Effects of scour-hole dimensions and bulb positions on the lateral response of under-reamed pile in soft clay

Abstract One of the most effective ways to reduce the water jet erosion power during dam overflow is to use splitters on the lower side of spillway. The dimensions of scouring holes and their location in the dam basin should be accurately determined. Experimental models and data driven techniques can be effectively used for estimating the dimensions of scouring holes. The focus of this paper is evaluating the effects of splitters on the downstream scour hole of overflow spillways and providing an optimized splitter configuration. The Support Vector Regression (SVR) method performance in predicting the scour hole dimensions and its location downstream of the dam has been examined using 116 experimental data. In order to evaluate the efficiency of the proposed model, we used different statistical measures. The results show that the presence of splitters decreases the slope of downstream scouring in all situations. It is also shown that the SVR method can accurately estimate the dimensions of the scour hole and its location.

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The relationship between the coefficient of discharge and the scour hole depth generated due to the combined flow over weir and below gates

MATEC Web of Conferences ◽

10.1051/matecconf/201816203010 ◽

2018 ◽

Vol 162 ◽

pp. 03010

Author(s):

Saleh Khassaf ◽

Hassan Omran ◽

Fadhel Abdulabbas

Keyword(s):

Median Size ◽

Two Samples ◽

Scour Hole ◽

Combined Structure ◽

Scour Hole Dimensions ◽

Coefficient Of Discharge ◽

Size Of Particles ◽

Hole Dimensions ◽

The Relationship ◽

Laboratory Models

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist of weir and gate due to the effect of the coefficient of discharge (Cd) due to flow above the compound weir to the flow under the gate. Fifteen models have been designed, and every model is formed from composite weir consisting of two geometric shapes with rectangular gate of constant dimensions. In this study, the experiment was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and depth of 1 m, where the laboratory models were installed after 7 m from the main gate which controlled the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, and then seventy-five experiments were conducted in order to derive the formulae for investigating the non-dimensional depth (SD/d50) and non-dimensional length (SL/d50) of the scour hole due to the effect of (Cd). The bed of the flume was spread with sand layer of 30 cm thick for a distance of 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles (d50), the first of 0.7 mm and the second of 1 mm. Using the Excel program 2017, Six polynomial relationships were derived to calculate the dimensionless scour depth (SD/d50) in terms of the coefficient of discharge (Cd), where the resultant coefficients of determinations (R2) from these relationships were high.

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