土石交界地层隧道爆破振动控制技术研究

Study of Blasting Vibration Control on Earth-rock Interface Tunnel

以空树河铁路隧道土石交界地层条件为研究背景,分析隧道地层地质条件和应力分布情况,并开展了隧道爆破方案设计和振动监测设计。分析结果表明:①当土石交界面为水平分布时,中下台阶具有较为明显的应力集中现象;土石交界面倾斜的情况下,内力呈现不对称分布,该类地层会造成隧道结构轴力和安全系数突变,但基本不影响弯矩。②当土石分界面位于掌子面时,振动波对混凝土钢拱架影响较为明显,顶拱部位振动速度最大可达7.97.9 cm/s,拱腰位置最小0.1-1.2 cm/s,受拉破坏的区域最大深度为顶拱以下2.6 m,分布于土石交界地层以上。③土石分界面位于顶拱以上时,土石分界面振动速度高达11.5 cm/s,大于其他开挖区;当振波穿过土石界限后振速衰减变快,受拉破坏最大深度为1.12 m。通过精细爆破设计、信息化施工、合理设置爆破参数和预加固措施,采用三台阶施工法有效控制土石交界地层隧道的爆破振害。

Based on the research background of the stratum breakage at the boundary of soil and rock in the tunnel of Kungshuhe Railway, the blasting scheme design and vibration monitoring design of the tunnel are carried out. The results show that:①When the soil-rock interface is horizontal distribution, the stress concentration is obvious in the middle and lower steps. This kind of stratum will cause the sudden change of the tunnel structure axial force and safety factor, but it does not affect the bending moment. ②When the soil-rock interface is located on the palm face. The maximum vibration velocity of the top arch can reach 7.97.9 cm/s,the minimum position of the arch waist(0.1-1.2 cm/s), and the maximum depth of tension damage is 2.6 m below the top arch, which distributes over the soil-rock interface. ③When the soil-rock interface is above the top arch, the vibration velocity of the soil-rock interface reaches 11.5 cm/s, which is larger than that of other excavation areas. When the shock wave passes through the soil-rock boundary, the vibration velocity decays faster, and the maximum depth of tension damage is 1.12 meters. Finally, through fine blasting design, information construction, reasonable setting of blasting parameters and pre-reinforcement measures, the three-step construction method can effectively control the blasting vibration damage of tunnels in the soil-rock interface stratum.