| In the last few years, with the rapid development of transportation in our country, the existing traffic facilities cannot meet the needs of the growing traffic. Hence, the expansion project increase gradually, the cases of new tunnels’ construction undercrosss or adjacent existing tunnel are become more and more complicated. As the main construction method of underground engineering, mining method had a great effect on the existing buildings. So it is necessary to study the blasting excavation’s effects on the existing tunnel in new tunnel’s construction.This thesis rely on the expansion of Xinling tunnels, study the influence of tunnel blasting on the existing tunnel with the use of two methods (site monitoring, numerical simulation). The next are main research results:(1) By analyzing the geological conditions and field conditions, this paper puts forward various blasting schemes for different surrounding rock conditions, and provides guidance for the field construction.(2) Based on field data, numerical simulation model is established, systematically study the existing tunnels’ response law of blasting excavation. By monitoring the speed of vibration, this paper analyzes the attenuation law of blasting vibration in formation, provides the basis for the subsequent simulation and monitoring. And through the site construction and monitoring to validate the feasibility of analysis.(3) According to different level of surrounding rock, simulates the blasting excavation by the finite element method, analyzes the existing tunnels’ response to the blasting excavation on different conditions, concludes the old tunnels’ blasting vibration velocity distribution along the transverse direction.(4) By simulating the different conditions, concludes the old tunnels’ blasting vibration velocity distribution along the longitudinal direction, and the stress distribution law of existing tunnels, provides guidance for vibration monitoring and protection. |
