A horizontal drainage performance testing device

Abstract

The present invention belongs to the technical field of drainage performance testing devices, and specifically relates to a horizontal drainage performance testing device, which is used to test the anti-clogging drainage ability of geosynthetics under conditions of different inclination angles and different head heights. The main structure comprises a water supply tank, a mixer, a water pipe, a drainage tank, a sewage pump, a high drainage hole, a low drainage hole, a drainage pipe, a water collecting tank and geosynthetics. Based on the fact that groundwater in tunnel engineering is often mixed with fine particles of surrounding rocks and mud, the amount of water varies in rainy and dry seasons, and the laying angle of geosynthetics varies from 0° to 90°, the actual working environment of the tunnel engineering is simulated, and horizontal drainage performance tests can be performed under different drainage conditions to obtain the anti-clogging drainage ability of geosynthetics under different conditions. The device has a simple structure, is environmentally friendly and energy-saving, is easy to implement, has low manufacturing and use costs, and the test results are accurate and reliable, and has great application prospects.

Description

Technical field:

[0001] The invention belongs to the technical field of drainage performance testing devices, and in particular relates to a horizontal drainage performance testing device for testing the anti-clogging and drainage ability of geosynthetics under conditions of different inclination angles and different water head heights. Background technology:

[0002] Geosynthetics are made of artificially synthesized polymers and are made into various types of products, including non-woven fabrics, geogrids, geomembranes, composite drainage nets, geonet mats, etc. Geosynthetics have excellent filtering, drainage, isolation and other functions, and are light in weight, high in tensile strength, good in permeability, and corrosion-resistant. They are widely used in water conservancy, transportation, construction engineering and other construction projects.

[0003] At present, tunnel water leakage occurs frequently. The defects in the design of tunnel drainage system are an important influencing factor. The existing drainage system is relatively complete, but it is difficult to make the waterproof board watertight due to the construction quality. Once the waterproof board cracks, there is no drainage channel between the waterproof board and the secondary lining. The groundwater will seep and accumulate between the waterproof board and the secondary lining, and finally seep out from the weak lining, causing water leakage.

[0004] During the use of geosynthetics, the internal pores or surfaces will intercept and continuously accumulate surrounding rock particles, silt particles, etc. mixed in the groundwater under seepage movement, which reduces the permeability. Therefore, geosynthetics need to have good anti-clogging ability, and the water conductivity under clogging conditions has also become an important parameter for design and application. In the existing technology, there is only a clogging tester for geosynthetics in the vertical direction. The "Testing Regulations for Geosynthetics in Highway Engineering JTGE50-2006" and "Testing Regulations for Geosynthetics SL235-2012" also only provide clogging tests for geosynthetics in the vertical direction, and the clogging test has not yet clearly defined the index value for judging the degree of clogging.

[0005] The Chinese patent 201910081800.3 discloses a drainage geogrid drainage performance test device and test method, the test device consists of a test box, a vertical load loading system and a test system; the test box consists of a stainless steel frame, a panel, a side panel, a bottom plate and a top cover; the vertical load loading system consists of a rigid loading plate, a rubber air bag, an air guide tube, an air pressure pump and an automatic air pressure regulating valve; the test system consists of a micro pore water pressure sensor, a data acquisition instrument and a wire; it can only measure the changes in the pore water pressure of the soil around the drainage geogrid under various levels of consolidation pressure, obtain the corresponding design parameters, and provide a basis for the application design of the drainage geogrid; the Chinese patent 201920095288.3 discloses a new type of modular drainage performance test device, which includes a test component and a simulated rainfall component; the test component includes a test module, and the test module includes a soil layer, a first geotextile, a ceramsite layer, a first geotextile layer, a second ... Two geotextiles, storage and drainage boards; the test component also includes four module side panels and a module bottom plate that are arranged to form a test trough, and the test module is located in the trough of the test trough; at least one drainage trough parallel to the module bottom plate is arranged around the outer wall of the test trough, and each drainage trough is connected to the test trough, and a drainage pipe connected to the drainage trough is arranged on the bottom of each drainage trough, and each drainage pipe is connected to a container with a scale; the simulated rainfall component includes a water tank, a water pump, a nozzle, a water spray valve, a flow meter, etc.; it simply simulates the storage and drainage performance of the roof through the design of the test component and the simulated rainfall component; no drainage capacity test device or equipment is given for siltation drainage along the horizontal direction of geosynthetics. Therefore, a drainage capacity test device for geosynthetics along the horizontal direction under siltation is designed and developed, with the drainage per unit time, permeability coefficient and drainage benefit ratio as indicators, to provide a reference for judging the drainage capacity of geosynthetics under anti-siltation conditions. Summary of the invention:

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and to design a horizontal drainage performance testing device to effectively obtain the horizontal drainage performance of geosynthetics under siltation conditions.

[0007] In order to achieve the above-mentioned purpose, the main structure of the horizontal drainage performance testing device of the present invention includes a water supply tank, a mixer, a water pipe, a drainage box, a sewage pump, a high drainage hole, a low drainage hole, a drainage pipe, a water collecting box and geosynthetics; a mixer is arranged in the water supply tank, the water supply tank is connected to the drainage box through a water pipe, a sewage pump is arranged on the water pipe, a high drainage hole and a low drainage hole are opened on the upper part of the drainage box, a drainage pipe is arranged at the bottom of the drainage box, the water outlet of the drainage pipe extends out of the drainage box, a water collecting box is arranged below the water outlet of the drainage pipe, the drainage pipe is located in the drainage box The part of the internal groove of the drainage box is grooved, and the geosynthetics connected to the inner wall of the drainage box are embedded in the groove ; The length, width and height of the drainage box are 500 mm, 250 mm and 750 mm respectively; the vertical distance between the high drainage hole and the low drainage hole is 200 mm, the vertical distance between the high drainage hole and the top of the drainage box is 50 mm, and the vertical distance between the low drainage hole and the top of the geosynthetics is 200 mm; the drainage pipe is a Φ30 PVC pipe with a thickness of 2.5 mm, the length of the drainage pipe outside the drainage box is 100 mm, the vertical distance between the center of the drainage pipe and the bottom of the drainage box is 50 mm, and the slot length of the drainage pipe is 205 mm; the height of the geosynthetics embedded in the drainage pipe is greater than 20 mm.

[0008] The horizontal drainage performance testing device according to the present invention comprises the following steps when testing:

[0009] (i) Test cutting: Cut the geosynthetics into blocks with a width of 200 mm or 100 mm and a height of 250 mm, and measure and record the initial weight;

[0010] (ii) Test placement: embed the geosynthetics into the grooves of the drainage pipes. The embedding height of the geosynthetics is greater than 20 mm. The back and sides of the geosynthetics are bonded with hot melt adhesive and the top end is sealed with silicone to prevent particles from entering from the top.

[0011] (III) Sand layer laying: A 50 mm thick coarse sand layer is laid in the drainage box to wrap the drainage pipe to prevent the soil from being damaged due to seepage deformation or loss, and to increase the water conduction effect;

[0012] (iv) Angle adjustment: The tilted geosynthetics will be laid at an angle of 0°-90°. The laying angle is selected based on the actual laying of the geosynthetics between the initial support and the secondary lining of the tunnel lining. The laying angle of the geosynthetics at the tunnel side wall is 90°, the laying angle at the arch waist gradually decreases, and the laying angle at the arch top is close to horizontal;

[0013] (V) Filter material filling: Lay a 250 mm thick layer of fine sand on top of the coarse sand layer, fill in layers of 50 mm and compact;

[0014] (VI) Preparation of turbid solution: Select soil particles with a particle size of less than 1 mm and prepare a sand content of 7 kg / m 3 The turbid water solution is prepared by agitating the turbid water solution, and the turbid water solution is pumped into a drainage tank by a sewage pump;

[0015] (VII) Water head adjustment: select 200 mm water head or 400 mm water head according to needs;

[0016] (VIII) Drainage test: The muddy water solution gradually saturates the filter layer composed of fine sand and geosynthetics. After the drainage volume of the drainage pipe stabilizes, the drainage is collected and the water flow and drainage time are recorded;

[0017] (IX) Data calculation: The drainage rate, comprehensive permeability coefficient and drainage benefit ratio are calculated based on the recorded water flow and drainage time:

[0018] 1. Use the formula Calculate the displacement per unit time, where Q is the displacement per unit time (cm 3 / s), Q n is the total discharge volume for the nth time, t' n is the end time of the nth recording, t n The starting time of the nth recording;

[0019] 2. Use the formula Calculate the drainage rate, where v is the drainage rate (cm / s) and Q is the amount of water discharged per unit time (cm 3 / s), A is the seepage area, i.e. the contact area between geosynthetics and the fine sand layer and the coarse sand layer (cm 2 );

[0020] 3. Use formula Calculate the comprehensive permeability coefficient, where k 综 is the comprehensive permeability coefficient (cm / s), v is the drainage rate (cm / s), i is the hydraulic gradient, L is the distance from the top of the fine sand layer to the center of the geosynthetics (cm), Δh is the hydraulic head difference, that is, the distance from the water surface (high drainage hole or low drainage hole) to the center of the geosynthetics (cm);

[0021] 4. Use formula Calculate the drainage benefit ratio, where d is the drainage benefit ratio, k 综 is the comprehensive permeability coefficient (cm / s), k 砂 The permeability coefficient (cm / s) of a single sand layer is measured through a geotechnical test (constant head permeability test).

[0022] Compared with the prior art, the present invention simulates the actual working environment of tunnel engineering based on the fact that groundwater in tunnel engineering is often mixed with fine particles of surrounding rock and mud, the water volume varies in rainy and dry seasons, and the laying angle of geosynthetics varies from 0° to 90°. It can perform horizontal drainage performance tests under different drainage conditions and obtain the anti-siltation and drainage capacity of geosynthetics under different conditions. It has a simple structure, is environmentally friendly and energy-saving, is easy to implement, has low manufacturing and use costs, and the test results are accurate and reliable, and has great application prospects. Description of the drawings:

[0023] Figure 1 It is a schematic diagram of the main structural principle of the present invention.

[0024] Figure 2 It is a schematic diagram of the main structure of the drainage box involved in the present invention.

[0025] Figure 3 This is a cross-sectional view of the main structure of the drainage box involved in the present invention.

[0026] Figure 4 It is a side view of the main structure of the drainage box involved in the present invention. Specific implementation method:

[0027] The present invention is further described below by way of implementation examples in conjunction with the accompanying drawings.

[0028] Embodiment 1:

[0029] The main structure of the horizontal drainage performance testing device involved in this embodiment includes a water supply tank 1, a mixer 2, a water pipe 3, a drainage box 4, a sewage pump 5, a high drainage hole 6, a low drainage hole 7, a drainage pipe 8, a water collecting box 9 and a geosynthetic material 10; the water supply tank 1 is provided with a mixer 2, the water supply tank 1 is connected to the drainage box 4 through the water pipe 3, the water pipe 3 is provided with a sewage pump 5, the upper part of the drainage box 4 is provided with a high drainage hole 6 and a low drainage hole 7, the bottom of the drainage box 4 is provided with a drainage pipe 8, the water outlet 80 of the drainage pipe 8 extends out of the drainage box 4, and a water collecting box 9 is provided below the water outlet 80 of the drainage pipe 8, the drainage pipe 8 is located in the drainage box 4 The part of the inner part of the drainage box 4 is grooved, and the geosynthetic material 10 connected to the inner wall of the drainage box 4 is embedded in the groove.

[0030] The length, width and height of the drainage box 4 involved in this embodiment are 500 mm, 250 mm and 750 mm respectively; the vertical distance between the high drainage hole 6 and the low drainage hole 7 is 200 mm, the vertical distance between the high drainage hole 6 and the top of the drainage box 4 is 50 mm, and the vertical distance between the low drainage hole 7 and the top of the geosynthetics 10 is 200 mm; the drainage pipe 8 is a Φ30 PVC pipe with a thickness of 2.5 mm, the length of the drainage pipe 8 outside the drainage box 4 is 100 mm, the vertical distance between the center of the drainage pipe 8 and the bottom of the drainage box 4 is 50 mm, and the slot length of the drainage pipe 8 is 205 mm; the height of the geosynthetics 10 embedded in the drainage pipe 8 is greater than 20 mm.

[0031] Embodiment 2:

[0032] When the horizontal drainage performance test device involved in this embodiment uses the capillary drainage belt as the geosynthetics 10 for testing, first, the capillary drainage belt is cut into a block with a width of 200 mm and a height of 250 mm and then inserted into the groove of the drainage pipe 8. The bottom of the capillary drainage belt is embedded in the drainage pipe 8 to a depth of 20 mm. The laying angle of the capillary drainage belt is 90°. Silica gel is used to seal the top of the capillary drainage belt to prevent fine particles from entering from the top of the capillary drainage belt and causing clogging of the drainage pipe 8; then, a coarse sand layer 90 with a thickness of 50 mm and a fine sand layer 100 with a thickness of 250 mm are laid in turn; finally, soil particles with a particle size less than 1 mm are selected to be configured with a sand content of 7 kg / m 3 The turbid water solution is prepared by stirring the mixer 1, and the sewage pump 5 is turned on to extract the turbid water solution to the drainage tank 4. A drainage test is performed using a water head of 400 mm. The turbid water solution passes through a filter material layer composed of a fine sand layer 100 and a capillary drainage belt and is collected at a drainage pipe 8 to start drainage. After the drainage volume stabilizes, drainage is collected and the water flow rate and drainage time are recorded.

[0033] Embodiment 3:

[0034] The horizontal drainage performance testing device involved in this embodiment uses non-woven geotextile as the geosynthetic material 10 for testing. The testing process is the same as that of Example 2, except that the width of the non-woven geotextile is 100 mm and the height is 250 mm; the non-woven geotextile has no drainage grooves and does not require silicone sealing on the top; the laying angle of the non-woven geotextile is 0°; and a 200 mm water head is used for the drainage test.

Claims

1. A horizontal drainage performance testing device, characterized in that: The main structure includes a water supply tank, a mixer, a water pipe, a drainage box, a sewage pump, a high drainage hole, a low drainage hole, a drainage pipe, a water collection box and geosynthetics; a mixer is arranged in the water supply tank, the water supply tank is connected to the drainage box through a water pipe, a sewage pump is arranged on the water pipe, a high drainage hole and a low drainage hole are opened on the upper part of the drainage box, a drainage pipe is arranged at the bottom of the drainage box, the water outlet of the drainage pipe extends out of the drainage box, a water collection box is arranged below the water outlet of the drainage pipe, the drainage pipe is located in the drainage box The part of the drainage box is grooved, and geosynthetics connected to the inner wall of the drainage box are embedded in the groove; The test includes the following steps: (i) Test cutting: Cut the geosynthetics into blocks with a width of 200 mm or 100 mm and a height of 250 mm, and measure and record the initial weight; (ii) Test placement: embed the geosynthetics into the grooves of the drainage pipes. The embedding height of the geosynthetics is greater than 20 mm. The back and sides of the geosynthetics are bonded with hot melt adhesive and the top end is sealed with silicone. (iii) Sand layer laying: Wrap the drainage pipe with a coarse sand layer of 50 mm thickness in the drainage box; (iv) Angle adjustment: The tilted geosynthetics will be laid at an angle of 0°-90°. The laying angle is selected based on the actual laying of the geosynthetics between the initial support and the secondary lining of the tunnel lining. The laying angle of the geosynthetics at the tunnel side wall is 90°, the laying angle at the arch waist gradually decreases, and the laying angle at the arch top is close to horizontal; (V) Filter material filling: Lay a 250 mm thick layer of fine sand on top of the coarse sand layer, fill in layers of 50 mm and compact; (VI) Preparation of turbid solution: Select soil particles with a particle size of less than 1 mm and prepare a sand content of 7 kg / m 3 The turbid water solution is prepared by agitating the turbid water solution, and the turbid water solution is pumped into a drainage tank by a sewage pump; (VII) Water head adjustment: select 200 mm water head or 400 mm water head according to needs; (VIII) Drainage test: The muddy water solution gradually saturates the filter layer composed of fine sand and geosynthetics. After the drainage volume of the drainage pipe stabilizes, the drainage is collected and the water flow and drainage time are recorded; (IX) Data calculation: Drainage rate, comprehensive permeability coefficient and drainage benefit ratio are calculated based on the recorded water flow and drainage time.

2. A horizontal drainage performance testing device according to claim 1, characterized in that: The length, width and height of the drainage box are 500 mm, 250 mm and 750 mm respectively; the vertical distance between the high drainage hole and the low drainage hole is 200 mm, the vertical distance between the high drainage hole and the top of the drainage box is 50 mm, and the vertical distance between the low drainage hole and the top of the geosynthetics is 200 mm; the drainage pipe is a Φ30 PVC pipe with a thickness of 2.5 mm, the length of the drainage pipe outside the drainage box is 100 mm, the vertical distance between the center of the drainage pipe and the bottom of the drainage box is 50 mm, and the groove length of the drainage pipe is 205 mm; the height of the geosynthetics embedded in the drainage pipe is greater than 20 mm.

3. A horizontal drainage performance testing device according to claim 1 or 2, characterized in that: The calculation process of drainage rate, comprehensive permeability coefficient and drainage benefit ratio is as follows:

1. Use the formula Calculate the displacement per unit time, where Q is the displacement per unit time, Q n is the total discharge volume for the nth time, t' n is the end time of the nth recording, t n The starting time of the nth recording; 2. Use the formula Calculate the drainage rate, where v is the drainage rate, Q is the drainage per unit time, and A is the seepage area, that is, the contact area between the geosynthetics and the fine sand layer and the coarse sand layer; 3. Use formula Calculate the comprehensive permeability coefficient, where k 综 is the comprehensive permeability coefficient, v is the drainage rate, i is the hydraulic gradient, L is the distance from the top of the fine sand layer to the center of the geosynthetics, and Δh is the hydraulic head difference, that is, the distance from the water surface to the center of the geosynthetics; 4. Use formula Calculate the drainage benefit ratio, where d is the drainage benefit ratio, k 综 is the comprehensive permeability coefficient, k 砂 To measure the permeability coefficient of a single sand layer through geotechnical tests.

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