The Tunnel Maojiawan Blasting Safety Of The Diversion Tunnel, Numerical Analysis And Vibration Control

As a main construction method, the borehole-blasting method is widely usedin tunnel excavation engineering. By this method, the blasting vibration effects areinevitable. The blasting vibration not only affects the stability of the surroundingrock, but also endangers the safety of buildings close to tunnel. To analyze theeffects of blasting vibration on building is the precondition to design the blastingschemes and control the blasting vibration. Considering the constructionenvironment of Mao Jiawan tunnel, the blasting vibration effects on the waterintake tunnel of Tai Pingyi power plant are studied and the control methods ofblasting vibration are put forward.Before blasting construction, the tunnel blasting vibration effects on thewater intake tunnel are analyzed by numerical simulation methods when thecharges are different. Based on the measured seismic wave in similar engineering,the vibration responses of the lining of the water intake tunnel are obtainedaccording to the peak of acceleration is 2.4g, 5g, 11g and 16g when the distancebetween the construction tunnel and the water intake tunnel is 150m, 200m, 220m,respectively. The attenuation of vibration intensity with distance also is analyzed.The results of calculation show that the vibration resulted from blasting in MaoJiawan tunnel cannot endanger the safety of the water intake tunnel and thedistance affects obviously the attenuation of vibration intension.In order to realize the spread character of blasting seismic in surroundingrock, the field experiments of vibration effects have been done. Under the sameblasting conditions, the blasting vibration velocity in diorite is 1.6～2.1 timesgreater than it in quartzite. For blasting in upside section, the attenuationparameters of seismic waves in Sadov's formula are K=157.81 andα=1.91 indiorite. In quartzite, which are K=129.55,α=2.30. It is forecast by Sadov'sformula that the vibration velocity of water intake tunnel of Tai Pingyi powerplant is 0.043～0.074cm/s when the maximum charge of per period is restrictedwithin 20Kg.Based on the measured blasting seismic waves in Mao Jiawan tunnel, thevibration responses of the water intake tunnel of Tai Pingyi power plant areanalyzed by numerical simulation methods. It is found that the vibration intensitydecreases rapidly with the distance in the place away from the blasting center being less than 15m; the distance exceeds 15m, the vibration decreases slower.The results of numerical calculation show that the vibration responses of waterintake tunnel in quartzite are smaller than which in diorite. The maximumvibration displacement is 2.872um; the maximum vibration velocity is0.0201cm/s and the maximum vibration acceleration 17.36mm/s~2 in diorite. Thevibration resulting from blasting in Mao Jiawan tunnel can't damage the safety ofthe water intake tunnel of Tai Pingyi power plant.