As to the stability of structures of masonry for this purpose, as
compared with earthwork, experience would seem to leave the question an
open one. Either method is liable to failure, and there certainly are as
many cases on record of the destruction of masonry dams as there are of
those constructed of earthwork, as instanced in Algeria within the past
few years. As regards masonry dams, the question of success does not seem
so much to depend upon their design, as far as the mere determination of
the suitable profile or cross section is concerned, as that has been very
exhaustively investigated, and fairly agreed upon, from a mathematical
point of view, but to be principally due to the correctness of the
estimate of the floods to be dealt with, and a sufficient provision of
by-wash allowed for the most extreme cases; and, lastly, perhaps the most
important of all, the securing a thoroughly good foundation, and a
careful execution of the work throughout.
These remarks equally apply to earthwork dams, as regards sufficient
provision of by-wash, careful execution of work, and security of
foundation, but their area of cross section, supposing them to be
water-tight, on account of the flatness of their slopes and consequent
breadth of base, is, of course, far in excess of that merely required for
stability; but in these latter, the method adopted for the water supply
discharge is of the very greatest importance, and will be again referred
to.
Pages:
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33