Yutaro Noda

Development of shield operation indexes for sharp curve tunneling

Mitsutaka Sugimoto

 In recent years, due to the complexity of tunnel alignment and the special cross-sectional shape of TBM, it is sometimes necessary to study the control method of a TBM and its behavior before construction. According to the site experience, the behavior of a TBM at a curve is controlled by three operating conditions: 1)jack thrust and jack moment, 2)articulated mechanism (angle and direction of articulation), and 3)copy cutter (length and range). However, it is difficult to determine these three operating conditions uniquely because they have collinearity and are affected by the TBM shape. In response to this, AI is currently applied to measured data to develop a suggestion on the method of TBM operation for a planned alignment. In this study, we analyzed the relationship between the operating conditions and the TBM behavior (1)tunneling speed,2)horizontal curvature of shield traces, and 3)vertical curvature of shield traces) to select the index used in AI.
 (1) Development of the indexes on TBM operation conditions
 The operation parameter controlling the TBM and the indexes representing the TBM behavior were examined, based on the geometrical conditions such as the machine shape and tunnel alignment, as well as the past construction results.
 (2) Examination of field measurement data
 Using measured data during shield tunneling, we examined the relationship between TBM operation conditions and TBM behavior.
 (3) Sensitivity analysis of TBM operation conditions 
 Using the shield kinematic model, the simulation along a multiple tunnel alignment (steep curves) was conducted under the field conditions at (2), and the relationship between operating conditions and TBM behavior was analyzed.As a result, the effects of the TBM operation indexes, which represent the above three operation conditions, on the TBM behavior were confirmed by the multiple regression analysis results using data sensitivity analysis in a relaxation curve.The articulation and the overcut by copy cutter have more effect on the horizontal curvature of the shield traces are larger than the jack moment, and the interaction of the articulation and the copy cutter was also confirmed.