Influence of groundwater flow on swelling in the Gipskeuper formation of the Belchentunnel (FGU2008/004_OBF)
Overview
Background & policy context:
Important swelling phenomena occurred in certain sections within the Gipskeuper formation of the Belchentunnel, whereas no swelling has been observed in other sections of the same formation. Groundwater circulation at different scales plays a major role in understanding these differences. The proposed research project is designed to investigate the influence of geological heterogeneities, topography, hydrology and loosening zones on groundwater circulation at different scales. The relationship between groundwater flow systems and swelling is still to be investigated. Therefore, we propose to develop a geo-hydraulic model to study the influence of the groundwater flow field alteration due to tunnel construction.
With the proposed approach, we would like to address the following questions:
What is the influence of the different groundwater circulation systems on the swelling phenomena in anhydrite-bearing clays?
How are the different-scale groundwater circulation systems altered due to the loosening zone, which develops with the beginning of the tunnel construction?
What are the effects of different model scenarios?
What are the types of measurements which would help to increase the confidence in a specific scenario compared to another?
Which are the scenarios with higher certainty, and which ones are of major relevance for the application?
The project is part of a research cooperation between the ETH Zurich and the University of Basel, investigating the swelling activity in the Gipskeuper formation. The results and the methods can lead to further projects to study the influence of the restoration tunnel on the groundwater flow field, and provides a general scientific basis for realization of future construction and restoration projects of tunnels in the Gipskeuper formation.
Objectives:
This project aims to find explanations why significant source phenomena occur in each section in Gipskeuper of Belchen-tunnel. We assume that the causes of the groundwater circulation, or the change in groundwater flow regime are. A reconstruction of the impact of construction on the groundwater flow conditions can therefore only take place with a geo-hydraulic modeling.
The proposed groundwater model serves as the basis for further studies on the impact of changes in the groundwater circulation systems in different scales. The regional scale of the model serves as a basis for defining the boundary conditions for local studies on the groundwater balance in the mountains and its relation to the gypsum sources (such as model refinements for transport models of solutes).
Methodology:
Accounting for the regional water balance
- Accounting geological profile in differently oriented sections
- Stationary two-dimensional groundwater modeling taking into account the heterogeneity of mountain in different scales (regional, local) and the resulting in tunneling EDZ
- Identification of zones with increased water flow
- Simulation scenarios to study the influence of various geological structures and the EDZ
- Interpretation of results
Share this page