ISSN 2096-4498

   CN 44-1745/U

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Tunnel Construction ›› 2024, Vol. 44 ›› Issue (S2): 452-461.DOI: 10.3973/j.issn.2096-4498.2024.S2.046

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Selection and Adaptability of Shields in Calcareous Cemented Strata in Israel: A Case Study of Tel Aviv Green Line Light Rail Project

LIU Xiaomin, SONG Ziwen*, WANG Shiyou, CHEN Hongke, JIN Chunshang, SONG Liwei   

  1. (China Construction Sixth Engineering Bureau Co., Ltd., Tianjin 300451, China)
  • Online:2024-12-20 Published:2024-12-20

Abstract: The Tel Aviv Green Line Light Rail Project is the second underground light rail line in Israel, facing challenges due to limited experience in tunneling with shield on smallradius curves within calcareous cemented strata (Kurkar). To address this issue, the authors propose a targeted design for the shield and conduct an adaptability study. The geological conditions in Israel and the specifics of the Green Line route are analyzed, identifying key technical challenges related to main drive torque, formation wear, surface settlement control, and smallradius curves. In response to these challenges, design solutions are proposed for cutterhead layout, power configuration, screw conveyor, muck conditioning, thrust system, and machine dimensions. Furthermore, the applicability of the shield is analyzed from the perspectives of tunneling parameters, cutter wear, and ground disturbance. The results indicate the following: (1) Central twin cutters should be avoided. (2) Shortening the shield length, setting active articulation cylinders, and using profiling cutters for 20 mm over-excavation successfully solve the R178.3 m small-radius curve issue. (3) Muck conditioning with foam and water achieves good plasticity, with a slump of approximately 160 mm. (4) The earth pressure in the soil chamber can be slightly lower than the theoretical active earth pressure value.

Key words: shield, calcareous cemented strata, small-radius curve, cutter wear, boring parameters