Environmental Engineering Reference
In-Depth Information
Table 5. Minimum survey points (boreholes) and replacement percentage by con-
tinuous penetration tests, according to cTe.
Minimum survey points (boreholes)
Replacement (%)
Building type
T-1
T-2
T-1
T-2
c-0
-
1
-
66
c-1
1
2
70
50
c-2
2
3
70
50
c-3
3
3
50
40
c-4
3
3
40
30
Table 6.
Minimum depth of prospecting.
Minimum depth of prospecting (m)
Geotechnical units/
Building type
iVa
(T-1)
iVb
(T-3)
Va
(T-2)
Vb
(T-3)
Vi
(T-2)
Viii
(T-3)
Viii
(T-3)
iX
(T-3)
i (T-3)
ii (T-1)
iii (T-3)
c-0
5
4
5
4
5
5
5
5
5
5
5
c-1
8
6
8
6
8
7
8
7
8
8
8
c-2
12
8
12
8
12
10
12
10
12
12
12
c-3
16
10
16
10
16
12
16
12
16
16
16
c-4
20
12
20
12
20
14
20
14
20
20
20
structure on the ground. in this case, the prospect-
ing that exceeds the number of the application of
Table 4, may be made by rotary-percussion drilling
system, under the technical direction and supervi-
sion of an expert in the geotechnical survey.
in the event that the maximum distance (d
max
)
exceeds the dimensions of the study area, distances
should be decreased until they reach the required
minimum number of points. The maximum distance
can be considered as the radius circle of the influ-
ence areas of the recognition points. The influence
circle areas of the research points obtained must
exceed 90% of the contact area with the ground.
in the case of buildings with floor area exceed-
ing 10,000 m
2
, the density of points on the surface
excess can be reduced. This reduction should not
exceed 50% of survey points obtained from apply-
ing the previous rule.
The initial number of survey points may be
replaced by continuous penetration tests, in those
geotechnical units that support this technique, in
the percentage indicated in Table 5.
construction. These considerations will be valid
unless it has previously reached a geotechnical unit
resistant (bedrock) such that the pressure applied
on it by the foundation of the building produce
significant deformations.
however, the minimum depth surveys has been
established taking into account the peculiarities
and problems associated with each of the geo-
technical units and type of building, as shown in
Table 6.
The depths indicated in Table 6 are referred to
the final level of excavation. To these are added, if
necessary, the thickness of artificial fillers or final
depth of excavation to achieve the planned foun-
dation level.
in the case of rotary-percussion drillings that
can be made in Geotechnical Units iii and iVb
the minimum depths to reach are those given in
Table 6 as well.
4
conclUsions
The geotechnical investigation guide for building
in volcanic environments is a most useful docu-
ment for architects, engineers and geotechnical
experts. it is a reference document for the geotech-
nical investigation in volcanic environments, as it
takes into account the peculiarities of these mate-
rials and applies the experience of many decades
building on them.
3.2
Depth of recognition points
The depth achieved will be one in which there is no
significant settlements under the loads transmitted
by the building. This depth can be that where net
increase of tension in the ground, by the building's
weight, is equal or less than 10% of the vertical
effective stress, in that level point before building
