Advances in Civil Engineering / 2021 / Article / Tab 3 / Research Article
Stability of a Rock Tunnel Passing through Talus-Like Formations: A Case Study in Southwestern China Table 3 Configuration of dynamically adaptive support system in talus-like formations in Tayi tunnel.
Supporting system Vd-1 Vd-2 Vd-3 Presupport φ 76 × 6 pipe shed, 9 m length, 6 m × 30 cm spacing, splicing length ≥3 mPrimary support Mortal anchor φ 25, 60 cm × 120 cm spacing3.5 m length 4 m length 4 m length Steel mesh φ 8, 20 cm × 20 cm spacingSteel arch 60 cm spacing I 22b I 25b Double layer Shotcrete C25 28 cm 31 cm Double layer Foot reinforcement bolt (each side) Upper bench: φ 42 × 2, 4.5 m length Upper bench: φ 42 × 2, 5 m length Matched to steel arch Middle bench: φ 89 × 2, 6 m length Lower bench: φ 89 × 1, 6 m length Reversed deformation 30∼35 cm 35∼40 cm 35∼40 cm Secondary support Reinforced concrete C30 50 cm 60 cm 60 cm Reinforcement N1: φ 22@20 N1: φ [email protected] N1: φ [email protected] N2: φ 22@20 N2: φ 22@20 N2: φ 22@20 N3: φ 14@30 N3: φ 14@30 N3: φ 14@30 N4: φ 8@30 N4: φ 8@30 N4: φ 8@30
Note: the primary support for Vd-3 is in the form of double-layer as shown in Figure
15 . The unit for diameter of pipes, anchors, and steel bars is mm. The steel bars in N1, N2 and N3 are HRB 400 while the ones in N4 are HPB 300.