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结合武汉市轨道交通2号线工程背景,采用现场监测和动力有限元数值模拟相结合的研究方法,对超浅埋通道下台阶爆破开挖地表振动传播规律进行研究。同时,为研究上台阶开挖空间对爆破地震波传播特征的影响,对通道全断面爆破开挖的地表振动传播规律进行数值模拟分析。研究结果表明:下台阶爆破开挖工况下,沿通道开挖导洞轴线方向,由于应力波的绕射,掌子面前方5 m处地表质点峰值振速达到最大值;垂直于通道开挖导洞轴线方向,掏槽孔孔底连心线中点正上方地表质点与爆源距离最小,但峰值振速并不是最大,且质点两侧2 m范围内,随着爆心距的增加,峰值振速不断增大。全断面爆破开挖工况下,沿通道开挖导洞轴线方向,掌子面前方2 m处地表质点峰值振速达到最大值;垂直于通道开挖导洞轴线方向,掏槽孔孔底连心线中点正上方地表质点峰值振速最大,且随着爆心距的增加,峰值振速不断减小。对比通道下台阶爆破开挖和全断面爆破开挖2种工况下地表质点振动特征,上台阶开挖空间的存在阻隔了应力波的传播,在一定空间范围内影响爆破地震波的传播特征,能够有效降低地表质点峰值振速。
Combined with the engineering background of Wuhan Metro Line 2, this paper studied the law of ground surface vibration propagation by step blasting and excavation under the super-shallow buried channel using the combination of on-site monitoring and dynamic finite element numerical simulation. At the same time, in order to study the influence of the upper excavation space on the propagation characteristics of blasting seismic waves, the numerical simulation of the surface vibration propagation of full-face tunnel blasting is carried out. The results show that under the blasting excavation conditions of the next step, the peak velocity of the surface mass at 5 m in front of the face of the palm reaches its maximum due to the diffraction of the stress wave along the axis of the guide tunnel along the tunnel. When vertical to the channel excavation In the direction of the axis of the pilot tunnel, the distance between the surface mass point and the explosion source just above the midpoint of the bottom hole of the cut hole is the smallest, but the peak vibration velocity is not the maximum. Within 2 m on both sides of the mass point, with the increase of the burst center distance, Vibration speed is increasing. Full-face blasting excavation conditions, along the tunnel excavation guide hole axis direction, the front surface of the palm 2 m at the surface mass peak vibration speed reaches the maximum value; perpendicular to the tunnel excavation guide hole axis direction, cut hole hole bottom with The peak velocity of the surface mass point is the maximum just above the midpoint of the line, and the peak velocity decreases with the increase of the burst center distance. Comparing with the vibration characteristics of surface particles under two conditions of step blasting excavation and full face blasting excavation under the channel, the propagation of stress waves is blocked by the presence of the upper excavation space, and the propagation characteristics of blasting seismic waves are affected within a certain spatial range. Effectively reduce the surface peak velocity.