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EXCAVATION STAGES
TOP HEADING: SHOTCRETE +
WIRE MESH + STEEL BEAM
BENCH
INVERT
TEMPORARY INVERT
EXCAVATION LINES
Figure 6
Figure 5
Conclusion
Determining the impact of the swelling pressure on the tunnel final lining required adopting analytical and
finite elements methods. We dealt with the swelling effect on the final lining through increasing the density of
the reinforcement within the invert. However, this solution was dropped due to logistical constraints and hence
the invert curvature was increased as a substitute solution.
The difference in swelling levels along the tunnel results in
differential settlements, causing cracks in the final lining after a
certain period of time.
For this reason, there was a need for longitudinal reinforcement
along tunnel axis, especially in transition zones between different
soil types with different swelling potentials. Depending on the
stress level and the cover above the tunnel, the swelling degree
was measured.
During advancement of the excavation, the initial design was
consistently checked against the actually encountered geologic
conditions and the deformation monitoring readings.
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A cure for swelling
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