Process controlling and data management - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 360

without delay directly into the model and receive selected calculation results, for example
surface settlements, ground stresses, loading on the tunnel lining etc.
Optimisation of the process requires further knowledge about the fluid mechanics pro-
cesses in the excavation chamber. When active face support is provided, the rheological
properties of the soil in the excavation chamber are important for optimised active support
pressure control, in addition to the pressure values P1, P2, P3 according to Fig. 10-5.
The material flow in the excavation chamber can also be realistically simulated using
numerical models.
When active conditioning is not used, the material flow in the excavation chamber concen-
trates in the immediate vicinity of the screw conveyor; in the other parts of the excavation
chamber, there is scarcely any flow of material. There is a danger that the soil consolidates
in these areas and thus loses its flowing properties. Through process-controlled soil condi-
tioning, the flow pattern can be reconstructed and actively manipulated or optimised. For
this reason, all sensors for the control of pressure and volume are included in the analysis
of the flow behaviour.
In summary, it can be stated that decisive interactions between ground and tunnelling ma-
chine can be at least qualitatively investigated through numerical simulations. The know-
ledge gained is used as part of the process controlling to optimise the advance. The shield
tunnelling processes can thus be represented with their complex interactions between ground
and machine and analysed using efficient system tools. The optimisation of the key para-
meters in real time and subsequently can be done through the implementation of the know-
how of the experts and through knowledge-based methods like fuzzy logic and neuronal
networks in the process controlling system, which makes the system capable of learning.
Figure 10-4 FEM model for the
analysis of system behaviour
[209]
Figure 10-5 FEM model for the
analysis of the hydraulic behav-
iour in the excavation chamber
[209] (Herrenknecht EPB;
Madrid M-30; D = 15.16 m)