Environmental Engineering Reference
In-Depth Information
Table 1.
Tunnel characteristics.
Tunnel
designation
Width
(m)
section
(m
2
)
length
(m)
Max. cover
(m)
Geological
conditions*
Queimada ii
9.0
75
745
95
Vcβ
2
access
Road a
7.0
57
202
70
Vcβ
2
Piquinho
(double)
9.0
75
2 ×449
35
Vcβ
1
&
Vcβ
2
Fazenda
(double)
9.0
75
30
2 ×163
Vcβ
2
access
Road e
7.0
57
185
40
Vcβ
2
caniçal
Tunnel
9.0
75
2 ×2100
>300
Vcβ
1
&
Vcβ
2
Portais
(double)
9.0
75
2 ×682
100
Vcβ
2
Palmeira
(double)
9.6
83
2 ×915
60
Vcβ
1
&
Vcβ
2
* Vc - Volcanic complexes.
2
GeoloGical-GeoTechnical
sURVeY
Table 2. Relationship between the length of tunnels
and the Machico-caniçal expressway (2 × 2 carriage-
ways).
The occurring geological-geotechnical conditions
are described in specific detail in Rodrigues et al.
(2009). nevertheless, we would point out that the
geotechnical surveying carried out was based on
detailed geological surveys of the surface together
with surface prospecting using trenches, and in-
depth prospecting comprised basically of rotation
boring. in order to survey the Machico-caniçal
expressway 146 bores were taken to survey around
8 km of the route, comprising a total of 3071 m of
drilling, which corresponds to 384 m of drilling for
each kilometre of the expressway.
of all the drilling made around 40% corre-
sponds to drilling to survey tunnels whilst the
remaining 60% is associated with the route lay-
out itself, retaining works and bridges. of the
prospecting completed for the tunnels, this corre-
sponds to an average of around 233 m per tunnel
(144 m per km). Bearing in mind the costs of pros-
pecting, each kilometre corresponds to on aver-
age €100,000 in prospecting work and €40,000 for
each tunnel. These costs correspond to around 0.5
to 1% of the price of the construction work.
Total length of expressway (m)
7 770
Total number of tunnels (including
double tunnels and access roads in tunnels)
14
Total development of tunnels (including
double tunnels and access roads in
tunnels) (m)
10 493
Total development of tunnel layout (including
double tunnels and access roads in
tunnels) (m)
4 991
Relationship between the development of tunnel
layout and total development of expressway (%)
64
are the double tunnels of Portais and Palmeira
cenor-Grid 2003a,b).
hence, a very significant part of the short stretch
of expressway between Machico and caniçal corre-
sponds to tunnels. in fact, as can be seen in Table 2,
64% of the route corresponds to underground
construction.
The current transverse cross-section of the sin-
gle direction tunnels has a working width between
walls of 9 m, comprising two 3.5 m road lanes
and clearance of 5 m. The section is comprised of
a semi-circular arch in the vault, with walls pro-
the Western portal of Fazenda Tunnel and acess
Road e.
3
chaRacTeRisaTion & DesiGn
For volcanic formations, being characterised by
substantial heterogeneity and lithological and
structural complexity,
the use
geomechanical
