In the Netherlands, geotechnical calculations almost always assume either fully water-saturated soil or completely dry soil. Below the normal average phreatic surface, the soil is assumed to be fully saturated with water. And above the normal average phreatic surface, the shear strength of the soil is described assuming it is completely dry. While in reality the soil above the normal average phreatic surface is not completely dry.
What makes the unsaturated zone special is the negative water pressure (capillary pressure or suction pressure) in this zone. This gives the soil additional strength which can be significant. However, due to the variation in moisture content over time, this extra strength is also variable. This raises the crucial question: what shear strength should be applied to these initially unsaturated soils? Deltares performed an extended research on the shear strength based on two reference projects and literature. However, at the moment there is no generic guideline on what default values for the shear strength may be applied in projects throughout the Netherlands.
The shear strength in unsaturated soils is a hot topic in the field. Witteveen+Bos is actively addressing this issue in dike reinforcement projects KIJK and Lith Bokhoven. Your research will play a vital role in contributing to these projects and the current guidelines in the Netherlands (WBI/I&M).
During you assignment, you will be part of a team of geotechnical engineers and be mentored by a daily supervisor and a specialist. You will also get the opportunity to:
- Visit different offices of Witteveen+Bos
- Engage with colleagues from Geotechnical Engineering & Flood Defenses and other disciplines
- Learn about our diverse range of projects
- Participate in our social events
- Receive an internship allowance
- Experience firsthand what it’s like to work with us
Supervision
Are you interested in this assignment? Contact the Master thesis coordinator:
