This paper chooses three kinds of waterproof and drainage pattern which are adopted in a tunnel under construction as the research object

builds up the fluid-solid coupling calculation model of its seepage field and stress field

explores the influence of some factors

such as thickness of grouting circle

permeability coefficient of grouting circle and controlled drainage quantity on the drainage quantity in tunnel and the distribution of external water pressure acting on lining

and gives the reasonable strengthening parameters and controlled drainage quantity

and optimal drainage mode.The research shows that:increasing the thickness of grouting circle and decreasing the permeability coefficient both can alleviate the water pressure acting on lining

but it doesn′t mean that with the increasing thickness of grouting layer or decreasing of the permeability coefficient

the control effect of the drainage quantity would be more obvious

in other words there would be a relative economical grouting parameter′s value;The controlled drainage quantity and drainage type play a decisive role in the control of the water pressure acting on the lining structure;The drainage form i.e.the combination of circumferential drainage blind pipes and drainage holes set in the lining wall is recommend

which is most favorable to lining structure bearing the force.