SMALL DAMS PETITS BARRAGES

In order to provide construction flexibility between the core and the downstream part, it is
advisable to adopt a sloping core dam. Especially in the cold regions where winter season
covers a long period, it will be more advantageous to prefer sloping core dam, because during
frozen period the placement of pervious weathering soils may still proceed, and the impervious
core may be placed in the next spring and summer, in this way the quality of impervious core
may be ensured. Furthermore, the sloping core may be readily extended toward the reservoir
to form the impervious blanket, thereby increasing the seepage path and decreasing the
leakage.
The soil materials for sloping core are the same as those for central core. However, the
embankment materials downstream of the sloping core besides having high shearing strength
and high perviousness, should be of small compressibility, and should not cause cracking in
the core due to differential settlement. Special care need to be taken with the possibility of
desiccation of the upstream core and its consequents cracks.
Fig. 2.6 – Shanxichong thin sloping core earth dam, China [1].
Fig.2.7 – Shangliyu earth dam with thick sloping core, China [1].
2.3.3 ZHAOGUSHE DAMS
1 – Sloping clay core
2 – Granular material
1 – Sloping clay core
2 – Sandy loam
3 – Pervious foundation
Zhaogushe type overflow earth-rock dams, which were first brought into being by the
people’s masses in Wenling County, Zhejiang Province, have been widely popularized since
1958 [1]. This type of dams is suitable in rocky mountainous regions where the river valley is
narrow with insufficient soil materials and the deposit on the river bed is shallow and where a
chute spillway would involve a large volume of excavation. This kind of overflow dam has
developed rapidly and has now numbered over 160 in the whole province. The maximum
height has reached 32.5 m. These dams can safely withstand small overflow discharges under
a head of about 1.0 m.
Necessary scientific researches will also be carried out for further raising the level of
their design and construction technique.
The Zhaogushe dam is a kind of earth-rock embankment, but mostly built of rock
materials. The dry-laid masonry constitutes the key part in ensuring safety, the impervious
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