Research on the method of excavation damage zone in the limestone tunnel:Taking Tongzi Tunnel as an example
[Objective]To determine the excavation damage zone and its damage characteristic are of great importance in the rock mass quality quantification and support of a tunnel.In this study,[Methods]many in-situ measurement including core logging,velocity measurement and borehole television were carried out in Tongzi tunnel,the longest tunnel in Guizhou.The excavation in-duced fractures and velocity in surrounding rock were studied,and the nuclear magnetic resonance measurement was carried out to study the micro-structure variation.[Results]Result show that the rock collected core rate decreased within the range of 1.25 times of the tunnel diameter,and the induced fractures was observed within the range of 1.25 times of the tunnel diameter.The velocity of rock decreased with the distance to the wall within the range of 0.4 to 0.6 times of the tunnel diameter.The porosity decreased rapidly within 0～3 m to the wall,and large pores increased in the zone.Many excavation damage zone calculation model were applied to determine the excavation damage zone.[Conclusion]and result showed that the EDZ range delineation using the Hoek-Brown criterion,unified strength theory and the numerical simulation are consistent.The study could provide sup-port for the excavation damage zone delineation.
万方数据
维普
