Application Of V-notch Blasting In Rock Anchor Beam Of Baihetan Hydropower Station Excavation

The excavation quality of rock anchor beam is related to driving safety,V-notch blasting can make the fracture surface be more smooth and reduce the damage range of rock mass which is produced by blasting.It can effectively improve the quality of rock anchor beam.This paper through theoretical analysis are obtained by analyzing the V-notch groove tip should stress intensity factor and the V-notch blasting mechanism,in Baihetan Hydropower Station Powerhouse Rock Anchor Beam blasting excavation engineering as the research object were established of single hole and double hole blasting model simulation of Blasting simulation experiment,and the calculation results are obtained moment effect of blasting on the blasting effect.According to the simulated results in Baihetan Hydropower Station beam anchored on rock blasting excavation in the V-notch blasting and conventional blasting test are compared,and the moment blasting and non carved blasting range of loose circle,smooth effect and economic benefit.The following conclusions are obtained:(1)The carved blasting in hole heart lines of equivalent stress was significantly larger than that of non notch blasting hole heart lines equivalent stress,which is get from the numerical simulation analysis of stress distribution rules in minute slot at the tip of the effective stress with engraved groove depth increases and increases,,get moment blasting smooth effect is obviously superior to the ordinary hole smooth blasting,groove is more conducive to the blasting crack is formed in a predetermined direction around the hole.(2)When the moment blasting and rock anchor beam routine bursting charge the same,groove explosion arrancar more smooth,moment blasting half hole rate by non moment blasting half hole rate of 70% increased to 80% and looseness of rock mass zone was reduced by 25%;when the reduced notch blasting charge,the half hole rate by up to 90% and looseness of rock mass zone of relatively non notch blasting is reduced by 50%.(3)From the borehole and groove required time analysis shows that groove of time is far less than the hole hole forming time,vertical hole smooth blasting minute time slot is about 10.2% of the drilling time,inclination of smooth blasting holes in minute time slot is about 14.1% of drilling time;when cutting groove hole by 30 cm increases to 40 cm from the,per unit volume of blasting required drilling time decreases about 15%;when the moment the groove hole by 30 cm increases to 50 cm from the,per unit volume of blasting required drilling time is reduced by 30%.(4)When rock anchor beam excavation hole spacing is 40 cm,vertical smooth blasting hole single hole charge is 109 g,inclination of smooth blasting hole single hole charge 125 g,the notch blasting is more suitable for rock anchor beam in underground powerhouse excavation in Baihetan Hydropower Station.In this condition,the cost of conventional production blasting of rock anchor beam is reduced by about 20%,and the efficiency of blasting excavation of rock anchor beam is improved,and the stability of rock anchor beam is strengthened.