爆破施工隧道围岩稳定性研究

Study on the Stability of the Surrounding Rock of Blasting Construction Tunnel

结合贵广铁路棋盘山隧道施工现场测试,研究隧道爆破近区围岩振动规律以及稳定性。对棋盘山隧道掌子面后方拱顶5 m范围内围岩的爆破振动速度进行测试和分析,结果表明:隧道爆破近区围岩的振动传播速度随爆破的比例距离呈幂指数衰减,棋盘山隧道Ⅲ级围岩的幂指数为-0.62。对爆破施工隧道的稳定性研究表明:隧道塌方主要是岩块沿着节理面滑动造成的,与节理面的抗剪强度和岩块的大小及形状相关。最不稳定拱顶位置关键块掉落的临界爆破振动速度,随关键块高度的增大而增大,而随关键块长度和宽度的增大而减小。因此,可根据隧道围岩关键块的形状和位置,计算关键块的临界爆破振动速度,进而得到保证关键块不掉落的炸药量,以控制围岩稳定,确保隧道施工安全。

Based on the field tests of Qipanshan tunnel of Gui-Guang Railway, the stability of the surrounding rock of the tunnel and the blasting vibration law in the area near the tunnel face were studied. The blasting vibration velocity of the surrounding rock within 5 m to the vault behind the tunnel face of Qipansban tunnel was tested and analyzed. The results show that the blasting vibration velocity of the surrounding rock near the tunnel blasting area is decaying exponentially with the scaled distance of blasting, and the power exponent of Ⅲ surrounding rock of Qipanshan tunnel is -0. 62. The stability of blasting constructed tunnel was analyzed. The results indicate that tunnel collapse is mainly resulted from the rock block slipping along the joint surface, and is related to the shear strength of the joint surface and shape as well as the size of the rock block. The critical blasting vibration velocity of the pivotal rock in the vault increases with the height of the pivotal rock, and decreases with its length and width. So, the critical blasting vibration velocity of the pivotal rock is calculated according to its shape and location, and the mass of the explosive charge is controlled, the stability and safety of tunnel are ensured.