The bridge scour depths in cohesive soil have been predicted using the scour
equations developed for cohesionless soils due to scarce of studies about cohesive soil.
The scour depths predicted by the conventional methods will result in significant errors.
For the cost effective design of bridge scour in cohesive soil, the Scour Rate In
COhesvie Soil (SRICOS) for the singular circular pier in deep water condition was
released in 1999, and has been developed for complex pier and contraction scour.
The present study is the part of SRICOS-EFA method to predict the history of
contraction scour, and local scours, such as abutment scour and pier scour. The main
objective is to develop the prediction methods for the maximum and the uniform
contraction scour depth, the maximum pier scour depth and the maximum abutment
using flume test results. The equations are basically composed with the difference
between the local Froude number and the critical Froude number. Because the scour
happens when the shear stress is bigger than the critical shear stress, which is the maximum shear stress the channel bed material can resist from the erosion, and
continues until the shear stress becomes equal to the critical shear stress.
All results obtained from flume tests for pier scour have been conducted in Texas
A&M University from 1997 to 2002 are collected and reanalyzed in this study. Since the
original pier scour equation did not include soil properties. The effect of water depth
effect, pier spacing, pier shape and flow attack angle for the rectangular pier are studied
and correction factors with respect to the circular pier in deep water condition were
newly developed in present study.
For the abutment scour, a series of flume tests in large scale was performed in the
present study. Two types of channel - rectangular channel, and compound channel -
were used. The effect of abutment length, shape and alignment of abutment were studied
and the correction factors were developed. The patterns of velocity and of scour were
compared, and it was found that the maximum local scour occurred where the maximum
turbulence was measured.
For the contraction scour, the results obtained from a series of flume tests
performed in 2002 and a series of flume tests for the abutment scour in the present study
are analyzed. The methodologies to predict the maximum contraction scour and the
uniform contraction scour in the compound channel was developed.
Although all prediction methods developed in the present study are for the
cohesive soils, those methods may be applicable to the cohesionless soils because the
critical shear stress is included in the methods. All prediction methods were verified by
the comparison with the databases obtained from flume test results and field data.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-12-7261 |
| Date | 2009 December 1900 |
| Creators | Oh, Seung Jae |
| Contributors | Briaud, Jean-Louis, Chang, Kuang-An |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | application/pdf |
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