Hydropower can be a source of sustainable energy, provided environmental considerations are taken into account and economic aspects of hydropower design are appropriately addressed. Using concrete-lined pressure tunnels instead of steel pipes may be economically attractive but may also have limitations due to the low tensile strength of concrete.
Cracking in concrete tunnel linings can lead to loss of energy production, extensive repairs, and even accidents. One of the techniques available to improve the bearing capacity of pressure tunnels is through prestressing the concrete lining by grouting the circumferential gap between the concrete lining and the rock mass at high pressure. A classical approach to determine the bearing capacity of such tunnels is based on the theory of elasticity, assuming impervious concrete. In this research, a new concept is introduced to assess the effect of seepage on the bearing capacity of pressure tunnels. Also, an innovative approach is proposed to explore the effects of the in-situ stress ratio on the lining performance. Distinction is made based on whether the rock mass behaves as an elasto-plastic isotropic, or elastic anisotropic material. Furthermore, a simplified method is introduced to quantify seepage associated with cracks around the tunnel, which is useful for assessing tunnel stability.
IHE Delft PhD programme leads to a deepening of a field of specialisation. PhD fellows do scientific research, often with conclusions that directly influence their region. At IHE Delft, PhD researchers from around the world participate in problem-focused and solution-oriented research on development issues, resulting in an inspiring research environment. PhD fellows work together with other researchers from many countries dealing with topics related to water and the environment.
PhD research is often carried out in the ‘sandwich’ model. Preparation and final reporting – the first and last portion of the programme – are carried out in Delft, while actual research is done in the fellow’s home country, under co-supervision of a local institute. Regular contacts with the promotor are maintained through visits and long-distance communication. This enables researchers to employ solutions directly to problems in their geographical region.
IHE Delft PhD degrees are awarded jointly with a university. The degrees are highly valued and fully recognised in all parts of the world.