Dams | Primary construction phases for CFRDs
Diversion Phase (CFRD) Excludes cofferdams from the main rockfill, resulting in the need for a larger volume of rockfill. Involves longer diversion tunnels, requiring more rockfill compared to ACRDs.
Sealing Activities External sealing encompasses concrete, external and internal joints, and internal water stops. This method tends to be more expensive and does not involve concerns related to uplift and pore pressure.
Transition Zones Transition zones include the extruded curb, employing the Itá Method [15], and areas like 2B and 3A, which have less elaborate transitions.
Above: Figure 6: CFRD , Zone 2 upstream processed fine transition (фmax 100mm); Zone 3A coarse transition zone, selected small rocks, (фmax 400mm)
Below: Figure 7: ACRD, zone 2 fine transition (фmax 75mm) and coarse transition zone 3 (фmax 300mm) (Foz do Chapecó 2010 )
Plinth External plinth for grouting, involving perimeter joints, and the use of costly water stops.
Concrete Face The external concrete face entails joints, various stages of water stops, rebars, and internal water stops.
Parapet Wall Upstream and downstream parapets offer a means of achieving rockfill cost-efficiency.
Industrial Facilities Necessitates the presence of a concrete batching plant, specialized slip forms, equipment for constructing copper water stops, and a concrete laboratory.
Reservoir Impounding Involves the construction of concrete Phase I, facilitating coordination with the reservoir filling process. This can be executed in stages. Increased number of slip forms.
SLAB 1
2 3 1.4 4 EL. 675.00 EL. 615.50 6 Grout Curtain
1) Filter processed limestone DMAX. 2) Transition processed DMAX.
3) Limestone, blasting excav. DMAX. 7.5cm 0.30m 0.80m
4) Mudstone, blasting excav. DMAX. 5) Limestone, blasting excav. DMAX.
6) Clay
Figure 8: TSQ.1 CFRD (178m, China) - grout curtain at upstream plinth foundation (Cruz, Bayardo, Freitas, 2009)
38 | November 2023 |
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0.80m 1.0m
3 5 5 EL. 660.00 EL. 650.00 1.0 20 30
N.A. normal EL. 780.00
EL. 791.00 EL. 765.00
EL. var. 1.25
1.0
Diversion Phase (ACRD) Incorporates cofferdams into the dam’s structure. Requires a reduced volume of rockfill. Involves shorter diversion tunnels, resulting in cost savings.
Sealing Activities Utilizes an internal asphaltic core without the need for joints. Requires special attention to weather conditions, placing transitions concurrently with core placement. Involves a unique asphalt design and rigorous laboratory control. Eliminates the use of water stops and extruded curb.
Primary construction phases for ACRDs
Seismic Activity Ensures a high level of seismic resistance for both the rockfill and the face slab’s impervious features, as seen in the Zi Ping Pu CFRD [12].
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