上覆岩土条件下孤石爆破预处理炸药单耗实验

盾构机在风化花岗岩地层掘进会遇到高强度孤石，为降低施工风险、避免刀盘及刀具严重损坏，常采用地面钻孔爆破对前方孤石进行预处理，但其炸药单耗一般由经验公式确定，导致爆破效果不理想。结合实际工程对爆破块度小于30 cm的特殊要求，采用爆破模型实验对炸药单耗进行研究。实验结果表明:满足特殊块度要求的陆地钻孔爆破炸药单耗是常规钻孔爆破的5.4~6.5倍；上覆地层厚度与炸药单耗呈线性递增关系；实验得出的炸药单耗是瑞典经验公式计算值的3.4~4.9倍。由此提出满足工程需要的炸药单耗修正公式，应用于实际工程并通过验证取得良好效果，为类似工程孤石爆破预处理炸药单耗的计算提供依据和参考。

Experiment of explosive consumption by blasting pretreated boulders with overlying stratum of rock-soil

During the tunneling construction in hard granite strata utilizing shield machines, pretreatment of boulders by blasting was commonly used to prevent the abrading cutter from serious damages and reduce construction risks, but the explosive consumption was usually determined based on empirical formula, resulting in that the blasting effect was often far from satisfactory. In the present work, aiming to meet the special requirement that rock fragments from the blasting should be less than 30 cm in practice, we investigate the explosive consumption using a model test of blasting. The results show that the explosive consumption of land blasting is 5.4-6.5 times that of conventional blasting when the requirement of rock fragmentation is satisfied; the explosive consumption increases linearly with the depth of overlying stratum; and the explosive consumption of model test was 3.4-4.9 times that of the empirical formula. Thus, the revised empirical formula is derived and proved valid based on the on-the-site practice. The revised formula can serve as calculation basis and reference value for similar projects of tunneling construction.