Study On The Influence Of Tunnel Blasting On The Stability Of Adjacent Pile Foundation

The construction of transportation infrastructure in China is in a period of vigorous development.some mountainous areas such as Yunnan,Guizhou,Tibet are building a large number of highways and railways.City in order to ease traffic pressure,but also focus on the construction of subway,light rail and other projects.As an economical and convenient method of tunnel excavation,drilling and blasting method is often used in tunnel excavation.It is a problem that can not be ignored that the seismic effect of the surrounding rock is built by the method of drilling and blasting.In this paper,based on the two phase of the project of Chongqing railway link,the ANSYS/LS-DYNA dynamic analysis software is used to analyze the numerical simulation.Based on the analysis of the influence of tunnel blasting on the stability of pile foundation,the following conclusions are obtained through calculation and analysis:(1)Through the numerical simulation calculation of pile distance of tunnel excavation peak vibration velocity boundary in the range of 10 m and decay quickly in the area of pile peak vibration velocity is greater than 3.5cm/s,exceeding the safety standard value,according to Ao Chen intervals similar shallow tunnels,the tunnel location process should ensure the pile distance between tunnel and the horizontal distance in the range of 10 m.The pile distance tunnel horizontal distance less than 10 m project should be used in non blasting excavation method.(2)Through the comparative analysis of X,y,z direction of pile peak vibration velocity and peak velocity variation obtained: Overall,variation of peak vibration velocity and vibration direction of y velocity variation is similar to that of Y pile,the vibration velocity direction and velocity by fitting better velocity components as the evaluation index should peak safety of pile foundation the vibration velocity in Y direction.(3)For the influence of tunnel blasting vibration control of adjacent pile should choose the appropriate scale of blasting excavation in Chongqing area,Mr Chen similar tunnel project,when blasting footage of 1m,the boundary line of excavation pile and tunnel safety distance is 12m;when the blasting footage is 1.5m,the boundary line of excavation pile and tunnel safety distance is 15m;when the blasting footage is 2m,the boundary line of excavation pile and tunnel safety distance is 18m;when the blasting footage is 2.5m,the boundary line of excavation pile and tunnel safety distance is 25 m.(4)Based on the monitoring of tunnel blasting vibration velocity Austria Chen process near the Longjing bay bridge pile foundation,the vibration velocity of pile vertical pile in the direction of maximum horizontal distance from the tunnel,25 m,vertical blasting vibration maximum speed of 2.59 M,did not exceed the prescribed value of pile blasting vibration safety,in this condition,the tunnel blasting will not cause damage to the pile foundation...