Geomembrane weld penetration performance test sample, sample making mold and measuring instrument

Abstract

The utility model relates to geomembrane weld penetration performance test sample, sample making mould and measuring instrument. The sample is based on geomembrane weld structure design, and the whole is rectangular, including geomembrane weld test piece, upper layer impermeable water welding ring and lower layer impermeable water welding ring, and two impermeable water welding rings are respectively equipped with sealing ring groove;The geomembrane weld test piece is made by two pieces of geomembrane lap joint first through hot melt welding and then through cutting;The impermeable water welding ring is formed by surfacing with the self -designed sample making mould and extrusion type plastic welding gun. The sample making mould is equipped with clamping groove and alternative clamping plate, and is used for the manufacture of different shape geomembrane weld penetration performance test sample. Using the above sample, combined with the matching measuring instrument, the penetration performance test can be carried out. The utility model can solve the problem that the measuring instrument clamp and the sample are not close enough in the prior art, and the measuring result is not accurate, and the penetration performance of geomembrane weld can be determined successfully.

Description

Technical Field

[0001] This utility model relates to a test specimen for the permeability performance of geomembrane welds, a specimen preparation mold, and a measuring instrument, and belongs to the field of geomembrane permeability performance testing. Background Technology

[0002] Geomembranes, with their low cost, convenient construction, and excellent permeability, are widely used in seepage control projects such as reservoirs, canals, and landfills. However, due to limitations in production technology, it is currently impossible to directly produce geomembranes of the same width as those used on construction sites. Geomembranes supplied in roll form must be welded together to form large-area seepage control layers of a specific shape and size. Because the selection of welding parameters during geomembrane welding often lacks scientific basis, and the permeability of geomembranes is difficult to assess, the weld seams often induce leakage, causing geomembrane seepage control failure. Accurately obtaining the permeability performance of geomembrane weld seams through testing helps guide the selection of welding parameters during the welding process and the establishment of relevant evaluation standards.

[0003] Currently, the testing of geomembrane permeability in China mainly refers to standard GB / T 19979, which includes tests for hydrostatic pressure resistance and permeability coefficient of geomembranes. Because geomembrane welds often have protrusions or depressions at the weld location, resulting in poor surface smoothness, the sample preparation methods provided in the current standard cannot effectively improve the smoothness of the weld area. Furthermore, the specified circular specimens are prone to damaging the original weld structure during cutting, affecting the representativeness of the test results. In addition, the testing instruments (fixtures) provided in the current standard cannot fit the specimen tightly, easily leading to leakage and causing the test results to deviate significantly from the true values. Therefore, the sample preparation methods and testing instruments in the existing standard are not suitable for testing the permeability of geomembrane welds, and there is an urgent need to develop specialized testing techniques for this unique structure. Utility Model Content

[0004] The main objective of this invention is to overcome the problems existing in the prior art and to propose a test specimen for the permeability performance of geomembrane welds, a corresponding specimen preparation mold, and a corresponding measuring instrument. First, the test specimen for the permeability performance of geomembrane welds is prepared using the specimen preparation mold, and then the specimen is tested using the corresponding measuring instrument. This method can successfully determine the permeability performance of geomembrane welds, thereby solving the problem of leakage caused by insufficient tightness between the test instrument clamp and the specimen during the measurement process in the prior art, which leads to inaccurate measurement results.

[0005] The technical solution of this utility model to solve its technical problem is as follows:

[0006] A geomembrane weld permeability test specimen includes a geomembrane weld specimen formed by welding two geomembranes; the geomembrane weld specimen has two hot wedge welds and an air inlet channel in the middle, the air inlet channel being located between the two hot wedge welds and parallel to each hot wedge weld; an upper waterproof weld ring is sealed and fixed to the upper surface of the geomembrane weld specimen, and a lower waterproof weld ring is sealed and fixed to the lower surface of the geomembrane weld specimen; the upper and lower waterproof weld rings are both rectangular rings; a first sealing ring groove is provided on the first side of the upper waterproof weld ring away from the geomembrane weld specimen, and a second sealing ring groove is provided on the second side of the lower waterproof weld ring away from the geomembrane weld specimen; the air inlet channel of the geomembrane weld specimen is sealed at both ends.

[0007] The test specimen is equipped with an upper waterproof weld ring and a lower waterproof weld ring, and further has a first sealing ring groove and a second sealing ring groove, so that the test specimen can be sealed with the corresponding measuring instrument, thereby solving the problem of inaccurate measurement results due to leakage in the existing technology.

[0008] The technical solution for further improving the test specimen of this utility model is as follows:

[0009] Preferably, the geomembrane weld specimen is formed by welding a first geomembrane and a second geomembrane; a distance is left between the edge of the first geomembrane located inside the upper impermeable weld ring and the inner wall of the upper impermeable weld ring; a distance is left between the edge of the second geomembrane located inside the lower impermeable weld ring and the inner wall of the lower impermeable weld ring.

[0010] Preferably, in the projection on the same horizontal plane, the upper waterproof weld ring and the lower waterproof weld ring are rectangular and coincident; the central axis of the inflation channel is the axis of symmetry of the upper or lower waterproof weld ring; the first sealing ring groove and the second sealing ring groove are rectangular rings and coincident; the distance between the outer edge of the first sealing ring groove and the outer edge of the upper waterproof weld ring, and the distance between the inner edge of the first sealing ring groove and the inner edge of the upper waterproof weld ring are equal; the distance between the outer edge of the second sealing ring groove and the outer edge of the lower waterproof weld ring, and the distance between the inner edge of the second sealing ring groove and the inner edge of the lower waterproof weld ring are equal.

[0011] Preferably, in the projection of the same vertical plane, the first side of the upper waterproof welded ring, the second side of the lower waterproof welded ring, the first geomembrane, and the second geomembrane are parallel to each other; the shortest distance between the first side and the upper surface of the first geomembrane is the same as the shortest distance between the second side and the lower surface of the second geomembrane; the cross-section of the groove of the first sealing ring and the cross-section of the groove of the second sealing ring are respectively semi-circular, and the cross-sectional diameter of the groove of the first sealing ring is the same as the cross-sectional diameter of the groove of the second sealing ring.

[0012] Preferably, the upper waterproof weld ring, the lower waterproof weld ring, the first geomembrane, and the second geomembrane are made of the same material.

[0013] By adopting the above preferred scheme, the specific structural details of the test specimen for the permeability performance of geomembrane welds can be further optimized.

[0014] This utility model also proposes:

[0015] A sample preparation mold for testing the permeability of geomembrane welds as described above includes an inner cylinder and an outer cylinder coaxially fitted together. The inner and outer cylinders are both cuboids, with a gap between them. The top edge of the inner cylinder is fixedly connected to the top edge of the outer cylinder via a top plate. The top plate is rectangular and has a coaxial rectangular groove with an upward-facing opening and a semi-circular cross-section. Each side of the groove is located at the center of the corresponding side of the top plate. Each side of the top plate has an observation port located on the side of the top plate closest to the inner cylinder. Each observation port has a small door, which is movably connected to the corresponding observation port via a spring clip. Each vertical side of the outer cylinder has a feed inlet on its upper part, which corresponds to the observation port and is located below the corresponding observation port. Each feed inlet has a cover plate, which is movably connected to the corresponding feed inlet via a spring clip.

[0016] The mold for making this sample is specifically designed for the geomembrane weld permeability test sample mentioned above. By making an upper waterproof weld ring and a lower waterproof weld ring on the geomembrane weld specimen, a geomembrane weld permeability test sample is obtained for testing the geomembrane weld permeability.

[0017] The technical solution for further improving the sample preparation mold of this utility model is as follows:

[0018] Preferably, each vertical side of the inner cylinder and the outer cylinder is composed of a fixed plate and a sliding plate, respectively. The fixed plate is located at the upper part of the vertical side, and the sliding plate is located at the lower part of the vertical side. The sliding plate is slidably connected to the fixed plate via a slider-rail structure, which is composed of a locking slider and a rail.

[0019] Preferably, each vertical side of the inner cylinder and the outer cylinder includes two first vertical sides parallel to the hot wedge weld of the geomembrane weld specimen, and two second vertical sides perpendicular to the hot wedge weld of the geomembrane weld specimen; the bottom edge of the first vertical side is in contact with the upper surface of the geomembrane weld specimen; the bottom edge of the second vertical side is provided with a slot, and each slot is provided with a replaceable card plate, the bottom of the card plate having a notch that is in contact with the air channel of the geomembrane weld specimen; the bottom edge of the second vertical side also includes a first edge and a second edge that are in contact with the upper surface of the geomembrane weld specimen, the first edge and the second edge are inverted step shape, and the second edge is located below the first edge.

[0020] By adopting the above preferred scheme, the specific structural details of the sample preparation mold can be further optimized.

[0021] This utility model also proposes:

[0022] An instrument for measuring the permeability of geomembrane welds includes an upper and lower water collection tray. The bottom surface of the upper water collection tray is a perforated plate, and the top surface of the lower water collection tray is open. The top surface of the upper water collection tray is equipped with a permeable water collection pipe and an air vent valve, which are respectively connected to the internal space of the upper water collection tray. The bottom surface of the lower water collection tray is connected to an inlet pressure regulating device and a pressure display, which are respectively connected to the internal space of the lower water collection tray. The outer edge of the bottom surface of the upper water collection tray faces... A first mounting plate extends outward, and a second mounting plate extends outward from the outer edge of the top surface of the lower water collection pan. The first mounting plate and the second mounting plate are fixedly connected by fasteners. A sealing ring groove is provided at the bottom edge of the upper water collection pan, and a first sealing ring corresponding to the first sealing ring groove of the geomembrane weld permeability test specimen mentioned above is provided in the sealing ring groove. A sealing ring groove is provided at the top edge of the lower water collection pan, and a second sealing ring corresponding to the second sealing ring groove of the geomembrane weld permeability test specimen is provided in the sealing ring groove.

[0023] The instrument is compatible with the geomembrane weld permeability test sample mentioned earlier. The two fit together tightly without leakage, which enables accurate measurement of the geomembrane weld permeability.

[0024] Preferably, the upper and lower water collection trays are both cuboids; the permeate collection pipe is marked with graduations; and the first and second sealing rings are both rectangular rings aligned with each other.

[0025] By adopting the above preferred scheme, the specific structural details of the measuring instrument can be further optimized.

[0026] By adopting this utility model, a test sample for the permeability performance of geomembrane welds is first made using a sample making mold, and then the sample is tested using a corresponding measuring instrument. This enables the successful determination of the permeability performance of geomembrane welds, thereby solving the problem of leakage caused by insufficient fit between the test instrument clamp and the sample during the measurement process in the existing technology, which leads to inaccurate measurement results.

[0027] This invention fills the gap in existing national standards that do not apply to the testing of permeability performance of geomembrane welds, helps to explore the failure law of permeability performance of geomembrane welds, and thus guides the selection of welding parameters and the establishment of relevant evaluation standards during the welding process of geomembranes. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] Figure 1 This is an overall schematic diagram of the geomembrane weld permeability test specimen in Embodiment 1 of this utility model, wherein the left figure is a schematic diagram of the upper surface of the test specimen and the right figure is a schematic diagram of the lower surface of the test specimen.

[0030] Figure 2 This is a top view schematic diagram of the geomembrane weld permeability test specimen in Embodiment 1 of this utility model.

[0031] Figure 3 This is a front view schematic diagram of the geomembrane weld permeability test specimen in Embodiment 1 of this utility model.

[0032] Figure 4 This is a perspective view of the sample making mold in Embodiment 2 of this utility model.

[0033] Figure 5 This is a schematic diagram of the cutting of the geomembrane weld test specimen in Embodiment 2 of this utility model.

[0034] Figure 6 This is a schematic diagram of the process of making a waterproof weld ring using a sample making mold in Embodiment 2 of this utility model.

[0035] Figure 7 This is a perspective view of the geomembrane weld permeability testing instrument in Embodiment 3 of this utility model.

[0036] Figure 8 These are longitudinal cross-sectional views and transverse cross-sectional top views of the geomembrane weld permeability testing instrument in Embodiment 3 of this utility model, wherein Figure A is a longitudinal cross-sectional view and Figure B is a transverse cross-sectional top view.

[0037] Figure 9 This is a graph showing the seepage flow-time relationship of the geomembrane weld coefficient determination test in Embodiment 3 of this utility model.

[0038] Figure 10 This is a schematic diagram illustrating the calculation principle of the permeability coefficient of the geomembrane weld in Embodiment 3 of this utility model. In the diagram, Figure A is a schematic diagram of the permeation direction and region, and Figure B is a schematic diagram of the region marking.

[0039] Figure 11 This is a graph showing the weld permeability coefficient-time relationship of the test for measuring the permeability coefficient of the geomembrane weld in Embodiment 3 of this utility model.

[0040] Figure 12 This is a graph showing the relationship between seepage flow and water pressure difference in the hydrostatic pressure test of the geomembrane weld in Embodiment 3 of this utility model. Detailed Implementation

[0041] Example 1

[0042] The geomembrane weld permeability test specimen in this embodiment is a geomembrane double-wedge weld permeability test specimen designed for the common double-wedge weld in geomembrane seepage prevention projects.

[0043] like Figures 1 to 3 As shown, the test specimen for the permeability performance of geomembrane welds includes a geomembrane weld specimen 3. An upper waterproof weld ring 1 is sealed and fixed to the upper surface of the geomembrane weld specimen 3, and a lower waterproof weld ring 2 is sealed and fixed to the lower surface of the geomembrane weld specimen 3. Both the upper and lower waterproof weld rings are rectangular rings. A first sealing ring groove 41 is provided on the first side of the upper waterproof weld ring 1 facing away from the geomembrane weld specimen 3, and a second sealing ring groove 42 is provided on the second side of the lower waterproof weld ring 2 facing away from the geomembrane weld specimen 3. The upper and lower waterproof weld rings 1 and 2 prevent leakage during the test due to pores between the test instrument fixture and the geomembrane weld specimen. The first and second sealing ring grooves 41 and 42 are used to place rubber sealing rings during the test, improving the specimen's sealing performance. In addition, the difference between the outer and inner edge lengths of the upper waterproof weld ring 1 and the lower waterproof weld ring 2 is the same as the size of the test instrument clamp, which facilitates the clamping of the sample.

[0044] The geomembrane weld specimen 3 is welded from a first geomembrane 31 and a second geomembrane 32. The geomembrane weld specimen 3 has two hot wedge welds 6 and an air inlet channel 5 in its middle. The air inlet channel 5 is located between the two hot wedge welds 6 and is parallel to each hot wedge weld 6. Both ends of the air inlet channel 5 are sealed. A distance is left between the edge of the first geomembrane 31 within the upper impermeable weld ring 1 and the inner wall of the upper impermeable weld ring 1. A distance is also left between the edge of the second geomembrane 32 within the lower impermeable weld ring 2 and the inner wall of the lower impermeable weld ring 2. The upper impermeable weld ring 1, the lower impermeable weld ring 2, the first geomembrane 31, and the second geomembrane 32 are made of the same material.

[0045] In the projection on the same horizontal plane, the upper waterproof welded ring 1 and the lower waterproof welded ring 2 are rectangular and coincident; the central axis of the air-filling channel 5 is the axis of symmetry of the upper waterproof welded ring 1 or the lower waterproof welded ring 2; the first sealing ring groove 41 and the second sealing ring groove 42 are rectangular rings and coincident; the distance between the outer edge of the first sealing ring groove 41 and the outer edge of the upper waterproof welded ring 1, and the distance between the inner edge of the first sealing ring groove 41 and the inner edge of the upper waterproof welded ring 1 are equal; the distance between the outer edge of the second sealing ring groove 42 and the outer edge of the lower waterproof welded ring 2, and the distance between the inner edge of the second sealing ring groove 42 and the inner edge of the lower waterproof welded ring 2 are equal.

[0046] In the projection of the same vertical plane, the first side of the upper waterproof welded ring 1, the second side of the lower waterproof welded ring 2, the first geomembrane 31, and the second geomembrane 32 are parallel to each other; the shortest distance between the first side and the upper surface of the first geomembrane 31 is the same as the shortest distance between the second side and the lower surface of the second geomembrane 32; the cross-section of the first sealing ring groove 41 and the cross-section of the second sealing ring groove 42 are semi-circular, and the cross-sectional diameter of the first sealing ring groove 41 is the same as the cross-sectional diameter of the second sealing ring groove 42.

[0047] In this embodiment, both the first geomembrane 31 and the second geomembrane 32 are single-layer HDPE geomembranes with a thickness of 0.8 mm; the geomembrane weld specimen 3 is 300 mm long and 200 mm wide; the outer edge of the upper waterproof weld ring 1 and the lower waterproof weld ring 2 is 270 mm long and 180 mm wide, and the inner edge is 210 mm long and 120 mm wide; the overall thickness of the upper waterproof weld ring 1 and the lower waterproof weld ring 2 is between 35 mm and 40 mm respectively. For uneven areas of the geomembrane weld specimen 3, the thickness of the upper waterproof weld ring 1 or the lower waterproof weld ring 2 should be adjusted according to the height of the protrusions or depressions. Adjustments are made to ensure that the first side of the upper waterproof welded ring 1, the second side of the lower waterproof welded ring 2, the first geomembrane 31, and the second geomembrane 32 remain parallel to each other; the distance between the inner wall of the upper waterproof welded ring 1 and the edge of the first geomembrane 31 is 30mm, and the distance between the inner wall of the lower waterproof welded ring 2 and the edge of the second geomembrane 32 is 20mm; the outer edges of the first sealing ring groove 41 and the second sealing ring groove 42 are 250mm long, 160mm wide, and have a cross-sectional diameter of 10mm, with the corresponding edges 10mm from the outer and inner edges of the corresponding upper waterproof welded ring 1 or lower waterproof welded ring 2.

[0048] Example 2

[0049] This embodiment is a sample preparation mold designed for the geomembrane weld permeability test sample of Example 1.

[0050] like Figure 4 As shown, the sample preparation mold includes an inner cylinder and an outer cylinder coaxially fitted together. The inner cylinder and the outer cylinder are both cuboids, with a gap between them. The top edge of the inner cylinder and the top edge of the outer cylinder are fixedly connected by a top plate 17. The top plate 17 is a rectangular ring shape and has a coaxial rectangular ring groove 11. The opening of the groove 11 faces upward and has a semi-circular cross-section. Each side of the groove 11 is located at the middle of the corresponding side of the top plate 17.

[0051] Each side of the top plate 17 is provided with an observation port 12, which is located on the side of the top plate 17 closest to the inner cylinder. Each observation port 12 is provided with a small door, which is movably connected to the corresponding observation port 12 by a spring clip. In this way, by opening and closing the small door, it is convenient to observe whether the amount of material added is sufficient and to observe the solidification state of the molten material.

[0052] Each vertical side 13 of the outer cylinder is provided with a feed inlet 14 on its upper part. Each feed inlet 14 corresponds to an observation port 12, and each feed inlet 14 is located below the corresponding observation port 12. Each feed inlet 14 is provided with a cover plate, and each cover plate is movably connected to the corresponding feed inlet 14 by a spring clip. This facilitates the injection of molten material into the gap between the inner and outer cylinders.

[0053] Each vertical side 13 of the inner and outer cylinders is composed of a fixed plate and a sliding plate. The fixed plate is located at the upper part of the vertical side 13, and the sliding plate is located at the lower part of the vertical side 13. The sliding plate is slidably connected to the fixed plate via a slider-rail structure, which consists of a locking slider and a rail. In this way, when the sliding plate slides to the appropriate position, it can be locked by the locking slider to fix the position of the sliding plate.

[0054] Each vertical side 13 of the inner and outer cylinders includes two first vertical sides parallel to the hot wedge weld 6 of the geomembrane weld specimen 3, and two second vertical sides perpendicular to the hot wedge weld 6 of the geomembrane weld specimen 3; the bottom edge of the first vertical side is in contact with the upper surface of the upper geomembrane or the upper surface of the lower geomembrane of the geomembrane weld specimen 3; the bottom edge of the second vertical side is provided with a slot 15, and each slot 15 is provided with a replaceable card plate 16, the bottom of the card plate 16 having a notch that is in contact with the air channel 5 of the geomembrane weld specimen 3; the bottom edge of the second vertical side also includes a first edge 18 that is in contact with the upper surface of the upper geomembrane of the geomembrane weld specimen 3, and a second edge 19 that is in contact with the upper surface of the lower geomembrane of the geomembrane weld specimen 3, the first edge 18 and the second edge 19 are inverted step shape, and the second edge 19 is located below the first edge 18. In this way, the first vertical side and the second vertical side of the inner cylinder and the outer cylinder can be tightly fitted to the geomembrane weld specimen 3, which is conducive to the production of the upper waterproof weld ring and the lower waterproof weld ring; wherein, a card plate 16 with a suitable notch shape can be selected as needed so that the mold can fit tightly to welds of different shapes.

[0055] In this embodiment, the sample preparation mold is 270mm long, 180mm wide, and 35mm-40mm high, adjusted according to the degree of concavity and convexity on the surface of the geomembrane weld. The outer edge of the groove 11 is 250mm long and 160mm wide, 10mm from the outer edge of the mold. The groove 11 has a semi-circular cross-section with a diameter of 10mm. The adjustable height of the sliding plate is 0-20mm, the feed port diameter is 15mm, and the slot is 100mm long and 20mm wide.

[0056] The specific usage process of this embodiment is as follows:

[0057] Step 1: Weld two geomembranes according to the dimensions of geomembrane weld specimen 3 in Example 1. Then, cut off the shorter side edges of each geomembrane along each hot wedge weld 6 to obtain geomembrane weld specimen 3. The cutting process and location are as follows: Figure 5 As shown.

[0058] The second step involves using an extrusion-type plastic welding gun and a specially designed sample-making mold to fabricate the upper and lower waterproof welding rings. The specific fabrication process is as follows:

[0059] S1. Place the geomembrane weld test specimen 3 with the first geomembrane 31 facing upwards, in preparation for the fabrication of the upper waterproof weld ring 1.

[0060] S2, such as Figure 6 As shown, a pad or filler is placed under the geomembrane weld specimen 3 to keep the first geomembrane 31 and the second geomembrane 32 of the geomembrane weld specimen 3 horizontal and flat, and to fix the position of the geomembrane weld specimen 3 to prevent the waterproof weld ring from being uneven due to shaking of the geomembrane weld specimen 3 during the production process.

[0061] S3, such as Figure 6 As shown, the sample preparation mold is placed on the geomembrane weld specimen 3. According to the shape of the air channel 5 of the geomembrane weld specimen 3, a suitable notch shape of the clamping plate 16 is selected and each clamping plate 16 is fixed in the corresponding groove 15. The sliding plates of each vertical side 13 of the inner cylinder and the outer cylinder are adjusted and locked in place so that the bottom edge of the sample preparation mold is in contact with the geomembrane weld specimen 3.

[0062] S4, such as Figure 6As shown, select a feed port 14 and open its cover. Open the small door of the observation port 12 corresponding to the feed port 14. Insert the extrusion-type plastic welding gun into the feed port 14 and add molten material. When the molten material overflows from the observation port 12, control the welding gun to stop feeding and pull the welding gun out of the feed port 14. Close the cover of the feed port 14 and observe the solidification state of the molten material through the observation port 12. After the molten material has completely solidified, close the small door of the observation port 12. Select the next feed port 14 and repeat the above steps of S4 until all feed ports 14 have been processed. Since the molten material extruded by the extrusion-type plastic welding gun lacks fluidity and solidifies quickly, feed ports 14 need to be set on each vertical side 13 of the outer cylinder to form each side of the waterproof welding ring separately, thereby ensuring sufficient uniformity and avoiding the formation of voids.

[0063] S5. Open all the small doors of observation ports 12 to check the solidification degree of the molten material. After solidification is completed, remove the sample to make a mold. At this point, the upper waterproof weld ring 1 is completed.

[0064] S6. Place the geomembrane weld test specimen 3 with the second geomembrane 32 facing upwards, in preparation for the fabrication of the lower waterproof weld ring 2.

[0065] S7. Repeat S3 to S4; then, open all the small doors of observation port 12 to check the solidification degree of the molten material. After solidification is completed, remove the sample to make a mold; at this point, the lower waterproof weld ring 2 is completed.

[0066] S8. After the upper waterproof weld ring 1 and the lower waterproof weld ring 2 have completely cooled down, use an extrusion plastic welding gun to seal the two ends of the air channel 5 of the geomembrane weld specimen 3 with molten material; after complete cooling, the geomembrane weld permeability test specimen is obtained.

[0067] Example 3

[0068] This embodiment describes an instrument for measuring the permeability of geomembrane welds designed for the test specimen of geomembrane weld permeability in Example 1. The permeability of the geomembrane welds measured includes the permeability coefficient and hydrostatic pressure resistance.

[0069] like Figures 7 to 8As shown, the geomembrane weld permeability testing instrument includes an upper water collection plate 21 and a lower water collection plate 23, both rectangular in shape. The bottom surface of the upper water collection plate 21 is a perforated plate 22, and the top surface of the lower water collection plate 23 is open. The top surface of the upper water collection plate 21 is equipped with a permeable water collection pipe 26 and an air vent valve 28, which are connected to the internal space of the upper water collection plate 21. The permeable water collection pipe 26 is graduated. The bottom surface of the lower water collection plate 23 is connected to an inlet pressure regulating device 24 and a pressure display 25, which are also connected to the internal space of the lower water collection plate 23. The permeable water collection pipe 26 is used to measure the amount of water seeping through the geomembrane weld during the test. The inlet pressure regulating device 24 is used to control the inlet water and adjust the osmotic pressure during the test. The pressure display 25 is used to display the osmotic pressure value during the test.

[0070] A first mounting plate 29 extends outward from the outer edge of the bottom surface of the upper water collection pan 21, and a second mounting plate 30 extends outward from the outer edge of the top surface of the lower water collection pan 23. The first mounting plate 29 and the second mounting plate 30 are fixedly connected by fasteners. A sealing ring groove is provided at the bottom edge of the upper water collection pan 21, and a first sealing ring 27-1 corresponding to the first sealing ring groove 41 of the geomembrane weld permeability test sample is provided in the sealing ring groove. A sealing ring groove is provided at the top edge of the lower water collection pan 23, and a second sealing ring 27-2 corresponding to the second sealing ring groove 42 of the geomembrane weld permeability test sample is provided in the sealing ring groove. The first sealing ring 27-1 and the second sealing ring 27-2 are rectangular rings and aligned with each other.

[0071] In this embodiment, the upper and lower water collection trays are 210mm long and 120mm wide. The outer edge of the bottom surface of the upper water collection tray and the outer edge of the top surface of the lower water collection tray extend outward by 100mm respectively for mounting bolts and sealing rings. The perforated plate is 210mm long and 120mm wide. Each sealing ring groove has a semi-circular cross-section, with an inner edge length of 230mm, a width of 140mm, and a cross-sectional diameter of 10mm.

[0072] The specific usage process of this embodiment is as follows:

[0073] Step 1: Activate the water inlet pressure regulating device 24 to inject water into the lower water collection pan 23; after the lower water collection pan 23 is full of water, place the geomembrane weld permeability test sample above the lower water collection pan 23, and insert the second sealing ring 27-2 into the second sealing ring groove 42 of the geomembrane weld permeability test sample; place the upper water collection pan 21 above the geomembrane weld permeability test sample, and insert the first sealing ring 27-1 into the first sealing ring groove 41 of the geomembrane weld permeability test sample; fasten the first mounting plate 29 and the second mounting plate 30 with fasteners to press the geomembrane weld permeability test sample.

[0074] The second step is to inject water into the upper water collection tray 21 through the permeate collection pipe 26, adjust the air vent valve 28 to expel the air bubbles in the upper water collection tray 21, and fill the upper water collection tray 21 with water; record the scale of the permeate collection pipe 26 at this time.

[0075] The third step is to determine the permeability coefficient of the geomembrane weld and / or the hydrostatic pressure resistance of the geomembrane weld.

[0076] (1) For example, the specific process for determining the permeability coefficient of a geomembrane weld is as follows:

[0077] T1. Start the inlet pressure regulating device 24 and set the pressure value (in this embodiment, the pressure value is set to 0.1 MPa). Record the water pressure difference between the upper water collection plate 21 and the lower water collection plate 23 according to the pressure display 25. Maintain this water pressure difference and time the test. Record the water level scale of the seepage water collection pipe 26 at regular intervals and calculate the seepage flow rate. When the change rate of seepage flow rate recorded twice consecutively is within 5%, stop the test and obtain the seepage flow rate-time relationship data. Figure 9 The permeation flow-time curve plotted based on this data is shown.

[0078] T2. Based on the seepage flow-time relationship data obtained in T1, calculate the permeability coefficient k2 of the geomembrane weld using the following formula: In this formula, Δt is the test duration, ΔV is the seepage flow rate within time Δt, and ΔP is the water pressure difference across the sample; k1 is the permeability coefficient of a single-layer geomembrane, L1 is the thickness of a single-layer geomembrane, A1 is the planar area of ​​the unwelded portion of the geomembrane weld permeability test sample within the waterproof weld ring; k2 is the vertical permeability coefficient of the geomembrane weld (i.e., the geomembrane weld permeability coefficient), L2 is the thickness of the geomembrane weld, A2 is the planar area of ​​the weld within the waterproof weld ring of the geomembrane weld permeability test sample; and A3 is the area of ​​the air-filled channel.

[0079] Specifically, the permeability coefficient of geomembrane welds is calculated using the following formula:

[0080]

[0081] Where, k eq is the equivalent permeability coefficient of the geomembrane weld, L is the thickness of a single layer of geomembrane, and A is the area of ​​the geomembrane weld permeability test sample within the waterproof weld ring; the meanings of the other parameters are the same as above.

[0082] Considering the good horizontal sealing of the geomembrane weld with almost no gaps, the seepage of permeate along the horizontal direction of the weld does not need to be considered. However, due to the special structure of the weld, air-filling channels exist. Therefore, the above formula is extended to:

[0083]

[0084] Based on the principle of welding, the air-filled channel is not heated, so the permeability coefficient of the air-filled channel is the same as that of a single-layer geomembrane, k1, and the permeation path length is twice the thickness of a single-layer geomembrane, 2L1.

[0085] The calculation principle of the permeability coefficient of geomembrane welds is as follows: Figure 10 As shown.

[0086] This embodiment calculates the vertical permeability coefficient of the 0.8mm HDPE geomembrane weld at different times, and the results are as follows: Figure 11 As shown, the permeability coefficient of the stabilized geomembrane weld is taken as k2 = 5.63935 × 10. -12 m / s.

[0087] (2) For example, the specific process for determining the hydrostatic pressure resistance of geomembrane welds is as follows:

[0088] Start the inlet pressure regulating device 24, starting from 0.0 MPa, and gradually increase the pressure in preset pressure increments (0.1 MPa in this embodiment), maintaining each increment for a preset duration (1 hour in this embodiment). Record the water level on the permeate collection pipe 26 and calculate the seepage flow rate. Based on the test results, ensure the seepage flow rate is no greater than 0.1 cm. 3 The pressure range of / h is used as the hydrostatic pressure resistance range of the geomembrane weld, or the seepage flow rate is greater than 0.1cm. 3 The pressure value preceding the pressure value per hour is used as the maximum hydrostatic pressure resistance value of the geomembrane weld.

[0089] The test results are as follows Figure 12 As shown, within a hydrostatic pressure range of 0.1 MPa to 0.5 MPa, the geomembrane welds did not rupture, and the seepage rate was no greater than 0.1 cm within the measured time range. 3 / h, the sample was well sealed, and there was no damage or leakage in the instrument and sample clamping area.

[0090] Note: The purpose of the above example is to verify the sealing performance of the waterproof weld ring, so the upper limit of the hydrostatic pressure resistance value is set to 0.5MPa, which cannot be used as the maximum hydrostatic pressure resistance value of the 0.8mm HDPE geomembrane weld.

[0091] It should be noted that this embodiment only involves the use of the software program and does not involve any improvement to the software program itself; in addition, the electrical components in this embodiment are all made of existing electronic components, and those skilled in the art can easily purchase the corresponding commercially available products based on the functions of each electrical component described in this embodiment, without the need for detailed description and guidance in this embodiment.

[0092] Furthermore, it should be noted that if this utility model mentions "fixed connection" or "fixed connection," unless otherwise specified, a suitable method can be selected from existing fixed connection methods such as fastener connection, welding connection, and integral molding connection. If this utility model mentions "rotational connection," unless otherwise specified, a suitable method can be selected from existing rotational connection methods such as bearing rotational connection, shaft rotational connection, and ball joint and ball seat rotational connection. These are all technical means that can be easily understood and implemented by those skilled in the art, and it is not necessary for this utility model to specifically list and draw drawings to explain their specific structures. There is no possibility that the content described in this utility model cannot constitute a clear and complete technical solution.

[0093] The above are merely specific embodiments of this utility model, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this utility model. Therefore, this utility model is not limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein. In addition to the embodiments described above, this utility model may have other embodiments. All technical solutions formed by equivalent substitutions or equivalent transformations fall within the protection scope claimed by this utility model.

Claims

1. A test sample for testing the permeability of a geomembrane weld, comprising a geomembrane weld test piece formed by welding two geomembranes together; characterized in that, The geomembrane weld specimen has two hot wedge welds and an air inlet in the middle. The air inlet is located between the two hot wedge welds and is parallel to each hot wedge weld. An upper waterproof weld ring is sealed and fixed to the upper surface of the geomembrane weld specimen, and a lower waterproof weld ring is sealed and fixed to the lower surface of the geomembrane weld specimen. The upper and lower waterproof weld rings are rectangular rings. The upper waterproof weld ring has a first sealing groove on its first side away from the geomembrane weld specimen, and the lower waterproof weld ring has a second sealing groove on its second side away from the geomembrane weld specimen. The air inlet of the geomembrane weld specimen is sealed at both ends.

2. A test specimen for testing the weld seam permeability of a geomembrane according to claim 1, characterized in that The geomembrane weld specimen is formed by welding a first geomembrane and a second geomembrane; a distance is left between the edge of the first geomembrane located inside the upper impermeable weld ring and the inner wall of the upper impermeable weld ring; a distance is left between the edge of the second geomembrane located inside the lower impermeable weld ring and the inner wall of the lower impermeable weld ring.

3. A test specimen for testing the weld seam permeability of a geomembrane according to claim 2, characterized in that In the projection on the same horizontal plane, the upper waterproof weld ring and the lower waterproof weld ring are rectangular and coincident; the central axis of the inflation channel is the axis of symmetry of the upper or lower waterproof weld ring; the first sealing ring groove and the second sealing ring groove are rectangular rings and coincident; the distance between the outer edge of the first sealing ring groove and the outer edge of the upper waterproof weld ring, and the distance between the inner edge of the first sealing ring groove and the inner edge of the upper waterproof weld ring are equal; the distance between the outer edge of the second sealing ring groove and the outer edge of the lower waterproof weld ring, and the distance between the inner edge of the second sealing ring groove and the inner edge of the lower waterproof weld ring are equal.

4. A test specimen for testing the weld seam permeability of a geomembrane according to claim 3, characterized in that In the projection of the same vertical plane, the first side of the upper waterproof welded ring, the second side of the lower waterproof welded ring, the first geomembrane, and the second geomembrane are parallel to each other; the shortest distance between the first side and the upper surface of the first geomembrane is the same as the shortest distance between the second side and the lower surface of the second geomembrane; the cross-section of the first sealing ring groove and the cross-section of the second sealing ring groove are respectively semi-circular, and the cross-sectional diameter of the first sealing ring groove is the same as the cross-sectional diameter of the second sealing ring groove.

5. A test specimen for testing the weld seam permeability of a geomembrane according to any one of claims 1 to 4, characterized in that The upper waterproof welded ring, the lower waterproof welded ring, the first geomembrane, and the second geomembrane are made of the same material.

6. A test sample production mold for a test sample for testing the weld seam permeability of a geomembrane according to any one of claims 1 to 5, characterized by, The device includes an inner cylinder and an outer cylinder coaxially fitted together. The inner and outer cylinders are both cuboids with a gap between them. The top edge of the inner cylinder is fixedly connected to the top edge of the outer cylinder via a top plate. The top plate is rectangular and has a coaxial rectangular annular groove with an upward-facing opening and a semi-circular cross-section. Each side of the groove is located at the center of the corresponding side of the top plate. Each side of the top plate has an observation port located on the side of the top plate closest to the inner cylinder. Each observation port has a small door, which is movably connected to the corresponding observation port via a spring clip. The upper part of each vertical side of the outer cylinder has a feed inlet, which corresponds one-to-one with the observation port and is located below the corresponding observation port. Each feed inlet has a cover plate, which is movably connected to the corresponding feed inlet via a spring clip.

7. The test piece production mold according to Claim 6, wherein Each vertical side of the inner and outer cylinders is composed of a fixed plate and a sliding plate. The fixed plate is located at the upper part of the vertical side, and the sliding plate is located at the lower part of the vertical side. The sliding plate is slidably connected to the fixed plate via a slider-rail structure, which consists of a locking slider and a rail.

8. The test piece production mold according to Claim 7, wherein Each vertical side of the inner and outer cylinders includes two first vertical sides parallel to the hot wedge weld of the geomembrane weld specimen, and two second vertical sides perpendicular to the hot wedge weld of the geomembrane weld specimen; the bottom edge of the first vertical side is in contact with the upper surface of the geomembrane weld specimen; the bottom edge of the second vertical side is provided with a slot, and each slot is provided with a replaceable card plate, the bottom of the card plate having a notch that is in contact with the air channel of the geomembrane weld specimen; the bottom edge of the second vertical side also includes a first edge and a second edge that are in contact with the upper surface of the geomembrane weld specimen, the first edge and the second edge are inverted step shape, and the second edge is located below the first edge.

9. An apparatus for measuring the permeability of a welded seam of a geomembrane, characterized in that It includes an upper water collection tray and a lower water collection tray that are joined together; the bottom surface of the upper water collection tray is a perforated plate, and the top surface of the lower water collection tray is open; the top surface of the upper water collection tray is provided with a permeable water collection pipe and an air vent valve, which are respectively connected to the internal space of the upper water collection tray; the bottom surface of the lower water collection tray is respectively connected to an inlet pressure regulating device and a pressure display, which are respectively connected to the internal space of the lower water collection tray; a first mounting plate extends outward from the outer edge of the bottom surface of the upper water collection tray, and the lower water collection tray... A second mounting plate extends outward from the outer edge of the top surface of the water tray, and the first mounting plate and the second mounting plate are fixedly connected by fasteners; a sealing ring groove is provided at the bottom edge of the upper water collection tray, and a first sealing ring corresponding to the first sealing ring groove of the geomembrane weld permeability test specimen according to any one of claims 1 to 5 is provided in the sealing ring groove; a sealing ring groove is provided at the top edge of the lower water collection tray, and a second sealing ring corresponding to the second sealing ring groove of the geomembrane weld permeability test specimen according to any one of claims 1 to 5 is provided in the sealing ring groove.

10. A device for measuring the permeability of a welded seam of a geomembrane according to claim 9, characterized in that The upper layer water collecting tray and the lower layer water collecting tray are cuboids respectively; the permeated water collecting pipe is provided with a scale; the first sealing ring and the second sealing ring are rectangular rings respectively and are aligned with each other.

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