Glass fiber warp-knitted composite geotextiles belong to new geomaterials, there is no large-scale application precedent, this paper discusses how to make geotextile bag body to meet the design and construction requirements to meet the requirements of engineering applications.
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1 What is glass fiber geotextile material?
Glass fiber warp-knitted composite geotextile (hereinafter referred to as glass fiber geotextile) is made of glass fiber as well as woven fabric composite, which has been used in soft foundation treatment and road engineering in recent years. After the warp-knitted composite, glass fiber geotextile is significantly The significant features are large weight per unit area, high strength, low ductility, and It has the performance of the knitted nonwoven fabric.
2 Project profile
The XXP-SG section of the West Breakwater Project of Lianyungang Port, Jiangsu Province, China is a typical stone-throwing slope type breakwater structure, and glass fiber geotextile is used in the structure of the dike. In the embankment structure, glass fiber geotextile is used to make filling bags for embankment construction, in which glass fiber filling bags are divided into glass fiber A type and glass fiber B type. The fiberglass bags are divided into fiberglass type A and fiberglass type B. The fiberglass material that needs to be processed and bonded is mainly the type A bags.
Figure 1 Breakwater structure type diagram
Figure 2 Structure of glass fiber geotextile A type filling bag
3 Application characteristics and difficulties of glass fiber geotextiles
Glass fiber geotextile bags are used in breakwater projects, mainly to play the role of embankment body Reinforcing role, glass fiber mainly bears the load of the upper embankment structure. As a new material, glass fiber fabric weighs 1200g per square meter and has a tensile strength of 300kN/m or more. The geotechnical fabrics used in the past for breakwater construction were all ordinary woven fabrics. The previous geotextiles used in breakwater construction are ordinary woven fabrics (weight and tensile strength are much smaller than glass fiber geotextiles). It is the first time that this material is used as a breakwater dike material on a large scale. How to process and shape the glass fiber geotextile and smoothly carry out the construction is the How to process and shape the glass fiber geotextile and construct it smoothly is the difficulty in the application of this material in engineering.
4 Glass fiber filled bag processing
1) Processing process selection
According to the design and relevant specification requirements, the strength of the geotextile after processing shall not be lower than the strength of the body material (300 kN/m), so the processing that, Therefore, the processing technology needs to be carefully selected.
Firstly, the traditional sewing machine sewing method is excluded. Because of the glass fiber, The material itself is flocculant, which is not easy to be sewn by sewing machine; using geotextile compound woven fabric for sewing. In the use of geotextile composite woven fabric for sewing, because the geotextile is needle-punch composite in the material, the strength after sewing is low. After sewing, the strength is low, and it is easy to fall off, so it cannot meet the design requirements.
The final choice is to adopt the epoxy resin bonded seam within 1 m width of the glass fiber geotextile at 5 m from the outside of the port. The program of using epoxy resin glued seam is carefully analyzed as follows.
① Epoxy resin adhesive has been applied quite widely, and there is a mature preparation method ② It is convenient to purchase raw materials for epoxy resin adhesive; ③ There are similar successful applications of epoxy resin for sewing and gluing 750g/m² geotextile in previous projects, so the epoxy resin is chosen for gluing glass fiber geotextile.
2) Formulation of epoxy resin adhesive
Epoxy resin 6101 is widely used and has excellent alkali resistance, acid resistance, and solvent resistance after curing. It has excellent alkali resistance, acid resistance, and solvent resistance after curing, as well as good adhesion, room temperature operation, easy construction, and other good technology, and the price is moderate.
According to the specification of epoxy resin 6101 and other reference materials, it is known that 4 factors have a direct influence on the strength of epoxy resin, curing agent, diluent (diethylenetriamine), and the strength of epoxy resin. Diluent (diethylenetriamine), and thinner (butyl glycidyl ether). In order to select the best epoxy resin ratio, three different ratios were formulated and the bonding, tensile and tensile strengths were measured. In order to select the best epoxy resin ratio, three different ratios were formulated, and the bonding and tensile tests were carried out, and the test results are shown in Table 1.
Table 1 Epoxy resin test ingredient list
| Amount of epoxy resin | Amount of curing agent | Amount of thinner | Gluing width | Tensile strength |
|---|---|---|---|---|
| 1 | 0.3 | None | 10 cm | 230 kN |
| 1 | 0.6 | None | 10 cm | 260 kN |
| 1 | 0.3 | Diethylenetriamine 0.07 Butyl glycidyl ether 0.15 | 10 cm | 320 kN |
From the test results in the above table, we can see that the third adhesive formula with The tensile strength of glass fiber geotextile bonding test reaches 320 kN/m, which meets the design requirements, so we finally choose the No.3 formulation as the adhesive formulation for this bonding. The test results of tensile strength of the bonded glass fiber geotextile specimens are as follows.
328 kN/m, 336 kN/m, 332 kN/m, 340 kN/m, 334 kN/m, 345 kN/m, 338 kN/m, 342 kN/m, 330 kN/m From the above data, the average strength was calculated as 336 kN/m. The average strength is 336 kN/m, which meets the design requirements. The finalized epoxy resin compounding ratio is shown in Table 2.
Table 2 Epoxy resin ingredient list
| Material name | Unit | Quantity |
|---|---|---|
| Epoxy resin（6101） | kg | 1 |
| Butyl glycidyl ether（501 | kg | 0.15 |
| Polyamide（650） | kg | 0.3 |
| Diethylenetriamine | kg | 0.07 |
3) Bag body size determination
The weight of the unit area of glass fiber geotextile reaches 1200g/m² and is processed into 16 m After processing into 16 m wide bags, the self-weight of glass fiber A type bags is about 3.4t. After finishing the processing, the bag is packed manually, the workers’ physical exertion is great, and the machinery is needed to assist, and In the process of dragging, it is easy to cause the bag to break; in the test phase, it is also found that due to The bag body is too heavy, it is easy to slide too fast in the process of laying down, causing material, Therefore, it is necessary to reduce the size of the bag while taking into account the construction efficiency and quality. Therefore, it is necessary to reduce the size of the bag, while taking into account the construction efficiency and quality, according to the comprehensive consideration, two glass fiber fabrics were selected to make an 8 m wide weight of glass fiber A type filling bag is 1.7t, which is convenient for bag packing and laying construction. The weight of the fiberglass A type filling bag is 1.7t, which is convenient for bag packing and laying out construction.
After the feasible processing size is clarified, according to the length of the filling bag of each section, the glass fiber fabric manufacturer is required to make the filling bag according to the requirements. The fiberglass fabric manufacturer is required to carry out the shaping process according to the requirements and perform the processing on each side of the 4 m width fiberglass fabric. 25 cm of woven fabric is reserved on each side of the 4 m width glass fiber cloth for the internal woven fabric of the filling bag. The sewing of the woven fabric bag body inside the filling bag.
4) Construction method
Spread the shaped and processed fiberglass fabric on the processing site, and first carry out sewing between the longitudinal bags, using the reserved 25 cm woven fabric, using sewing The sewing machine is used for sewing, with 3 channels of nylon thread, 7 mm stitch spacing, and the ding stitch method.
The joint part of the glass fiber A-bag is glued with the blended epoxy resin glue. The bottom layer of fiberglass material is evenly applied by brush according to the dosage, and the upper layer of fiberglass material is manually aligned with the glued part after the application is completed, and the upper layer is manually rolled and flattened by the bar and ballasted until the glued part hardens.
The joint part of the glass fiber B-bag does not need to be glued, and it can be sewn by hand using conventional technology. Hand sewing can be done.
5) Process optimization
- Longitudinal stay seam is not glued. Because the epoxy resin glue hardens after solidification, it is easy to occur brittle fracture in the packing process, which causes the fiberglass geotextile to break and affects the strength of the bag, so it is necessary to leave a certain gap in the gluing process to facilitate packing. Each piece of fiberglass fabric (4 m/block) is left with a 10 cm gap every 90 cm, and plastic film is padded at the bottom to prevent the outflow of colloid, and attention is also paid to ensure the effective width (1 m) of gluing at the seam.
- Seam flatness control. In the actual gluing process, it is impossible to completely achieve uniform application, in order to avoid uneven shrinkage of the gluing parts, should be taken to quantitative application, after the completion of the gluing using a heavy ballast, to be glued solidification hardening after unloading the heavy, in order to achieve the requirements of the control of the flatness of the seam.
- Reserve the bag construction connection pull ring. Due to the completion of the processing of glass fiber filling bag single size is only 8 m, in the construction of such as a single put down will be time-consuming and laborious, not conducive to the rapid formation of the construction section, so the processing needs to consider the construction requirements of multiple bags put down at the same time. In order to avoid the separation of the bags caused by the sea currents when they are lowered and the section is discontinuous, the reinforced tape edging should be sewn along the lowering direction when the bags are sewn, with 2 stitches for each reinforced tape and the spacing between stitches is not more than 7 mm.
6) Finished product formation and protection
Cover in time after packing, raise the bottom of the storage site with a wooden square, and the top covered with a colorful cloth to avoid sun and rain to prevent material aging; packing, lifting, stacking process is strictly prohibited. The use of iron hooks and other sharp objects is strictly prohibited in the process of packing, lifting, and stacking to prevent damage to the bag body. The bag body is not allowed to be damaged.
5 Conclusion
This project uses glass fiber geotextile to make the filling bag body, there is no similar There is no similar method and standard for the fiberglass geotextile bag used in this project. The research on the processing technology of glass fiber geotextile bags has improved the dike construction technology of the breakwater using glass fiber geotextile filling bags, which can provide a reference experience for the application of similar projects in the future. The study of glass fiber geotextile bag processing technology has improved the breakwater construction technology by applying glass fiber geotextile bags, which can provide reference experience for similar projects in the future.
[References]
[1] Application of glass fiber warp-knitted composite geotextiles in slope type breakwater [J]. Niu Yanzeng,Wu Chunyan. China Water Transport (2nd half month). 2017(02)
[2]Construction technology of glass fiber composite geotextile filled bags[J]. Fan Kaiyi,Du Wei. China Water Transport (second half of the month). 2015(06)
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