Environmental Engineering Reference
In-Depth Information
Figure 8. The initial alignment of the project is shown, with two branches at each side after reaching the old cliff.
The final alignment of the gallery is also depicted. The formed ponds are identified as a and B in the first phase, and
c and F during the second stage.
Figure 9. Different views of the recovery gallery at
Fuente santa spring. To the left, the start of the opera-
tion showing the supporting structure constituted by
steel trusses spaced every meter and connected by rods,
packing the extrados with the same boulders (the largest
ones) that were recovered from the heading excavation.
Figure 10. This photo shows the first pool and the
chamber made to excavate it at a site with the boring
where the 42°c temperature was recorded.
progress even with the use of a shield. a collapse
of the heading finally convinced us that a change
in the method was necessary.
see Figure 11 with the front of the gallery con-
stituted almost exclusively by cinders with small-
size particles and with certain cohesion, slightly
higher than at the stones carried by the front of
the lava flow.
To be able to continue with the excavation it
became necessary to stabilize the roof, remove
During the second stage a new excavation was
started. Room temperature and the emission of car-
bon dioxide inside the gallery showed an increase
and it became necessary to work by blowing fresh
air in. The material encountered was still formed
by loose stones with very variable grain size dis-
tribution and soon the lack of stability prevented
