Analysis Of Blasting Vibration Influence On Neighborhood Tunnel And The Engineering Application

Neighborhood Tunnel is a special tunnel structure style adapt to the currentcomplex and narrow surrounding environment. But the design and constructiontechnology is still under developing. Therefore, Many kinds of problems is stillremained to be solve, especially the mutual influence between two holes due to theblasting vibration when drilling-blasting method is adopted to excavate tunnels.Blasting vibration can cause severe damage to the tunnel support and the wall rock, ifwe do not take measures to control the blast vibration level. The key factor to studyblasting vibration is how to quantify and simulate the blasting load. Although there aremany theories or empirical methods based on practical engineering about it, thequantification and simulation of the blasting load are still not very perfect because ofthe instantaneity and complexity of the blasting load itself. And further research is stillneeded to be done.According to the characteristic of Neighborhood Tunnel, this paper suggests a newtype method to quantify and simulate the diachronic change process of the millisecondblasting load and gives the time-history curve to describe the process. Through the fieldtest on Sai Ling Neighborhood Tunnel of San Xi Highway, the author verifies theapplicability of the method. Then this paper deeply analyses the blasting scheme and thesupport stability of Sai Ling Neighborhood Tunnel under blasting load by this method,and adapts the achievements to guide the tunnel construction. It gains a good effect.The main achievements are as follows:(1)The paper suggests a new type method to quantify and simulate the diachronic change process of the millisecond blasting load and gives the time-history curve of theblasting load.(2)Based on the fact that rock material in the explosion influence area is weakened,this paper suggests that the modulus value of the rock material in the tunnel face andout the tunnel face must be considered separately and the modulus value of the rockmaterial in the tunnel face must be reduced. Through comparison of the resultscoming from numerical simulation and field test, this paper suggests a relativelyreasonable modulus value of rock material in the tunnel face after reduction.(3)Based on the Sai Ling Neighborhood Tunnel of San Xi Highway, bythree-dimensional numerical analysis, this paper studies the longitudinal influence rangeof the blasting vibration when two holes explode simultaneously in different rock gradesand different buried depths. And the result gives a reasonable distance between the twotunnel faces of two holes. Then by two-dimensional numerical analysis, this paperstudies force condition of the tunnel support of the first hole under the explosion. Andthe result shows the unfavorable position of the support structure. All the achievementsare used to guide the tunnel construction and it gains a good effect.