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Geomechanics and Engineering Volume 35, Number 6, December25 2023 , pages 571-580 DOI: https://doi.org/10.12989/gae.2023.35.6.571 |
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Effects of structural characteristics of screw conveyor on spewing during EPB shield tunnelling |
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Xiaochun Zhong, Siyuan Huang, Rongguo Huai, Yikang Hu and Xuquan Chen
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| Abstract | ||
| During EPB shield tunnelling, construction speed and safety are severely affected by spewing. In this study, a theoretical seepage model is established to capture of the effects of screw conveyor geometry and turbulent flow on spewing. Experimental test results are used to verify the proposed theoretical seepage model. It is found that the seepage is greatly affected by the length of screw conveyor and soil permeability. The proposed model can increase the screw conveyor length and reduce soil discharge sections simultaneously, the permeability of treated muck thus decreases by one order of magnitude. By using the proposed theoretical seepage model, the criterion of critical soil permeability used to identify spewing is proposed. When the water head applied at tunnel face reaches 40 m and 50 m, the critical permeability coefficients of treated muck should be less than 10-5 m/s and 10-6 m/s to avoid spewing. For a given permeability coefficient of soil, the water flow rate is overestimated if structural characteristics of screw conveyor is not considered. Consequently, the occurrence of spewing is greatly overestimated, which increases construction cost substantially. | ||
| Key Words | ||
| critical permeability coefficient; EPB shield tunnelling; screw conveyor; spewing | ||
| Address | ||
| Xiaochun Zhong and Siyuan Huang: College of Civil and Transportation Engineering, Hohai University, Nanjing 210098, China ongguo Huai, Yikang Hu and Xuquan Chen:2China Railway No.5 Engineering Group Co., LTD., Changshan 410117, China | ||