Environmental Engineering Reference
In-Depth Information
Table 2.
stabilization solutions adopted on the cliffs.
Geology
sítio do
Massapez
BrD/β
sítio da
Vargem
βF +BrD +T
lugar de
Baixo
βF +Br +T
sítio do
calvário
β+BrD
saint João
Batista Fort
T +βF
stabilization
solutions
excavation
X
X
X
shotcrete associated
to bolts
X
X
X
shotcrete
X
X
locally applied bolts
X
X
X
X
Joint sealing
X
X
cave filling with
cyclopean concrete
X
in general, when the cliffs are affected by a consid-
erable rock mass volume instabilization, the stabiliza-
tion works consist on the removal of the unstabilized
mass and on the protection of the resulting slope
with shotcrete and bolts.
in other cases, when superficial cliff instability
situation are identified, lighter interventions are
recommended, such as shotcrete, locally applied
bolts, joint sealing and cave filling with cyclopean
concrete.
after the execution of the designed solutions, it
was also necessary to pay attention to landscape
impact. colour additives matching the surround-
ing geological formations were applied in the shot-
crete and sealing grout.
a. General view of the slope after the stabilization works
5
sTaBiliZaTion WoRks eXecUTeD
5.1
Cliff above the ER101 at Sítio do Massapez
in February of 2006 a crack about 13 m long,
2.5 m deep and 1 to 2 m wide was identified at the
top of the cliff at elevation 240.00 m.
after a detailed survey it was possible to con-
firm that this crack represented the top of an
unstable mass of about 30 000 m
3
, with a sliding
surface 60 m wide and 40 m high, located 12 m to
the inside of the cliff.
This cliff is crossed by the eR101 road at eleva-
tion 104.00 m, below which Fajã village is located.
The cliffs comprehended essentially thick layers
of disaggregated breccias and fractured basalts,
overlaying a thick layer of volcanic tuffs. slope
deposits were identified on the terraces that existed
along the cliff and at its base (cenorgeo, 2006a).
The adopted solution was to excavate the unsta-
ble mass from elevation 240.00 m to 210.00 m,
along 2V/1h slopes, with 3 m wide and 10 m verti-
cally spaced berms.
To deal with the essentially breccious nature of
the rock mass, a systematic shotcrete lining of the
b. cross-section
Figure 2.
cliff above the eR101 at sítio do Massapez.
slope associated to bolts 4 to 12 m long was car-
ried out. Wherever possible, in the basalt layers
this lining was substituted by locally applied bolts
