Study on drainage mode and anti-clogging performance of new waterproofing and drainage system in a tunnel

With an increase in tunnel construction and retention, traditional waterproofing and drainage systems have been unable to meet the needs of tunnels in heavy rainfall areas, and disasters such as tunnel lining cracking, leakage, and even collapse, occur frequently. In order to ensure the safe operation and maintenance of tunnels, this paper analyses the characteristics of the traditional waterproofing and drainage system, and puts forward a new drainage structure through numerical simulation and indoor testing. This structure removes the circular drainage blind pipe and adds a convex shell drainage plate between the waterproof board and the secondary lining. The research shows that the new drainage system greatly decreases the water pressure in the easily blocked area of the drainage structure. With the special surface discharge model, the external water pressure of the lining far away from the blocked area can quickly fall back to the normal level. In addition, the drainage capacity of different waterproof and drainage boards is different. With an increase in support pressure, the drainage capacity decreases; the geotextile decreases the most, followed by the capillary drainage board and then the convex shell drainage board. At the same time, after the muddy water drainage test of the three materials, it is found that the convex shell type drainage plate has the best anti-sludge performance. The research in this paper provides a beneficial attempt for the design of waterproofing and drainage structure of a water-rich karst tunnel, and provides a guarantee for the safe operation and maintenance of the tunnel.