The Dynamic Response Characteristics Of Anchorage Tunnel By Excavation Blasting And Control Technology Research

As an important bearing component of suspension Bridge, the stability of surrounding rock during Anchorage tunnel’s excavation is in relation to the project’s success or failure, especially in the small spacing section of anchorage tunnel. Because its crossing section is larger, the rock wall insulation thickness is thinner. The tunnel surrounding rock is under the influence of blasting load easily. Therefore, it is necessary to study the dynamic response characteristics of Anchorage tunnel’s excavation blasting, and on the basis of this, coming up with the control measures of anchorage tunnel’s excavation blasting vibration and the speed control standards.This thesis is based on the anchorage tunnel of the Yakang high-speed Dadu river suspension bridge in Yaan shore. Through multiple field test and vibration monitoring, analyzing blasting vibration characteristics of the anchorage tunnel in face side and the attenuation law of blasting seismic wave in the rock wall insulation. Test results show that when the anchorage tunnel excavation blasting, the biggest vibration velocity of particles is produced by the blasting of cutting hole. When the charge is equal, the blasting vibration of cutting hole is stronger than the blasting vibration of lighting hole. At the same time, along with anchorage tunnel excavation depth increasing, the rock wall insulation of high thickness ratio increasing. The vibration of the spandrel, vault and arch foot strength increases to some extent, hance and spandrel position the peak value of vibration velocity is bigger than the growth in vault and arch foot position vibration speed growth. In addition, vibration velocity’s attenuation rule of anchorage tunnel’s excavation blasting along the tunnel axis does not accord with Steve’s formula in the rock wall.In order to analyze of the dynamic response characteristics in small and clear distance tunnel segment of anchorage tunnel entirely, the paper is based on LS-DYNA, selecting three typical sections of different distance from the mouth, and studying the vibration velocity and maximum principal stress from two angles. After the calculation results show that the blasting vibration velocity and maximum principal stress of first order hole side is greater than the Sequence hole’s when the Sequence hole is blasting. Velocity and the maximum principal stress decreases gradually in the tunnel axis when the distance from blasting source is increasing, and particularly around 15m scope. Vibration velocity and the maximum principal stress attenuation more quickly compared with the front’s.Combined with numerical simulation and field test results of vibration monitoring, it is aim to put forward five control measures in allusion to the excavation blasting of anchorage tunnel. According to the structure characteristics of the anchorage tunnel, establishing the control standard of vibration velocity in allusion to three part. Namely, the limit vibration velocity is 20 cm/s in the upper of anchorage tunnel. The limit vibration velocity is 15 cm/s in the middle of anchorage tunnel. The limit vibration velocity is 11 cm/s in the upper of anchorage tunnel.