土压平衡盾构掘进高瓦斯水工隧洞的HSP法超前地质预报

Advanced Geological Prediction Technology using HSP Method for High Gas Hydraulic Tunnel Excavation with Earth Pressure Balance Shield Tunneling

针对土压平衡盾构法掘进高瓦斯隧洞的超前地质预报技术难题,在讨论隧洞开挖方法与瓦斯潜在逸散的基础上,采用HSP预报方法进行高瓦斯盾构掘进施工超前地质预报。结果表明:HSP通过盾构破岩土震源可以获得较好的围岩强反射区域信号,对掌子面前向100 m、径向2倍洞径范围内的断层破碎带、溶洞、软弱夹层、孤石(规模均为等效直径≥2 m)探测准确率≥80%,异常体定位误差≤3 m;通过综合预判前方地质构造及瓦斯状态,进而确定选取常压作业开仓检查及换刀的位置,大幅降低了开仓检查和换刀作业风险,为久隆水库关门山充水隧洞奠定了安全基础,也可为今后类似工程提供借鉴。

In response to the technical difficulties of advanced geological prediction in the excavation of high gas tunnels using the earth pressure balance shield tunneling method,based on the discussion of tunnel excavation methods and potential gas escape,the HSP prediction method is adopted for advanced geological prediction in high gas shield tunneling construction.The on-site application results show that HSP can obtain good signals of strong reflection in the surrounding rock through shield-breaking rock and soil seismic sources.The detection accuracy for fault fracture zones,karst caves,weak interlayers,and solitary rocks(all with equivalent diameters≥2 m)within a radius of 2 times the tunnel diameter and 100 meters in front of the work face is≥80%,and the positioning error of abnormal bodies is≤3 m;it is possible to comprehensively predict the geological structure and gas status ahead,and then determine the location for opening inspection and tool replacement during atmospheric pressure operations,greatly reducing the risk of opening inspection and tool replacement operations.This lays a safety foundation for the Guanmenshan water filling tunnel of the Jiulong Reservoir and can also provide reference for similar projects in the future.