Vibration Monitoring And Control For Tunnel Engineering Under Blasting Load

The tunnel engineering is a typical underground structure, excavated mainly by blasting.The remaining rock and tunnel structure were damaged inevitably by the blasting load. It is very important for preventing the damage of engineering structures and the safety accidents, and avoiding the economic loss and personal injury by carrying out the research on vibration monitoring and control for the tunnel engineering under the blasting load.The blasting vibration velocity was predicted by BP neural network. The measured blasting vibration signals were analyzed by wavelet analysis.The numerical analysis model of tunnel blasting was established by the ANSYS/LS-DYNA finite element program, and the tunnel engineering effects under blasting load were studied on the basis of the mechanism and theoretical models of blasting load effects on the tunnel.Some control measures of the blasting load for the tunnel engineering were proposed. The main contents and conclusions are as follows.(1)Based on the site test of blasting vibration monitoring, some empirical formulae and a BP neural network model were established to predict the blasting vibration velocity for tunnel excavation, and applied in the tunnel engineering practice.(2) After analyzing the blasting vibration signals by wavelet analysis, the concentration distribution of dominant frequency for blasting signal was obtained, and frequency energy distribution for blast vibration was revealed, which give guidance to evaluate the damage induced blasting vibration on tunnel engineering.(3)Considering the dominant frequency, the natural frequency of controlled structure and the energy distribution of frequency domain, a new method for blasting hazard evaluation based on the assess parameter of blasting vibration hazards was proposed, and blasting hazard on tunnel engineering can be quantificationally evaluated.(4) Through dynamic analysis of blasting dynamic load on tunnel, the curve of the vibration velocity, displacement, and maximum principal stress were obtained. It shows that the relative error between the calculated peak particle velocity and the measured results is less than 8% by comparing the simulation results and measured data. The blasting signals of numerical simulation and the measured blasting signals were analyzed respectively by wavelet decomposition, and the result shows that the two decomposition results are consistent.(5)The effects of blasting parameters on blasting hazarded were analyzed by numerical simulation after analyzing the main factors of blasting load for tunnel engineering, and some measures and methods of optimizing blasting parameters for controlling blasting load on tunnel engineering were proposed.