Research purposes: The purpose is how to use the blasting subsurface excavation method for the metro shallow tunnel nearly under - passing ground high - rise building on the premise of ensuring the safety of ground building and construction security.Research conclusions:Application of the upper and lower section bench method and taking measures of absorption of vibration along with following the non - millisecond detonator blast sequence can effectively control the seismic effect caused by the tunneling with blasting subsurface excavation, achieve the tunneling footage and ensure the safety of the ground building.By controlling the reasonable parameters of tunneling footage of a cycle and the Max.charge volume,the ground vibration velocity induced by blasting can be controlled within the standard limit of 2 cm/s to the ground building with the wall rock's recovery depth less than 10 m, and it can avoid the secondary disaster to the ground building.The engineering practice indicates under the condition of high strength of the wall rock, application of shortdistance control blasting technology not only can ensure the crashing degree of the wall rock and be easy to tag slag to achieve high utilization rate of explosive hole, but also can avoid the over - excavation and under - excavation when excavating the tunnel boundary due to the cutting effect of the vibration - reduction hole to ensure the smoothness of the boundary excavation and the stability of the wall rock.%研究目的:在保证地面建筑物与施工安全的前提下,解决浅埋暗挖法近距离穿越高层建筑的地铁隧道爆破技术问题.研究结论:采用上下断面台阶法和减震爆破措施,并使用非电毫秒雷管控制起爆顺序,可有效地控制爆破暗挖地震效应并保证掘进进尺,是确保地面建筑物安全的可行施工技术;通过控制合理的爆破掘进单循环进尺和分段最大装药量等参数,对于Ⅳ级围岩覆盖层厚度不足10 m的地面建筑物,能够将爆破引起的地表震动速度值控制在规范限定的2 cm/s范围内,确保地面建筑不会产生爆破震动次生损害;工程实践表明,在围岩强度较高的情况下采用近距离控制爆破技术,既能保证爆破岩块破碎适度,便于出渣,达到较高的炮孔利用率,也可通过减震孔的切割作用,有效避免隧道开挖边界超挖和欠挖,保证开挖边界的平整性和围岩稳定性.
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