Takuji Yamamoto

Evaluation of the geological condition ahead of the tunnel face by geostatistical techniques using TBM driving data

In tunnel excavation by Tunnel Boring Machine (TBM), it is difficult to grasp the ground condition ahead of and surrounding the tunnel face because the face cannot be observed during tunnel driving. This is the reason why it has not been possible to make the best use of high-speed excavation capability of the TBM, especially in ground under complex conditions. Thus, the TBM Excavation Control System was developed to realize the accurate prediction of the geological condition ahead of and surrounding the tunnel face simultaneously with excavation. The special feature of this system is that geostatistical techniques are introduced into the data analysis using both drill logging data from pilot boring and TBM driving data obtained during excavation, in order to improve the precision of the ground mapping.

EFFECT OF THE NEW FORE PILING METHOD WITH MIDDLE LENGTH PIPES

With regard to the current practice of tunnelling construction for railways and roads it is desired that a more practical method be developed so as to save time and cost as well as more safety. Lecentry, long forepiling method has been used widely so that the tunnel crown settlement in soil ground, can be restrained. On the other hand, cost by such method is generally high in case special technique or machine must be adopted. In addition, the effect by reinforcement using forepiling method is difficult to be made clear theoretically. We developed a new forepiling method using middle length steel gas pipes for the purpose of lowering the construction cost with enough reinforcement effect. These reinforcement can be easily installed by conventional tunnelling machine. This paper reports the technical features and construction procedure. Next, the practical measuring results are shown. As a result, it is proved that the new forepiling method is effective in cost and reinforcement.