| Summary: | 碩士 === 國立臺灣大學 === 農業工程學系 === 85 === This study carried out a hydraulic modeling test which used the
Froude Number for geometric similarity between prototype and
model, the similarity of the critical tractive force for
sediment diameter , as well as the Ho-Huang''s Model for
sediment deposition period and its discharge. Under the
conditions of return period of 25 and 50 years of flow
discharge, different forms, setup angles, numbers, and length of
spur dike was conducted to discuss the river phenomena of
scour and fill on river band.
Based on 12 sets of available tests and 168 data of cross
sections, the following results was got :The variation of
river bed was principally occurredon the section of river bed
,in which , scouring area was located in concave zone and
depositing area in convex zone . Moreover , constructing sets of
spurdikes could decrease current scour and foot scour of
embankment ; The effectiveness of changing flow direction
between overflow and non-overflow spur dike was
insignificantly, but the non-overflow one t greater water
pressure ; The porous spur dike was better than non-porous one
in decreasing the toe scouring of bank revetment ;The vertical
spur dike was most effective in decreasing the scouring of the
downstream river bank. where as the downstreamed type
one was second , upstreamed type one was third .However , the
variety between them was insignificantly. In which , the
vertical spur dike got so much water pressure that we choosed
the downstream one ; Under thesame setup of spur dikes ,that
the eroon and scour at the top area of bend was more
significantly for flow discharge of 50 return period years than
that of 25 years showed the tendency of "large flood go
straightly".
|
|---|
