Scour Below Submerged Skewed Pipeline
| dc.contributor.author | MOHD YUSOFF, MOHD AZLAN | |
| dc.date.accessioned | 2016-04-12T01:22:25Z | |
| dc.date.available | 2016-04-12T01:22:25Z | |
| dc.date.issued | 2015-01 | |
| dc.description.abstract | Local scour below submerged pipelines occurs due to the erosive and action of currents which cause pipeline failure. The presence of pipe across river initiates the piping effect combined with the stagnation eddy and vortex system undermine the pipeline and mark the onset of scour. The main objective of the research is to investigate the physics of scour below pipeline in river crossing as well as its factor associated. In this study, experiments were conducted to investigate the effect of four different pipeline angles (30º, 45º, 60º and 90º) across a channel. Gene Expression Programming (GEP) have been widely applied in engineering practice in recent years. Thus, the study aims to apply GEP and regression models as the predictive tools on the scour depth below skew pipeline across river. The initial scour process for flow shallowness y/D= 3 increases rapidly due to the piping effect which leads to the tunnel erosion, lee erosion and luff erosion. Whilst, for flow shallowness, y/D = 4 the scour process at initial stage is slower than the case of flow shallowness, y/D = 3. A small gap between the pipeline and undisturbed sediment bed allowing a jet like of high velocity flow through the gap. The maximum scour location for skew pipe occurs near to the left sidewall as the reaction of hydrodynamic forces towards the channel wall at the left side. The regression model (Equation 4.4) with R2 = 0.55, and a low root mean square error (RMSE = 0.47) was validated with the external data sets from previous research works. The validation shows a good correlation with R = 0.71. The GEP prediction on the scour depth also is significant with high R2 and low root mean square error. The proposed GEP model (Equation 4.7 ) showed a good agreement with R = 0.94 for training and R = 0.9 for testing. From the sensitivity analysis, the flow depth and time variation of scour depth are the most dominant factors for the scour predictions. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/1885 | |
| dc.subject | Scour Below Submerged | en_US |
| dc.subject | Skewed Pipeline | en_US |
| dc.title | Scour Below Submerged Skewed Pipeline | en_US |
| dc.type | Thesis | en_US |