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Geomechanics and Engineering Volume 28, Number 5, March10 2022 , pages 531-546 DOI: https://doi.org/10.12989/gae.2022.28.5.531 |
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Investigation on ground displacements induced by excavation of overlapping twin shield tunnels |
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Weiqiang Qi, Zhiyong Yang, Yusheng Jiang, Xing Yang, Xiaokang Shao and Hongbin An
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| Abstract | ||
| Ground displacements caused by the construction of overlapping twin shield tunnels with small turning radius are complex, especially under special geological conditions of construction. To investigate the ground displacements caused due to shield machines in the unique calcareous sand layers in Israel for the first time and determine the main factors affecting the ground displacements, field monitoring, laboratory geological analysis, theoretical calculations, and parameter studies were adopted. By using rod extensometers, inclinometers, total stations, and automatic segment-displacement monitors, subsurface tunneling-induced displacement, surface settlement, and displacement of the down-track tunnel segments caused by the construction of an up-track tunnel were analyzed. The up-track tunnel and the down-track tunnel pass through different stratum, resulting in different construction parameters and ground displacements. The laws of variation of thrust and torque, soil pressure in the chamber, excavated soil quantity, synchronous grouting pressure, and grout volume of the two tunnels from parallel to fully overlapping orientations were compared. The thrust and torque of the shield in the fine sand are larger than those in the Kurkar layer, and the grouting amount in fine sand is unstable. According to fuzzy statistics and Gaussian curve fitting of the shield tunneling speed, the tunneling speed in the Kurkar stratum is twice that in the fine-sand stratum. | ||
| Key Words | ||
| calcareous sand stratum; geological characteristics; ground displacement; parametric study; shield tunneling | ||
| Address | ||
| Weiqiang Qi, Zhiyong Yang, Yusheng Jiang, Xing Yang and Xiaokang Shao: School of Mechanics and Civil Engineering, China University of Mining and Technology-Beijinig, Ding, No. 11 Xueyuan Road, Haidian District, Beijing, 100083, P.R. China Hongbin An: China Railway 12th Bureau Group Co., Ltd., No. 19 Renmin South Road, Xiaodian District, Taiyuan, Shanxi, 030000, P.R. China | ||