IMPACT OF TRANSPORT LOAD ON A TUNNEL REINFORCED WITH A THREE-LAYER LINING

Abstract

This paper presents an analytical solution to investigate the dynamic behavior of a shallow tunnel subjected to a stationary transport load (a load of constant form generated by uniformly moving traffic or transported cargo within the tunnel). The need to address this problem arises from the fact that the lining of the tunnel is still commonly analyzed using a highly simplified quasi-static method. The solution was based on mathematical modeling. The lining of the tunnel modeled in an elastic half-space consists of three rigidly connected cylindrical circular layers with different physical and mechanical properties: a thick middle layer (filler) and thin outer layers (facing). In the problem formulation, this lining is considered as a circular three-layer shell. The motion of the half-space and the middle layer of the shell is described by the exact equations of elasticity theory, while the motion of the thin inner shell layer (along which the load moves) and the thin outer layer is described by approximate equations. The case of a shallow tunnel reinforced with a three-layer steel-concrete lining (comprising a concrete filler and steel facing layers of equal thickness) subjected to a uniformly distributed axisymmetric normal load moving at a constant velocity within a specified interval is considered. Using the computer program developed by the authors based on the obtained analytical solution, numerical experiments were conducted to study the influence of the type of contact between the tunnel lining and the rock mass (rigid or sliding) on the stress-strain state of the lining and the rock mass.