Study On The Influence Of Bedding Structure On Stress Wave Propagation And Penetration Ability Of Shaped Charge Hydraulic Blasting

In order to clarify the law of influence of bedding structure on stress wave propagation and penetration ability of energy-accumulating hydraulic blasting,based on the theories of energy-accumulating blasting,hydraulic blasting and stress wave propagation,the process of penetrating bedded rock mass by energy-accumulating hydraulic blasting is simulated by ANSYS/LS-DYNA numerical software,and then the influence law of different bedding parameters on penetration ability of energyaccumulating hydraulic blasting is analyzed,and the parameter sensitivity analysis of rock mass damage index is carried out by orthogonal test.The influence degree of each bedding parameter on the effect of concentrated energy hydraulic blasting is further determined.Based on the simulation results,the PMMA blasting crack growth experiment and the penetration experiment of the concentrated water pressure blasting were carried out,and the numerical simulation results were verified by combining the SEM scanning electron microscope technology.Finally,according to the slope model established on the project site,the differences between energy-accumulating hydraulic blasting and conventional blasting in slope excavation are compared and analyzed,and the rationality and feasibility of energy-accumulating hydraulic blasting in actual engineering application are discussed.The main conclusions are as follows:(1)The penetration law of energy-accumulating jet and the influence law of discontinuous structure on stress wave propagation are revealed.Combining explosion mechanics and fracture mechanics,the fracture mechanics model of concentrated blasting is established by introducing energy factor,and the relationship between damage radius and jet strength of concentrated blasting is deduced.According to the law of conservation of particle momentum and the continuity of interface,the calculation method of transmission coefficient T and reflection coefficient R of stress wave vertically incident to discontinuous structural surface is obtained.By calculating the transmission wave strength under water and air coupling,it is proved that Water-coupled charge can effectively improve the transmission efficiency of stress wave and enhance the ability of blasting to break rock.(2)The hole wall pressure and rock mass damage of conventional air uncoupled blasting and energy-accumulating hydraulic blasting under the same charge are compared and analyzed.Under the combined action of energy-accumulating cover and water,the hole wall pressure and crack propagation radius in the direction of energy-accumulating are 1.37 and 1.57 times of non-energy-accumulating direction respectively,and 4.05 and2.08 times of air uncoupled blasting,which proves that the energy-accumulating hydraulic blasting can not only improve the utilization rate of explosive,strengthen the penetration of rock mass in the direction of energy-accumulating,but also protect rock mass in the direction of non-energy-accumulating.(3)The influence laws of different bedding parameters on stress wave propagation and penetration ability of concentrated hydraulic blasting are revealed.By establishing the single-hole blasting model of energy-accumulating hydraulic blasting,the influence rule of each bedding parameter on rock-breaking effect of energy-accumulating hydraulic blasting is studied.Through parameter sensitivity analysis,it is concluded that the angle between bedding and energy-accumulating direction is the main factor to control the blasting effect.With the decrease of the angle between the lamination and the direction of energy accumulation,the transmission coefficient of stress wave,the damage quantity in the lamination zone and the deflection angle of the main crack show a downward trend,but the effective crack propagation radius increases significantly.In practical engineering application,when the direction of bedding has been proven,reducing the angle between opening direction of shaped charge cover and bedding is the priority when laying blasting holes to achieve the purpose of improving blasting effect.(4)Through experimental study,the differences of crack growth between conventional blasting and energy-accumulating hydraulic blasting under different bedding parameters are compared and analyzed.The experimental results show that there are a lot of tensile cracks in the rock mass in the fractured zone,the length and width of which are both high and the damage to the rock mass is the most serious.It proves that the superposition of stress wave and reflected wave in the fractured zone will intensify the tensile failure of the rock mass.Under the action of concentrated energy hydraulic blasting,obvious penetration damage occurs to the rock mass in the direction of concentrated energy,with the penetration damage radius reaching 1.32 times of the original blasting hole radius,while the damage degree of rock mass in the direction of non-concentrated energy is significantly lower than that in the direction of concentrated energy.The damage distribution and crack propagation path of blasting rock mass are directly affected by the bedding angle and bedding distance.The deflection angle of main crack can be reduced by reducing the bedding angle or increasing the bedding distance.The damage law is basically consistent with the numerical simulation conclusion,which verifies the correctness of the numerical simulation results.(5)The feasibility and technical advantages of energy-accumulating hydraulic blasting in slope excavation are proved.According to the slope model established on the project site,the damage of rock mass and particle vibration under conventional blasting and energy-accumulating hydraulic blasting are compared and analyzed.The results show that under the action of energy-accumulating hydraulic blasting,the influence of bedding on Z-direction component of vibration wave is the most significant,and the maximum increase of peak particle velocity can reach 132.9%;The damage depth of rock mass in non-accumulative direction is 4.8 cm,which is 48.9% lower than that of conventional blasting.The peak vibration velocity of the upper step is 6.30 cm/s,which is 44.7% lower than the specified threshold value,which verifies the vibration attenuation of the concentrated hydraulic blasting and the protection of the non-concentrated direction rock mass.