Study On Blasting Vibration Response During The Construction Of Small Interval Tunnel

It uses the small clearance tunnel for its unique advantages in facilitating the overall line planning and line optimization of the road.It complicates the construction of small clearance tunnels.For the small thickness of the intermediate partition walls between the two tunnels,the use of drilling and blasting to excavate small clear tunnels will affect the tunnel surrounding rock and adjacent tunnel structures,which will lead to safety problems.In drilling and blasting construction of small clear distance tunnel,it analyzes the response characteristics of a tunnel surrounding rock and tunnel structure,and someone studies the distribution of vibration velocity,displacement,settlement and stress of surrounding rock and adjacent tunnel structure after blasting vibration.Determine the construction plan for small clearance tunnels.Reduce the adverse effects of blasting vibration on construction and ensure on-site construction safety.Therefore,research on blasting vibration of small clear tunnels has important practical significance and economic benefits.Based on the cofunction small clear tunnel project constructed by drilling and blasting methods,this paper analyzes the theory of rock blasting and the theory of stress wave propagation.Then,the blasting vibration monitoring is carried out on the construction of a small clear distance tunnel,and I carry the vibration monitoring out.The data were analyzed and analyzed.Finally,numerical simulation was carried out to study the interaction law of small-spaced first-and second-pass tunnel blasting vibrations under different working conditions and effective engineering vibration reduction measures.It gets the construction parameters of a small clear tunnel,which has a certain reference value for the construction and theoretical research of a small clear tunnel.The main research contents and results are as follows:(1)When rock blasting,the position of the blasting center is different,the rock damage form is different,and the rock at the blasting center is damaged by impact and pressure.With the increase of the distance,the force of the rock is the tensile and compressive three-way stress.State,based on shearing damage.(2)The analysis of the blasting vibration theory shows that the vibration velocity and vibration frequency generated by the blasting in the surrounding rock and the supporting structure can reflect the blasting vibration intensity.Combined with the vibration monitoring data of the tunnelconstruction,the blasting vibration and the tunnel will not produce resonance phenomenon,so it selects the vibration velocity as the safety standard of the blasting vibration.(3)The analysis of on-site blasting vibration monitoring data shows that the maximum vibration velocity is proportional to the distance from the measuring point to the blasting working surface.There is no obvious law for the main frequency and distance of the vibration.In the drilling and blasting method,the blasting side is more than the back blasting side.It is affected by the blasting vibration early and the vibration velocity on the explosion side is larger than that on the back explosion side.(4)The three-dimensional model was established by using Midas-GTS numerical simulation software.It studied the interaction between the first and second tunnels under the action of blasting vibration.Under the construction conditions of the upper and lower steps,different surrounding rock grades and different thicknesses of the middle wall were used to tunnel the lining.Structure,prewearing surrounding rock and the influence of the middle rock wall.Research shows:(1)Under the same construction conditions,the blasting vibration generated by the lower step excavation of the tunnel is larger than that of the upper step,and the distribution range of the potential failure surface and the stress distribution area exceeding the tensile strength of the rock mass are also the same.(2)Under the same tunnel clearance condition,the higher the surrounding rock level,the greater the influence of blasting vibration on the lining structure,pre-pierced surrounding rock and middle rock wall at the same position.The concrete manifestation is that the peak vibration velocity of the lining structure becomes larger,and the tensile stress of the pre-pierced surrounding rock and the middle rock wall exceeds the tensile strength,and the plastic strain potential failure surface becomes larger.(3)Under the condition of the same surrounding rock level,the lining structure,the pre-pierced surrounding rock and the middle rock wall are reduced by the blasting vibration during the process of the two tunnels increasing from 2m to 2D.They reduce the plastic strain potential failure surface distribution area And the stress distribution area exceeding the tensile strength.(5)The paper analyzes the mutual influence of blasting vibration of small clear tunnel from three aspects of vibration velocity,plastic strain and stress,and concludes that the minimum safeclearance of the two tunnels is 0.5D.