Process flow of composite geomembrane

The composite geomembrane anti-seepage of the Zhoutou Reservoir Dam adopts a cyclic operation of excavation, laying, compaction, and protection at the same time.
Base cleaning
The foundation surface must be cleaned according to the design requirements, which is the key to ensuring the anti-seepage effect, especially for debris such as sharp stones and tree roots. Local unevenness is not allowed on the foundation surface. The cleaned foundation surface should be compacted tightly with a hammer or plate to make it dense and flat.
Composite laying
When laying the film, it must be laid from bottom to top. The membrane should be pressed flat and tightly between the membrane and the substrate, but it should not be pulled too tightly. Generally, it should be slightly loose, but there should be no bubbles left at the bottom of the membrane. Because the geotextile membrane is relatively thin and light, it is easy to be blown by the wind before the protective layer is laid. Therefore, it is not advisable to cover a large area of geotextile membrane at one time. It is best to cover the protective layer soil material while laying the membrane.
According to the information provided by the manufacturer, the width of the composite geomembrane is 1.0~1.9m. In this project, a width of 1.9m is selected to reduce the use of joint materials. The joints have methods such as hot bonding, adhesive bonding, and overlap. The design of this project adopts adhesive bonding, with a joint width of 50mm.
If any puncture or tear is found on the geomembrane, it is necessary to use three times the damaged area of geomembrane adhesive to fix it.
Protective cover
The protective layer soil material with a thickness of 10cm against the geomembrane must be sieved, and particles with a particle size greater than 6mm are not allowed, otherwise it is easy to puncture the geomembrane. The protective layer soil material must be compacted with a compactor to ensure a dry bulk density of 1.5 or above, and sampling and inspection should be carried out at any time. When backfilling the protective layer and building block stone cover, it is necessary to handle it gently to avoid breaking the geomembrane. Under the block stone protection surface, a 100mm thick gravel or gravel cushion layer should be laid to prevent the soil protection layer from being brushed due to factors such as water level changes and wind waves. The dry block stones are laid manually with hanging lines, and the stones should be tightly embedded. The individual weight of the surface block stones should be greater than 48kg, and all gaps should be filled with small stones.
Peripheral processing
The requirement for peripheral boundary treatment is to tightly connect the composite geomembrane with the surrounding soil, block the seepage entrance, cut off the lateral leakage path, prevent seepage water from entering the bottom surface of the geomembrane, form water bubbles, and expand and break the geomembrane when the reservoir water level drops. Therefore, it is necessary to excavate a cutoff ditch for the surrounding boundary and bury the geomembrane in the ditch