Study On Controlled Blasting Technology Of Large Section Tunnel Based On Damage Control Of Surrounding Rock

Drilling and blasting method is one of the main ways of tunnel excavation.Some large-span highway tunnels are usually constructed by drilling and blasting method,especially in some mountain areas.Based on the project of Qinfeng large section flat highway tunnel,this paper carries out the research work of "controlled blasting technology for large section tunnel based on surrounding rock damage control".Based on the project of Qinfeng large section flat highway tunnel,according to the characteristics of large tunnel length,large excavation span,large burial depth,tight construction period and poor integrity of surrounding rock,this paper carries out the research work of "controlled blasting technology for large section tunnel based on damage control of surrounding rock".The main contents of this paper are as follows:(1)This paper studies the theory of blasting vibration,grasps the basic theory of the generation and propagation of blasting seismic wave,and makes preparations for the analysis and numerical simulation of monitoring data in the field.(2)Through monitoring the peak vibration velocity of particle in the process of blasting excavation of tunnels in situ,a more reasonable blasting excavation construction scheme is developed by changing the blasting construction parameters(mainly cut hole and peripheral hole),which can effectively control the over-excavation and under-excavation,thus reducing the cost and expenditure,and ensuring the construction quality,safety and progress meet the requirements.(3)The damage characteristics of tunnel surrounding rock under blasting vibration are explored.The cumulative damage of tunnel surrounding rock is monitored by a double-receiving single-hole tester,and the damage law of tunnel surrounding rock under multiple blasting vibration loads is studied.(4)Ansys/Ls-dyna is used to simulate the peak vibration velocity of particles during blasting excavation of tunnels.The relationship between the damage of tunnel surrounding rock and the peak velocity of particle is explored.Peak velocity of particle caused by different charge quantity.