Numerical Analysis of Temperature Field of Cup-Shaped Frozen Soil Wall Reinforcement at Shield Shaft

Abstract:

Determining the freezing reinforcement required range and reinforcement method, acquiring the development and distribution pattens of frozen soil wall temperature field are the key issues needed to be addressed when using cup-shaped horizontal freezing method for the soil reinforcement of shield tunnel ends. Based on the shield launching project of the west side of Yixianqiao station in Nanjing subway line 2 and the finite element numerical analysis software, the development and distribution patterns of the cup-shaped frozen soil wall reinforcement were studied. The numerical simulation showed that, after freezing for 30 days, the x = -1 section temperature field evenly distributed around the center tube. And the freezing temperatures within the outer tubes were usually below-20°C. The temperature field circled around the center tube and the temperature gradually increased from the inside to the outside to 0°C within the range of about 1 m outside the outer tubes. The freezing temperatures within the range of 2 m thickness of the cup-bottom in the y= 0 section were usually below-10°C and the temperatures changed from inner to outer significantly until rising to 0 °C at the freezing pipe ends of the cup-bottom. Freeze wall formed firstly in the outer tubes, then the intermediate tubes, and lastly the outer tubes. And the freeze wall closure time that closed cup-shaped frozen soil wall formed was 15 days in this designed freezing method.

• Periodical: Applied Mechanics and Materials (Volumes 341-342)
• Pages: 1467-1471
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.341-342.1467
• Online since: July 2013
• Authors: Jun Hu, Hui Zeng, Xiao Bin Wang
• Keywords: Cup-Shaped Frozen, Numerical Simulation, Shield Launching, Temperature Field

References

[1] J. Hu, P. Yang, C.W. Dong, T.W. Ma, T. Zhang, Chemical Reinforcement Area at Shield Start Shaft and Its Technology Study, Railway Engineering, 15 (2010) 47-51. (in Chinese).

[2] J. Hu, P. Yang, C.W. Dong, R. Cai, Study on Numerical Simulation of Cup-shaped Horizontal Freezing Reinforcement Project near Shield Launching, 2011 International Conference on Electric Technology and Civil Engineering (ICETCE). China: IEEE. 4 (2011).

DOI: 10.1109/icetce.2011.5776395

[3] J. Hu, H. Zeng, X.B. Wang, Study on Construction Risk Analysis and Risk Counter-measures of River-crossing Tunnel of Large-diameter Metro, Applied Mechanics and Materials, 166 (2012) 2680-2683.

DOI: 10.4028/www.scientific.net/amm.166-169.2680

[4] J. Hu, P. Yang, C.W. Dong, R. Cai, In-situ investigation of mode to strengthen shield-tunnel end on Suzhou metro line No. 1, Railway Engineering, 11 (2010) 32-35. (in Chinese).

[5] J. Hu, The Study of the Shield Tunnel End Reinforcement Method and the Key Issues on Suzhou Metro, Thesis, Nanjing Forestry University, 2009. (in Chinese).

[6] J. Hu, Study on the Reinforcement Methods of Subway Large-diameter Shield Launching in the Sandy Clay with High Water Pressure, Thesis, Nanjing Forestry University, 2012. (in Chinese).