预留光爆层水压爆破在大断面公路隧道施工中降低爆破危害的应用

针对光面爆破技术开挖大断面公路隧道时普遍存在的线性超挖量大、光面爆破效果差、爆破振动大以及粉尘与爆生有害气体浓度高等一系列问题,采用预留光爆层水压爆破技术对新疆东天山特长公路隧道Ⅳ级大断面进行了开挖试验。结果表明,采用预留光爆层水压爆破能有效控制爆破危害,平均线性超挖量由0.924 m减至0.205 m,炮孔痕迹率由49.3%提高至91.1%,炸药单耗由1.348 kg/m³降至1.261 kg/m³,爆破振动幅值由5.057 cm/s降至3.249 cm/s,粉尘和各种有毒有害气体浓度随时间变化显著降低。试验结果证明预留光爆层水压爆破技术对大断面特长公路隧道掘进爆破危害控制的可行性,达到了隧道安全开挖、快速掘进、绿色钻爆等效果,对类似工程具有指导和借鉴意义。

Application of Water Pressure Blasting with a Reserved Smooth Blasting Layer in the Construction of Large-section Highway Tunnel for Mitigating Blasting Impacts

In view of the existent problems in excavation of large-section highway tunnels with smooth blasting technology, such as a large quantity of linear over-excavation, poor blasting effect, greater blasting vibration and high concentration of harmful dust and gases caused by explosion, the water pressure blasting with a reserved smooth blasting layer was used in the excavation test for the class Ⅳ large-section super long highway tunnel in the East Tianshan. The results show that the water pressure blasting with a reserved smooth blasting layer can effectively control the blasting hazards, with the average linear over-excavation reduced from 0.924 m to 0.205 m, the blast hole trace rate increased from 49.3% to 91.1%, the unit consumption of explosive dropped from 1.348 kg/m³ to 1.261 kg/m³, and the amplitude of blasting vibration down from 5.057 cm/s to 3.249 cm/s. Furthermore, the concentrations of dust and various toxic and harmful gases also decrease significantly over time. The test results prove that it is feasible to control blasting hazards by using the water pressure blasting with a reserved smooth blasting layer in the construction of super-long highway tunnel of large section, indicating the target of safe excavation, rapid advancement and green blasting can be achieved. It can provide some guidance and reference for similar projects.