Water-rich Tunnel Drainage Method and Distribution Characteristics of Water Pressure at Bottoms
A non-destructive test was conducted on a certain railway tunnel bottom for the occurrence of slurry and mud damage,and the types and causes of diseases were analyzed.On this basis,a three-dimensional seepage model of the tunnel was established,and the measures of setting drainage wells or drainage ditches inside the tunnel were analyzed.The results show that,when excavating drainage wells inside the car shelter,the greater distance between drainage wells,the greater maximum water pressure acting on the inverted arch bottom.Moreover,when the distance between one side exceeds 60 m and the two sides are staggered,the drainage pressure effect is not significant.The overall drainage effect of setting up drainage wells in the center is not as good as that of setting up drainage wells inside the car shelter.When the drainage wells are installed on the centerline and the spacing is less than 5 m,the maximum water pressure acting on the inverted arch bottom shows a linear increasing trend with the increase of the spacing between the central drainage wells,and the growth rate is relatively large.After exceeding 5 m,the maximum water pressure growth rate on the inverted arch bottom decreases,and the shorter the distance between the drainage wells on the centerline,the more obvious the drainage pressure effect.When drainage ditches are set up on both sides and in the center of the tunnel,the maximum water pressure acting on the inverted arch bottom shows a non-linear decreasing trend as the depth of the drainage ditch increases.When the depth of the drainage ditch on both sides and in the center is less than 1.0 m,the maximum water pressure drops rapidly.After exceeding 1.0 m,the maximum water pressure drop gradually slows down,and the deeper the drainage ditch,the more obvious the drainage pressure effect.The overall drainage effect of setting up drainage ditches in the center is not as good as that of setting up drainage ditches on both sides.From the perspectives of construction feasibility,economy,and drainage effectiveness,setting up drainage wells is more effective than drainage ditches.
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