Dynamic Finite Element Analysis of Young Shotcrete in Rock Tunnels

This paper demonstrates how a finite element model can be implemented together with material data for young shotcrete to determine the minimum ages that can be allowed for hardening shotcrete on rock subjected to vibrations from blastings. An elastic finite element model is proposed that consists of beam elements used to model the flexural stiffness and mass of the shotcrete lining and a section of rock. Spring elements are added for elastic coupling between shotcrete and rock. The loads on the model are acceleration-time series. Scaling laws for the magnitude of vibration velocities in rock as a function of distance and amount of explosives are used to study the damage to shotcrete at various distances from the source of an explosion. Age-dependent shotcrete material properties are varied to investigate the vulnerability of young shotcrete exposed to explosion-induced vibrations. Recommended minimum shotcrete ages, based on the numerical results, are given for practical use. These recommendations are accurate when compared with in-place observations. This method will be of great importance in tunneling, excavation and shotcrete repair applications.

Language

  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01044758
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 6 2007 10:44AM