Research On Mechanical Characteristics Of Underground Tunnel Engeering

Concerning on the physical problems in the underground engineering, the deformations and stresses of the elastic-plastic rock and visco-elastic rock surrounding of underground tunnel are numerically simulated by means of the finite element method. The displacement variations of elastic-plastic rock surrounding of underground tunnel under different initial stresses are studied at first. The numerical results show that the geologic configuration stress is the main factor that causes the deformations of deep underground tunnel. Furthermore, the effects of the lateral pressure coefficient on the plastic boundary regions of the rock, as well as the reinforcement of concrete lining support structures on the surrounding rock are discussed.For visco-elastic soft rock, the influences of different excavation technics and interval of double-hole are numerically simulated on the displacements of underground tunnel, and the reasonable excavation technics, which would reduce the disturbance of the surrounding rock, are derived. The results display that the effect of creep must be considered in the decision of the minimal safe interval of double-hole. The effect of time should be considered in support of the tunnel in the soft rock, and the secondary support structure should be implemented at the time of the creep of the surrounding rock just entering the stable stage.All the numerical results in the paper provide theory guide in excavation and support of underground tunnel, showing the significance in the engineering practice.