EXPERIMENTING ON THE EFFECTIVENESS OF RIP RAP ROCKS AS AN ENERGY DISSIPATING STRUCTURE

The design of the energy dissipator probably includes more options than any other phase
of a spillway design. The selection of the type and design details of the dissipater is
largely dependant upon the pertinent characteristics of the site, the magnitude of energy
to be dissipated and to a lesser use. Good judgment is imperative to assure that all
requirements of the particular project are met. Regardless of the type of dissipater
selected, any spillway energy dissipator must operate safely at high discharges for
extended periods of time. This study presents a detailed explanation on the various
designs of rip rap rock energy dissipators and their applications on a spillway. The
importance of energy dissipator on a spillway is to protect structures downstream from a
spillway. The purpose of energy dissipator is to dissipate energy from the flow of water
so that is not strong enough to harm or damage downstream structures of a dam. Thus,
the objectives of this study are as follows, to design several designs of rip rap rocks
energy dissipating structures, to perform experiments on the model using various flows
and to compare the performance of the designed rip rap models. Three designs have been
selected for modeling and presented in this report. The three models were constructed
with reference to the rip rap design located on the spillway on the Kenyir Dam in
Terengganu, baffled blocks basin designs, baffled apron drop design and gabion designs.
These models will then be experimented in a flume available in the laboratory using
various flows to determine the most effective energy dissipator. Upon experimentation, it
is understood that the model that was built with reference to the design of the energy
dissipator located at the Kenyir Dam, was found to be the most effective energy
dissipator for it was able to dissipate the most amount of energy compared to the other
models that were constructed. Furthermore, it had a larger surface roughness area
compared to the other models as well.