Mechanism Research And Engineering Application Of Blasting Vibration Reduction Ditch

Blasting is the main construction method of important projects such as mining,water conservancy,railway and nuclear power.In addition to rock breaking,explosives are also accompanied by blasting vibration,which not only affects the surrounding people and animals,but also builds around the blast source Structures)structures and objects to be protected produce a certain degree of damage and destruction.In order to reduce and prevent blasting vibration,this paper relies on the infrastructure projects of Hongyanhe Nuclear Power Station and Xiapu Nuclear Power Station,and proposes to excavate vibration reduction trenches to reduce vibrations of blasting vibration.And the numerical simulation of the vibration damping effect of different parameters of the damping ditch is carried out.(1)Analyze the vibration-damping mechanism of the vibration-damping groove theoretically.The propagation process of the vibration wave generated by the explosive explosion depends on the propagation of the medium.In the absence of any measures to reduce the vibration,the propagation medium of the vibration wave can be regarded as a continuity.,The propagation medium is changed from rock mass or other medium to air medium,which makes the blasting vibration wave refract,reflect and diffract,reduce the vibration wave energy and continue to propagate forward.Therefore,this paper intends to use joint stiffness to study the propagation between the vibration wave and the interface of different media,and regard the interface of different media as the contact surface with discontinuous linear elastic half space.If the transmission coefficient is less than 0,it means that when the medium is air,the damping groove completely cuts off the blasting vibration wave.(2)Based on the three-dimensional and two-dimensional basis of ANSYS/LS-DYNA,establish a three-dimensional model of a rectangular parallelepiped with a length of 25m,a width of 20m and a height of 15m,and establish a plane with a length of 60m and a width of30m with different sizes of vibration reduction The two-dimensional model of the trench,by simulating the impact of the width,depth,distance of the blast source and vibration wavelength on the damping effect of the damping groove,it is concluded that the damping effect is 8m and the width is 3m and the depth is 8m.It is best to achieve 0.93 in the horizontal direction and 0.91 in the vertical direction;the comparative analysis of engineering practice and numerical simulation shows that the vibration reduction rate of numerical simulation is much higher than that of engineering practice.The optimal vibration damping effect of the vibration damping groove is related to the specific width,depth,position,length and vibration wavelength of the vibration damping groove.Assuming one of the factors,such as the best vibration damping effect,the other four factors have a certain relationship.The study believes that when the vibration wave?λ_R of the damping groove has a proportional relationship with the width,depth,position,and length,that is,the width is about 0.3?λ_R,the depth is about 0.81?λ_R,the position is about 0.81?λ_R,and the length is about 0.81?λ_R,the best damping effect.(3)Through the analysis and fitting of the field test data,it can be seen that the damping groove has obvious damping effect.The fitting result of the field test monitoring data shows that the change curve of the fitting curve in the horizontal direction and the vertical direction is similar.Its vibration damping rate is between 0.37-0.87 in the horizontal direction and0.35-0.86 in the vertical direction.The damping effect of numerical simulation reaches 0.93 in the horizontal direction and 0.91 in the vertical direction.The results of on-site damping rate matching are compared with the numerical calculation data.The curve of the damping rate in the vertical direction is roughly consistent,and the maximum value of the damping rate in the horizontal direction is close to the numerical simulation.Is reliable.(4)According to the analysis of the field test monitoring data of the excavation damping trench,the amplitude of the particle vibration velocity did not exceed the safety threshold of the power plant.The vibration damping effect in the horizontal direction is up to 87%,and the vertical direction is up to 86%,indicating that the damping groove It has a good damping effect,reduces the impact of blasting vibration on the protected objects,and provides safety guarantee and reference for the subsequent blasting construction on the protected objects.