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Stability Estimation of the Pillar between Twin Tunnels Considering Various Site Conditions

다양한 현장조건을 고려한 병설터널 필라의 안정성평가

  • Received : 2017.04.11
  • Accepted : 2017.04.21
  • Published : 2017.04.30

Abstract

A lot of twin tunnels were modelled with different pillar widths, rock mass classes and stress ratios in order to consider various site conditions, and the stabilities of the pillars were estimated by numerical analyses and scaled model tests. The strength-stress ratios of the pillar were obtained from three different methods which were using the stresses appeared at the middle point, the whole average and the left/right edges of the pillar. The strength-stress ratio of the pillar edges showed relatively conservative values among them, and it was also practically consistent with the tunnel excavating steps comprising the construction sequence analyses which included the partial excavation and the support system. Scaled model tests were also performed to investigate the tunnel stability, where it was found that cracks were progressively generated from the pillar edges toward the middle point of the pillar. Therefore, in order to both prevent the local damage of pillar and conservatively estimate the tunnel stability, it was thought to be an appropriate method using the strength-stress ratio obtained from the left/right edges of the pillar.

Keywords

Twin tunnels;Pillar;Stability;Strength-stress ratio;Scaled model test

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