| Author | Sompong Chamgramol |
| Call Number | AIT Thesis no.WM-97-25 |
| Subject(s) | Dam failures
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Flood waves due to sudden outflow through dam breach section cause severe damages
downstream of the dam. An accurate estimation of outflow through the dam breach section is
important as it is the upstream boundary condition for flood routing toward the downstream
direction. The height of peak of flood wave and travel time of the flood wave, if known
properly, can be used as a guide for evacuation preparation which can significantly reduce the
downstream damage and losses of lift.
Model dam made of medium sand with Dso = 0.65 mm. was built in a 1 m. wide and 40
m long flume with horizontal bed and transparent walls on both sides. Six experimental runs
were conducted. The upstream slope of the dam is fixed at 1V:3H but the downstream slope is
varied from 1V:3H to 1V:2.5H and 1V:2H for Run No.I, 2 and 3 in which the height of the
dam is 0.55 m. In Run No.4, the setup is the same as Run No.2 but the dam height is changed
to 0.80 m. In Run No.5 and 6, sand of D50 = 0.85 mm. is used and the dam height is 0.55 m.
The downstream slope is 1 V:3H and 1 V:2H. The upstream inflow to the reservoir is 9. 3 lps for
Run No. 1to4 and 7.8 lps for Run No.5 and 6.
The physical model dam shows that the breach starts at the center of dam crest and the
overtopping flow causes the breach channel along the downstream face of the dam to enlarge
to a larger channel. In addition to the effect of breach enlargement, the collapse of the breach
side wall or mass failure accelerates the lowering of the dam crest and the total failure of the
dam. During the erosion process, the dam crest propagates in the upstream direction in which
the crest elevation reduces exponentially with time and distance. The geometry of breach
section and the overtopping discharge can be correlated by a power law. Lastly, the MIKE-11
dambreak model developed by the Danish Hydraulic Institute is used to simulate the dam
breaching section geometry and the overtopping discharge. It is found that the MIKE-11 model
gives a very underestimated result compared to the experiments. |
| Year | 1998 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Tawatchai Tingsanchali; |
| Examination Committee(s) | Kubo, Naritaka;Sutat Weesakul; |
| Scholarship Donor(s) | Asian Institute of Technology;Royal Thai Govenment ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |