cracking by sawn transverse joints, or by the cutting of a regular series of
slots to act as crack inducers.
The very considerable cost savings attaching to RCC construction
are dependent upon plant and RCC mix optimization, and hence con-
tinuity of the RCC placing operation. This in turn requires that design fea-
tures which interfere with continuous unobstructed end-to-end placing
of the RCC, e.g. galleries, internal pipework, etc., must be kept to the
minimum and simplified. Experiments with retrospectively excavating gal-
leries by trenching and by driving a heading in the placed RCC fill at Riou,
France, have proved successful (Goubet and Guérinet, 1992).
Vertical rates of raising of 2.0–2.5 m week^1 are attainable for RDLC
and high-paste RCCs compared with 1.0–1.5 m week^1 for RCD con-
struction. As one example, the Concepcíon dam, Honduras, referred to
earlier was raised in seven months. A lean RCC mix (cement content
80–95 kg m^3 ) was employed for the 290 103 m^3 of RCC fill, and a contin-
uous mixing plant was used in conjunction with a high-speed belt conveyor
system. Placing rates of up to 4000 m^3 day^1 were ultimately attained (Gio-
vagnoli, Schrader and Ercoli, 1992).
The employment of RCC fill has also been extended to the upgrad-
ing of existing dams, e.g. by placing a downstream shoulder where stability
is deficient (Section 3.2.9). RCC has also been applied to general remedial
works and to raising or rebuilding older dams. The benefits of RCC con-
struction have also been appropriate, in special circumstances, to the con-
struction of smaller dams, e.g. Holbeam Wood and New Mills in the UK
(Iffla, Millmore and Dunstan, 1992).
ICOLD Bulletin 126 (ICOLD, 2004) provides a comprehensive over-
view of the use of RCC for dam construction. US developments are dis-
cussed in Hansen (1994). Design options with respect to upstream face
construction have been reviewed in some detail by Schrader (1993).
Construction in RCC is recognized as providing the way forward in
concrete dam engineering. Extensive reviews of current issues in RCC
dam design and construction are presented in Li (1998), and in Berga et al.
(2003). Major issues discussed include the need, or otherwise, for a con-
ventional concrete upstream face, and the question of resistance to high
seismic loading, where dynamic tensile strength of the interlayer bond
between successive layers of RCC will be critical.
The recently completed 95 m high RCC gravity dam, at Pla-
tanovryssi, Greece, located in a seismic zone, is described in Stefanakos
and Dunstan (1999). The design peak ground acceleration corresponding
to the MCE at Platanovryssi was determined as 0.385 g, equating to a
maximum dynamic tensile stress of c.2 MN/m^2 , requiring a cylinder com-
pressive strength for the RCC of 28 MN/m^2. The high-paste RCC employed
contained 50 kg/m^3 of PFA. Platanovryssi does not have an upstream face
of conventional concrete, and vertical contraction ‘joints’ were induced at
25 m intervals by slots sawn in the upstream face in conjunction with steel
amelia
(Amelia)
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