Case Study of Tunnel Waterproof Board Engineering

　　1. The construction technology and method of tunnel waterproof boards adopt nailless paving and double track welding/hot melt welding processes. The waterproof board of the tunnel can be pre assembled into large blocks through double track hot melt outside the tunnel. Choose a flat site outside the tunnel. The waterproof board is arranged according to the perimeter of the internal contour of the tunnel and the construction length of the lining ring. The seam is welded using an automatic crawling dual rail welding machine, which is rolled up after passing the test.

　　2. The trolley of the suspended trolley tunnel is paved with a simple trolley. The trolley should have sufficient strength and stiffness, as well as a more flexible walking device, and be equipped with a platform that can reach any part of the surrounding tunnel. Fix the non-woven fabric in the predetermined position using a simple trolley, and then firmly nail the non-woven fabric onto the initial support surface using thermoplastic EVA washers. The laying of non-woven fabrics should be carried out from bottom to top. The non-woven fabric should be pressed on top and a certain margin should be reserved.

　　When reserving the suspension of tunnel waterproof boards, they should be laid from the bottom of the upper ring. The waterproof board is fixed using thermocouples, and after melting, plastic washers are used to firmly bond the tunnel with the waterproof board. The overlapping joints between the waterproof boards in the tunnel should be welded on both sides, using a fully automatic peristaltic hot melt welding machine with the function of adjusting temperature and hot wedge speed. After welding, a ventilation channel should be left between the two welds.

　　2： The second specific method

　　The protruding parts of the waterproof board, such as the steel mesh at the bottom of the tunnel, need to be disconnected first, and then smoothed with cement mortar and plain mortar for construction.

　　When there are obvious pipelines, disconnect them and smooth them with cement mortar.

　　When laying waterproof boards in the tunnel and encountering a protruding part of the anchor cable, the screw head should be saved for 5mm and removed, and then tightened with a plastic cap

　　4. Cement stabilized soil should have a smooth and even surface, and the protrusion and concavity should not exceed 5cm.

　　5. Place 350g/m2 geotextile on the surface of concrete with gaskets. When there is a drainage board, place it at the same time. Then, nail it firmly with a nail gun and anchor it with cement steel nails. The length should not be less than 50mm, with an average arch of 3-4/m2 and a side wall of 23/m2

　　To prevent cement mortar from penetrating the geotextile, the geotextile should be laid first and then the waterproof board should be laid.

　　When laying waterproof boards in tunnels, manual welding machines should be used to heat melt them onto the inner lining. The bonding tensile strength of the two should not be less than the compressive strength of the waterproof board, and it is required to be sturdy and compact.

　　8. The waterproof board should be thermally bonded using a welding machine, and the bonding area should not be less than 10 centimeters. The tensile strength of the bonding should not be less than 80% of the compressive strength.

　　9. The distance between the waterproof board at the joint in the tunnel and the middle of the secondary lining should not be less than 1.0m. Before the ground waterproof pavement, the waterproof board should not be tightened, and the surface should be closely aligned with the cement stabilized soil surface without cracking.