Study On The Law Of Amplitude And Frequency Of Surrounding Rock Vibration Induced By Blasting Excavation Of Underground Caverns

The blasting vibration of underground caverns will inevitably affect the stability and safety of excavation caverns and adjacent caverns.It has become one of the technical difficulties in blasting construction of caverns.According to relevant codes at home and abroad,the blasting vibration duration and the vibration frequency have great influence on blasting vibration effect and safety assessment besides blasting vibration peak value.However,the study of blasting vibration frequency in existing blasting vibration research is not perfect.Therefore,it is of great theoretical significance and important engineering significance to study the amplitude frequency variation law of surrounding rock vibration induced by blasting in underground cavern group.Taking the blasting excavation of underground circular caverns as the research object,the amplitude frequency law of surrounding rock vibration induced by blasting excavation of underground cavern group is studied by means of theoretical deduction,regression analysis and dynamic finite element numerical simulation.According to the law,the vibration velocity amplitude spectrum expression of surrounding rock is derived,and the formula is verified by blasting engineering of the diversion tunnel group of the waterfall ditch.The main research work and achievements are as follows:(1)through theoretical analysis,the frequency domain expressions of triangular and exponential attenuation blasting loads are derived,and based on the amplitude spectrum of blasting vibration velocity in viscous rock masses,The velocity amplitude spectrum of rock mass excited by cut hole and non cutting hole is obtained.The velocity amplitude spectrum of group hole blasting is related to the distance between blasting core,hole spacing,radius of elastic zone,blasting load parameters,rock parameters and so on.(2)the dynamic and finite element numerical simulation method is used to study the axial and radial propagation of blasting seismic waves in the surrounding rock of different hole caving diameters and different blasting footage.Combined with the amplitude frequency variation law of the surrounding rock in the cavern,the velocity amplitude spectrum of the surrounding rock of the underground chamber is deduced.(3)the three-dimensional model of underground circular caverns is established.The influence of the spacing and size of caverns on the amplitude and frequency variation of surrounding rocks of underground caverns during blasting is studied.According to the law of amplitude frequency variation,the velocity amplitude spectrum of the arch waist of adjacent hole on the adjacent hole is derived.(4)taking the blasting engineering of the diversion tunnel group of the waterfall tunnel as background,the formula of the vibration velocity amplitude spectrum is verified,and its application scope is given.