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HDPE anti-seepage membrane has strong thermal expansion characteristics
HDPE anti-seepage membrane has strong thermal expansion characteristics. Linear expansion will increase or decrease the length direction of every 100m long membrane by 14cm when the temperature increases or decreases by 100 ℃. Due to the large temperature difference between day and night in some areas during autumn (measured to range from 60 ℃ to 200 ℃), there is a temperature difference of 400 ℃, which can cause a variation of 56cm for a 100m long anti-seepage membrane. Therefore, during construction, it is necessary to consider the impact of changes in membrane length on the laying quality and effectiveness, especially at the foot of the slope, which is prone to hanging or wrinkling due to the expansion and contraction of the membrane.

Solution to the Influence of Temperature Difference on the Quality of HDPE Anti seepage Membrane
Construction should minimize the laying of films during high or low temperatures during the day; Adjust the reserved length of the film according to the average temperature difference; The anti-seepage film laid on different dates should be adjusted to the same temperature environment as the last time it was laid for welding to reduce wrinkles. After practice, the solution using a dual track welding machine is to appropriately reserve the overlap width. The overlap width is 8cm in the morning, 10cm in the afternoon, and 14cm in the afternoon, which can ensure the smooth welding of the dual tracks as a whole; However, the longitudinal overlap (between the slope and the bottom of the site) should be reserved based on the slope length. Usually, the overlap 1.5m outside the slope foot should be reserved for 40-50cm (membrane laid in the afternoon), and the connection time with the anti-seepage membrane at the bottom of the site is the next morning (after a night of contraction and stress balance, its expansion and contraction have been basically stable); Secondly, the welding of adjacent two films should be carried out after the same temperature environment, especially when welding the film laid in the morning with the film laid yesterday. This factor should be taken into account because the rolled film is not sensitive to changes in external temperature, while the laid film is very sensitive to temperature differences. Otherwise, it will cause lateral wrinkles to occur on both sides of the welding film, one is flat, while the other is uniform, The solution is not to weld the piece immediately after it is laid, but to wait for half an hour before welding.