In the process of tunnel construction, solving the waterproof problem is an important link to ensure the quality of tunnel engineering, fundamentally eliminate tunnel diseases and increase tunnel life, and choosing waterproof materials and correct construction methods are the key to the success of tunnel waterproof.
First, the construction preparation
1, construction equipment preparation
(1) 1-2 heat sealing welding machine: used for heat sealing welding when waterproof materials overlap.
(2) 1-2 hot air welding gun: used to repair the damage of waterproof board caused by man-made or other reasons during the laying of waterproof materials.
(3) Leak detector: used to detect the lap quality of double welds and check whether the welding is firm under pressure.
(4) In addition, we need 1 working platform, 2 electric drills, 2 electric winding irons (75W), 2 small rollers and 2 nails.
2, the preparation of the construction site
(1) The construction platform car should be as convenient as possible to ensure safety.
(2) According to the specification requirements, try to level off the base surface, and handle the overbreak and underbreak.
(3) The exposed bolts and sharp objects in the initial support should be treated to avoid damaging the waterproof material.
(4) Clean up the work site and remove all sharp objects that may damage the waterproof material.
Second, the construction technology and process
1, laying waterproof board
(1) When laying waterproof cloth, use special plastic gaskets, and choose steel nails, screws and plastic expansion pipes around the base surface as far as possible according to the different conditions of the base surface, and fix the waterproof board on the base surface.
(2) When laying the tarpaulin, the tarpaulin should maintain a certain degree of looseness, and the looseness of sticking the tarpaulin on the rock surface with the palm of your hand is not accurate in Zhang Liwei; When laying in circumferential direction, it should be noted that the longitudinal direction of waterproof board is perpendicular to the longitudinal direction of tunnel.
(3) In the process of laying, there should be an overlap margin of not less than 20cm at the overlap of two waterproof boards, and the weld width of waterproof boards is 10-20cm.
(4) Before welding, preheat the welding machine and set the temperature and crawling progress. The temperature is generally set at around 300℃ and the speed is set at 2 speed units. When the indicator light changes from green to red, it can be operated. In the welding process, the temperature or speed should be adjusted at any time according to the hot melting situation of the weld to control the distortion until the welding of the weld achieves the best effect.
(5) Welding shall be completed at one time as far as possible, and the number of interruptions and shutdowns shall be reduced as much as possible to avoid unnecessary repair. If there is any interruption or downtime, it should be repaired in time.
(6) When the longitudinal weld and the transverse weld of the waterproof board overlap, trim the edge of the weld to about 100cm, then weld another weld, and then weld the overlapping part of the two welds firmly with a hot air torch.
(7) When laying waterproof board, the next lap allowance of 1-2m shall be reserved.
2. Acceptance
(1) The foreman should check the welding quality at any time and check whether there are holes in the waterproof cloth. If there is a hole, circle it with a black marker. The quality inspector should also check the installation quality at any time and circle the damaged part with a red marker. Paper net
(2) The gas band formed in the middle of the overlapped double welds of the waterproof board shall be detected by the leak detector. If there is pressure relief, find out the leakage point in time and repair it with hot air welding gun until it is qualified.
(3) After the laying is completed, before the secondary lining, the waterproof board shall be thoroughly and seriously inspected to prevent omissions and man-made damage in the construction process.
(4) Mark the found damage and repair it with hot air welding torch in time. When repairing, the patch should be cut into rounded corners, not too small. The quality of repair should be based on the fact that it cannot be torn off by hand. If it can be torn off, it needs to be repaired again.
(5) Before secondary lining, attention should also be paid to strengthening the protection of waterproof board to avoid man-made damage and unnecessary repair.
(6) When pouring the secondary lining, more attention should be paid to the protection of the waterproof board, because if the waterproof board is damaged again at this time, it will be beyond repair and will leave hidden dangers forever.
(7) After the secondary lining is completed, attention should be paid to the protection of the reserved part of the waterproof board to ensure the smooth progress of the next construction period.
Third, the protection of waterproof board and construction matters needing attention
1, protection of waterproof board
(1) When the lining is closely followed by excavation, protective measures shall be taken for the joint waterproof board reserved at the end of the lining to prevent flying stones from damaging the waterproof board during excavation.
(2) The installation of lining reinforcement, the setting of various embedded parts, the installation of supporting formwork, the placement of concrete conveying pipes and the pouring of concrete may cause the waterproof board to break, puncture or burn through. Once the flashing is damaged, it must be repaired immediately.
2. Matters needing attention in construction
(1) Before hanging the tarpaulin, check the rock surface for sharp edges and stones. If there is, first knock out the sharp edges and corners, and fill up the particularly large depressions with spray cymbals.
(2) When hanging the outer waterproof board, make the waterproof board close to the rock surface, nail the ground anchor as much as possible, leave some free space for the waterproof board, and weld the waterproof board to prevent it from falling off.
(3) For the damaged places when hanging the floodwater, check them one by one and repair them by welding.
(4) In the scraping process, check the waterproof board for pulling, falling off and damage at any time, and repair it in time if any, and assign special personnel to check the repair quality at the scene.
Fourth, the relationship between waterproof board laying and related processes
1, smooth blasting and initial support are the basic working procedures. Although smooth blasting and initial support do not belong to waterproof and drainage system construction, they are closely related to waterproof and drainage system construction. The smooth blasting effect is good, and the circumferential spring drainage pipes can be arranged smoothly along the surrounding rock surface. When the initial supporting surface is smooth (the l/chord length of the concave-convex part of the surface is ≤ 1/6), the local leveling link before hanging the waterproof board can be omitted, so that the waterproof board can be closely attached to the sprayed concrete surface.
2. All kinds of drainage pipes behind the lining must be carefully set up according to the design, and the principle of "drainage first, combined with drainage prevention" should be followed to ensure smooth drainage, so as to reduce the water pressure behind the secondary lining, thus prolonging the service life of the waterproof board and achieving waterproof and reliable results.
3. Before pouring the secondary lining concrete, the scum at the base of the side wall must be cleaned up, otherwise it will cause uneven settlement of the tunnel lining, and the waterproof board at the joint of concrete construction is easy to crack.
4. When pouring secondary lining concrete, a protective object should be set at the discharge port of the delivery pump to prevent the material flow of the discharge pipe from continuously impacting the waterproof board and wearing it.
Verb (abbreviation of verb) conclusion
The application of waterproof board is in a vital position in tunnel construction, which is an important link to ensure the quality of tunnel engineering, fundamentally eliminate tunnel diseases and increase tunnel life.
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