TECHNICAL | GROUND CONDITIONING
Right, figure 7: Madrid MetroSur - inappropriate soil conditioning in Clay
Far right, figure 8: Madrid MetroSur - well adopted soil conditioning in Clay
TBM DEVELOPMENT
The TBM design itself and its key components are of highest importance for the efficient use of soil conditioners as well as for the whole tunnelling project. The TBM design shall give a high degree of flexibility for using the soil conditioning additives, for example using polymers not only in their diluted form but also as concentration or inside the foam. The more possibilities the TBM design offers, the more efficient the soil conditioners will be. High attention should also be paid to the TBM driver. The driver is one of the key persons for successful EPB tunnelling and should be supported well, both with optimisation proposals as well as displaying information rapidly if something is not running as it should be, such as: blockage of foam
injection ports; too much compressed air being used; rising muck temperatures; and much more. Here, active soil conditioning guiding systems may take an important role in the future.
Foam Injection Ports The cutterhead is one of the most important parts of the EPB-TBM. Therefore, we need to have as many foam injection ports as possible at the cutterhead, directly connected to the foam system at the TBM gantry. Until the year 2000, TBMs were partly using revolver
swivels and had split foam lines, coming from the foam generator, to serve two or more injection points on the cutterhead. This arrangement quite often resulted in
Torque values M-30 North
100 95
90 85 80 75
Right, figure 9: Madrid M30 torque records
PHOTO CREDIT: FCC FOMENTO
70 65 60 55
50 45 40 35
30 25 20 15
10 5 0
Installed torque
Calculated torque (centre + big cutterhead)
01 59 118 177 235 294 353 411 470 529 588 646 705 764 822 881 940 998 1057 1116 1175 1233 1292 1351 14091468 1527 1585 1644 1703 1762 Ring
Maximumwert Drehmoment Schneidrad [MNm] Rechnerisches Drehmoment [MNm]
Installiertes Drehmoment [MNm] Mittelwert Schneidrad [MNm]
14 | November 2023
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