Influence Of Blasting Vibration On The Stability Of Steep Dip Stratified Rock Mass Tunnel

The drilling and blasting method is a major construction method for tunneling, but under the action of blasting vibration, the stability of surrounding rocks and supporting structure will be affected. As the stability of surrounding rocks is the most important security issue in the construction, it is necessary to make certain of dynamic response of surrounding rocks and supporting structure to blasting vibration, controlling the impact brought by blasting within the allowable range.Based on the characteristics of steep dip stratified rock masses, the research background of the Qingshan tunnel of Hangrui Expressway in Guizhou Province and the study on the blasting vibration attenuation law, this paper systematically explores the dynamic response law of vibration velocity, stress and displacement of the surrounding rock and supporting structure under the action of blasting vibration through using the numerical simulation method and the on-site monitoring. The main research fruits are as follows:1. Through the on-site monitoring, the blasting vibration velocity at different blasting sources away from the arch foot in the Qingshan tunnel is obtained. And then the M.A Sadaovsk formula is used to establish the formula of transmission attenuation law of blasting vibration along the tunnel arch foot through the regression analysis to predict the maximum explosive charge of each section under the safe vibration velocity. In addition, through monitoring the blasting vibration of other two tunnels with different geological conditions and blasting programs, the reasonable vibration control measures are put forward.2. The ADINA finite element software is used to establish the three-dimensional numerical model of tunnel for the section the same as the on-site monitoring section. In addition, on the basis of considering the rock structural plane, the transmission attenuation law of explosion seismic wave in Class III surrounding rocks of the Qingshan tunnel is explored; meanwhile, the change laws of stress field and displacement field for the surrounding rock and support structure in the blasting process are analyzed.3. The mechanism of instability of the steep dip stratified rock mass tunnel induced by the blasting vibration is analyzed. Moreover, several common forms of instability of the steep dip stratified rock masses are also analyzed, and the critical vibration velocity of instability of surrounding rocks is predicted.