production and estimation of a variable impact weight for
simple penetration tests
Naomasa HONDA Takenobu OKUMURA Yasuyuki TADA
Abstract
The resistance value in simple penetration tests, i.e., the Nc]value, is useful
for investigating sliding surfaces or the surface soil layer of a forest slope.
However, the impact weight of 5]kgf, which is the conventional one used in the
tests, is too great for accurately estimating the physical characteristics of
soil within the surface soil layer when the soil layer is soft. This paper proposes
a new type of impact weight for simple penetration tests that is variable from
1]kgf to 5]kgf in 1]kgf increments. Many simple penetration tests are conducted
in order to estimate the effect of this weight on an actual forest slope. Experimental
results provide a detailed description of the vertical distribution of the penetration
resistance value within the surface soil layer. This is made possible by using
lighter weights than the conventional one, especially the weights 2]kgf and 3]kgf
ones. In addition, the penetration resistance value obtained with the 3]kgf weight
is nearly equal to that with Hasegawa 's soil penetration test, but detail is
improved further by using the 2]kgf and 1]kgf weights.
Key words:Simple penetration test, variable impact weight, improvement of penetration
resistance
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