Site Treatment
Level and compact the foundation of the landfill. Remove sharp objects, stones, iron wires and other debris to ensure that the foundation surface is solid, flat, and free of cracks, bumps or depressions. If the foundation conditions are poor, reinforcement measures need to be taken.
Material Preparation
According to the design requirements, prepare a sufficient quantity and appropriate specifications of geomembranes, as well as auxiliary materials such as welding materials, sandbags, and anchoring materials. Inspect the quality of the geomembranes to ensure that there are no damages, wrinkles, aging or other problems.
Equipment Preparation
Prepare the equipment required for laying geomembranes, such as membrane laying machines, welding machines, cutting tools, etc. Debug and inspect the equipment to ensure its normal operation.
Personnel Training
Provide technical training for construction workers to make them familiar with the laying process of geomembranes, welding techniques, quality control key points, etc., ensuring that construction workers have the corresponding skills and experience.
Laying Process
Laying Sequence
Generally, the slope laying is carried out first, followed by the bottom laying of the landfill. When laying the slope, it should be laid from the top of the slope to the bottom; for the bottom laying, it should start from the lowest part and extend to the higher part. At the same time, the amount of splicing should be minimized, avoid forcefully pulling the geomembrane, and do not create permanent folds.
Overlapping Method
The longitudinal joints of two adjacent geomembranes should be staggered by more than 1 meter, and should be more than 1.5 meters away from the dam toe and corners, and be set on the plane. The overlapping width shall be in accordance with the design requirements, generally about 10 cm. A double - pass welding seam method is adopted to provide multiple protection.
Slope Laying
According to the actual situation of the project, determine whether to lay parallel or perpendicular to the maximum slope line based on the principles of minimizing joints, facilitating construction, and reasonable cutting. The joints should avoid corners and be set at the flat part. For areas with a large slope, install soft ladders, and construction workers carry out the welding joint construction of the geomembrane on the soft ladders.
Reserved Extra Width
During the laying process, do not pull the geomembrane too tightly. Leave a sufficient extra width, about 1.5%, to prepare for local subsidence and stretching.
Welding Construction
Trial Welding
Before formal welding, conduct a trial welding. Select appropriate welding parameters, such as welding temperature, speed, and pressure, according to the weather conditions of the day.
Welding Equipment
Professional welding equipment should be used, such as double - track hot - melt automatic crawling welding machines, hot - melt extrusion welding machines, etc. For T - shaped and cross - shaped welding and patching, a hot - melt extrusion welding machine should be used.
Welding Operation
Weld with a hot welding machine according to the designed membrane laying direction. When welding, wipe the floating soil on the geomembrane clean to prevent the welding machine from being blocked and welding through the geomembrane, which may affect the welding speed and quality. In case of large temperature and wind speed changes, adjust the temperature and speed to avoid curved, overlapping seams, as well as poorly welded or burned - through welds.
Quality Inspection
Appearance Inspection
During the laying and welding process, inspect the appearance of the geomembrane at any time to ensure that there are no damages, wrinkles, air bubbles or other defects. Inspect the weld seams visually to ensure that the weld seams are uniform, flat, and free of missed welding, false welding, welding beads or other problems.
Weld Seam Inspection
Methods such as the inflation method, vacuum box method, ultrasonic flaw detection, and infrared thermal imaging can be used to inspect the weld seams to ensure that there are no leaks. The inspection frequency and standards should comply with the design and specification requirements.
Overall Inspection
After the laying of the geomembrane is completed, conduct an overall impermeability performance inspection. Methods such as the water injection test and permeability coefficient test can be used to ensure that the impermeability effect of the geomembrane meets the design requirements.
Post - construction Treatment
Anchoring Construction
The anchoring trench should be excavated at the position specified in the design before placing the geomembrane. When excavating the anchoring trench in easily - dried clay, it should be excavated a few days before laying. During the anchoring construction, after the top of the geomembrane is laid at the designed position of the anchoring trench, temporary anchoring measures should be taken at the end. The final anchoring is carried out after the overall construction of the landfill geomembrane is completed.
Protective Layer Construction
Lay a protective layer on the geomembrane, such as long - filament non - woven geotextiles, leachate drainage layers, non - woven geotextiles, etc., to prevent the damage to the geomembrane impermeable layer caused by the growth of plant roots and the gnawing damage to the geomembrane by rodents.
Acceptance and Handover
After completing all the above construction procedures, organize relevant departments and personnel for acceptance. After passing the acceptance, go through the handover procedures and deliver the landfill for use.
