- Construction requirements for HDPE geomembrane laying
(1) Before laying HDPE geomembrane, please supervise engineers to fully confirm the site conditions to ensure that the foundation surface is flat, no convex, no sharp particles and hard debris that can damage HDPE geomembrane. The material (various performance indicators, whether there are bubbles on the surface, holes, wrinkles, damage, etc.) is sent to a third party agency for strict inspection and qualification, and then laid after confirmation.
(2) Each roll of HDPE geomembrane should be numbered and placed in order. Geomembrane numbers shall be submitted to the supervising engineer for inspection.
(3) geomembrane materials stored on site should not be exposed to sunlight for a long time, and should be away from the source of fire.
(4) During the laying process, the staff shall not wear shoes that will damage the geomembrane, and shall not smoke at the laying site to carry out other activities that may damage the geomembrane.
(5) The antifouling bag should be placed on the antifouling bag in time to prevent it from being blown apart by the wind.
(6) The outdoor laying and welding of geomembrane should be carried out in the weather where the temperature is higher than 5°C, the wind is lower than 4, and it must not rain or snow.
(7) Vehicles are not allowed to pass directly through HDPE geomembranes and non-wovens, and metal or sharp tools (such as shovels) are not allowed to be used for HDPE geomembranes and non-wovens.
(8) During the construction process, try to avoid shrinkage, wrinkling or material stress caused by temperature changes.
(9) In the welding process of HDPE geomembrane, the supervision engineer’s operating procedures, laying and welding quality should be checked in time, and if there are quality problems, it should be repaired in time.
(10) There should be no roots and obvious spiky materials in the anchoring ditch of the geomembrane platform.
(11) Weld position and welding technical requirements
When laying geomembrane on the slope, the lap joint should be parallel to the direction of the slope, and the position of the transverse lap weld of the slope should be greater than 1.5m from the bottom edge of the slope.
② Minimize corner joint Settings and irregular geometry.
(3) Formal welding shall not begin until the sample welded by the welding equipment has not passed the test welding inspection or has not been confirmed by the supervision engineer.
Before welding, it is necessary to clean the dust, dirt and other foreign objects on the surface of the geomembrane.
⑤ The lap part of the two welded geomembranes shall not be less than 10㎝.
⑥ If the ambient temperature is below 5 ° C or above 40 ° C, construction is not allowed.
⑦ Double welding lap welding. Squeeze welding is only used for repair (servicing, covering) and welding equipment cannot be used.
⑧ The bonding strength of the welding should be higher than the strength of the base material.
(12) The construction site has sufficient welding construction equipment to ensure continuous welding construction.
- Climate requirements
(1) Considering the thermal expansion and contraction of geomembrane, the temperature should be 5-40℃, according to experience, the geomembrane should be densely placed at low temperature; You should relax in hot weather; However, it should be noted that high noon temperatures should be avoided in summer.
(2) Wind power rainy days: wind power more than 4 days or rainy days should stop construction; When the wind is small, the geomembrane should be compressed with sandbags to facilitate construction.
- Laying principles
(1) It should extend from the bottom to a higher position, do not pull too tight, and leave a margin of 1.50% to prepare for partial sinking and stretching.
(2) The two adjacent longitudinal joints should not be on the horizontal line, and should be staggered more than 1m from each other.
(3) The longitudinal joint should be more than 1.5m away from the dam foot and bending foot, and should be placed on a plane.
(4) Tilt first and then tilt again.
(5) When laying the slope, the direction of the film should be basically parallel to the maximum slope line.
- Construction method:
After the foundation treatment of the pile leaching site, the clay layer (water-blocking layer) →HDPE geomembrane → compacted loess →HDPE geomembrane → compacted and screened fine soil → nonwoven geotextile from bottom to top. During the laying process, bricks, stones and other sharp objects that may Pierce the geomembrane at the bottom of the pool should be further inspected and removed.
- Construction technical requirements:
(1) Before laying, the installation unit must provide the laying and welding plan of the layout, require a reasonable choice of laying direction, as far as possible to reduce the joint stress, reasonable arrangement of the position of each material, and strive to reduce the joint as far as possible, slope slope slope slope greater than 10% within 10m should not be horizontal joints;
(2) Prior to laying, the owner and the supervising engineer shall jointly confirm under site conditions to ensure that the base surface of the bottom of the pool is smooth, free of flat, sharp particles, and free of hard debris that may damage the film. There must be no harmful debris at the depth of 25 surface ㎜ and the quality of impermeable materials (various performance indicators, whether there are bubbles, holes, wrinkles, damage, etc.) on the surface should be strictly tested, and it can be laid after confirmation;
(3) the laying should be smooth, firm, reduce wrinkles, after laying should be timely ballast and anchorage;
(4) Each geomemofilm must be welded on the day it is laid, and appropriate protective measures should be taken to prevent rain from entering the ground below;
(5) Welding requirements of geomembrane
① The welding form is generally double lap welding. Extrusion welding is only used for maintenance (repair, covering), and welding equipment cannot be used;
(2) The construction site should have enough welding construction equipment to ensure continuous welding construction;
(3) The construction site should be equipped with a test laboratory, equipped with necessary test equipment, and through eye inspection, pressure testing, vacuum testing and destructive testing of geomembrane weld field testing;
(4) Before the sample of the welding equipment has not passed the test welding inspection or supervision engineer confirmation, shall not begin formal welding;
⑤ If the ambient temperature is lower than 0 degrees or higher than 40 degrees, the construction unit shall provide a written certificate of welding quality equivalent to the specified temperature range, and require the supervision engineer to confirm, and then carry out construction.
Before welding, it is necessary to remove dust, dirt and other foreign objects on the surface of the geomembrane, and clean the welding edge;
7 Try to keep the vertical front end of the welder on the welding surface and maintain a certain pressure when welding;
⑧ Pay attention to the change of the lap width in the welding process at any time, so that the corresponding treatment can be carried out according to the actual situation. For double-pass fusion welding, the lap width of the weld is not less than 100mm. For extrusion welding, the lap width of the weld is not less than 75㎜, and the joint strength of the weld should not be less than the strength of the base material.
trusion extrusion welding must first bond the upper and lower geomembranes with hot air, and remove the oxide layer on the surface of the geomembranes with a sander at the welding position. The grinding width should be the same as that of extrusion welding.
⑩ After welding the geomembrane, the weld should be sampled at the seam length of each welding machine at 150 meters per weld and the frequency of the strength of the welded joint should be tested;
In the case of double-track welding, the enclosed space formed by the geomemofilm between the two welds shall be tested for air pressure leakage detection, and for extrusion welding, vacuum test or electric spark test shall be used;
