Main Points of Geomembrane Application in Artificial Lake
In recent years, with the development of urban construction and the improvement of people’s living standards, the environmental functions of water have received more and more attention. Artificial lakes have appeared in public playgrounds, residential areas, universities, and other places. As an anti-seepage material for artificial lakes, wholesale textured geomembrane has the advantages of a lightweight, large elongation, good anti-seepage performance, adaptability to deformation, simple construction, and low cost.
1. The choice of anti-seepage materials
Anti-seepage geomembrane is an important material for the anti-seepage of artificial lakes. Therefore, it is necessary to select a suitable and high-quality geomembrane first, and also consider the convenience of construction. When selecting a geomembrane, pay attention to the following points:
(1) When the thickness of the film is less than 0.35mm, the welding process is difficult to hold when using a hot-melt welding machine on the site, and it is easy to cause the leakage of the geomembrane due to the quality of the welding.
(2) During the film-laying process, welds, especially cross welds, should be minimized to reduce the hidden danger of leakage.
(3) In addition, the artificial lake has a water depth of about 3m and a depth of up to 5m. Therefore, it is necessary to ensure that the strength of the geomembrane is sufficient, and the foundation of the artificial lake is critical. Once the foundation is deformed to a large extent, the geomembrane will Withstand various loads.
Therefore, when choosing a geomembrane, the more important characteristics are:
The thickness of the geomembrane should be more than 0.5mm; The width is recommended to be 8m. At present, most domestic manufacturers produce 7m geomembrane. For example, the geomembrane produced by Shandong Xinyu has a width of 8 meters, which can effectively reduce the weld seam compared to the 7-meter wholesale LDPE geomembrane.
Puncture resistance, resistance to environmental stress cracking, and right-angle tear strength are also very important indicators;
2. Construction procedures
(1) Dig the shape of the lake according to the drawings, including the depth of the lake and the surrounding slopes;
(2) Level the bottom of the lake and tamp the base plain soil to modify the shape of the lake;
(3) The surrounding façade is lined with 180 or 240mm thick soil external walls, and the impermeable membrane is laid on the wall;
(4) Make blind drainage ditch, water collecting well and overflow well;
(5) A large area of 150-200 thick gravel layer is laid on the bottom surface. The function of the gravel layer is to divert groundwater and prevent the groundwater from lifting the impervious layer when the lake is drained;
(6) The gravel layer or the medium-coarse sand layer is 80mm thick to level the base surface;
(7) Lay a layer of 100g non-woven fabric as the isolation layer;
(8) Lay a 1mm LLDPE barrier film;
(9) Lay 100 grams of non-woven fabric as the isolation layer;
(10) Lay the cement stone powder mixed layer 100mm thick, and then approve the 30mm thick mortar screed. Set the leveling layer with 3 * 3m grid joints (you can also lay 60 thick red bricklayers on the 60 thick stone powder layer, and then apply 25 thick mortar Screed);
(11) The surrounding façade is lined with a 180mm thick brick inner wall, which is a protective wall with an anti-seepage membrane on the façade;
3. Main construction methods and technical measures
Ⅰ. Construction of the base part:
(1) The shape, height and surrounding slope of the lake should be trimmed in strict accordance with the drawings. Set a fixed elevation point in the lake to adjust the elevation of each part and construction sequence in the lake;
(2) The mud layer in the lake should be cleaned up or the soft soil should be compacted with sufficient crushed stone or stone powder;
(3) According to the design, if a small island is to be backfilled or a boulder is piled up, the cornerstone layer should be 300-500 thick, or 200-300 thick reinforced concrete slabs should be poured to strengthen the foundation strength;
(4) The bedding stone cannot reveal the edges and corners of the stone, and it must be covered with stone powder.
(5) The isolation cloth should be laid flat, and the overlapped part should be overlapped by more than 10 cm.
Ⅱ. Welding and paving of impermeable membrane:
(1) Determine the construction order of the site according to the site conditions such as the shape of the lake, the slope, and the arrangement of the inlet, and then lay and weld in sequence.
(2) Irregular parts should be cut into different shapes according to the site conditions, and then use a special electric welder to weld the cut-off membranes.
(3) The welding parts must be firm and dense. The impervious film is at the welding line. The upper and lower two impervious films must be melted to make them melt into one body. The visual inspection of the welding line must be smooth and consistent in color. The welding machine temperature and walking speed should be strictly controlled according to regulations to prevent welding from being unstable or burning out the waterproof membrane.
(4) The corners that cannot be constructed with a welding machine are also constructed with special welding guns.
Ⅲ. Construction of joints such as nozzles, columns, and walls:
(1) At the mouth of the pipe, the diameter of the pipe can be measured first. Use a circle on the impermeable membrane to plan a circle with a diameter of 1-2 mm smaller than the diameter of the pipe. Then carefully cut and dig with a cutter, and then insert the impermeable membrane into the pipe. Practice close cooperation. The base of the tube root should be solid and flat. The sleeve is stable, and then a cylindrical waterproof membrane is added.
(2) If the pipe end is too large or the column cannot be covered with a waterproof membrane, first wrap a few rubber sheets tightly around the pipe body, and then wrap the anti-seepage membrane as a complete tube on the pipe, depending on the diameter Tighten with stainless steel hoops separately, tie them in two or more places, apply waterproof glue, and seal with sealant at the upper end of the interface.
(3) For some interfaces on the underground concrete wall, first, trim and level them at the interface. Paste a 5mm thick and 30-50mm wide rubber band along the interface line as a gasket. After laying a waterproof membrane, add a rubber cushion band on the surface. A 1-2mm thick stainless steel pressure plate is pressurized on top, and the steel plate is pulled tight with a pull rose to make the interface tight and watertight, and a waterproof sealant is added at the back seam.
Ⅳ. Construction of protective layer:
(1) After repeated inspections, confirm that the laps of the waterproof membrane are welded well and the large surface is not damaged, then a protective isolation cloth can be laid. Laying should be carried out in sequence, followed by pressing with stone powder or sand.
(2) Place a layer of stone powder (sand) on the protective cloth layer. The bucket truck carrying the material cannot walk directly on the waterproof film surface layer. A layer of stone powder (sand) more than 10 cm thick must be laid, and then 2 cm thick Wooden boards can only be used to carry hopper cars.
(3) When transporting large stones and materials to the lake, be careful not to throw them directly on the waterproof layer. Prevent stones and bricks from damaging the waterproofing membrane.
(4) After the waterproof membrane is covered, the overlapped part is left around. Sharp objects cannot be placed. Temporary protection measures must be taken. For example, cover with a cloth first, and then press on the cloth with wooden boards or bricks. You can also add 100. -150 thick stone powder layer.
(5) If you want to backfill the soil to make small islands or pile huge stones on the waterproof layer in the lake, you should pour a certain thickness of the concrete layer on the protective layer on the waterproof layer, and then do other construction on the concrete layer.
Ⅴ. Blind ditch, water collecting well, overflow well and water inlet pipe parts:
(1) The excavation of the blind ditch should choose the part that can fully drain and drain. The size of the blind ditch is 40 * 40cm. The collecting well is set in a place where the ground is easy to collect water, and the interval is reasonable. The diameter of the well is generally 1 * 1 * 1m.
(2) Drill enough holes for the 4 inch PVC pipe in the blind ditch. After the burial, the pipe should be covered with crushed stone and then stone powder.
(3) The connection device between the water in the lake and the groundwater in the catchment well shall be easy to operate and sealed to ensure that there is no water leakage when the water is filled in the lake. When the bottom of the lake is drained, the waterproof layer will not be caused by the pressure of the groundwater. drum.
(4) The overflow well should be able to drain excess lake water in a timely manner and facilitate drainage and cleaning of the lake bottom.
(5) the water inlet should be installed firmly and smoothly.