Stress characteristics of surrounding rocks for inner water exosmosis in high-pressure hydraulic tunnels

Abstract

Seepage and stress redistribution are the main factors affecting the stability of surrounding rock in high-pressure hydraulic tunnels. In this work, the effects of the seepage field were firstly simplified as a seepage factor acting on the stress field, and the equilibrium equation of high pressure inner water exosmosis was established based on physical theory. Then, the plane strain theory was used to solve the problem of elasticity, and the analytic expression of surrounding rock stress was obtained. On the basis of criterion of Norway, the influences of seepage, pore water pressure and buried depth on the characteristics of the stress distribution of surrounding rocks were studied. The analyses show that the first water-filling plays a decisive role in the stability of the surrounding rock; the influence of seepage on the stress field around the tunnel is the greatest, and the change of the seepage factor is approximately consistent with the logarithm divergence. With the effects of the rock pore water pressure, the circumferential stress shows the exchange between large and small, but the radial stress does not. Increasing the buried depth can enhance the arching effect of the surrounding rock, thus improving the stability.