(1. Key Laboratory of Energy Engineering Safety and Disaster Mechanics,Sichuan University,Chengdu,Sichuan 610065,China;2. School of Architecture and Environment,Sichuan University,Chengdu,Sichuan 610065,China)
Abstract:Tunnels contain radial cracks due to the blasting excavation,and these cracks affect the tunnel stability significantly. In order to study the dynamic fracture behavior of tunnels containing radial cracks under the impact loading,the medium and low speed impact experiment was carried out by using the sandstone tunnel models,and the finite difference code AUTODYN was used for the numerical simulation. The propagation path and the arrest of the crack under the impact loading were studied,and the crack initiation toughness and propagation speed were calculated with the experimental-numerical-analytical methods. The fracturing behaviors of surrounding rock under the static and dynamic loadings are quite different. The damage under the dynamic loading is only the crack initiation and propagation at the crack tips,whereas the damage under the static loading occurrs at the crack tip,arch shoulder,arch foot and sidewalls. The propagation path of the radial crack is along the original direction of the crack under the impact loading,and the crack arrest phenomena was observed clearly in the propagation path. The experimental-numerical-analytical method can be used to determinate the initiation and propagation speed quite well. The curves of the dynamic stress intensity factors of cracks versus the time were obtained by using the displacement extrapolation method. The dynamic initiation toughness was determined using the initiation time measured with the strain gauges.
王 蒙,朱哲明,谢 军. 岩石I-II复合型裂纹动态扩展SHPB实验及数值模拟研究[J]. 岩石力学与工程学报,2015,34(12):2 474-2 485.(WANG Meng,ZHU Zheming,XIE Jun. Experimental and numerical studies of the mixed-mode I and II crack propagation under dynamic loading using SPHB[J]. Chinese Journal of Rock Mechanics and Engineering,2015,34(12):2 474-2 485.(in Chinese))
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ZHANG Q B,ZHAO J. Determination of mechanical properties and full-field strain measurements of rock material under dynamic loads[J]. International Journal of Rock Mechanics and Mining Sciences,2013,60(8):423-439.
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