The Extension of the URF HADES: Realization and Observations
An important step in the feasibility study of radioactive waste disposal in Boom Clay is the demonstration that we can construct galleries using industrial techniques, keeping the disturbance of the host-rock at an acceptable level for the long term safety of the disposal site. The successful construction of a connecting gallery of 85m in less than 6 weeks demonstrated the feasibility. To limit the disturbance, an expanding lining type was used: the wedge-block system; for the same reason, the lining was installed as soon as possible after excavation and a minimal excavation rate (2m/day) was imposed. The total radial convergence was limited to about 0.09m; the excavation radius was 2.445m. An extensive instrumentation and observation program accompanied the construction of the connecting gallery. Sensors measuring displacements, total pressure and pore water pressure were installed in the host rock to study the hydro-mechanical behavior of the clay when the gallery was excavated. Sensors in the tunneling shield gave information about the instantaneous convergence and excavation parameters. Strain gauges were placed in three sections of the lining to study the evolution of stresses in the lining with time. A systematic observation of the face and side-walls provided a useful database of the shape and orientation of encountered fractures. This way, the origin of the fractures can be explained and substantiated. The fractures were induced by differential stresses, about 6m ahead of the excavation face. No evidence of natural induced fractures was found. On the other hand, qualitative evidence of self healing and self-sealing of the host rock was encountered.
- Research Organization:
- EIG EURIDICE (BE)
- Sponsoring Organization:
- none (US)
- OSTI ID:
- 825935
- Resource Relation:
- Conference: Waste Management 2003 Symposium, Tucson, AZ (US), 02/23/2003--02/27/2003; Other Information: PBD: 27 Feb 2003
- Country of Publication:
- United States
- Language:
- English
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