VARIATIONS IN VOLTAGE FIELDS AROUND THE REDUCED-SECTION TUNNEL FROM THE ACTION OF WATER PRESSURE
This article defines the patterns of change in stress fields around the tunnel, taking into account the action of the pressure (free-flow) of water. At the beginning, a mathematical model of the stress state of massifs with mountainous relief was built, and then the influence of water pressure on the stress distribution around the tunnel was set. The problem is solved using the conformal mapping apparatus and two boundary conditions when the tunnel contour is free and the pressure P0 acts. The calculation results were obtained using the MATHCAD software and the numerical values of stresses σ ρ (1, θ) , σ θ (1, θ) , τ ρθ (1, θ) (MPa) are given in the table. The regularities of the change in all stress components around the hydraulic tunnel, when the hydrostatic head acts on the tunnel contour, have been investigated. The results of the work are used to substantiate design solutions to ensure the stability of mine workings and pressure (gravity) tunnels.