Treatment of special parts of HDPE geomembrane
1) At the intersection of slopes, the laying and welding of HDPE geomembrane is a special case; corresponding measures should be taken according to local conditions to make the membrane more closely fit with the base.
The main points of construction in this case are: the diaphragm in the irregular range such as turning should be cut into an “inverted trapezoid” with a small width at the top and a small bottom. If the ratio is inaccurate, it will cause the geomembrane surface on the slope to “bulge” or “suspend”.
2) Special treatment is also required at the foot of the slope where the entire slope of the landfill area connects with the bottom of the reservoir. The main points of construction are: Lay the HDPE geomembrane of the slope along the slope surface 1.5m away from the foot of the slope, and then weld it with the HDPE membrane at the bottom of the reservoir.
3) At the place where the leachate collection pipe penetrates the dam in the landfill area, the connection and welding between the pipe and the membrane should be constructed using the special process of “pipe piercing the membrane”.
The key points of its construction are: first use HDPE geomembrane to make a trumpet-shaped sleeve, the radius of which is consistent with the diameter of the membrane-piercing pipe, and the maximum radius is about 0.8 meters (the specific size will be determined during installation) and divided into 6-8 small pieces, and then put The sleeves are inserted into the dam pipe in order from large to small.
Adjust the position of the sleeves according to the actual situation on site and temporarily stabilize them with a hot air gun. The large and small sockets of the pipe are welded on the HDPE geomembrane surface of the anti-seepage layer and the leachate collection pipe, and a stainless steel hoop is added to the HDPE collection pipe.
4) During the entire construction process, for the repaired parts after sampling and the places where normal welding construction cannot be used, it is necessary to formulate construction details according to local conditions according to the actual situation on site, and use special technology for construction of geomembrane.
The secondary welding of welds such as “T type” and “double T type” belongs to special part welding.