The rock mass joints can affect the propagation of explosive stress waves.The angle between their di-rection and the surrounding holes and the relative position changes have different effects on the blasting effect.Based on the attenuation law of stress waves at different jointed angles,a method was proposed for zoning the surrounding holes of tunnel blasting in jointed rock masses.The parameters of the surrounding holes are optimized when the angle between the joint and the surrounding hole is 30°,60°,90°,and 0°(parallel).The zoning layout method was valida-ted by combining LS-PREPOST numerical simulation and on-site tests regarding rock damage depth and blasting vi-bration speed.The results show that the rock mass's damage depth and blasting vibration speed under the zoning ar-rangement of surrounding holes are significantly better than that of the original layout plan of surrounding holes.Based on the geological conditions of the research section of the Bayueshan Tunnel of the Tongliang Anyue Express-way,the angles between the joints and the surrounding holes are set to 30°,60°,and 90°,respectively.The spacings between the surrounding holes are set to 43 cm,50 cm,58 cm,and 60 cm when the joints parallel the surrounding holes.The average over-excavation value can be controlled at 18cm after blasting,and the over-consumption of con-crete is controlled within 100％per linear meter.
维普
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