爆破地震波作用下浅埋隧道地表振动的空洞效应研究

以成贵高铁豆子湾隧道为工程背景，对浅埋隧道爆破开挖时地表振动速度进行了监测。实测数据表明，以掌子面为对称面，隧道已开挖成洞区拱顶上方地表的振动速度是对称位置未开挖区的1.1~1.7倍，即存在空洞效应。由于空洞效应的影响，导致隧道开挖成洞区上方地表的爆破地震波衰减规律不满足萨道夫斯基公式。运用ANSYS/LS-DYNA有限元软件进行数值模拟计算，得到在隧道中心线方向，随距掌子面距离的增大，空洞效应的影响有一个先增大后减小的过程，并且当距掌子面为1.5~2.0倍的隧道洞径时，空洞效应的影响不再明显。

Study on Hollow Effect of Ground Vibration under Blasting Seismic Wave in Shallow Tunnel

Taking the project of Douziwan shallow tunnel for Chengdu-Guiyang high-speed railway as the background, the experiment of vibration velocity of the ground surface has been done when monitoring the blasting excavation of shallow tunnel. The measured data show that the ground surface vibration velocity above the vault in excavation area is 1.1~1.7 times of that in the unexcavated area in symmetric position. The hollow effect has been discovered from the experiment. Due to the influence of hollow effect, the attenuation law of the blasting seismic wave of the surface above the tunnel excavation cavitation area does not satisfy the Sadov’s formula. The ANSYS/LS-DYNA finite element software has been applied to numerical simulation calculation. The calculations show that the effect of hollow effect firstly increases and then decreases with the increase of distance from the excavating face along the direction of tunnel center line. When the distance away from the excavating face is 1.5~2.0 times of tunnel hole diameter, the influence of hollow effect is no longer obvious.