浅表层隧道爆破对临近古建振动影响的现场模拟试验研究

Field Test Study on Influence of Superficial Tunnel Blasting on Vibration Response of Adjacent Ancient Building

隧道掘进爆破施工威胁临近建筑物的安全,尤其是结构性能日益衰退的古建筑。为降低此类爆破施工的环境影响,结合南京地铁4号线鼓楼站爆破施工现场模拟试验,对比分析了单孔爆破和多孔孔间毫秒延迟爆破对省级木结构保护文物鼓楼的振动安全影响。根据现场地质资料,模拟爆破点选在离古建筑距离较远而地质条件相近的拟建风道口处。根据6种爆破强度的模拟结果,研究了地表振动衰减和古建筑振动响应规律,并以此预估实际爆破施工时古建筑的峰值振动速度。试验结果表明:2种爆破方式均未造成古建筑鼓楼的进一步损伤,但相比于单孔装药量为500 g的爆破结果,总装药量为1100 g的6孔毫秒延时爆破能显著地减小峰值振速。文物鼓楼处地表的水平和竖直向振动衰减规律均符合萨道夫斯基公式,水平振动占主导地位;单孔爆破400 g装药量下共振效应最为显著,速度放大效应约为2.4倍。

Tunneling and blasting construction threatens the safety of adjacent buildings,especially ancient buildings with declining structural performance.In order to reduce the environmental impact of such blasting construction,this paper reports the field test of blasting construction of Gulou Station of Nanjing Metro Line 4 and studies the impacts on the vibration safety of the provincial protection cultural relic drum building due to single-hole blasting and millisecond delay blasting between porous holes,respectively.According to the on-site geological data,the simulated blasting point was selected at the proposed airway opening which was far away enough from the cultural relic drum building but still of the similar geological conditions.According to the test results of six kinds of blasting strength,the vibration response law of the surface of the simulated blasting point and the surface of the Drum Tower and the monument building were studied,and the peak vibration velocity of the actual blasting position of the Drum Tower was estimated.The test results show that the Drum Tower is still within the influence range of the blasting vibration,but the construction will not cause further damages.Compared with the blasting result with a single hole charge of 500 g,the 6-hole millisecond time-delay blast with a total charge of 1100 g can significantly reduce the peak vibration velocity.The horizontal and vertical vibrations of the surface of Drum Tower follow the Sadowski formula,with the horizontal vibration being the dominant one.The velocity in the case of the single-hole blasting with 400 g charge is amplified by 2.4 times which causes the most significant resonance effect in all cases.