A Back Analysis Method For Strength Parameters Of The Surround Rock In The Blast Loosen Range Of Tunnel

In this paper, a method of elastoplastic back analysis for the surround rock in the blast loosen range of tunnel is proposed. The loosen range for the surround rock can be determined through the measurement first.The displacements of the surround rock during the tunnel excavation are studied and divided into two parts: the elastic displacement during tunneling and the plastic displacement when tunneling stop.A back analysis approach for the rock strength parameters in the loosen range is then proposed based on such measured plastic deformation, which is always believed unmeasurable. A test example for the back analysis shows the proposed back analysis approach is reliable and useful for tunnel engineers.Lastly, a back analysis and calculate for the surround rock is presented and the using effect is validated...