Dynamic Response Of Existing Tunnel Induced By Blasting From Adjacent Newly-Built Tunnel And The Controlling Techniques

In recent years, the speed of transport infrastructure construction accelerated in China Western region. Due to terrain conditions and alignment requirements, there has been a large number of new tunnels adjacent to existing lines. Currently, construction of the mountain tunnel is still dominated by drill and blast method, Seismic waves generated by new tunnel blasting will affect the structural safety and normal operation of existing tunnel. Especially when large-scale blasting, poor rock conditions as well as existing buildings is more important, more stringent control standard of blasting vibration are required. Therefore, study on the dynamic response of existing tunnel induced by newly-built tunnel blasting has a very important significance.In this paper, based on the new Gala mountain highway tunnel adjacent to existing Gala Mountain tunnel project, will have a system research, through data collection, analysis, numerical simulation and in situ testing, on the dynamic response of existing tunnel and damping technology under the blasting load generated by the construction of newly-built tunnel. Main contents and the results in this paper are as follows:1) First, this paper has described the vibration problems of existing tunnel under the new tunnel blasting, summarized the current domestic and international obtained theoretical research and accumulated engineering practice experience on study of dynamic response subjected to the tunnel blasting, at home and abroad control standards of blasting safety were compared, the rationality of vibration velocity as a criterion for blasting vibration were discussed.2)Details the advantages of ANSYS/LS-DYNA in nonlinear dynamic analysis of high-speed collisions, explosions,and describes the process of simulation analysis of tunnel blasting using fluid-solid coupling algorithm, build corresponding 3D finite element model of actual project and simulated different blasting program.Obtained the peak particle velocity on the secondary lining of existing tunnel under different blasting program, and compared with the field test results of blasting vibration.Provided a certain basis to ensure the safety of existing tunnel,optimizing blasting parameters and choice of appropriate footage.3)Got the vibration velocity distribution, curve of peak particle velocity and displacement images of the tunnel lining under the action of newly-built tunnel blasting by numerical simulation; Furtherly simulated varying sizes and different spacing and other conditions, studied the relationship between maximum vibration velocity and spacing or charge for tunnel blasting.4)With the simulation of the construction of new tunnel using millisecond blasting, Got the dynamic response of tunnel lining caused by different millisecond intervals. According to the maximum vibration velocity-time curve, when the millisecond intervals greater than a certain value, millisecond blasting can stagger vibration effects in time by different explosives, thus play a good damping effect.