University of Twente Student Theses

Analysis of the effects of dike structures on heave failure at screens. Evaluation on the effects on hydraulic heave failure through an experimental heave screen setup and an analytical two-pressure stability model

Raadschelders, L.T. (2023) Analysis of the effects of dike structures on heave failure at screens. Evaluation on the effects on hydraulic heave failure through an experimental heave screen setup and an analytical two-pressure stability model.

PDF
2MB

Abstract:	In the upcoming years, the network of dikes and levees in the Netherlands will be reinforced to meet the new safety norms for dikes. One crucial failure mechanism for dikes is the piping failure mechanism. The placement of a heave screen is a reinforcement method to reduce the risk of piping at a dike. This reinforcement method introduces another possible failure mechanism: hydraulic heave failure. This research project investigates the effects of dike structures on hydraulic heave failure. Two phenomena related to dike structures can be distinguished which influence hydraulic heave failure: the effects of vertical loading of a dike structure on heave failure and the effect of the occurrence of piping on heave failure. Both these effects have been analysed with a two-dimensional analytical two-pressure model and through an experimental design of a heave screen. The analytical two-pressure model is a computation model which determines the two main pressures in the process of heave failure. Namely, the total downward soil pressure and the total upward seepage pressure. In this two-pressure analytical model, the effects of vertical loading and the occurrence of piping have been integrated. The analytical model is then used to compute the different experimental scenarios. The experimental design is constructed as a representation of a scaled version of a dike structure with a heave screen. In this experimental setup, multiple experimental scenarios are recreated to investigate both effects of a dike structure and piping on heave failure. The analytical two-pressure model and the experimental model of a heave screen are compared with quantitative and measurable variables. The critical upstream water height is the critical point for hydraulic heave failure to occur both analytically and experimentally. Analytically, this critical point of failure can also be expressed as the factor of safety. Experimental and analytical results on the critical upstream water height are plotted compared to the applied vertical loading by the dike structure. From these results, conclusions can be drawn on the relationship between the critical point of hydraulic heave failure and the applied vertical load. The analytical results show a clear positive correlation between the critical upstream water height and the applied vertical load. The experimental results, however, show a weak positive correlation was found between both variables. Therefore, it is concluded that the resistance against heave failure is positively correlated with the vertical loading of a dike structure. However, it should be noted that for the quantification of the effect of vertical top load on heave failure further experimental research is recommended. This study introduces the meso scale analysis on heave failure. The effects of the occurrence of piping on heave failure are investigated on meso scale. The meso scale analysis shows specific locations in the heave zone for which heave failure could already occur before the macro scale analysis indicates heave failure. The comparison of experimental and analytical results shows a relation between the pipe width and the critical point of heave failure. This suggests a direct relation between piping and heave failure at heave screens. Therefore, further research into this relation is recommended before a concrete conclusion substantiated by a calculation model can be formulated on the effects of the occurrence of piping on heave failure.
Item Type:	Essay (Bachelor)
Faculty:	ET: Engineering Technology
Programme:	Civil Engineering BSc (56952)
Link to this item:	https://purl.utwente.nl/essays/96375
Export this item as:	BibTeX EndNote HTML Citation Reference Manager

Show download statistics for this publication

Repository Staff Only: item control page