Study On Blasting Dynamic Response And Safety Protection Of Multistage High And Steep Rock Slope

Highway construction in mountainous areas is an important link to improve China's traffic network and promote the development of poor mountainous areas.The highway construction in mountainous area often needs to face the problems of high and steep slope,difficult slope laying and large amount of stone.Blasting excavation has become an important excavation method for highway construction of high and steep slope in mountainous area due to its characteristics of economy,convenience and less mechanical occupation.However,blasting rock,dust and other factors brought by blasting excavation will bring great safety risks.At the same time,unreasonable blasting methods and blasting parameters will cause great harm to engineering rock mass and cause safety accidents.Aiming at this problem,this paper studies the blasting dynamic response and safety protection of multi-stage high and steep rock slope by means of theoretical research,formula deduction and simulation analysis.Firstly,the principle of rock breaking by blasting is summarized,and based on this,the basic equations of blasting load propagation under different charging structures are deduced.The rock damage mechanics model is given to calculate the damage factor.The cause of the instability of multi-stage high and steep rock slope induced by blasting excavation is given.Then,the construction,optimization and verification of the dynamic response model of presplitting blasting for multi-stage high and steep rock slopes were carried out based on the Otusco-Combayu Highway Extension Project in Cajamarca Region,Peru.The blasting dynamic response characteristics of rock mass under different radial decoupling coefficients are studied,and the optimal radial decoupling coefficients are obtained.The blasting dynamic response of rock mass under different hole spacing of pre-hole was studied,and the optimal hole spacing of pre-hole was given,and the blasting damage attenuation law was revealed.The dynamic response characteristics of pre-splitting blasting for rocks with different hardness levels are studied,and the attenuation law of vibration velocity near the blasting source area is revealed,and the vibration velocity propagation characteristics of adjacent slope surface are given.Then,based on Hoek-Brown damage theory and damage attenuation law,the mechanical parameters of rock mass affected by pre-splitting blasting disturbance were calculated.The displacement field,stress field,strain field and stability coefficient of multi-stage high and steep rock slope were investigated when the pre-splitting blasting excavated to each level.The bolting and shotcrete support scheme of one stage excavation and one stage support is put forward,and the stability of slope is studied when excavation reaches all levels and timely support is provided.At last,the slope geological disasters that may be induced by pre-splitting blasting excavation of multi-stage high and steep rock slope are analyzed,and the blasting safety protection technology is summarized from the two aspects of pre-splitting blasting process and slope reinforcement,and the blasting safety protection scheme and blasting safety protection suggestions are given accordingly.The research results provide construction guidance and safety protection suggestions for blasting excavation of multi-level high and steep rock slopes,and can provide reference for blasting excavation of similar high rock slopes in mountainous areas.