Experimental Study of Dynamic Responses of Special Tunnel Sections under Near-Fault Ground Motion

Abstract

Data surveys show that near-fault ground motion does great damage to tunnel structures, especially the portal section and fault zone. In this paper, a series of shaking table model tests of near-fault tunnels were conducted and the surrounding-rock fault-zone-lining model of the near-fault tunnel was established. Accelerometers and strain gauges were arranged at specific locations, and the experimental process of earthquake occurrence was simulated by inputting seismic waves of different working conditions, which obtained the characteristics of stress, damage and deformation of the tunnel model. The tested results showed that the acceleration response of the tunnel portal section was close to the wave shape of the inputted seismic wave, and the acceleration response of the arch shoulder, arch waist and arch foot was more prominent. The internal force of lining at the arch shoulder and arch foot was greater than that at the arch crown, and the peak internal force appeared at the arch foot. The internal force and the maximum or minimum principal stress of the lining under impulse ground motion were larger than those under non-impulse ground motion. Additionally, the surrounding rock had a filtering effect on the high-frequency band of seismic waves. Meanwhile, when the geological characteristics of the fault zone were poor, and the tensile damage first appeared at the arch foot, the compressive damage appeared at the junction of the surrounding rock and fault zone. This study will offer a practical guidance for tunnel engineering earthquake damage.