Mechanical-hydraulic interaction in the cracking process of pressure tunnel linings

Pressure tunnels are subjected to internal water pressure during operation. When the hoop tensile stress acting at the lining intrados exceeds the tensile strength of the concrete, longitudinal cracks can occur in the concrete lining. As a consequence of crack openings, the internal water pressure will act at the lining extrados and cause high local water losses. If left untreated, these losses will induce the washing out of joint fillings and increase the risk of hydro-jacking of the surrounding rock mass. When pressure tunnels are situated close to valley slopes, excessive water losses can endanger the stability of the rock mass and cause a landslide. This paper presents a method to estimate the distribution of seepage pressures and water losses around concrete-lined pressure tunnels pre-stressed by grouting.