Construction scheme of geomembrane in seepage prevention of landfill

Geomembrane, especially high density polyethylene (HDPE) geomembrane, plays a crucial role in the seepage prevention project of landfill. Its excellent impermeability and durability make it the preferred material for modern landfill construction.

The primary task of landfill seepage prevention engineering is to ensure the flatness and compactness of the base surface.

The flatness of the base surface should be controlled within ±2cm/m² to ensure the straight and smooth laying of geomemofilm. The compaction degree needs to reach 95% to ensure the stability of the base surface and prevent the geomembrane from being damaged by the settlement of the base surface. In addition, the vertical and horizontal slope of the base surface should be maintained at more than 2%, which is conducive to the diversion of leachate and prevent water accumulation. Cleanliness is equally important, there should be no pointed debris such as roots, rubble, stones in the vertical depth of 2.5cm of the base surface, so as not to Pierce the soil membrane.

Construction climate conditions are also the key factors affecting the quality of geomembrane laying.

 The temperature should be controlled between 5-40 ° C, taking into account the thermal expansion and contraction of geomemofilm, it should be laid tightly when the weather is cold, and it should be properly relaxed when the weather is hot. Wind more than 4 or rainy days should stop construction, wind hours can be used to press the geomembrane, to facilitate construction.

The laying and construction of geomembrane should follow certain steps.

First of all, it should be extended from the bottom to the high, do not pull too tight, and should leave a margin of 1.5% for local sinking and stretching. The laying sequence of the slope is usually from top to bottom, and the longitudinal joints of the two adjacent pieces should be staggered more than 1m to avoid being on a horizontal line. The longitudinal joint should be located on the plane, more than 1.5m away from the dam foot and bend foot. When the slope is laid, the film spreading direction should be basically parallel to the maximum slope line. During the laying process, the geomembrane should be built in line with each other to avoid folds and ripples. After the laying is completed, the geomembrane should be pressed with sand bags in time to prevent wind blowing and pulling. A certain anti-seepage film should be reserved in the anchoring trench according to the design requirements for local sinking and stretching.

Welding is a key link in geomembrane impermeable engineering.

 Experimental welding should be performed before welding to check and adjust the welding equipment. Only after the successful completion of the experimental welding can the welding equipment and welding personnel proceed to the next step of production welding. The length direction of the weld shall extend along the slope and shall not cross. When welding, the welding temperature, speed and pressure of the clamping rod should be maintained to achieve the best welding results. After the weld is completed, quality inspection should be carried out, including product surface inspection and weld inspection, to ensure the quality of welding.

In addition, the landfill seepage prevention project also needs to pay attention to some special parts of the construction. 

For example, the junction between the slope and the bottom of the reservoir should be designed and connected with the bottom film of the reservoir. For the connection of dam pipe and geomembrane, the geomembrane should first be cut into a horn shaped tube sleeve, and then inserted into the dam pipe and welded.

To sum up, the construction scheme of geomembrane in landfill seepage prevention projects needs to strictly control the key links such as base conditions, construction climate conditions, laying construction steps and welding quality. Only by ensuring that each link meets the standard requirements can we ensure the quality and effect of the landfill seepage prevention project.