Device and method for measuring leakage behaviors of composite liner geomembrane folds and fold network

Abstract

The invention discloses a device and a method for measuring leakage behaviors of composite liner geomembrane folds and a fold network. The measuring device comprises a supporting frame which is arranged on a test bed; the constant pressure supply system is fixedly mounted at the top of the supporting frame; the leakage test system is fixedly mounted at the bottom of the support frame and connected with the constant pressure supply system; and the Markov bottle is connected with the leakage testing system. The method comprises the following steps: firstly, arranging a system without a geomembrane in the measuring device for pressurizing and measuring the stable outflow, then respectively arranging a geomembrane system with a single fold and a geomembrane system with crossed folds, then measuring the corresponding stable outflow, and finally, carrying out comprehensive treatment to obtain the total leakage. A top outflow mode and a composite liner structure are adopted, and the defect that the leakage behavior of the composite liner containing the complex wrinkle network cannot be predicted and evaluated through an existing test method is overcome.

Description

Technical Field

[0001] The invention belongs to the field of geomembrane / soil composite liner anti-seepage performance testing, and specifically relates to a device and method for measuring the leakage behavior of composite liner geomembrane folds and fold networks. Technical Background

[0002] Geomembrane / soil composite barriers are widely used in pollution prevention and control of urban solid waste landfills, industrial solid waste landfills, hazardous waste landfills, and remediation of industrial pollution sites due to their excellent anti-seepage and anti-fouling properties. Due to the cycle of day and night temperature changes, geomembranes often have wrinkles caused by expansion and contraction, which in turn forms a wrinkle network. During the service of the composite liner, the leachate will fill the wrinkles through the holes that appear in the geomembrane during manufacturing, transportation, construction, and service, thus forming a dominant leakage channel, which ultimately shortens the service life of the composite liner. Therefore, when designing composite liners for landfills or contaminated sites, it is necessary to consider the situation of geomembranes with wrinkle networks.

[0003] The conventional permeability coefficient test method can be used to determine the leakage rate of a conventional barrier, which is obtained by measuring the permeability coefficient of a homogeneous soil layer under a certain hydraulic gradient. However, due to the complex hydraulic boundary conditions provided by the fold network of the composite liner, and the presence of an extremely thin interface layer due to incomplete contact between the geomembrane and the soil, leakage occurs in the soil layer and the flow field is complex, which is not suitable for the conventional permeability coefficient test method and Darcy's law for corresponding calculation and analysis. At the same time, the existing instruments and devices designed for the breakdown behavior of composite liners can only simulate the leakage breakdown process of a single hole in the geomembrane, but cannot analyze the more common conditions containing folds or fold networks. Therefore, there is still a lack of reliable simulation test methods that reflect the leakage mode of composite liners underground in actual engineering sites. Summary of the invention

[0004] In order to solve the problems in the background technology, the present invention provides a device and method for measuring the leakage behavior of folds and fold networks of a composite liner geomembrane.

[0005] The technical solution adopted by the present invention is as follows:

[0006] 1. A device for measuring the leakage behavior of folds and fold networks of composite liner geomembrane

[0007] The invention comprises a support frame arranged on a test bench; a constant pressure supply system fixedly installed on the top of the support frame; a leakage test system fixedly installed on the bottom of the support frame and connected to the constant pressure supply system, the constant pressure supply system provides constant air pressure for the leakage test system; a water guide groove is provided at the bottom of the leakage test system, the bottom end of the water guide groove serves as the inlet of the leakage test system; an outflow water guide groove is provided at the top of the leakage test system, the outflow water guide groove serves as the outlet of the leakage test system; a Marsh flask is connected to the water guide groove of the leakage test system through a pipeline, and provides constant water for the leakage test system.

[0008] The leakage test system comprises an outflow liquid collecting bottle, an upper cover, an organic glass cylinder and a base; the base is installed at the bottom of the support frame, a water guide groove is provided on the base, the organic glass cylinder is a hollow rectangular parallelepiped, the organic glass cylinder is fixedly installed on the base through a flange, a to-be-tested piece is placed in the organic glass cylinder, the to-be-tested piece is mainly composed of a lower permeable stone, a geomembrane, a soil body and an upper permeable stone arranged in sequence from bottom to top, a through hole is provided in the middle of the geomembrane, the lower permeable stone is arranged on the water guide groove, the upper cover is installed on the upper permeable stone, the upper cover is connected to a constant pressure supply system, an outflow water guide groove is provided at the side wall of the organic glass barrel above the installation position of the upper cover, a collecting bottle is arranged below the outflow water guide groove, and liquid flowing out of the outflow water guide groove as an outlet is collected by the collecting bottle; the bottom end of the water guide groove is connected to a Martens flask through a pipeline as an inlet of the base, and the liquid provided by the Martens flask flows into the soil body through the pipeline, the water guide groove, the through holes of the lower permeable stone and the geomembrane in sequence.

[0009] A sealing ring groove is provided on the inner circumference of the lower part of the plexiglass tube, and a geomembrane sealing ring is arranged in the sealing ring groove. The geomembrane sealing ring is arranged on the outer circumference of the geomembrane and the upper surface of the lower permeable stone. The plexiglass tube is sealed and connected to the geomembrane and the soil respectively through the geomembrane sealing ring. A plexiglass barrel sealing ring is provided on the bottom of the plexiglass tube, and the plexiglass barrel sealing ring is arranged on the outer circumference of the lower permeable stone. The plexiglass tube is sealed and connected to the base respectively through the plexiglass barrel sealing ring, and the plexiglass tube is sealed and connected to the lower permeable stone through the geomembrane sealing ring and the plexiglass barrel sealing ring.

[0010] The constant pressure supply system includes a cylinder, an air pump, a pressure regulating valve and a pressure gauge; the output end of the air pump is connected to the input end of the cylinder through a pipeline, and the pressure regulating valve and the pressure gauge are sequentially arranged on the pipeline from the air pump to the cylinder, the piston rod of the cylinder is fixedly connected to the upper cover of the leakage testing system, and the outer shell of the cylinder is fixedly installed on the top of the support frame.

[0011] 2. A method for determining the leakage behavior of folds and fold networks of composite liner geomembrane

[0012] S1. Arrange the lower permeable stone on the base, put a plexiglass tube sealing ring on the outer periphery of the lower permeable stone, arrange a geomembrane sealing ring on the upper surface of the lower permeable stone, and then fix the plexiglass tube on the base.

[0013] S2. Fill the soil into the plexiglass cylinder and level the soil surface. Arrange permeable stones on the soil surface, place an upper cover on the permeable stones, connect the upper cover to the cylinder, use the cylinder to place the upper cover into the plexiglass cylinder, and arrange an outflow liquid collection bottle under the outflow water guide groove on the side wall of the plexiglass cylinder.

[0014] S3. Use the pressure regulating valve in the constant pressure supply system to control the soil pressure p applied on the soil, and gradually increase the soil pressure p to obtain a stable outflow Q at each level of soil pressure p when no geomembrane is installed. p '.

[0015] S4, based on the stable outflow Q when geomembrane is not installed p 'Get the permeability coefficient k of the soil under various soil pressures p sp .

[0016] S5. Place a single fold geomembrane and a cross-fold geomembrane under the geomembrane twice, and then obtain the single fold stable outflow Q p1 Cross-fold stable outflow Q p2 , according to the stable outflow Q of a single fold p1 , fold cross stable outflow Q p2 and the permeability coefficient k sp The total leakage Q t .

[0017] The geomembrane and the soil form a composite liner.

[0018] The pleat network is a channel of pleat lines generated after pleats are formed on the geomembrane. The channel of pleat lines will have leakage behavior.

[0019] The step S3 is specifically as follows:

[0020] S31, adjusting the soil pressure p to a preset initial soil pressure value p0.

[0021] S32. Use a constant pressure supply system to continuously apply constant pressure to the soil so that the soil is completely consolidated under the current soil pressure p, and measure the consolidation height of the soil after consolidation.

[0022] S33, open the switch valve on the pipe connected to the Martens flask, so that the water in the Martens flask flows to the soil, and use the outflow collection bottle to obtain the outflow of the soil, and use the stabilized outflow of the soil as the stable outflow Q under the current soil pressure p p '.

[0023] S34, gradually increasing the soil pressure p, and repeating steps S32-S33 to obtain a stable outflow rate under each level of soil pressure p when the geomembrane is not installed.

[0024] The permeability coefficient k in step S4 sp According to the following formula:

[0025]

[0026] Among them, k sp is the permeability coefficient; h w ' is the pressure water size on the top of the soil when the geomembrane is not installed; H sp ' is the soil consolidation height under soil pressure p when geomembrane is not installed; Q p ' is the stable outflow under various soil pressures p when geomembrane is not installed; B is the width of the organic glass tube; L is the length of the organic glass tube.

[0027] The step S5 is specifically as follows:

[0028] S51. Remove the upper cover from the organic glass cylinder and take out the upper permeable stone and soil. Place a single folded geomembrane on the lower permeable stone and in the geomembrane sealing ring. Then fill the organic glass cylinder with soil and level the soil surface. Use the same method as steps 2 and 3 to obtain the single fold stable outflow Q under various soil pressures p when there is a single fold on the geomembrane. p1 The single corrugated geomembrane and soil together constitute the first composite liner system.

[0029] The single-strip corrugated geomembrane is a geomembrane formed by cutting the long central axis of a non-corrugated geomembrane.

[0030] S52, the permeability coefficient k of the soil obtained according to step S4 sp And a single fold stable outflow Q p1 According to the interface conduction treatment method, the interface conductivity value θ between the geomembrane and the soil at each level of soil pressure p is obtained.

[0031] S53, remove the upper cover from the organic glass cylinder and take out the upper permeable stone, soil and geomembrane, put the geomembrane with cross folds on the lower permeable stone and in the geomembrane sealing ring, then fill the organic glass cylinder with soil and level the soil surface, and use the same method as steps 2 and 3 to obtain the cross fold stable outflow Q under various soil pressures p when there are cross folds on the geomembrane p2 The cross-folded geomembrane and soil together constitute a second composite liner system.

[0032] The cross-fold geomembrane is a geomembrane formed by cross-cutting a non-folded geomembrane along a long central axis and a short central axis.

[0033] S54, stable outflow Q based on a single fold p1 Cross-fold stable outflow Q p2 The total leakage evaluation method is used to obtain the total leakage Q of the two composite liner systems under various soil pressures p. t .

[0034] The interface conduction processing method in step S52 is set according to the following formula:

[0035]

[0036] Among them, h w H is the pressure water size on the top of the soil when the geomembrane is installed; sp Q is the soil consolidation height under soil pressure p when geomembrane is installed; p1 is the stable outflow rate of a single fold under various soil pressures p when a geomembrane with a single fold is arranged; exp() represents an exponential function with the natural number e as the base; ∞ represents infinity; θ represents the interface conductivity; and n represents the soil porosity.

[0037] The total leakage evaluation method in step S54 is set according to the following formula:

[0038]

[0039] Among them, Q t Indicates the total leakage; L F represents the total length of connected folds; N represents the total number of fold intersections; Q p2 It represents the stable outflow of fold cross under various soil pressures p when a geomembrane with fold cross is arranged.

[0040] The innovation of the present invention lies in the use of a top outflow method and a composite liner structure, which avoids the problem of soil particle loss caused by side outflow, and also avoids the difference in soil permeability coefficient test values ​​caused by different test devices, bringing the beneficial effect of not only obtaining the interface conductivity value but also further obtaining the total leakage amount of the composite liner system, achieving the advantage of more reliable test results and the test results being able to truly reflect the actual site leakage situation.

[0041] The beneficial effects of the present invention are:

[0042] 1. During the test, the top of the structure is evenly compressed and directly acts on the test piece. The loading pressure is the pressure on the composite liner interface. The overburden load can be adjusted quickly and conveniently according to the actual site pressure conditions. The test results can truly reflect the actual site leakage conditions.

[0043] 2. The device of the present invention adopts top outflow to avoid the problem of soil particle loss caused by side outflow; the device seals the bottom of the measuring device by arranging a geomembrane sealing ring and a plexiglass barrel sealing ring to ensure that no leakage occurs during the test, and the test results are more reliable.

[0044] 3. The device of the present invention can use the same set of devices to test the outflow when there is a geomembrane on the top of the soil and when there is no geomembrane, as well as the leakage of a composite liner with a single fold or a cross network of multiple folds, thereby avoiding the difference in the test value of the soil permeability coefficient caused by different test devices. Based on the above results, the interface conductivity between the membrane and the soil at different pressures and composite liner forms can also be obtained, thereby performing a more accurate analysis of the leakage behavior of the composite liner.

[0045] 4. The present invention is suitable for testing the interface conductivity between various geomembranes and soil barrier materials, and is also suitable for testing the interface conductivity between geomembranes and general soil materials such as silt and sand. It has wide applicability and a simple testing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of a composite gasket leakage behavior testing system in an embodiment of the present invention.

[0047] Figure 2 Schematic diagram of a leakage testing system in an embodiment of the present invention.

[0048] Figure 3 It is a top view of the organic glass cylinder and the flange in the embodiment of the present invention.

[0049] Figure 4 It is a top view of the base in the embodiment of the present invention.

[0050] In the figure: 1. leakage test system; 2. support frame; 3. cylinder; 4. Martens flask; 5. air pump; 6. pressure regulating valve; 7. pressure gauge; 8. outflow liquid collection bottle; 9. soil; 10. geomembrane; 11. upper cover; 12. plexiglass cylinder; 13. flange; 14. base; 15. lower permeable stone; 16. upper permeable stone; 17. water guide trough; 18. geomembrane sealing ring; 19. plexiglass barrel sealing ring; 20. outflow water guide trough. DETAILED DESCRIPTION

[0051] The following is a further description of the test method for the leakage behavior of the folds and fold networks of the composite liner geomembrane in the present invention in conjunction with specific examples. The following examples are intended to help those skilled in the art to further understand the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modifications and changes made to the present invention fall within the protection scope of the present invention. The operations not specifically described in the examples are performed with reference to the methods already given in the content of the invention, and will not be repeated here.

[0052] like Figure 1 As shown, the measuring device of the embodiment of the present invention comprises:

[0053] A support frame 2 is arranged on the test bench; a constant pressure supply system is fixedly installed on the top of the support frame 2; a leakage test system 1 is fixedly installed on the bottom of the support frame 2 and connected to the output end of the constant pressure supply system, and the constant pressure supply system provides constant air pressure for the leakage test system 1; a conductive water channel 17 is provided at the bottom of the leakage test system 1, and the bottom end of the water channel 17 serves as the inlet of the leakage test system 1; an outflow water channel 20 is provided on the upper part of the leakage test system 1, and the outflow water channel 20 serves as the outlet of the leakage test system 1; a Martens flask 4, the output end of which is connected to the water channel 17 of the leakage test system 1 through a pipeline, so as to provide constant water for the leakage test system 1.

[0054] like Figure 2 , Figure 3 and Figure 4 As shown, the leakage test system 1 includes an outflow liquid collecting bottle 8, an upper cover 11, an organic glass tube 12 and a base 14; the base 14 is installed at the bottom of the support frame 2, and a conductive water guide groove 17 is provided on the base 14. The organic glass tube 12 is a hollow rectangular parallelepiped, and the organic glass tube 12 is fixedly installed on the base 14 through a flange 13. The test piece is placed in the organic glass tube 12, and the test piece is mainly composed of a lower permeable stone 15, a geomembrane 10, a soil body 9 and an upper permeable stone 16 stacked in sequence from bottom to top. A through hole is opened in the middle of the geomembrane 10, the lower permeable stone 15 is arranged on the water guide groove 17, the upper cover 11 is installed on the upper permeable stone 16, and the upper cover 11 is connected to the constant pressure supply system. An outflow water guide groove 20 is opened on the side wall of the organic glass barrel 12 above the installation position of the upper cover 11, and the collecting bottle 8 is arranged below the outflow water guide groove 20. The liquid flowing out of the outflow water guide groove 20 as the outlet is collected by the collecting bottle 8.

[0055] The bottom end of the water channel 17 serves as the inlet of the base 14 and is connected to the Malchnitz flask 4 through a pipeline. The liquid with constant water pressure provided by the Malchnitz flask 4 flows into the soil 9 through the pipeline, the water channel 17, the lower permeable stone 15 and the through holes of the geomembrane 10 in sequence.

[0056] A sealing ring groove is provided on the inner periphery of the lower part of the plexiglass tube 12, and a geomembrane sealing ring 18 is arranged in the sealing ring groove. The geomembrane sealing ring 18 is arranged on the outer periphery of the geomembrane 10 and the upper surface of the lower permeable stone 15. The lower part of the plexiglass tube 12 is sealed and connected with the geomembrane 10 and the soil 9 respectively through the geomembrane sealing ring 18. An plexiglass barrel sealing ring 19 is provided on the bottom of the plexiglass tube 12. The plexiglass barrel sealing ring 19 is arranged on the outer periphery of the lower permeable stone 15. The bottom of the plexiglass tube 12 is sealed and connected with the base 14 respectively through the plexiglass barrel sealing ring 19. The plexiglass tube 12 is sealed and connected with the lower permeable stone 15 through the geomembrane sealing ring 18 and the plexiglass barrel sealing ring 19.

[0057] The thickness of the sealing ring groove is about half of the thickness of the cylinder wall. The thickness of the geomembrane sealing ring 18 under static conditions should be slightly larger than the difference between the height of the sealing ring groove and the height of the lower permeable stone 15.

[0058] The constant pressure supply system includes a cylinder 3, an air pump 5, a pressure regulating valve 6 and a pressure gauge 7; the output end of the air pump 5 is connected to the input end of the cylinder 3 through a pipeline, and the pressure regulating valve 6 and the pressure gauge 7 are sequentially arranged on the pipeline from the air pump 5 to the cylinder 3. The piston rod of the cylinder 3 is fixedly connected to the upper cover 11 of the leakage testing system 1 by bolts, and the outer shell of the cylinder 3 is fixedly installed on the top of the support frame 2.

[0059] In a specific implementation, the pressure regulating valve 6 and the pressure gauge 7 are fixed on the outer shell of the cylinder 3, the inlet of the pressure regulating valve 6 is connected to the air pump 5, the outlet of the pressure regulating valve 6 is connected to the switch of the cylinder 3, and the other interface of the pressure regulating valve 6 is connected to the pressure gauge 7; the cylinder 3 and the Martens flask 4 are both connected to the leakage testing system 1; the cylinder 3, the air pump 5 and the pressure regulating valve 6 provide a constant pressure for the leakage testing system 1; the Martens flask 4 provides a constant water pressure for the leakage testing system 1.

[0060] In a specific implementation, the soil 9 is clay, soil-bentonite, cement-bentonite, soil-cement-bentonite or geosynthetic clay, and the ratio of the height of the soil 9 to the width of the plexiglass tube 12 is consistent with the thickness of the simulated on-site compacted soil layer and the average distance of the geomembrane folds.

[0061] The geomembrane 10 is a high-density polyethylene HDPE film, a low-density polyethylene LDPE film, a linear low-density polyethylene LLDPE film, an ethylene-vinyl acetate copolymer EVA film or a composite geomembrane, and the thickness of the geomembrane 10 is 1.5 to 3 mm.

[0062] The embodiment of the present invention is implemented according to the following measuring method:

[0063] S1. Arrange the lower permeable stone 15 on the base 14, put the plexiglass tube sealing ring 19 on the outer periphery of the lower permeable stone 15, arrange the geomembrane sealing ring 18 on the upper surface of the lower permeable stone 15, and then fix the plexiglass tube 12 on the base 14, connect the bottom end of the water guide groove 17 to the Malchnitz flask 4 through a pipeline, and the pipeline is provided with a switch valve to exhaust the air in the connecting pipe.

[0064] S2, fill the soil 9 into the organic glass cylinder 12 and level the surface of the soil 9, arrange the permeable stone 16 on the surface of the soil 9, place the upper cover 11 on the upper permeable stone 16, connect the upper cover 11 with the cylinder 3, use the cylinder 3 to slowly place the upper cover 11 into the organic glass cylinder 12, and arrange the outflow liquid collection bottle 8 below the outflow water guide groove 20 on the side wall of the organic glass cylinder 12;

[0065] S3. Use the pressure regulating valve 6 in the constant pressure supply system to control the soil pressure p applied to the soil 9, and gradually increase the soil pressure p to obtain a stable outflow Q at each level of soil pressure p when the geomembrane 10 is not installed. p '.

[0066] S31, adjusting the soil pressure p to a preset initial soil pressure value p0.

[0067] S32, using a constant pressure supply system to continuously apply constant pressure to the soil 9, so that the soil 9 is completely consolidated under the current soil pressure p, and after consolidation, measuring the consolidation height of the soil 9.

[0068] S33, open the switch valve on the pipe connected to the Malchnitz flask 4, so that the water in the Malchnitz flask 4 flows to the soil 9, and use the outflow collection bottle 8 to obtain the outflow of the soil 9, and use the stabilized outflow of the soil 9 as the stable outflow Q under the current soil pressure p p '.

[0069] S34, increasing the soil pressure p step by step according to the preset increments, and repeating steps S32-S33 to obtain a stable outflow rate under each level of soil pressure p when the geomembrane 10 is not installed.

[0070] In a specific implementation, a method for obtaining a stable outflow is as follows: after the water in the Malchow flask 4 flows toward the soil 9, the outflow volume V collected by the outflow collection bottle 8 in N consecutive time periods is obtained, and the outflow q=V / T of each time period is obtained, where T is the total duration of each time period, and the outflow error between two adjacent time periods is compared. If the outflow error between two adjacent time periods in four consecutive time periods is less than 15%, it indicates that the outflow of the soil 9 tends to be stable, and then the average outflow q of the last two time periods in the four time periods is obtained as the stable outflow under the current soil pressure p.

[0071] S4, based on the stable outflow Q when the geomembrane 10 is not installed p 'Get the permeability coefficient k of soil 9 under various soil pressures p sp .

[0072] Permeability coefficient k sp According to the following formula:

[0073]

[0074] Among them, k sp is the permeability coefficient; h w ' is the pressure water level on the top of the soil 9 when the geomembrane 10 is not installed, that is, the height difference between the liquid level of the Malvern flask 4 and the outflow water channel 20; H sp ' is the soil consolidation height under soil pressure p when the geomembrane 10 is not installed; Q p ' is the stable outflow under various soil pressures p when the geomembrane 10 is not installed; B is the width of the organic glass tube 12; L is the length of the organic glass tube 12.

[0075] S5. Place a single folded geomembrane 10 and a cross-folded geomembrane 10 under the geomembrane 10 twice, and then obtain the single fold stable outflow Q p1 Cross-fold stable outflow Q p2 , according to the stable outflow Q of a single fold p1 , fold cross stable outflow Q p2 and the permeability coefficient k sp The total leakage Q t .

[0076] The geomembrane 10 and the soil 9 form a composite liner. The fold network is a channel of fold lines generated after folds are formed on the geomembrane 10. The channel of the fold lines will have leakage behavior.

[0077] S51, remove the upper cover 11 from the organic glass tube 12 and take out the upper permeable stone 16 and the soil 9, put a single folded geomembrane 10 on the lower permeable stone 15 and in the geomembrane sealing ring 18, then fill new soil 9 into the organic glass tube 12 and level the surface of the soil 9. The soil 9 in step S5 is consistent with the soil material in step S2, and the filling height is consistent. The same method as step 2 and step 3 is used to obtain the single fold stable outflow Q under various soil pressures p when there is a single fold on the geomembrane 10 p1 The single corrugated geomembrane 10 and the soil 9 together constitute a first composite liner system.

[0078] The single-strip corrugated geomembrane 10 is a geomembrane 10 formed by cutting the long central axis of the non-corrugated geomembrane 10 .

[0079] The surface of the non-wrinkled geomembrane 10 is rectangular and can be cut along the long middle axis or the short middle axis in sequence.

[0080] S52: The permeability coefficient k of the soil 9 obtained in step S4 sp And a single fold stable outflow Q p1 According to the interface conduction processing method, the interface conductivity value θ between the geomembrane 10 and the soil 9 at each level of soil pressure p is obtained.

[0081] The interface conduction treatment method is set according to the following formula:

[0082]

[0083] Among them, h w H is the pressure water level on the top of the soil 9 when the geomembrane 10 is installed, that is, the height difference between the liquid level of the Malvern flask 4 and the outflow water channel 20; sp Q is the soil consolidation height under soil pressure p when the geomembrane 10 is installed; p1 is the stable outflow rate of a single fold under various soil pressures p when a single fold geomembrane 10 is arranged; exp() represents an exponential function with the natural number e as the base; ∞ represents infinity; π is 3.14; θ represents the interface conductivity; and n represents the soil porosity.

[0084] S53, remove the upper cover 11 from the organic glass tube 12 and take out the upper permeable stone 16, soil 9 and geomembrane 10, put the geomembrane 10 with folds crossed on the lower permeable stone 15 and in the geomembrane sealing ring 18, then fill new soil 9 into the organic glass tube 12 and level the surface of the soil 9. The soil 9 in step S5 is consistent with the soil material in step S2, and the filling height is consistent. The same method as step 2 and step 3 is used to obtain the fold cross stable outflow Q under each level of soil pressure p when there are folds crossed on the geomembrane 10 p2 , the folded and crossed geomembrane 10 and the soil 9 together constitute a second composite liner system;

[0085] The cross-fold geomembrane 10 is a geomembrane 10 formed by cross-cutting a non-folded geomembrane 10 along a long central axis and a short central axis.

[0086] S54, stable outflow Q based on a single fold p1 Cross-fold stable outflow Q p2 The total leakage evaluation method is used to obtain the total leakage Q of the two composite liner systems under various soil pressures p. t .

[0087] The total leakage assessment method is set according to the following formula:

[0088]

[0089] Among them, Q t Indicates the total leakage; L F represents the total length of connected folds in the actual site; N represents the total number of fold intersections in the connected fold network in the actual site; Q p2 It represents the stable outflow rate of the fold cross under various soil pressures p when the geomembrane 10 is arranged with fold crosses.

[0090] During the test, the connection between the base 14 and the organic glass tube 12, and the side wall of the organic glass tube 12 and the geomembrane 10 need to be tested for sealing. After the soil 9 is placed in the organic glass tube 12, the surface needs to be leveled, and the height of the soil 9 in all directions needs to be measured with the scale on the organic glass tube 12 to ensure that the height of the soil 9 in all directions is the same; the constant pressure water h on the top of the geomembrane 10 w Should not exceed 2m.

[0091] After measuring the stable outflow rate and soil permeability coefficient under a certain pressure level, the interface conductivity θ between the geomembrane 10 and the soil 9 and the total leakage Q under the composite liner system can be further calculated. t For parallel tests, when the interface conductivity θ or total leakage calculated by two parallel tests differs within 50%, the test results are considered reliable. Otherwise, a third set of parallel tests is required, and the average of the two closer test results among the three sets of parallel tests is taken as the final interface conductivity θ.

[0092] The present invention achieves water tightness between the geomembrane and the test system while fixing the side wall of the measuring device by inverting the composite liner system to be tested, thereby ensuring that no side leakage affects the test results during the test; directly applies pressure to the composite liner soil layer through a constant pressure supply system, thereby avoiding the problem of possible damage caused by friction with the side wall during pressure transmission, resulting in the inability to truly reflect the actual site pressure conditions; under the same set of equipment, by cutting and simulating different folds or fold networks of the geomembrane, testing and analysis of various fold forms can be achieved.

[0093] The innovation of the present invention lies in the use of a top outflow method and a composite liner structure, which avoids the problem of soil particle loss caused by side outflow, and also avoids the difference in soil permeability coefficient test values ​​caused by different test devices, bringing the beneficial effect of not only obtaining the interface conductivity value but also further obtaining the total leakage amount of the composite liner system, achieving the advantage of more reliable test results and the test results being able to truly reflect the actual site leakage situation.

[0094] During the test process of the present invention, the interface contact between the geomembrane and the soil is uniform, the measurement result is accurate, the test method is simple, and it is suitable for the simulation of leakage behavior and the evaluation of interface conductivity of geomembrane and various composite liner material combinations such as clay, soil-bentonite, cement-bentonite, soil-cement-bentonite, etc., which overcomes the defect that the current test method cannot predict and evaluate the leakage behavior of composite liners containing complex fold networks.

Claims

1. A device for measuring the leakage behavior of folds and fold networks of composite liner geomembrane, characterized in that: include: A support frame (2) is arranged on the test bench; A constant pressure supply system, fixedly mounted on the top of the support frame (2); A leakage test system (1) is fixedly mounted on the bottom of a support frame (2) and connected to a constant pressure supply system, the constant pressure supply system providing a constant air pressure for the leakage test system (1); a water guide groove (17) is provided at the bottom of the leakage test system (1), the bottom end of the water guide groove (17) serves as an inlet of the leakage test system (1); an outflow water guide groove (20) is provided at the top of the leakage test system (1), the outflow water guide groove (20) serves as an outlet of the leakage test system (1); The Martens flask (4) is connected to the water channel (17) of the leakage test system (1) through a pipeline to provide constant water for the leakage test system (1).

2. The device for measuring the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 1, characterized in that: The leakage test system (1) comprises an outflow liquid collection bottle (8), an upper cover (11), an organic glass tube (12) and a base (14); the base (14) is installed at the bottom of the support frame (2), a water guide groove (17) is provided on the base (14), the organic glass tube (12) is a hollow rectangular parallelepiped, the organic glass tube (12) is fixedly installed on the base (14) through a flange (13), and a test object is placed in the organic glass tube (12), and the test object mainly consists of a lower permeable stone (15), a geomembrane (10), a soil body (9) and an upper The permeable stones (16) are stacked in order from bottom to top, a through hole is opened in the middle of the geomembrane (10), the lower permeable stone (15) is arranged on the water guide groove (17), the upper cover (11) is installed on the upper permeable stone (16), the upper cover (11) is connected to the constant pressure supply system, and an outflow water guide groove (20) is opened on the side wall of the organic glass barrel (12) above the installation position of the upper cover (11), and a collection bottle (8) is arranged below the outflow water guide groove (20), and the liquid flowing out of the outflow water guide groove (20) as an outlet is collected by the collection bottle (8); The bottom end of the water channel (17) serves as the inlet of the base (14) and is connected to the Malchnitz flask (4) through a pipeline. The liquid provided by the Malchnitz flask (4) flows into the soil (9) through the pipeline, the water channel (17), the lower permeable stone (15) and the through holes of the geomembrane (10) in sequence.

3. The device for measuring the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 1, characterized in that: A sealing ring groove is provided on the inner periphery of the lower part of the organic glass cylinder (12), and a geomembrane sealing ring (18) is arranged in the sealing ring groove. The geomembrane sealing ring (18) is arranged on the outer periphery of the geomembrane (10) and the upper surface of the lower permeable stone (15). The organic glass cylinder (12) is sealedly connected to the geomembrane (10) and the soil (9) through the geomembrane sealing ring (18). An organic glass barrel sealing ring (19) is provided on the bottom of the organic glass cylinder (12). The organic glass barrel sealing ring (19) is arranged on the outer periphery of the lower permeable stone (15). The organic glass cylinder (12) is sealedly connected to the base (14) through the organic glass barrel sealing ring (19). The organic glass cylinder (12) is sealedly connected to the lower permeable stone (15) through the geomembrane sealing ring (18) and the organic glass barrel sealing ring (19).

4. The device for measuring the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 1, characterized in that: The constant pressure supply system comprises a cylinder (3), an air pump (5), a pressure regulating valve (6) and a pressure gauge (7); the output end of the air pump (5) is connected to the input end of the cylinder (3) via a pipeline, the pressure regulating valve (6) and the pressure gauge (7) are sequentially arranged on the pipeline from the air pump (5) to the cylinder (3), the piston rod of the cylinder (3) is fixedly connected to the upper cover (11) of the leakage test system (1), and the outer shell of the cylinder (3) is fixedly installed on the top of the support frame (2).

5. A method for measuring the leakage behavior of folds and fold networks of composite liner geomembrane applied to the measuring device according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Arrange a lower permeable stone (15) on the base (14), cover the outer periphery of the lower permeable stone (15) with an organic glass tube sealing ring (19), arrange a geomembrane sealing ring (18) on the upper surface of the lower permeable stone (15), and then fix the organic glass tube (12) on the base (14); S2, filling the soil (9) into the organic glass cylinder (12) and leveling the surface of the soil (9), arranging the upper permeable stone (16) on the surface of the soil (9), placing the upper cover (11) on the upper permeable stone (16), connecting the upper cover (11) with the cylinder (3), placing the upper cover (11) into the organic glass cylinder (12) by using the cylinder (3), and arranging the outflow liquid collection bottle (8) below the outflow water guide groove (20) on the side wall of the organic glass cylinder (12); S3, using the pressure regulating valve (6) in the constant pressure supply system to control the soil pressure p applied to the soil (9), and gradually increase the soil pressure p to obtain a stable outflow Q at each soil pressure p when the geomembrane (10) is not installed p '; S4, based on the stable outflow Q when the geomembrane (10) is not installed p 'Get the permeability coefficient k of the soil (9) under various soil pressures p sp ; S5. Place a single-fold geomembrane (10) and a geomembrane (10) with crossed folds under the geomembrane (10) twice, and then obtain the single-fold stable outflow Q p1 Cross-fold stable outflow Q p2 , according to the stable outflow Q of a single fold p1 , fold cross stable outflow Q p2 and the permeability coefficient k sp The total leakage Q t .

6. The method for determining the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 5, characterized in that: The step S3 is specifically as follows: S31, adjusting the soil pressure p to a preset initial soil pressure value p0; S32, using a constant pressure supply system to continuously apply constant pressure to the soil (9), so that the soil (9) is completely consolidated under the current soil pressure p, and after consolidation, measuring the consolidation height of the soil (9); S33, opening the switch valve on the pipe connected to the Martens flask (4) so ​​that the water in the Martens flask (4) flows to the soil (9), and at the same time using the outflow liquid collection bottle (8) to obtain the outflow of the soil (9), and taking the stabilized outflow of the soil (9) as the stable outflow Q under the current soil pressure p p '; S34, increasing the soil pressure p step by step, and repeating steps S32 to S33, so as to obtain a stable outflow rate under each level of soil pressure p when the geomembrane (10) is not installed.

7. The method for determining the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 5, characterized in that: The permeability coefficient k in step S4 sp According to the following formula: Among them, k sp is the permeability coefficient; h w ' is the pressure water level on the top of the soil (9) when the geomembrane (10) is not installed; H sp ' is the soil consolidation height under soil pressure p when the geomembrane (10) is not installed; Q p ' is the stable outflow rate under various soil pressures p when the geomembrane (10) is not installed; B is the width of the organic glass tube (12); and L is the length of the organic glass tube (12).

8. The method for determining the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 5, characterized in that: The step S5 is specifically as follows: S51, remove the upper cover (11) from the organic glass cylinder (12) and take out the upper permeable stone (16) and the soil (9), put a single folded geomembrane (10) on the lower permeable stone (15) and in the geomembrane sealing ring (18), then fill the soil (9) into the organic glass cylinder (12) and level the surface of the soil (9), and use the same method as steps 2 and 3 to obtain the single fold stable outflow Q under various soil pressures p when there is a single fold on the geomembrane (10) p1 The single folded geomembrane (10) and the soil (9) together constitute a first composite liner system; The single-strip corrugated geomembrane (10) is a geomembrane (10) formed by cutting the long central axis of a non-corrugated geomembrane (10); S52: The permeability coefficient k of the soil (9) obtained in step S4 sp And a single fold stable outflow Q p1 , according to the interface conduction processing method, the interface conductivity value θ between the geomembrane (10) and the soil (9) under each level of soil pressure p is obtained; S53, remove the upper cover (11) from the organic glass cylinder (12) and take out the upper permeable stone (16), soil (9) and geomembrane (10), put the geomembrane (10) with cross folds on the lower permeable stone (15) and in the geomembrane sealing ring (18), then fill the soil (9) into the organic glass cylinder (12) and level the surface of the soil (9), and use the same method as steps 2 and 3 to obtain the cross fold stable outflow Q under various soil pressures p when there are cross folds on the geomembrane (10) p2 The cross-folded geomembrane (10) and the soil (9) together constitute a second composite liner system; The cross-fold geomembrane (10) is a geomembrane (10) formed by cutting a non-folded geomembrane (10) in a cross shape along the long middle axis and the short middle axis; S54, stable outflow Q based on a single fold p1 Cross-fold stable outflow Q p2 The total leakage evaluation method is used to obtain the total leakage Q of the two composite liner systems under various soil pressures p. t .

9. The method for determining the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 8, characterized in that: The interface conduction processing method in step S52 is set according to the following formula: Among them, h w H is the water pressure on the top of the soil (9) when the geomembrane (10) is installed; sp Q is the soil consolidation height under soil pressure p when the geomembrane (10) is installed; p1 is the stable outflow rate of a single fold under various soil pressures p when a geomembrane (10) having a single fold is arranged; exp() represents an exponential function with a natural number e as the base; ∞ represents infinity; θ represents the interface conductivity; and n represents the soil porosity.

10. The method for determining the leakage behavior of folds and fold networks of composite liner geomembrane according to claim 8, characterized in that: The total leakage evaluation method in step S54 is set according to the following formula: Among them, Q t Indicates the total leakage; L F represents the total length of connected folds; N represents the total number of fold intersections; Q p2 It represents the stable outflow rate of the fold cross under various soil pressures p when the fold cross geomembrane (10) is arranged.

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