Study On Dynamic Response Of The Blasting Construction Of Newly-Bulit Tunnel On Existing Multi-Arch Tunnel

In the 21st century, with the rapid increase of vehicle population, the phenomenon that traffic volume has reached saturation state is becoming more and more prominent among existing expressways, which leads to these roads can’t meet the actual traffic needs in the future directly, as a result, it is very necessary to widen these roads and building a new adjacent tunnel is the most common action to be taken to widen existing tunnel at the same time. As we all know, the blasting vibration of new tunnel has a very large influence on the existing tunnel, especially it is multi-arch tunnel, therefore, it is very necessary to research the dynamic response of blasting construction of newly-built tunnel on existing multi-arch tunnel.Based on the project of capacity expansion Ningbo-Taizhou-Wenzhou Expressway and with the main method of three-dimensional numerical simulation in connection with some existing research results, this paper research the regular influence of blasting vibration of newly-built tunnel on existing multi-arch tunnel. The main research results are as follows:(1) Establish numerical model based on the characteristics of the tunnels and analyze the dynamic response rules in both velocity and stress fields of existing multi-arch tunnel on the conditions of different surrounding rocks, based on that, conclude the changing rules under the situations different distance and depth.(2) On the basis of preliminary design, this paper put forward different and targeted construction methods to different surrounding rocks by referring to the data about approaching construction at home and aboard at the same time. By comparing dynamic response rules on existing tunnel under conditions of different construction methods, and conclude reasonable method for different surrounding rocks to the project.(3) By systematically analyzing the dynamic response rules of existing tunnel on the damaged condition of filling uncompacted above the middle wall (cavities), especially analyzing the mechanical behavior of middle wall under the effect of blasting, so as to reveal to what degree does the blasting vibration affect existing tunnel.(4) According to above analysis, with the method of numerical simulation to analyze the response rules on the conditions of different millisecond time, and propose the reasonable millisecond time of the project.