Abstract:

In order to investigate the seepage pressure and discharge of mountain tunnels and reveal the effect of grouting reinforcement parameters on groundwater seepage,the distribution law of seepage pressure and the formulas of seepage discharge are deduced based on the assumption that there exists a radial stable and isotropic seepage around a circular tunnel. Then,a case study is performed. It is found that the distribution of the seepage pressure is nonlinear and that the reinforcement rim and the primary support greatly reduce the seepage pressure loading on the lining and the groundwater discharge in drainage conditions. The seepage discharge of the unlined tunnel calculated by the proposed formulas is close to the actual monitoring data,which means that the proposed method is feasible in evaluating the water inflow of similar tunnels. Moreover,according to the correlation between the reinforcement parameters and the seepage pressure as well as the seepage discharge,it can be deduced that,with the decrease
in the permeability coefficient and with the increase in the reinforcement rim thickness,both the seepage pressure on the secondary lining and the seepage discharge decrease sharply at first,and then remain unchanged when the reinforcement parameters increase to certain values.

Key words: circular tunnel, seepage pressure, seepage discharge, reinforcement coefficient