FACE STABILITY OF TUNNELS
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Controlling the face stability
During the construction of bored tunnels the face stability is an important issue. An adequately controlled TBM face is of great importance to minimize settlements at the ground surface and to obtain the best results.
The process of TBM tunneling makes that the soil is removed one-sided whereby local soil stresses are changed. As a result of these changes in soil stresses local displacements can occur at surface level. Therefore the objective is to maintain the original stresses as much as possible, this is done by applying a certain support pressure.
This support pressure can be obtained by air, a support fluid or the excavated material itself. The support pressure can be variated between a minimum and a maximum value: the adjustment range.
ProceedingsArthe provides several product considering face stability of tunnels:
- Analytical approaches of the minimum and maximum support pressures for several sizes and types of TBMs
- Analyses of the expected excess pore pressures at the tunnel face
- Numerical calculations of the face stability for the minimum and maximum support pressures
- The design and dimensioning of temporary preloading mounds
- Risk assessments concerning the tunneling process
- Numerical determination of the displacements resulting from the tunneling process