| Summary: | Abstract: Shallow foundation is normally utilized for
simple buildings or housings in sandy beach areas. Parangtritis
beach at south coast of Yogyakarta is an example where a lot of
houses are built based on shallow foundation. Other similar
beach may be found in Indonesia. Parangtritis area is certainly
prone to tsunami attack. Tsunami disaster in 2006 which directly
hit Pangandaran beach has minimal impact on Parangtritis
beach. However, more significant and damaging result may
happen if larger tsunami were generated directly to the south of
Parangtritis beach. When tsunami surge hit a structure, the surge
is deflected to both sides of the building and creates turbulence
at the rear of the building. The speed of the surge and the highly
non parallel flow around the building easily lift up the sand
particle resulted in scouring around the structure. Such scouring
may endanger the structure stability. Once the structure is
toppled or lifted up by tsunami, it may be brought further
downstream, hit other buildings and create more damages.
Therefore it is important to study the impact of tsunami surge on
scouring around structures erected on shallow foundation in
sandy beach.Physical model was conducted at Center for
Engineering Science Universitas Gadjah Mada to study the
scouring around coastal buildings which was represented by
cylinder and square columns and vertical wall due to tsunami
surge. The lay out was designed to enabled the study of the
tsunami surge on sandy beach based on dam break model.
Various tsunami heights, position of columns and vertical wall
were simulated. Some existing formulae were compared with the
present results to examine their used for approximating the
scouring around structure under tsunami attack.
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