Control And Analysis Of An Existing Tunnel Vibration Induced By Blasting Construction Of Nearby Tunnel

With the rapid development of China's transportation network, a large number of single line tunnels should be need built multiple-line tunnels. The distance of the new railway tunnel and the existed tunnel is usually small. It is very important for researching how to not only ensure the existing tunnel structure safety and its normal operation during the new tunnel blasting construction, but also ensure the construction quality and progress of the new tunnel.Basing on consulting a large amount of existing relevant literatures and research achievements, the control and analysis of the existing tunnel vibration induced by blasting construction of the nearby tunnel were carried out by taking the Wangjiashan Tunnel of Shichang Multiple-line Railway as an example in this thesis. The main research contents and results are as follows:(1) An empirical formulas of the propagation and attenuation characteristics of blasting induced vibration for the IV class surrounding rock was formulated by analyzing the results of the blasting vibration monitoring on site.(2) The lining dynamic response of the tunnel lining with defects(e.g. cracks) under the blast loads was studied by using the ANSYS software and the transient dynamic method, and the stress distribution and the tolerable safety factor of the tunnel lining with the different depth of cracks under the blast loads were obtained.(3) The lining dynamic response of the tunnel lining with defects (e.g. cavities) under the blast loads was studied by using the ANSYS/LS-DYNA finite element software to establish the three-dimensional model, and the relation of the change of the particle vibration velocity, the displacement and stress distribution of the key parts of the tunnel lining and the height of the cavity on the vaults of the lining were obtained. It is proved that the existing tunnel lining is safety when the amount of coupled charge is 8.0kg.(4) Some blasting schemes were designed for the different class surrounding rocks in order to control the blasting vibration. The ceiling limilt value of the maximum charge in one delay time, which is 9.8kg, was determined by the analysis of DYNA reverse simulation based on the maximum blasting vibration velocity when the obtained information of the propagation and attenuation characteristics of blasting induced vibration was not complete and accurate, and the mass point's particle vibration velocity, displacement vector close distribution, and the maximum principal stress distribution state of the tunnel lining were analyzed.