Journal of Northeastern University(Natural Science) ›› 2022, Vol. 43 ›› Issue (10): 1469-1476.DOI: 10.12068/j.issn.1005-3026.2022.10.014

• Resources & Civil Engineering • Previous Articles     Next Articles

Expansion Type of In-situ Expansion of the Intersection Between Main Tunnel and Shaft in the Existing Tunnel

WANG Xin, ZHAO Wen, BAI Qian   

  1. School of Resources & Civil Engineering, Northeastern University, Shenyang 110819, China.
  • Revised:2021-10-11 Accepted:2021-10-11 Published:2022-11-07
  • Contact: ZHAO Wen
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Abstract: In order to explore the optimal in-situ expansion type of the intersection of the main tunnel and the shaft in the existing tunnel, a three-dimensional finite element model of the expansion process at the intersection of the main tunnel and the shaft was established based on the in-situ expansion project of the Nanling tunnel, and the changes of surrounding rock deformation and stress with the excavation process under the single-side expansion and double-side expansion were studied. Considering the spatial position relationship between the shaft and the tunnel, formulas for calculating the pressure of the surrounding rock of the tunnel with different expansion types were proposed based on Terzaghi′s theory. The results show that the deformation rate of surrounding rock within 1 time of the tunnel diameter between the tunnel face and the cross section of the shaft and the tunnel is larger. The single-side expansion makes the surrounding rock stress release unevenly and form a bias effect, causing a larger surrounding rock stress than that of the double-side expansion. The choice of expansion type has a great influence on the distribution of surrounding rock pressure, when the surrounding rock is in grade Ⅲ~Ⅴ, the calculated value of the surrounding rock pressure formula are the largest of the double-side expansion, followed by the Terzaghi′s theory, and the smallest for the single-sided expansion.

Key words: tunnel engineering; in-situ expansion; expansion type; numerical simulation; surrounding rock pressure

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