Liner pressure in high-speed railway tunnels under high groundwater pressure

Being different from other mountain tunnels, the requirement of waterproofing of high-speed railway tunnels is more stringent. The liner must sustain heavy external water pressure. Based on fluid-mechanical interaction principle, the theoretical analysis, the numerical analysis and the outdoor model test are conducted to investigate the relationship between the water pressure behind the liner and the discharge water inflow for different drainage conditions. The results show that the permeability ratios kl/kr and kl/kg have great effect on the water pressure on liner. If the discharge being controlled about one-third of the full water inflow from the ground, the reduction of four-fifths water pressure will be obtained. Therefore, the water pressure trapped behind the liner depends on the discharge capacity of the drainage system relative to the water inflow from the ground. Although the grouting circle can reduce the discharge from tunnels, the appropriate thickness of grouting circle and liner should be selected for a safe and economical design. In view of the disadvantageous distribution of water pressure on liner, more attention should be paid on design of invert form and support of tunnel. All these factors have important implications for high-speed railway tunnels construction practice. © 2014, EJGE.