풍화대를 통과하는 도로 NATM 터널의 천단부 함몰에 대한 연구

Shin, Eun-Chul;Yoo, Jai-Sung
신은철;유재성

• Accepted : 2016.06.17
• Published : 2016.06.30
• 25 12

Abstract

The construction of the road NATM tunnel, which undergoes the weathered zone of the mountain, was in process with the reinforcement methods such as the rock bolt, shotcrete depositing, and the multi step grout with large diameter steel pipe. The collapse from the ceiling, and on the ground surface area(sink hole), of which were measured to be 25m from the ground surface($V=12m(W){\times}14m(L){\times}5m(H)=840m^3$), as well as excessive displacements in the tunnel, had occurred. In order to execute the necessary reconstruction work, the causes of the surface collapses were inspected through the field investigation, in-situ tests, and numerical analysis. As a result, several proper solutions were suggested for both internal and external reinforcements for the tunnel. As a result of numerical analysis, the collapsed zone of the tunnel was reinforced up to 0.5D~1.0D laterally by the cement grouting on the ground surface, 0.5D longitudinally by the multi step grout with large diameter steel pipe in tunnel. With further reinforcement implemented by rebars in lining, the forward horizontal boring was executed to the rest of the tunnel to evaluate the overall status of the tunnel face. Appropriate reinforcement methods were provided if needed.

Keywords

NATM;Surface collapse(Sink hole);Multi step grout with large diameter steel pipe;Core stone

References

1. Jung, J., Kim, O., Lee, S., Kim, j., and Lee, S., (2004), A Case study of collapse restoration on highway
2. Karol R. H. (1983), "Chemical grouting", Marcel Dekker. Inc.
3. Kim, N., Kim, H., Oh, Y., Kim, C., and Yang, T., (2012), A case study on excessive displacements occurred in the tunnels caused by rainfall, Journal of Korean Tunnelling and Underground Space Assoication, Vol.14, No.6, pp.561-573 (in Korean). https://doi.org/10.9711/KTAJ.2012.14.6.561
4. Korea institute of construction technology (2007), Development of technologies for minimizing and preventing the disaster on tunnel construction(IV), pp.24-77 (in Korean).
5. Korean Tunnelling and Underground Space Association (2010), Case Histories of Tunnel Collapses, pp.16-27 (in Korean).
6. Korean Tunnelling and Underground Space Association (2012), Technical report on Surface Collapse of the C.L. NATM Tunnel.
7. Ministry of Land, Transport and Maritime Affairs(2012), concrete structure design standard, pp.63-64 (in Korean).