Environmental Engineering Reference
In-Depth Information
Table 15.14.
Factors to be considered, and methods for assisting in the estimation of the likelihood of
initiation of a concentrated leak in CFRD (Southcott et al., 2003).
Methods for assisting in the estimation
Initiator
Factors to consider
of likelihood of concentrated leak
(A)
Factors applicable to all load conditions
Perimetric joint
• Crest and face slab deformation,
Compared to population, and degree
opens
first fill and continuing
of variation across dam
• Joint meter and face slab
Compared to design displacement
inclinometer displacement
and to population
• Deep plinth, and local deep
Calculate joint displacement from
fill at plinth in overbreak and
depth, construction modulus,
steep plinth sections
for zone 3A or modulus of zone
2F, allowing for water loading
(depth)
• Leakage flow rates vs reservoir
If no leakage measurements are
level and time. If there is increasing
available, use a range of values of
leakage, or
50 l/s? Maybe a
likelihood to reflect the uncertainty
1000 l/s certainly a leak
•Waterstop deterioration, accounting
for waterstop type, acidity of
water, displacement
leak,
Vertical joints open
• Crest settlement, horizontal
Compared to population, and degree
displacement and face slab
of variation across dam
deformation first fill and
continuing
• Joint meter and face slab
Compared to design displacement
inclinometer displacements
and to population
•Valley profile - e.g. steep valley sides
Estimated total settlement and
leading to large differential settlements
surface profile
•Opening of crest wall joints
If no leakage measurements use a
(transverse)
range of value
• Leakage flow rates vs reservoir
level and time. If there is increasing
leakage or
50 l/s? May be a leak,
1000 l/s certainly a leak
Face slab cracking
• Crest and face slab deformation,
Compared to population
first fill and continuing
• Staged rockfill and/or staging
Construction data, calculation from
of face slab construction effects,
rockfill depth, construction modulus,
with potentially different modulus
allowing for water loading (depth)
for lower and upper part
and link to total deformation
•Deep plinth, and local deep fill
Construction data, from rockfill
at plinth in over break and steep
depth, construction modulus,
plinth sections
allowing for water loading (depth)
and link to total deformation
calculation
• Location of and nature of
If no leakage measurements are
difficult construction joints
available use a range of values of
likelihood to reflect the
uncertainty
• Leakage flow rates vs reservoir level
and time. Increasing leakage or
50 l/s? Maybe a leak,
1000 l/s certainly a leak
• Crack mapping of face slab
• Sudden changes in slab thickness
(Continued)
