1. Geomembrane field

The geomembrane stacking site should be selected in a high terrain area, requiring a flat ground, no tree roots, sundries and other items that may cause damage to the geomembrane, and at the same time, it is required to stay away from fire sources and harmful chemicals. Each stockyard covers an area of ​​about 450m2. 2 stacks can be stacked, the stack spacing is 3m, and fire escapes are reserved. The stack height is not more than 4 layers, the length is not more than 20 rolls, and each stack can be stacked with 2mm thick geomembrane 58800m2. The site must reserve the working space of vehicles (cranes and transport vehicles) for loading and unloading film and the site for unloading (film exhibition, cutting). If the site is restricted by terrain, the reserves can be appropriately reduced, but safety must be guaranteed.


2. Geotextile and GCL stockyard

Geotextiles should be transported away from fire sources and chemically corrosive substances. At the same time, high terrain and flat areas should be selected, and drainage should be smooth to prevent geotextiles from being soaked in water. Be careful during loading, unloading and transportation to avoid breaking the package and contaminating the material. The geotextile can be set up in a separate yard or stored together with the geomembrane. This project plans to store the geotextile and GCL bentonite pad on the same site. .

GCL bentonite pad is mainly used as auxiliary anti-seepage layer of HDPE geomembrane. The amount of bentonite used in this project is 4800g/m2. 5.8m, 40m long, 1.14T in weight, packed with plastic film for external use. The material yard should be selected in a flat and high terrain area. During loading, unloading, transportation and storage, it should be handled with care, and brutal operation is prohibited. Do not damage the waterproof plastic outer packaging to prevent moisture, mechanical damage and vibration. If necessary, 1mm HDPE geomembrane should be used for backing protection. If the site has accumulated water or the base is uneven, the bottom of the geotextile and GCL bentonite pad must be raised with a log to avoid being soaked in water or breaking its outer packaging and reducing its performance.

⑶HDPE pipe yard

Since HDPE pipes are mainly used for leachate drainage, they are all installed at the bottom of the landfill. Therefore, in order to reduce the secondary handling volume of the construction site, speed up the construction period and ensure the quality. HDPE pipe material yard should be placed in convenient transportation for easy transportation and handling.


⑷ On-site inspection

When the material enters the site for unloading and stacking, it is necessary to check whether the factory label of each roll of material is complete and complete, and compare it with the manufacturer's "factory inspection report" to check the appearance and packaging quality; compare the performance indicators of the manufacturer's "factory inspection report" with The performance indicators of the bidding are compared; at the same time, the sampling is witnessed on-site under the supervision of the owner's on-site representative and the supervision engineer, and the on-site sampling materials are sent to the authoritative testing and appraisal unit authorized by the national quality supervision and inspection department for re-testing, and the use of unqualified products is strictly prohibited. Finally, the relevant information is prepared and sent to the owner for inspection and filing.

The HDPE impermeable membrane is purchased and ordered, constructed by a professional team, and the joint fusion conforms to the product design. The middle sand layer under the anti-seepage film is compacted by rolling with a roller, the surface is smooth and smooth, and there should be no obvious depressions and protrusions, and no sharp corners.

5.2.4 Filling with pebbles: After the flower tube is installed, on the basis of the correct self-inspection, the quality inspector shall report to the supervisor and Party A for acceptance. After passing the test, start backfilling with pebbles. The size of the pebbles is 16-50mm. The material stacking site shall be transported to each area by scraper trucks, and then manual carts shall be used according to the laying position and height in the drawings. Since geotextiles have been prepared at the bottom of the site, scaffolding boards shall be laid during carts to prevent damage to the geotextiles.


Construction deployment and construction layout

The specific construction sequence of the landfill site: site leveling and trimming of the site bottom and side slopes → excavation of blind ditch for guide drainage at the site bottom and anchoring ditch at the side slope and pit opening → laying clay layer → laying bentonite → anti-seepage membrane → geotextile → pressing Solid clay → geotextile → coarse sand cushion for collection pipe → leachate collection branch pipe → leachate collection main pipe → pebble filling → geotextile → air-conducting gabion.

Landfill Engineering

Site leveling is carried out with bulldozers and scrapers.

Anti-seepage membrane (HDPE anti-seepage membrane, geotextile, GCL bentonite)

All construction personnel, materials and construction equipment are in place. After the materials are delivered to the site, they will be accepted and qualified for use. The welding rod and the welding equipment are transported to the site at the same time. Keep it clean to prevent oil, dust and other contamination.

HDPE geomembrane construction method and process flow


⑴ construction preparation

Before the HDPE geomembrane is laid, the debris on the surface of the base layer that may cause damage to it must be cleaned. Construction equipment, machinery and HDPE membrane materials must be inspected before construction, and the mechanical damage and production damage, holes, breakage and other defects found have been recorded and repaired. The damaged and difficult to repair geomembrane must be cut off, and the quality of the geomembrane must be approved by the on-site engineer and supervisor before construction.

General waste landfill construction process flow chart

Acceptance of the base layer→300g/m2 geotextile construction under the slope membrane→HDPE geomembrane construction→500g/m2 geotextile construction on the slope membrane→300g/m2 geotextile construction under the membrane→HDPE geomembrane construction→00g/m2 geotextile construction →DPE leachate collection pipe construction →Completion inspection

HDPE geomembrane construction process flow chart

Laying, cutting → aligning, lap jointing → temporary anchoring → wiping dust → welding test → welding → testing → repairing → re-inspection → acceptance


HDPE geomembrane construction method

① Laying principle

A. In general, each slope section should be laid with a whole piece of geomembrane, that is, no transverse joints are allowed, and the upper end of the HDPE geomembrane must be reliably anchored, and the lower end must be reliably welded with the anchored HDPE geomembrane of the next slope section.

b. The laying of the geomembrane should be along the direction of the maximum gradient line, and at the same time, it should be as perpendicular to the central axis of the anchoring ditch as possible. If the above conditions are not met, the anchoring effect should be the best for laying, and flexible treatment should be carried out according to the site conditions.

c. Due to the limitation of natural terrain conditions, the HDPE geomembrane must be reasonably cut for the possible fan-shaped or trapezoidal areas. In order to ensure the reliable anchoring of HDPE geomembrane, the width of the upper end of each membrane must be greater than or equal to 1.5m; in order to avoid excessive stress concentration, the distance between the welds at the lower end should not be less than 0.5m.

D. At the intersection of the side slope and the bottom of the reservoir, the HDPE geomembrane generally needs to be extended from the side slope to the bottom of the reservoir by more than 1.5m to avoid excessive stress concentration.

E. At the bottom of the landfill, there are leachate drainage pipe networks, pipe trenches, etc., which are the concentrated parts of the leachate and the top priority of the anti-seepage project. Therefore, in order to reduce the welding seam, the method of laying the whole film is generally adopted. In other parts of the silo bottom, it should be laid along the specified slope or natural slope of the silo bottom as much as possible, and the membrane on the slope should be kept on top and the membrane on the bottom of the slope should be laid down, that is, laying along the slope.

② laying requirements

Smooth, moderately tight, close to the base layer, leaving enough margin to prevent the slope foot from arching or floating due to shrinkage stress.

③ Overlap and alignment

After laying and checking each piece of geomembrane, overlap the next piece of geomembrane on the previous piece with a reference of not less than 10cm. The overlap size is based on the surface mark of the geomembrane. Use pressure clamps when moving and adjusting the geomembrane. After the geomembrane is adjusted and straightened, temporary anchoring (usually pressing soil bags or sand bags) must be carried out to prevent the material from slipping or moving.

④Welding

There are two main types of welding: double-sided welding and extrusion welding. Double-track welding is mainly used for large-area HDPE geomembrane welding, and extrusion welding is mainly used for repairing and strengthening areas.

A. Trial welding: Before the formal welding, on-site welding test must be carried out. The size of the test piece is 100cm×30cm, and the overlapping part is more than 10cm in the middle seam. After the test is completed, four test blocks with a width of 2.5 cm are cut from the sample, and the tear strength and the welding seam shear strength are quantitatively tested with a tensile meter according to the ASTMD4437 method. When the test block has the following results in the tear test and shear test, it will be passed: a. The material itself is damaged during the tearing strength test; b. The damage is repairable.

b. Before welding, clean the two overlapping HDPE geomembrane surfaces within 16-20cm, wipe off dust and dirt with a damp cloth, and keep them clean and dry.

c. After the HDPE geomembrane to be welded is cleaned and dried, the construction is started immediately, and the joints are welded to avoid the influence of the geomembrane on the construction quality due to thermal expansion and contraction or weather changes.

D. After the HDPE geomembrane is laid, it is not allowed to backfill immediately. If it is backfilled immediately, it is possible that when the geomembrane shrinks, it is easy to cause stress and arching at the slope foot and other parts, which will affect the quality of the project. At this point, it is only necessary to do as little backfill as possible to stabilize the geomembrane and sand bag until the geomembrane is fully shrunk.

⑤ Inspection test

Inspection test is divided into non-destructive inspection and destructive test.

The non-destructive tests mainly include the gas-filled method, the vacuum method and the electric spark method, of which the gas-filled method is suitable for the inspection of heat-sealed double welds; the vacuum method and the electric spark method are suitable for the inspection of extrusion fusion welded single welds.

A. Inflation method: temporarily seal both ends of the entire weld to be inspected, insert a special hollow needle between the welds, and inflate with a pump. Keep it under 0.2Mpa pressure for 5 minutes, if the pressure gauge value does not drop, it is qualified. Then open the remote temporary seal and observe the pressure reduction process of the pressure gauge to check whether the weld of the HDPE geomembrane is penetrated. b. Vacuum method: spray and wet the area to be tested with soapy water, start the vacuum pump, press the vacuum cover down on the area to be tested, open the vacuum valve, and keep it under the pressure of 0.028~0.055Mpa (4~8psi) for more than 10 seconds. Observe whether there are bubbles on the transparent vacuum cover, if no bubbles are generated, it is qualified.

c. Electric spark method: Using the characteristics of HDPE geomembrane as an electrical insulator, when the instrument scans the part where there are holes and the ground is connected, a bright electric spark is generated.

D. Destructive test: During the project acceptance, whether it is a heat-sealed double weld or an extruded single weld, the strength test of the weld shall be carried out. According to the standard of taking one piece per 10,000 square meters, it shall be designated by the owner and the supervisor or randomly selected. Take samples and send them to the department authorized by the national quality inspection department for inspection and identification. The shear and peel strength of the weld shall not be lower than the specified standard.

⑥Defect repair

After the project is completed, destructive or non-destructive tests are carried out. Any part that fails the test must be repaired. For different situations, there are mainly the following repair methods:

Main construction repair methods


Precautions

①The surface of the base layer must be dry during welding, and the surface of the HDPE geomembrane must be wiped clean with gauze before construction.

② It is forbidden to bring fire into the construction site.

③ It is forbidden to wear spiked shoes, high heels and hard-soled shoes on the geomembrane. Do not discard cigarette butts and other items that are easy to damage the geomembrane on the HDPE membrane. At the same time, contact between hot tools and the geomembrane is strictly prohibited.

④The geomembrane materials stored on site shall not be exposed to the sun for a long time, and shall be kept away from fire sources.

⑤ No vehicles are allowed to pass directly on HDPE and non-woven fabrics.

⑥ In order to avoid material shrinkage, wrinkle phenomenon or material stress due to temperature change, the laid HDPE geomembrane should be welded in time, and the protective material should be covered in time after passing the inspection.

⑦ Geomembrane welding should be carried out in the weather where the temperature is above 5°C and the wind force is below level 4 without rain and snow.

⑧ During the welding process of HDPE film, the supervising engineer should be invited to check the operation procedures, laying and welding quality in time, and rectify in time if any quality problems are found.

⑨ The geomembrane anchoring ditch shall not have tree roots and obvious thorns.

⑩When laying HDPE geomembrane and the diversion layer and protective layer on the geotextile, because the HDPE geomembrane is not allowed to be rolled by a trolley exceeding 4200N/m2, a 1m-thick soil layer must be placed in advance before the trolley is allowed to pass. , so as not to damage or cause dark injury, reduce the anti-seepage effect.

5.2.3.4 Geotextile construction method

⑴ basic requirements

Before the construction of the geotextile, the surface of the HDPE geomembrane must be checked and accepted together with the owner, the supervisor and the design unit. After the HDPE membrane has been completely repaired and passed the acceptance, the "Concealed Engineering Acceptance Form" can be filled in before the geotextile can be laid.

(2) Construction methods and processes

①There are three ways to lay geotextiles, namely lap joint, stitching and welding. This project mainly uses hand-held electric sewing machine for sewing, and the lap width is not less than 20cm.

②Before laying geotextiles, the laying range must be measured, and the appropriate laying method must be determined according to the requirements of the design and on-site supervision engineers.

③ The geotextile on the slope shall be laid from top to bottom, that is, the laying direction of the geotextile shall be perpendicular to the direction of the slope, and there shall be no transverse joints within 1.5 meters of the slope surface and the slope foot with a slope greater than 10%. When laying, the slope is first and then the bottom of the silo, and make sure that the bottom is flat. After the geotextile is laid, it will be backfilled in a timely manner after being approved by the on-site supervision engineer.

④The geotextile must be buried in the anchoring ditch together with the geomembrane in the part with the anchoring ditch.

⑤ The work shoes and construction equipment used by the construction personnel shall not damage the geotextile, and the construction personnel shall not smoke on the laid geotextile or poke the geotextile with sharp tools.

⑥ In order to ensure the safe laying of geotextiles, open the packaging film before laying the geotextiles, that is, lay a roll, open a roll, and inspect the appearance quality.

⑦ Geotextiles should be checked and accepted in time after they arrive at the site. After the construction is completed and qualified, they must be certified in time.

GCL Bentonite Cushion Construction Method#Geomembrane#


(1) GCL bentonite pads should be transported and laid by cranes due to their large self-weight. It is necessary to avoid vibration and impact during the lifting process as much as possible, and it is best to place them in place at one time.

(2) The base layer of the GCL bentonite mat is laid, and there shall be no objects such as stagnant water, cracks, sharp objects and tree roots that may pierce the GCL bentonite mat.

(3) The surface of GCL bentonite pad is only allowed to be constructed by approved equipment to avoid damage to GCL.

(4) Work shoes are soft-soled work shoes without heels. Large-toe shoes or shoes with iron soles and heels are not allowed to enter.

⑸ GCL bentonite mats cannot be installed in places with accumulated water, and installation in rainy and windy weather is strictly prohibited; the laid GCL must be dry and tidy to avoid artificial wrinkles and creases.

⑹ GCL bentonite pads are not allowed to be freely opened by gravity on the top of the slope. Mechanical lifting is used to assist the construction method of manual laying.

(7) The GCL should be parallel to the slope line when installed on the slope, and the overlap width should be at least 1m.

(8) GCL bentonite mats installed every day must be covered with geomembrane or waterproof rain cloth on the same day, and cannot be stacked outdoors without any covering; in hot weather, GCL should be covered within 8 hours after installation.

(9) The lap width of the GCL longitudinal lap shall not be less than 300mm, and the longitudinal lap shall be sewn by the sewing method permitted by the supervisor. When laying at the bottom of the field, the length of the overlap at the end should not be less than 600mm; there should be no loose soil particles or other debris in the overlap area.

(10) After the installation of the GCL, our company will use a metal detector to detect whether there are residual broken needles in the GCL. The supervision unit must be present during the detection and confirm the result in writing.

(11) For the place where bentonite needs to be added in the overlapping area, sodium-based bentonite should be placed on the surface of the overlapping area at the edge of the lower sheet, with a width of 450mm and a quantity of 0.4kg
/m.

(12) If the GCL is damaged during installation, a patch can be cut to cover the damaged area. The patch can be cut from the new GCL sheet, and its maximum size should be 300mm beyond the periphery of the damaged area. Before placing the patch, use microbentonite or creamed bentonite around the damaged area and use an approved method to secure the patch to prevent it from moving.
We develop, manufacture and supply innovative and reliable geosynthetics to improve the performance of our customers' products. The main business of the company is the production and export of geotextiles, geomembranes, geogrids, geounits, three-dimensional composite drainage nets, eco-bags, drainage panels and other one-stop services. Our customers come from more than 60 countries on five continents.


Geotextile OEM& Manufacturer Email: [email protected]
Company Name: GD Geosynthetics
Contact Person: NOLAN
Email: [email protected]
City: Foshan
State: Guangdong
Country: China
Website:https://gdfaucet.cn