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› Mae 25
› TOMOGRAPHIC SEISMIC EXPLORATION
This survey method is used to identify
physical-geometrical anomalies of the
sub-soil with a definitely higher resolution
compared to the other seismic
exploring methods, giving the opportunity
to create an image of the subsoil
containing all the anomalies, even
the most complex ones, which cannot
be resolved with other methods.
In particular, the tomographic method
allows to reconstruct the geometric
distribution of the elements that
constitute a specific section, starting
from the analysis of the behaviour of
the radiations that cross it.
› DOWN-HOLE SEISMIC EXPLORING
This type of survey is performed for
the mechanical characterisations of
grounds crossed during the probing
phase. The technique consists
in the measurement of the travelling
times of the elastic waves between
the seismic source on the
surface and the geophones located
inside the probing hole, properly conditioned
with PVC pipe or geo-technical
pipe. The seismic exploring activity
in the down-hole takes place by
placing one or more triplets of sensors
(horizontal and vertical) inside
one of the probing holes and at various
depths, aimed at receiving the
seismic signals generated through
ram on anchored plate. Energy will
be supplied in phase inversion in order
to polarise phases S on a horizontal
plane H, according to an orientation
of 180°. Through seismic speeds
Vp and Vs, it is possible to obtain information,
such as elastic modules
and geo-seismic parameters. Vs 30
can be measured on probing holes
up to 30 metres of depth (O.P.C.M
3274/2003).
› CROSS-HOLE SEISMIC EXPLORING
This type of survey is performed
through the physical –dynamic characterisation
of the portion of ground
between the two probing holes. The
technique consists in the measurement
of the travelling times of the elastic
waves between the source located
in a hole and the geophone/s located
in another hole/s at the same depth.
The cross-hole is made by introducing
the borehole in one of the holes
and the tridimensional geophone (or
geophones) in another hole/s aimed at
receiving the seismic signal incoming
from the source at the same level. The
elastic modules and mitigations of the
medium between the holes can be obtained
from this test.