THE TRANSPORT LOAD INFLUENCE ON A REINFORCED TWO-LAYERED TUNNEL LINING.

Despite significant achievements in the field of tunnel construction, adequate methods for their dynamic calculation under transportation load (loads from moving transport within the tunnel) are still practically nonexistent. Particularly significant challenges arise during the calculation of shallowly embedded tunnels. Using the mathematical modelling method, such a calculation was performed for a tunnel supported by a circular cylindrical homogeneous lining. In the presented work, a shallowly embedded tunnel reinforced with a two-layer lining is considered. When creating the mathematical model, the tunnel is represented as a circular cylindrical twolayer shell located in an elastic half-space. The load-free horizontal boundary of the half-space (ground surface) is parallel to the shell axis. Dynamic equations of elasticity theory in Lamé potentials are used to describe the motion of the internal thick layer of the shell and the surrounding body. The vibrations of the external thin layer of the shell are described by classical shell theory equations. The equations are represented in moving Cartesian and cylindrical coordinate systems associated with a load moving uniformly along the inner surface of the shell. Based on the obtained solution to the problem and numerical experiments, the stress-strain state of the two-layer lining of a shallowly embedded tunnel and the surrounding rock body is investigated under the action of a uniformly moving axisymmetric normal load. It is established that at the ground surface when the lining has a rigid contact with the rock body, the displacements and stresses are lower compared to when the contact is sliding. [ABSTRACT FROM AUTHOR]