四车道扩挖隧道爆破振动对新建隧道的影响

Influence of Expanded Four-Lane Tunnel Blasting Vibration on New Tunnel

以泉厦高速公路大帽山隧道为工程背景,应用数值模拟方法从振动速度、振动应力和应力波3个方面分析得出沿扩挖隧道轴向动力特性,同时分析自由面对爆破地震波的影响.结果表明:距掌子面15m处振速衰减达50%,且在离掌子面10m处振速已经低于安全临界值;最大主应力峰值在距掌子面15m的范围内衰减最快,在离掌子面15以上时爆破振动影响逐渐趋于稳定;应力波在0.4ms时应力达到最大值13.3GPa,而在0.6ms时最大应力衰减到771.2MPa,只有0.4ms时的5.80%;自由面对爆破地震波的反射作用使能量损失55.6%,但先建隧道自由面使地震波反射叠加,从而使能量增加.

Taking Tai Mao Shan tunnel in Quanxia express way as example,the analysis of the vibration velocity,vibration stress and stress wave was carried out by the numerical simulation,to obtain the dynamic axial characteristics during the tunnel expansion,the influence of the free face on seismic wave of blasting was investigated.The results show that： the velocity attenuation is up to 50% 15 meters away from the tunnel face,and the velocity is below the safe value 10 meters away from the tunnel face;the attenuation of the peak maximum principal stress is the largest within 15 meters away from the tunnel face,for the region more than 15 meters away from the tunnel face,the blasting vibration tends to be stable;the stress wave reaches the maximum stress 13.3 GPa at 0.4 ms,and maximum stress attenuation to 771.2 MPa at 0.6 ms,which is only 5.80% of 0.4 ms;the energy dissipation is up to 55.6% due to the blasting seismic wave reflection caused by free face effects,but the free face of the constructed tunnel superposes the seismic reflection,so that the energy increases.