Large-Scale Experimental and Numerical Study of Blast Acceleration Created by Close-In Buried Explosion on Underground Tunnel Lining

Abstract

Despite growing demands for structures in water transportation tunnels, underground installations, subsurface dams, and subterranean channels, there is limited field knowledge about the dynamic behavior of these structures in the face of near-fault earthquakes or impulse excitations. This study conducted a large-scale test on underground tunnel excited by two close-in subsurface explosions. The horizontal and vertical acceleration were recorded on the vertical wall of the tunnel and the free field data including the acceleration on the ground surface at 11-meter distance from the tunnel. The frequency domain analysis of recorded results determined the frequency 961 Hz and 968 Hz for 1.69 kg and 2.76 kg equivalent T.N.T., respectively. Then, finite element analysis results were compared with the test data. The comparisons demonstrated a good correlation and satisfied the field data. Finally, based on numerical modeling, a parametric study was applied to determine the effects of shear wave velocity distance of the crater with respect to the tunnel on impulse response of the tunnel.

Study on the Correlation of Vibration Properties and Crack Index in the Health Assessment of Tunnel Lining

“…The crack index 0 was expressed as the sum of longitudinal and transverse components as shown in (2). Associating (1) and (2), the crack index 0 can be derived as (3) in the following:…”

“…The tunnels play an important role in the transportation projects. A large number of tunnels have been in service for decades all over the world, and they were mainly supported by concrete lining [1]. The persistent ageing and earthquake cause many problems to the concrete lining, such as cracking, corrosion, and seepage [2,3].…”

“…A more effective approach was proposed by the authors [15], which evaluated condition of tunnel lining by the ambient vibration test. This method was proposed based on the basic x j(=2) l (2) t (2) l (1) t (1)  physical principle: the stability of the tunnel lining is closely related to its strength and stiffness, and the strength and stiffness are closely related to the vibration properties. The damage of the tunnel lining will cause changes in the strength and stiffness, subsequently affecting the vibration characteristics.…”

A New Health Assessment Index of Tunnel Lining Based on the Digital Inspection of Surface Cracks

“…F 11 and F 22 obtained by the Equation (1) indicated the longitudinal component and the transverse components of the TCI, respectively. The crack index F 0 was expressed as the sum of longitudinal and transverse components as shown in Equation (2). Associating Equation (1) with Equation (2), the crack index F 0 can be derived as Equation (3).…”

A New Health Assessment Index of Tunnel Lining Based on the Digital Inspection of Surface Cracks

“…Tunnels were mainly supported by concrete lining [1,2]. The type of concrete lining can be divided into three categories, including shotcrete, prefab and cast-in-place lining.…”