Study Of Vibration-Reducing Blasting Technology In Super Shallow Tunnel Unde-Travelling The Dense Houses Based On HHT

On the design and construction of railway tunnel, design units have a wealth of experience and design results. But for the large section in shallow tunnel, expecially under the complicated construction environment, there are still many technical problems need to be solved. It is the primary how to effectively control the vibration damage and correctly handle the contradictions between vibration control and efficiency of projects.Focusing on the technical problem of the requirement of surface vibration control when Xiannvyan tunnel under-travel the area packed with houses, two control blasting program, staged cutting and with the interference of seismic waves, were proposed in this thesis through analyzing on the field monitoring data in Hilbert-Huang Transform. The program that the single circle footage of tunnel is 80cm can effectively control surface vibration by reduce signle delay charge. And the other program of single circle footage is 1.8m, also can control the vibration by axial decoupling charging, but the energy inputting to the building is higher than the former. The two programs can be selected according to field.Getting marginal spectrum and instantaneous energy spectrum of the detection signal by HHT, marginal spectrum reflect the energy concentration in different frequency, and instantaneous energy spectrum performance the instantaneous input energy for buildings. Energy will be improved if vibration velocity become bigger and frequency become lower. Energy is more suitable to be as safety criteria for blasting vibration because it is the common reflection of both vibration velocity and frequency.For Xiannvyan tunnel with large section in super shallow, comprehensive measures should be taken to decrease vibration. Many measures such as shorten single circle footage, create free face artificially and reduce single delay charge can be taken together. The key of the interference of seismic waves is the selection of delay time. In this thesis, the best time range is 10-20ms by signal averaging that the single segment single obtained through the numerical simulation. Through superposition single segment single at intervals of 10s, the vibration velocity can reduce 12%, and the result is not the best when the intervals is 1/2 cycle,but causing the effect that the peak of single is eliminated.Stimulate tunneling blasting with 0.6m sectional blasting,80cm sectional blasting and 1.8m axial decoupling charging with the interference of seismic waves. And the result reflect the surface vibration velocity is influenced importantly by depth of tunnel, signle delay charge and new free face.