The Study On Blasting Vibration Of Xiamen Undersea Tunnel Constructed By Drilling And Blasting Method

The technique of driving blasting is used as a main constructive way in shallow tunnels in rocky zone. By this way, blasting seismic effect is inevitable. The control of blasting seismic effect is concerned with not only the blasting quality, the tunnel constructive efficiency and the benefit of the tunnel construction, but also the stability of the surrounding rock, the effect of tunnel timbering and the safety of buildings around the tunnel. In order to control the blasting seismic effect effectively, the , blasting seismic waves' characters should be studied.In view of the Xiamen undersea tunnel, we have studied how the blasting seismic wave generated by the lineal explosive package spread inside the tunnel. The field experiments have been done. By analyzing the results of these experiments, we found some laws: there are different laws for the spreading of the blasting seismic wave along the axial direction and the radial direction of the lineal explosive package .the blasting seismic waves' velocity along the axial direction is weakened much faster than along the radial direction of the lineal explosive package. the blasting seismic waves' velocity is different when the surrounding rock' level is changed .generally speaking, the blasting seismic waves' velocity in high level surrounding rock is wakened much more slow than in the low level surrounding rock .the release of the blasting energy is influenced by the squeezing effect of the surrounding rock.Some crucial experiments cann't be constructed because of the project's construction. In order to overcome this difficulty, we simulated the procedure of the blasting of the tunnel by computer software. In this way , we expanded the research area of the blasting seismic wave. By analyzing the results of the computer simulation, we find the laws below: the existed channel will magnify the vibration velocity. The strong evidence is the vibration velocities obtained from the front of the blasting face is larger than those obtained from the back of the blasting face. The number of the magnified coefficient follow some laws. The changed region inside the tunnel will also influence the spreading of the blasting seismic wave. the magnified effect of the vibration velocity caused by the expanding of the digging surface can prove this conclusion.