English to Spanish Tech/Engineering Mining & Minerals / Gems Tronadura/Mecánica de Rocas

The most common representation of rock substance
strength is the unconfined compressive strength (UCS)
which requires the laboratory measurement of a sample of
defined dimensions following an international standard
procedure (Brown, 1981). The test is expensive and is
unlikely to be undertaken in large numbers. UCS values
are likely to be biased towards high values because only
intact core can be selected for testing and the test result is
rejected if a structural imperfection interferes with the
expected failure mechanism of induced shear. Such small
scale structures do contribute to blast breakage.
A problem arises when other simpler estimates of
strength are described in data bases as being UCS values.
These estimates may be from simple classifications or field
indices based on the blow of a geological hammer.
Strength may be interpreted from geophysics or converted
from point load tests. Point Load Test results can form a
very useful guide to blasting requirements. The test is
simple and inexpensive and can be performed on field
samples by site personnel in the field. While the results are
subject to some scatter, a sufficient number of tests can
result in indices that correlate well with blasting, crushing
and mill performance. However, it is important that the
basis of any conversion between point load strength and
UCS is known