Construction method

Do not drag or pull the geomembrane during transportation to avoid injury from sharp objects.

1. Extend from the bottom to the high position, don't pull it too tightly, and leave a margin of 1.50% to prepare for local sinking and stretching. Taking into account the actual situation of the project, the slope shall be laid from top to bottom;

2. The longitudinal joints of two adjacent panels should not be on the same horizontal line, and should be staggered by more than 1m;

3. The longitudinal joint should be more than 1.50m away from the dam foot and bent foot, and should be located on a plane;

4. Slope first and bottom of the field;

5. When laying on a slope, the film spreading direction should be basically parallel to the line of steep slope.

layout

1. Before laying the geomembrane, the corresponding qualified acceptance certificate of civil engineering shall be obtained.

2. Before cutting the geomembrane, the relevant dimensions should be accurately measured and then cut according to the actual size. Generally, it is not advisable to cut according to the size shown in the figure. It should be numbered piece by piece and recorded in detail on the special form.

3. When laying geomembrane, we should try to minimize the number of welds and save raw materials as much as possible on the premise of quality. It is also easy to quality.

4. The overlap width of the seam between the film and the film is generally not less than 10cm, and the welding seam is usually arranged parallel to the large slope, that is, arranged along the slope direction.

5. Generally, in areas with deformed corners, the length of the joint should be as short as possible. Except for special requirements, on slopes with a slope greater than 1:6, within 1.5 meters from the top slope or stress concentration area, there should be no welds as much as possible.

6. During the laying of geomembrane, artificial wrinkles should be avoided. When the temperature is low, it should be tightened and flattened as much as possible.

7. After the geomembrane is laid, it is necessary to minimize walking and moving tools on the surface of the membrane. Anything that can cause harm to the impermeable membrane should not be placed on the membrane or carried on the membrane to avoid damage to the membrane. Cause accidental damage.

Welding specification

Geomembrane welding specification

1. Process flow ●Foundation excavation ●Making mortar protection layer of lake bottom (H20-30mm)

●Cutting, compacting and leveling

●The composite geomembrane is pasted on the vertical retaining wall

●The base surface is leveled, cleared, and the process is handed over

●Sealing of underwater water pipe mouth

●Laying and welding of composite geomembrane

●Process transfer

●Quality acceptance of welding and repair

●Completion acceptance

2. Project Overview

1. High design water level: about 0.6m.

2. The total area of waterproof construction is about 800 square meters.

3. Ceramsite brick masonry retaining wall.

4. There are craters underwater.

3. Main waterproof materials

1. Composite geomembrane coil, specifications: 50*4m; 150g/㎡/0.5mm/150g/㎡.

2. GB rubber water stop strip.

Four, basic conditions

1. After foundation shaping and excavation, slope cutting, leveling and rolling or compaction must be carried out. Displacement and backfill of disturbed soil shall be sprinkled or compacted in layers, each layer thickness ≯400mm.

2. Remove the exposed materials on the surface of the foundation with hidden dangers of puncture, such as bricks, stones, tiles; glass and metal debris; branches, plant rhizomes, etc. Clear obstacles in the site and provide necessary paving construction conditions.

3. The installation and reservation of the surrounding water retaining walls, pump pits, and bridge foundations, as well as underwater pipe openings, must be completed before the construction of the composite geomembrane. Five, welding and laying technology

1. Welding technology:

       ①Lap width of weld bead: 80~100mm; the natural folds of the plane and vertical surface are respectively: 5%~8%; reserved expansion and contraction: 3%~5%; residual amount of leftover material: 2%~5%.

②The working temperature of hot melt welding is 280~300℃; the traveling speed is 2~3m/min; the welding form is double bead. ③Repair method of damaged parts, cut the same specifications of materials, hot melt adhesive repair, polyethylene rubber seal.

④ There is no imitation cloth connection at the welding bead, and mechanical stitching is adopted.

⑤The sealing and water stop of the underwater pipe mouth is sealed with GB rubber water stop strip, metal wrapped and anti-corrosion treatment.

2. Laying technology

①The laying and unfolding direction of the composite geomembrane is from E to W or from W to E. Each laying length, including the height of the retaining walls on both sides, is completed at one time. ②Laying sequence, advance from the channel axis to both sides of S and N.

③In the construction process, first do the mortar protection layer (20-30mm) of the composite geomembrane at the bottom of the lake, and then do the pasting with the vertical retaining wall.

④ Pasting process of composite geomembrane and retaining wall. Apply the adhesive on the adhesive surface of the composite geomembrane and the retaining wall, dry and stand for about 5 minutes, then paste, squeeze, and flatten. The adhesive is made by mixing asphalt emulsion paint, cement and water. After the pasting is completed, the brazing nails are anchored above the water level, and waterproof and anti-corrosion treatments are done.

Six, quality acceptance

1. The material and construction of composite geomembrane are in accordance with the standards of polyethylene geomembrane and composite geomembrane issued by the Bureau of Quality and Technical Supervision.

2. Construction quality acceptance is divided into self-inspection by the construction unit and random inspection by the contractor.

3. Welding quality inspection adopts the "inflation pressure method" and the "visual inspection method" for damage repair. The inflation pressure detection index is 0.06Mpa.

4. The quality acceptance process includes the process handover procedures, completion acceptance and so on.

5. Normal leakage of artificial lake: ≤15mm/24h (including seasonal evaporation loss).

Seven, construction progress

1. Daily efficiency, a unit is 2000~2500㎡ per day according to the construction area.

2. The planned construction period is 3 days.

8. Suggestions

1. Strengthen the protection and management of the finished composite geomembrane, improve the waterproof awareness of relevant construction personnel, and put the project into normal operation on schedule. Has a very important meaning.

2. It is recommended that the contractor should notify and assign a special person to supervise. If the construction personnel related to waterproof materials find the composite geomembrane is damaged, they should notify the waterproof construction personnel to repair it if necessary.

3. The composite geomembrane must be prevented from sticking to oil stains, otherwise the bonding strength will be reduced. Storage and protection "See Introduction to Geomembrane Construction Method".

4. It is recommended that this project pay attention to the following links:

①After the composite geomembrane is welded into the finished product, the lake bottom mortar protective layer must be made first.

②The bridge foundation is waterproof, and the steel bar penetration welding method is adopted, and the mortar protection layer is used to prevent the hidden quality problems caused by electric welding.

③The pasting of composite geomembrane and wall shall prevent the appearance of large-area hollowing.