Indoor model test method and device for testing the anti-seepage and water-blocking performance of hydrophobic particles

Abstract

The present invention discloses an indoor model test method for testing the anti-seepage and water-barrier properties of hydrophobic particles, comprising the following steps: 1) providing two holding tanks and placing the two holding tanks in a temperature-controlled chamber; 2) loading the two holding tanks with samples, scaling them up, and simulating an actual application prototype; embedding temperature and moisture monitoring probes in the two holding tanks while the samples are being loaded, and connecting the temperature and moisture monitoring probes to a data acquisition device or a PC; 3) regulating the temperature of the temperature-controlled chamber and the bottom temperature of the holding tanks to create a temperature difference between the loaded samples; 4) based on the sample humidity change data of the indoor model over time, converting the permeability trend of the anti-permeability air sand layer in the prototype into the permeability trend of the permeable air sand layer in the indoor model, and evaluating the permeability. The present invention can simulate hydraulic activities such as capillary water rise and water migration that occur in engineering projects, and the test results can reflect permeability coefficient indicators, which can be used to evaluate the long-term anti-seepage effect of anti-permeability air sand projects.

Description

Technical Field

[0001] The invention relates to a performance test of an anti-permeation granular material, and in particular to an indoor model test method and a test device for testing the anti-permeation and water-insulating performance of hydrophobic particles. Background Art

[0002] Anti-permeability breathable particles are a kind of anti-permeability material with breathable properties, which is made of aggregate particles such as gold mine tailings, lead-zinc tailings, aeolian sand, and desert sand as the main raw materials. Anti-permeability breathable particles have broad application prospects in modern agriculture, construction, transportation, ecological protection and environmental governance. They can effectively solve the current problems faced by mankind, such as water shortage and soil environmental deterioration. However, when dealing with engineering leakage, roadbed soil collapse and secondary salinization problems, the existing technology has the problem that it is difficult to evaluate the long-term anti-permeability effect of anti-permeability breathable particles.

[0003] At present, the anti-seepage performance test of anti-permeability gas particles uses a special test device for anti-permeability gas particles. This device can test the anti-seepage and air permeability performance of non-sticky and hydrophobic anti-permeability gas particles by adding water and pressurizing them. However, the test process does not simulate the hydraulic activities such as capillary water rise and moisture migration that occur in the process of dry-wet and freeze-thaw cycles in the project. The test results do not reflect the permeability coefficient index and cannot be directly used for permeability evaluation in engineering anti-seepage. In addition, the test method cannot verify the long-term water-proof effect.

[0004] In addition, geotechnical permeameters used in geotechnical testing are divided into constant-head permeameters and variable-head permeameters. Variable-head permeameters are not suitable for non-viscous particles, and the inner wall of the sample container and the impermeable particles cannot form a water barrier, which will increase test errors. Constant-head permeameters are suitable for permeable non-viscous particles and are not suitable for hydrophobic particles. Therefore, impermeable particles are not suitable for permeability coefficient evaluation in geotechnical permeameters.

[0005] Based on the problems in the above background technology, those skilled in the art have proposed an indoor model test method and test device for testing the anti-seepage and water-blocking performance of hydrophobic particles. Summary of the Invention

[0006] The purpose of the present invention is to provide an indoor model test method and test device for testing the anti-seepage and water-proof performance of hydrophobic particles, so as to solve the problems that the existing anti-seepage and air-permeability test methods of anti-permeability and air-permeability particles do not simulate the hydraulic activities such as capillary water rise and moisture migration that occur in the project, and the test results do not reflect permeability coefficient indicators and cannot be directly used for permeability evaluation in engineering anti-seepage, the existing technology is difficult to evaluate the long-term anti-seepage effect of anti-permeability and air-proof particles in engineering, and the existing civil permeameters have poor applicability.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] An indoor model test method for testing the anti-seepage and water-barrier performance of hydrophobic particles comprises the following steps:

[0009] 1) Provide two holding tanks with bottom heating function and thermal insulation structure, and place the two holding tanks in a temperature-controlled room;

[0010] 2) A permeable stone layer, a saturated loess layer, an impermeable gas sand layer, and an unsaturated loess layer are laid layer by layer in one holding tank from the bottom upward; a permeable stone layer, a saturated loess layer, a contrast material layer, and an unsaturated loess layer are laid layer by layer in another holding tank from the bottom upward; when the saturated loess layer and the unsaturated loess layer are laid in both holding tanks, multiple temperature and moisture monitoring probes are buried at intervals along the longitudinal direction, and the multiple temperature and moisture monitoring probes are connected to a data collector or a PC;

[0011] 3) regulating the room temperature of the temperature control chamber and the bottom temperature of the two holding tanks so that a temperature difference is synchronously generated between the lower surface of the saturated loess layer and the upper surface of the unsaturated loess layer in the two holding tanks;

[0012] 4) Based on the humidity change data of the saturated and unsaturated loess filling layers in the indoor model over time, the permeability performance trend of the anti-permeability air-sand layer in the prototype was converted into the permeability performance trend of the permeable air-sand layer in the indoor model and evaluated.

[0013] Furthermore, in step 2), when laying the permeable stone layer, the saturated loess layer, the impermeable gas sand layer, and the unsaturated loess layer, the laying thickness is scaled according to the prototype of actual application. The scaling ratio is the spatial similarity ratio. After the spatial similarity ratio is determined, the temporal similarity ratio is determined according to the heat conduction similarity criterion, so that the indoor model and the prototype are connected in space and time.

[0014] Furthermore, the spatial similarity ratio and the temporal similarity ratio satisfy:

[0015]

[0016] in, Refers to the similarity ratio at the time level, Refers to the spatial level similarity ratio; is the actual simulation time, For indoor simulation time; The length, width and height of the actual project on site. is the length, width and height of the indoor model.

[0017] Furthermore, in step 2), a convex frame structure is formed on the lower surface of the anti-permeability gas sand layer and is in contact with the inner wall of the receiving tank.

[0018] Furthermore, in step 2), at least two groups of temperature and moisture monitoring probes are arranged in the containing tank at intervals in a transverse direction.

[0019] Another object of the present invention is to provide a test device for an indoor model test method for testing the anti-seepage and water-barrier properties of hydrophobic particles, the device comprising:

[0020] A heat preservation tank, the inner wall of which is provided with a heat preservation and insulation layer;

[0021] A temperature regulating plate, which is arranged on the bottom wall of the insulation tank;

[0022] The insulation partition is arranged in the middle of the insulation tank and divides the insulation layer into two independent tanks. The insulation partition is sealed with the opposite side walls of the insulation tank and the upper surface of the temperature regulating plate.

[0023] Furthermore, the temperature regulating plate includes a hollow heat conducting plate and a heat conducting water pipe arranged in the hollow heat conducting plate. The heat conducting water pipe is arranged in a serpentine shape inside the hollow heat conducting plate, and one end of the heat conducting water pipe extends to the outside of the insulation tank.

[0024] Furthermore, a slow-release cooling layer is provided on the upper surface of the hollow heat-conducting plate.

[0025] Furthermore, the slow-release cooling layer includes quartz blocks laid on the upper surface of the hollow heat conducting plate, river sand filled in the quartz blocks, and a waterproof membrane coated on the outside of the quartz blocks and the river sand.

[0026] The beneficial effects of the present invention are:

[0027] 1. This invention simulates the effects of dry-wet and freeze-thaw cycles in earthfill projects, and uses hydraulic activities such as capillary water rise and water migration driven by temperature gradients to replace the traditional method of measuring the anti-seepage performance of hydrophobic particles by adding water and applying pressure. This solves the problem that existing technologies have difficulty in evaluating the long-term anti-seepage effect of anti-permeability and breathable particle projects.

[0028] 2. The present invention establishes a spatial and temporal connection between the indoor model and the prototype. Based on the humidity change data of the saturated and unsaturated loess layers in the indoor model over time, the permeability performance of the anti-permeability air sand layer in the prototype is inferred. This method is stable, convenient, and reliable, and is conducive to accurately evaluating the long-term anti-permeability performance of the anti-permeability air sand layer.

[0029] 3. The present invention utilizes the cooperation between the holding tank and the temperature control chamber to synchronously generate a temperature difference between the lower surface of the saturated loess layer and the upper surface of the unsaturated loess layer, which can more conveniently simulate the changing process of dry-wet and freeze-thaw cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1This is a graph showing the evolution of the water-proof performance of the anti-permeability granular water-proof layer of the present invention after 10 years of indoor testing simulation;

[0031] Figure 2 It is a structural schematic diagram of the test device in the present invention;

[0032] Figure 3 Schematic diagram of the top view of the test device in the present invention.

[0033] Among them, 1-insulation tank; 2-temperature regulating plate; 3-insulation partition; 4-insulation layer; 5-hollow heat conduction plate; 6-heat conduction water pipe; 7-slow-release cooling layer. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention are described below with reference to the accompanying drawings.

[0035] like Figures 1 to 3 As shown, an indoor model test method for testing the anti-seepage and water-barrier performance of hydrophobic particles comprises the following steps:

[0036] 1) Provide two holding tanks; the inner wall of the holding tank is provided with an insulation structure layer, and the insulation structure layer can be made of aluminum silicate rock wool board or polyurethane foam board; one of the two holding tanks is used for testing and the other is used for comparison; both holding tanks are placed in a temperature-controlled room, and the temperature adjustment function of the temperature-controlled room is used to affect the temperature change of the material layer at the port of the holding tank. The insulation structure layer of the holding tank is used to prevent the temperature of the temperature-controlled room from affecting the inner wall and bottom surface of the holding tank; the holding tank has a bottom heating function, which can be achieved by an electric heating plate or by water circulation heat release. Other appropriate methods can also be used.

[0037] 2) One holding tank was layered from the bottom upward with a permeable stone layer, a saturated loess layer, an impermeable gas sand layer, and an unsaturated loess layer. The other holding tank was layered from the bottom upward with a permeable stone layer, a saturated loess layer, a comparison material layer, and an unsaturated loess layer. The thicknesses of the permeable stone layer, saturated loess layer, impermeable gas sand layer, and unsaturated loess layer were scaled proportionally to the thickness of the material layers in the actual prototype. This scaling ratio is known as the spatial similarity ratio. The length, width, and height of the actual prototype were inferred from the length, width, and height of the holding tank interior according to the spatial similarity ratio. After determining the spatial similarity ratio, the temporal similarity ratio was determined using the heat conduction similarity criterion to establish a spatial and temporal connection between the indoor model and the prototype. To avoid the problem of the impermeable gas particles failing to form a water barrier at the contact point with the inner wall of the device, a convex frame structure was formed on the lower surface of the impermeable gas sand layer, which was aligned with the inner wall of the holding tank. This increased the longitudinal width of the impermeable gas sand layer in contact with the wall. When the two holding tanks are filled with saturated loess layers and unsaturated loess layers, multiple temperature and moisture monitoring probes are buried at intervals along the longitudinal direction. The multiple temperature and moisture monitoring probes are connected to a data collector or a PC, and data is obtained by the data collector or the PC for comparative analysis. In order to improve the accuracy of the detection data, at least two groups of temperature and moisture monitoring probes are arranged at intervals in the horizontal direction of the holding tank. The numerical error detected by the two groups of temperature and moisture monitoring probes in each holding tank is within the range of 0.1 numerical difference, and the data is deemed valid.

[0038] The spatial similarity ratio and the temporal similarity ratio satisfy:

[0039]

[0040] in, Refers to the similarity ratio at the time level, Refers to the spatial level similarity ratio; is the actual simulation time, For indoor simulation time; The length, width and height of the actual project on site. is the length, width and height of the indoor model.

[0041] 3) The room temperature of the temperature-controlled room and the bottom temperature of the two holding tanks are regulated to synchronously generate a temperature difference between the lower surface of the saturated loess layer and the upper surface of the unsaturated loess layer in the two holding tanks; the process of generating a temperature difference between the lower surface of the saturated loess layer and the upper surface of the unsaturated loess layer achieves the conditions of dry-wet and freeze-thaw cycles.

[0042] 4) Based on the humidity change data of the saturated and unsaturated loess filling layers in the indoor model over time, the permeability performance trend of the anti-permeability air-sand layer in the prototype was converted into the permeability performance trend of the permeable air-sand layer in the indoor model and evaluated.

[0043] According to the scale of the indoor model test of the anti-seepage and water-proof performance test of hydrophobic particles for engineering, the spatial similarity ratio is determined to be 10:1. According to the heat conduction similarity criterion, the similarity ratios at the spatial and temporal levels meet 、 、 (in, Refers to the similarity ratio at the time level, Refers to the spatial level similarity ratio; is the actual simulation time, For indoor simulation time; The length, width and height of the actual project on site. The time similarity ratio is 100:1. The test parameters are detailed in Table 1.

[0044]

[0045] The upper boundary condition of the model box, that is, the temperature function of the control room, is in the form of:

[0046]

[0047] Where T refers to the temperature cycle period, t refers to the test running time (the unit is consistent with T), a, b, and c are fitting parameters, and the specific values are obtained by fitting the actual annual average temperature of the project location.

[0048] The present invention is described by taking an indoor test simulation test of the water-proof performance of the anti-permeable gas particle water-proof layer after 10 years as an example.

[0049] First, two holding tanks were placed in a dedicated controlled chamber for sample loading. In one holding tank, permeable stone, a saturated loess layer, an impermeable air sand layer, and an unsaturated (optimal moisture content) loess layer were placed in order from bottom to top. Temperature and moisture monitoring probes were buried at the specified depth during the loess filling. In the other holding tank, permeable stone, a saturated loess layer, a comparison material layer, and an unsaturated (optimal moisture content) loess layer were placed in order from bottom to top. Temperature and moisture monitoring probes were buried at the specified depth during the loess filling. The permeable stone has a certain rigidity, facilitating tamping above. The permeable stone is laid to a fixed thickness, controllable between 0 and 10 cm. The comparison material layer is loess. Since the loess is unsaturated and has a suboptimal moisture content, conventional loess can be used. The loess comparison material layer can also be replaced with permeable stone. When comparing with other existing products, the comparison material layer can also be selected from existing products. The thickness of each material layer during sample loading is shown in Table 2. After the sample is loaded, the heating temperature of the bottom of the holding tank is set on the temperature control device, and the specific temperature value is 8.05°C.

[0050]

[0051] The temperature function of the controlled room is:

[0052]

[0053] The unit of t is minutes.

[0054] The data acquisition systems of the two holding tanks and the temperature control system of the controlled-temperature chamber were activated to conduct the test. A temperature difference was observed between the lower surface of the saturated loess layer and the upper surface of the loess layer at the optimum moisture content. Under the influence of the temperature gradient and matrix suction, the temperature of the loess layer at the optimum moisture content alternated between positive and negative cycles, driving water to repeatedly migrate between the two layers. Moisture and temperature probes detected changes in moisture content at monitoring points in the soil layer to determine the water-repellent effect of the hydrophobic sand.

[0055] After the test, the data were exported and analyzed to obtain the temporal variation of the average monthly volumetric water content at the four monitoring points above the anti-seepage sand layer and the comparison layer. The results are as follows: Figure 1 As shown in the figure, the monthly average volumetric moisture content change of the upper fill of the anti-seepage sand layer changes with the temperature cycle, and the monthly average volumetric moisture content change of the upper fill of the loess comparison layer gradually increases with time and eventually tends to saturation. The test results verify the water-proof performance of the hydrophobic granular aquiclude after 10 years of use; the evaluation results show that the anti-seepage air sand layer in the prototype can ensure the waterproof effect after 10 years of use.

[0056] like Figure 2 and 3The present invention also provides a test apparatus for an indoor model test method for testing the anti-seepage and water-barrier properties of hydrophobic particles. The apparatus comprises a heat preservation tank 1, a temperature regulating plate 2, and a heat preservation partition 3. The heat preservation tank 1 provides a storage space for sample materials and performs a heat preservation function. The temperature regulating plate 2 heats the bottom of the heat preservation tank 1. The heat preservation partition 3 divides the heat preservation tank 1 into two independent storage spaces.

[0057] The inner wall of the insulation tank 1 is provided with an insulation layer 4, which is a polyurethane foam layer or an aluminum silicate rock wool board coated with a plastic protective film. The insulation layer 4 forms an insulation structure on the inner wall of the insulation tank 1; the insulation tank 1 is a cubic shape as a whole, and the groove formed is a cubic shape. The insulation tank can be made of welded steel plates or by cement masonry.

[0058] The temperature regulating plate 2 is arranged on the bottom wall inside the insulation tank 1. The temperature regulating plate 2 includes a hollow heat conducting plate 5 and a hot water pipe 6. The hollow heat conducting plate 5 is composed of a rectangular frame and an iron plate wrapped around the outside of the rectangular frame. The hollow heat conducting plate 5 is laid on the bottom of the insulation tank 1. The hot water pipe 6 is placed inside the hollow heat conducting plate 5 and arranged in a serpentine shape. The hot water pipe 6 can be made of PVC pipe or steel pipe. One end of the hot water pipe 6 extends to the outside of the insulation tank 1 and is connected to the hot and cold water machine to achieve temperature control by circulating hot and cold water.

[0059] The insulation partition 3 is arranged in the middle of the insulation tank 1 and divides the insulation layer into two independent tanks. The insulation partition 3 is also sealed with the opposite side walls of the insulation tank 1 and the upper surface of the temperature regulating plate 2; the insulation partition 3 can be made of a polyurethane foam board or an aluminum silicate rock wool board coated with a plastic protective film.

[0060] The temperature stability of the temperature regulating plate 2 is conducive to ensuring the accuracy and reliability of the test. In order to avoid excessive temperature differences in the temperature of the temperature regulating plate 2, a slow-release cooling layer 7 is provided on the upper surface of the hollow heat conducting plate 5. The slow-release cooling layer 7 includes quartz stones laid on the upper surface of the hollow heat conducting plate 5, river sand filled in the quartz stones, and a waterproof diaphragm wrapped around the outside of the quartz stones and river sand. The waterproof diaphragm can be a waterproof plastic film; in order to avoid the water circulation failure of the hot water pipe 6 affecting the test, a silicone rubber heating sheet can be laid on the lower side or inside of the slow-release cooling layer 7. When the temperature regulating plate 2 fails, the temperature setting is maintained by the silicone rubber heating sheet; the quartz stones and river sand form a protective layer that can slowly heat up and slowly cool down, which can reduce the impact of the abnormal temperature of the temperature regulating plate 2 on the test.

[0061] This device is used in an indoor model test method for testing the anti-seepage and water-blocking properties of hydrophobic particles for engineering applications: The device is placed in a temperature-controlled room, and the hot and cold water dispenser outside the temperature control unit is connected to the hot water pipe 6 via an insulated pipe. One groove of the insulation tank 1 is sequentially arranged from bottom to top with permeable stone, a saturated loess filling layer, an impermeable air sand layer, and an unsaturated (optimal moisture content) loess filling layer. Temperature and moisture monitoring probes are buried at the specified depth during the loess filling. Another groove is sequentially arranged from bottom to top with permeable stone, a saturated loess filling layer, a contrast material layer, and an unsaturated (optimal moisture content) loess filling layer. Temperature and moisture monitoring probes are buried at the specified depth during the loess filling. The control system of the temperature control room, the control system of the hot and cold water dispenser, and a data logger or PC are activated. The internal temperature of the temperature control room and the temperature of the thermostat 2 are controlled according to the test requirements. The temperature and moisture monitoring probes are used to collect real-time data, which is then analyzed and evaluated.

Claims

1. An indoor model test method for testing the anti-seepage and water-barrier performance of hydrophobic particles for engineering, characterized in that: The steps include: 1) Provide two holding tanks with bottom heating function and thermal insulation structure, and place the two holding tanks in a temperature-controlled room; 2) A permeable stone layer, a saturated loess layer, an impermeable gas sand layer, and an unsaturated loess layer are laid layer by layer in one holding tank from the bottom upward; a permeable stone layer, a saturated loess layer, a contrast material layer, and an unsaturated loess layer are laid layer by layer in another holding tank from the bottom upward; when the saturated loess layer and the unsaturated loess layer are laid in both holding tanks, multiple temperature and moisture monitoring probes are buried at intervals along the longitudinal direction, and the multiple temperature and moisture monitoring probes are connected to a data collector or a PC; 3) regulating the room temperature of the temperature control chamber and the bottom temperature of the two holding tanks so that a temperature difference is synchronously generated between the lower surface of the saturated loess layer and the upper surface of the unsaturated loess layer in the two holding tanks; 4) Based on the humidity change data of the saturated and unsaturated loess filling layers in the indoor model over time, the permeability performance trend of the anti-permeability air-sand layer in the prototype was converted into the permeability performance trend of the permeable air-sand layer in the indoor model and evaluated.

2. The indoor model test method for testing the anti-seepage and water-barrier performance of hydrophobic particles for engineering use according to claim 1, characterized in that: In step 2), when laying the permeable stone layer, the saturated loess layer, the impermeable gas sand layer, and the unsaturated loess layer, the laying thickness is scaled based on the prototype in actual application. The scaling ratio is the spatial similarity ratio. After the spatial similarity ratio is determined, the temporal similarity ratio is determined according to the heat conduction similarity criterion, so that the indoor model and the prototype are connected in space and time.

3. The indoor model test method for testing the anti-seepage and water-barrier performance of hydrophobic particles for engineering use according to claim 2, characterized in that: The spatial similarity ratio and the temporal similarity ratio satisfy: in, Refers to the similarity ratio at the time level, Refers to the spatial level similarity ratio; is the actual simulation time, For indoor simulation time; The length, width and height of the actual project on site. is the length, width and height of the indoor model.

4. The indoor model test method for testing the anti-seepage and water-barrier performance of hydrophobic particles for engineering use according to claim 1, characterized in that: In the step 2), a convex frame structure is formed on the lower surface of the anti-permeability gas sand layer and is in contact with the inner wall of the receiving tank.

5. The indoor model test method for testing the anti-seepage and water-barrier performance of hydrophobic particles for engineering use according to claim 1, characterized in that: In the step 2), at least two groups of temperature and moisture monitoring probes are arranged in the containing tank at intervals in a transverse direction.

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