Study On Blast-Resistant Characteristics Of Tunnel In Rock Under Internal Explosion

With vigorous development of world civilization, traffic problems become much more serious in the world. As a solution to this problem, subway and road tunnels have become more important in large cities such as Shanghai,Beijing. At the same time, subway and road tunnels are also at high risk of terrorist attack. Besides this, sometimes accidental explosions in tunnels also happen. Internal explosion in subway and road tunnels can cause great disaster. This paper presents a numerical simulation study on explosions inside a tunnel using software LS-DYNA. The main research works are as followings:1. Based on blast resistance test of tunnel, we depicted some macroscopic damage phenomenon caused by internal explosion. At the same time, we analyzed characteristics of blast wave when an explosion happened inside a tunnel.2. Characteristics of blast wave when an explosion happened inside a tunnel was different from an explosion happened in free atmosphere. Due to boundary reflection, blast wave raised and fell with multiple peaks. Numerical simulation results showed that when an explosion of cube charge happened in the centre of tunnel cross section, blast wave had complex interaction phenomena near the charge. But with the blasting distance increasing, weaker of the peak overpressure of blast loading and longer of duration time. High frequency components also reduced.3. We obtained a formula of shock wave peak overpressure of explosion in a tunnel as following:The verification is accomplished through comparison with other experiment formulas.4. When an explosion of cube charge happened in the centre of tunnel cross section, the lining in four positions became damaged firstly: top of the charge, bottom of the charge, left of the charge and right of the charge. When an explosion of spherical charge happened in the centre of tunnel cross section, to the lining units of same radius in a tunnel cross section, variation of effective stress, displacement and velocity was basically same.5. With the same charge weight, when an explosion happened in the centre of tunnel cross section, dynamic response of cube charge was greater than spherical charge. With the same charge condition, lower the charge height, more serious the lining damaged. If the charge height was reduced to a certain height, the tunnel lining may even penetrate. 6. With the same charge condition, tunnel lining damaged much more seriously according to eccentric explosion than central explosion.7. With the lining structure, surrounding rock damaged much lighter. Meanwhile, greater stiffness of the surrounding rock, better capacity of tunnel anti-explosion property.8. When an explosion happened inside a tunnel, shock wave can impact the surrounding rock within 1 time of tunnel radius.