Abstract
Debris accumulations upstream and through crossing hydraulic structures such as culverts cause the upstream water level and the downstream scour depth to increase, which can lead to structure failure. This experimental study aimed to investigate the effects of various inlet blockage ratios on culvert efficiency and scour hole depth. In a non-blocked case, various submergence ratios (S = 1.06, 1.33, 1.60, and 1.90) were tested with different discharge rates. In a blocked case, the effects of inlet blockage with various blockage ratios (Ar = 10%, 20%, and 30%) were seen as sediment blockage on the pipe bed or floating debris upstream of the culvert. The results show that as the submergence ratio increases, the maximum scour depth decreases at the same discharge rate, and the relative energy loss also decreases in the non-blocked case. In the sediment blockage (Ar d) case, the relative maximum depth increases with increasing densimetric Froude number and with an increasing blockage ratio. An empirical equation was developed to predict the relative scour depth under the present study conditions.
Highlights
Culverts are hydraulic structures used to transport water below roads and railways
Culvert efficiency decreases to 70% at S = 1.06 and reaches up to 80% at S = 1.90 when Froude number (Fd) = 6.64
The relative scour depth increases by 1.32%, 2.63% and 7.90% compared to the non-blocked caseon when relative blockage area ArEfficiency d becomes 10%, 20% and 30%, respectively
Summary
Culverts are hydraulic structures used to transport water below roads and railways. Local scour downstream of culverts involves the removal of granular bed material through the action of hydrodynamic forces. As the maximum scour depth downstream of the culvert increases, the stability of the foundation of the structure may be threatened, with a consequent risk of damage and failure [1]. Abt [2,3] experimentally studied the effect of culvert shape on scour hole dimensions. Different culvert sections such as square, arch and rectangular culvert shapes were investigated with uniform graded sand (D50 at 1.86 mm). Abt [6] studied the culvert slope influence on the maximum scour depth. The results showed that the maximum scour depth increased as the culvert slope increased within the range of the slopes tested
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