Abstract:In order to realize accurate prediction of tunnel water inflow when there is permeable interlayer on the side of the tunnel, based on "round island model" and mapping principle, to deduce the prediction formula of tunnel water inflow under special geological environment. By changing the permeability coefficient of surrounding rock, the thickness of permeable interlayer and the distance between the center of tunnel and permeable interlayer, the influence law of each factor on the tunnel water inflow was analyzed. The results show: The theoretical calculated value is basically consistent with the actual survey value, and the error is 10.4%. With the increase of the permeability coefficient of surrounding rock or the thickness of permeable interlayer, the water inflow value of the tunnel increases linearly, with the increase of about 30% and 20% respectively when it tends to be stable. With the increase of the distance between the tunnel and the permeable interlayer, the water inflow value of the tunnel decreased nonlinearly, the maximum decrease was 27.7%, and the decrease was about 8% when it was stable. If two of the permeability coefficient of surrounding rock, the thickness of permeable interlayer, and the center distance between tunnel and permeable interlayer are changed simultaneously, the analysis show that the permeability coefficient of surrounding rock has the most obvious influence on the water inflow of the tunnel, followed by the thickness of permeable interlayer, and the distance between the center of tunnel and permeable interlayer is the weakest.