This article discusses the composition, role, usage, and precautions of geotextiles and geomembranes, and gives a detailed description of each main index to achieve the purpose of providing a technical reference for construction and design personnel.
Let’s dive right in now, and you can click on the question that interest you,
1 What are geosynthetics?
Geosynthetics material is a new type of geotechnical engineering material, which is made of synthetic fiber, plastic, synthetic rubber, and other polymers and glass fiber as raw materials of various types of products, placed on the surface of the soil or between the layers of the soil, to protect or strengthen the role of the soil. Geosynthetic materials can be divided into geotextiles, geomembranes (cloth), geocomposites, and geotechnical special materials. Geosynthetics can be divided into geotextiles, geomembranes (cloths), geocomposites, and geotechnical special materials, which have various functions such as impermeability, filtration, drainage, protection, isolation, reinforcement, and consolidation. In recent years, it has been widely used in various geotechnical projects, especially in water conservancy seepage control projects.
2 How to control the quality of geotextile laying
In the construction process, the supervising engineer shall supervise the contractor The supervisory engineer shall supervise the construction unit in accordance with the approved construction measures plan and the contract technical regulations. The supervising engineer shall supervise the contractor to operate in accordance with the approved construction measures plan and contract technical regulations, and strictly implement the “three inspections” system for process quality. Without the inspection visa of the supervising engineer, the next process is strictly prohibited to start work. The supervising engineer should also inspect, track, check, and record the operation process. inspection, tracking, inspection, and record, found to violate the technical rules and regulations The supervising engineer should also inspect, follow up, check and record the operation process, and if he finds that the technical regulations are violated, he can take verbal warning, written warning until the instruction to rework, stop work and other ways to stop.
1）Raw material entry control
The contractor should contact the material manufacturer according to the technical specifications required by the design documents, and in addition to checking its product specifications and indicators, it should also ask the manufacturer for samples of geotextiles (membranes) and anvils (cloth generally with an area greater than 8m²), which are tested by qualified and competent testing units. Test items should be determined according to the design requirements, usually unit area quality degree, strip stretching, grip stretching, tearing, top break, CBR top break, puncture, vertical permeability coefficient, static art pressure resistance, the reliability of the open joint agent. After passing the inspection, report to the supervising engineer for review and approval. When the supervising engineer examines, he should check the inspection test report of the testing unit, reliability test report of the adhesive, geomembrane adhesive test report, manufacturer, product label, production date, number and product specification, etc. The materials without the supervising engineer’s approval shall not be used in the work.
2）Raw material storage
During transportation, raw materials should not be exposed to direct sunlight in transportation, should be covered or packed; in storage, should avoid sunlight When stored, avoid sunlight, keep away from fire, and the storage period shall not exceed the effective period of the products. The storage period shall not exceed the validity period of the products; all kinds of products shall be stored separately, and the adhesive shall be stored separately from the geomembrane and geotextile. Geotextile fabric should be stored separately.
3） Acceptance of geomembrane laying base surface
Before the geomembrane is laid, the debris on the base surface should be removed and dried. The size, flatness, compaction, and bedding layer of the base surface should be clean. Drainage The infiltration facilities, geomembrane fixed ditch, etc. should be checked and signed by the supervisor. No geomembrane laying shall be carried out without inspection and visa.
4) Geomembrane connection
Geomembrane connection includes the connection between geomembrane and vertical impermeable wall, the connection between geomembrane, the geomembrane itself, the upper part of the geomembrane, and the top of the good capping platform or reinforced concrete floodwall. Geomembrane connection The geomembrane should be connected to the vertical impermeable wall first, and then to the geomembrane to the top of the good capping platform or reinforced concrete floodwall. wall. The constructed geomembrane joints should be properly protected Protected to avoid human factors or mechanical damage.
Method of connecting the bottom of geomembrane
①The bottom of the geomembrane collides with the vertical impermeable wall. should wait until the construction of this section of the wall is completed and approved by the supervisor The construction of joint processing shall be carried out only after the construction of this section of wall is completed and approved by the supervisor.
② When the bottom of the geomembrane is embedded with the wall, the geotechnical joint in the Geomembrane near the wall of the impermeable wall should be folded 10cm to prevent Uneven deformation of the foundation.
③When connecting the bottom of the geomembrane expansion joint, the contractor should paste another 20cm wide geomembrane strip on its joint boundary to strengthen the structure to prevent water leakage.
Self-exclusion method
① Geomembrane should be tested by field test. The strength of the geomembrane should not be reduced after the knotting, and the knotting agent should be soaked in water
The strength should not be lower than the design strength. After passing the test, and reported to the supervising engineer for approval, before construction.
② before the construction of an open knot, should check whether there is damage, found damage should be immediately repaired. Should be ready to plan the light board, open knot construction, board pre-pad in the lower part of the geomembrane, flatten the membrane body, in the interface with the electric blowing wind to dust after the application of open knot agent, according to the performance requirements of the open knot agent to open knot, and constantly with cotton yarn rub pressure. The width of the geomembrane’s own private joints is generally 10cm and should ensure that the width of the junction is not less than 8cm.
③ geomembrane itself should be first in the indoor open knot, splicing workshop should have a roof to prevent rain, natural ventilation, easy to bur knot agent and other organic solvent evaporation, and should strengthen the workers labor protection measures.
④ site open knot, the contractor should be based on different climatic conditions, take different construction measures, sunny days need to wipe diligently to prevent dust and debris fall to the open knot surface; rainy days ready should rack canopy, must keep the open knot surface dry and Her rubber dry (or according to the factory regulations and requirements of the use of open knot), has been open good geomembrane Must be covered with rain cloth to prevent damage, to have been spliced good geotechnical Geomembrane left edge interface, should be protected by film to prevent the interface geomembrane is contaminated. Geomembrane is contaminated.
5) Geomembrane seam detection
Visual inspection.
Observe whether there is any leakage of joint, whether the seam is free of scalding damage, no abrasion wrinkle, whether uniform, etc.
On-site inspection
All welds should be inspected. Inspection. Commonly used vacuum method and inflation method. ① Vacuum method. The use of suction cups, vacuum pumps, and vacuum Machine set of equipment. Test the part to be measured when the brush is clean, self Soap and water, put on the suction cup, press, pump, and vacuum machine. Vacuum pump and vacuum machine set of equipment. When testing the parts to be tested, brush clean, soap and water, put on the suction cups, press, vacuum pump, and vacuum machine set of equipment. Apply soapy water, put on the suction cup, press it tightly, and pump the vacuum to negative pressure. 0.02-0.03MPa, turn off the air pump. Stand still for about 30s, see the suction whether there is a soap bubble in the transparent cover of the foot, and the vacuum degree has decreased or not. If there is, it means air leakage and should be remedied. ②Inflation method. The welding seam is double, leaving a cavity of about 10mm between the two. 10mm cavity. Seal both ends of the section to be tested, insert the steam needle, inflate to 0.05 ~ 0.20MPa (depending on the film thickness selection), the 30s, observe the vacuum table, such as air pressure does not drop, that does not Leakage, seam qualified, otherwise should be promptly repaired. ③Sampling test. About 1000m3 Take a test piece and make a tensile strength test. Tensile strength test, the required strength is not less than 80% of the parent material, and the specimen fracture shall not be in the joint, otherwise the quality of the joint does not Otherwise, the quality of the joint is not qualified.
6) Geomembrane Laying
- Geomembrane laying should be carried out in dry and warm weather.
- In the process of laying, in order to relieve the membrane stress conditions and adapt to the deformation of the embankment base, it is necessary to lay the geomembrane at intervals along the laying axis. conditions and adapt to the deformation of the embankment base, an expansion joint should be set up along the laying axis every 100m along the laying axis and set up an expansion joint between the geomembrane and other impermeable bodies. The expansion joint should be set up according to the requirements of the geomembrane and other impermeable body joints, as well as the laying corners and folding lines. Expansion joints shall be made according to the requirements shown in the design drawings.
- When laying, it should not be too tight and should leave enough margin (about 1.5%), and generally adopt the wave-shaped slack laying type, which should be coordinated with the filling of the embankment base. The construction should be coordinated with the filling of the embankment base.
7) Soil backfill
After the geomembrane is laid and checked, it should be backfilled according to the design (1) For the filler on both sides of the geomembrane, the particle size should be strictly controlled. diameter composition, generally using heck soil, and do not allow the inclusion of sharp-edged gravel (2) The contractor should plan the construction road, take reliable engineering measures for vehicles and other mechanical equipment to cross the geomembrane and construction area (such as setting up protection frame), and coordinate the backfill protection material and geomembrane laying construction. (3) Construction machinery or human damage to geomembranes should be avoided during the construction process. Once geomembranes are found to be damaged, report to the supervisory authority and replace the damaged parts or make repairs according to the instructions of the supervisory authority.
8) Acceptance of geotextile laying substrate
Before geotextile laying, the debris on the base surface should be cleared, geotextile fixed ditch, etc. should be checked and signed by the supervising engineer.
Certificate, the size of the base surface, flatness, compaction and mat laying, geotextile laying without inspection visa shall not be carried out.
9)Geotextile connection
(1) Adjacent geotextile blocks can be lapped or sewn together. The lap width of flat ground is 30cm, the uneven ground should be not less than 50cm, underwater paving should be appropriately widened. (2) It is expected that the geotextile may be larger during the work when the geotextile is pulled apart due to displacement, it should be sewn. (3) The connection with the slope structure should be connected according to the design document. (3) The connection with the slope structure should be properly connected according to the design document, no gap should be left, and the combination should be good. The upper part of the paving to the road requires good protection to prevent damage by humans and animals.
10)Geotextile laying
(1) Geotextile should be cut according to the requirements of the project, and geotextile should be repaired or replaced immediately when it is damaged. It should be repaired or replaced immediately when it is damaged. (2) The laying requirements are smooth, loose, and tight, spreading width, to Avoid geotextile being damaged and keep it free from pollution. Hairdressing is not The fabric should be tautly pulled too tightly, the fabric should be closely attached to the foundation, leaving no gaps. (3) The slope surface should be laid from bottom to top, and the top and foot of the slope should be fixed with an anchor ditch or other reliable methods, and the anchor length should be more than 50cm. The length should be more than 50cm and the continuity with the structure of the slope. No gaps shall be left and the combination shall be good. (4) Laying workers should wear soft-soled shoes to avoid damaging the geotextile. Geotextile. (5) After the geotextile is laid, it should be protected from direct sunlight. Fill with paving, or take protective measures. (6) geotextile laying construction process, the contractor should Do a good job at the scene “three checks”, the supervising engineer should line side Station supervision, geotextile laying inspection should be carried out on-site visa. Sign After the certificate, only after the implementation of the cover. (7) The construction process should avoid construction machinery or man-made damage to the geotextile. Once the geotextile is found to be damaged, report to the supervisory agency. Once the geotextile is found to be damaged, report to the supervisory authority and replace the damaged part or carry out repair according to the instructions of the supervisory authority.
3 Conclusion
This paper summarizes the composition, function, usage, and precautions of geotextiles and geomembranes, and explains the importance of using geotextiles and geomembranes, which provides a good reference for relevant construction and management personnel.
【References】
[1] Application of geotextiles in temporary drainage facilities for sandy soil roadbed construction [J]. Wei W. Guangdong water conservancy and hydropower. 2013(S1)
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