Research on the Influence of the Number of Tunnel Blasting Free faces on Ground Vibration Based on ANSYS/LSDYNA

In order to study the influence of tunnel blasting free face number on ground vibration velocity, based on the blasting construction of the Tunnel Boring Mechine (TBM) double-conducting tunnel with a large cross section in the section between Guizhou Road Station and Xizhen Station of Qingdao Metro Line 1. The ANSYS/LS-DYNA finite element program was used to carry out numerical simulation research on tunnel blasting under single, two and three free face conditions. By extracting the ground nodes vibration velocity and the blasting center distance, the calculation formula of blasting vibration velocity under the condition of different number of free faces is obtained by fitting regression. Studies have shown that (1) the values of K and la gradually decrease with the increase of the free face, and the decay rate of the K is more significant. In the process of increasing the number of free faces from 1 to 3, the decreasing rate of K was 61.56% and 80.4%, and the decreasing rate of la was 8.49% and 30.16%, respectively. (2) Tunnel blasting vibration is affected by the number of free faces. Under the condition of equal charge of 1.2kg, the decay rate of the overall vibration velocity of blasting under the condition of a single free face to the vibration velocity of two or three free faces is 26.12% , 34.85%, the vibration velocity shows a non-linear decreasing trend with the increase of the number of free faces.

Automated summary

This study investigates the influence of different free face numbers on ground vibration velocity during tunnel blasting. Numerical simulations were conducted using the ANSYS/LS-DYNA finite element program for single, two, and three free face conditions. The results reveal that as the number of free faces increases, the vibration velocity decreases significantly, showing a non-linear decreasing trend.