Evaluation Device and Method for Leached Pollutants of Solid Waste Used as Subgrade Filler

Abstract

The present invention discloses an evaluation device and method for leaching pollutants of solid waste used as subgrade filler. The device includes a collection component, a pressure component and a reaction force component; the collection component includes a cylinder body, a sampling hole and a reaction force frame fixing hole, and the sampling hole and the reaction force frame fixing hole are arranged on the cylinder body; the pressure component includes a pressing rod, a pressure mechanism, a pressure gauge and a pressure transmission gasket, and the pressing rod, the pressure mechanism and the pressure gauge are arranged at the upper end of the pressure transmission gasket; the reaction force component includes a reaction force rod, a reaction force frame, a fixing bolt and a height adjustment hole. The present invention comprehensively considers the boundary conditions such as different depths, different structural layers and different stress states of solid waste used as subgrade filler, so as to evaluate its long-term law of pollutant leaching, and by comparing with relevant standards (specifications) of the concentration of toxic and harmful substances in the leachate, the environmental safety of using this solid waste material as subgrade filler is judged.

Description

Technical Field

[0001] The present invention relates to the technical field of road construction material evaluation, and particularly to an evaluation device and method for leached pollutants of solid waste used as subgrade filling material. Background Art

[0002] A large amount of road construction materials are required for mountain highway construction. Using solid waste for road construction under the idea of "treating waste with waste and minimizing excavation and maximizing filling" has broad application prospects. Under the sustainable development strategy, promoting the comprehensive utilization of bulk solid waste is an important part of deeply implementing the sustainable development strategy. Currently, inventions related to solid waste mostly focus on solid waste treatment, and there are few inventions on the environmental safety evaluation and devices of the leachates from the application of industrial solid waste as subgrade filling materials in particular.

[0003] The prior art mainly evaluates the leaching law of pollutants in solid waste after pollution-free treatment from the material perspective alone, without considering its stress characteristics and the structural layer position when it is used as subgrade filling material, and cannot match the boundary conditions of the actual working conditions. Summary of the Invention

[0004] The present invention is provided to solve the problems raised in the background art. Therefore, an evaluation device and method for leached pollutants of solid waste used as subgrade filling material are needed. The invention comprehensively considers boundary conditions such as different depths, different structural layer positions, and different stress states of solid waste used as subgrade filling material to evaluate its long-term leaching law of pollutants, and judges the environmental safety of the solid waste material as subgrade filling material by comparing with relevant standards (specifications) for the concentrations of toxic and harmful substances in the leachate.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] According to a first aspect of the present invention, an evaluation device for leached pollutants of solid waste used as subgrade filling material is provided, including a collection component, a pressure component, and a reaction force component;

[0007] The collection component includes a cylinder body, a sampling hole, and a reaction force frame fixing hole, and the sampling hole and the reaction force frame fixing hole are arranged on the cylinder body;

[0008] The pressure component includes a pressing rod, a pressure mechanism, a pressure gauge, and a pressure transmission gasket, and the pressing rod, the pressure mechanism, and the pressure gauge are arranged at the upper end of the pressure transmission gasket;

[0009] The reaction force component includes a reaction force rod, a reaction force frame, fixing bolts, and height adjustment holes; two reaction force frames are provided, and a plurality of height adjustment holes are arranged on the reaction force frames. The reaction force frames are fixed to the upper end of the cylinder body through the fixing bolts in cooperation with the height adjustment holes and the reaction force frame fixing holes, and both ends of the reaction force rod are fixedly installed through one of the reaction force frames respectively.

[0010] Furthermore, the collecting component further includes supports, and a plurality of supports are provided and fixedly support the cylinder.

[0011] Furthermore, a reaction rod fixing hole is provided on the reaction frame, and both ends of the reaction rod are fixedly installed through the reaction rod fixing holes provided on the reaction frame respectively.

[0012] According to the second aspect of the present invention, an evaluation method for leaching pollutants of solid waste used as subgrade filler is provided. Based on the evaluation device as described above, the evaluation method includes:

[0013] Determine the pressure applied by the pressure component according to the deviator stress of the layer where the solid waste is used as subgrade filler;

[0014] Place the standard specimen in the cylinder, and with the sampling hole closed, add distilled water into the cylinder until the top of the standard specimen is submerged;

[0015] Place the pressure transmitting gasket on the top of the standard specimen and apply pressure to the standard specimen according to the determined pressure;

[0016] After static pressure for the expected static pressure time, take out the leachate through the sampling hole and detect the concentration of the target component in the leachate;

[0017] Evaluate the environmental safety of the material used for road filling according to the concentration of the target component.

[0018] Furthermore, the deviator stress of the layer where the solid waste is used as subgrade filler is determined by the following method:

[0019] Determine that the layer where the solid waste is used as subgrade filler is the stress calculation layer, and the stress calculation layer includes a plurality of stress calculation points;

[0020] Based on the mechanics of layered elastic system, calculate the vertical stress of the vehicle load acting on each stress calculation point;

[0021] Calculate the self-weight stress of the upper soil mass received by each stress calculation point according to formula (1):

[0022]

[0023] In the formula: the subscript i is the layer number of the subgrade from top to bottom; n is the total number of layers; γ is the unit weight of soil (kN / m 3 ); h is the soil layer thickness (m); F is the cross-sectional area of the soil column.

[0024] Superimpose the vertical stress of the vehicle load acting on each stress calculation point and the self-weight stress of the upper soil mass received by the corresponding stress calculation point to obtain the vertical total stress received by each stress calculation point;

[0025] Subtract the horizontal stress on the soil caused by the load from the vertical total stress on each stress calculation point to obtain the deviator stress on each stress calculation point;

[0026] Select the point with the maximum deviator stress in each stress calculation layer as the deviator stress of the layer where the solid waste is used as subgrade filler.

[0027] Further, the pressure F applied by the pressure component is F = p * A, where p is the deviator stress of the layer where the solid waste is used as subgrade filler, and A is the cross-sectional area of the pressure transmission gasket.

[0028] Further, placing the pressure transmission gasket on the top of the standard specimen and applying pressure to the standard specimen according to the determined pressure specifically includes:

[0029] Pass the reaction rod through the two reaction frames in sequence;

[0030] Adjust the reaction device to a preset height, and at this time, pass the fixing bolt through the height adjustment hole and the reaction frame fixing hole in sequence and tighten it;

[0031] Adjust the pressure application rod to make the pressure mechanism generate pressure. When the reading of the pressure gauge reaches the pressure applied by the determined pressure component, stop the operation of the pressure application rod.

[0032] Further, the target component concentration includes one or a combination of manganese concentration and ammonia nitrogen concentration.

[0033] Further, evaluating the environmental safety of the materials used for road filling according to the target component concentration specifically includes:

[0034] Construct a regression index model based on the target component concentrations of the leachate obtained under different expected static pressure times;

[0035] Calculate the leaching amount of the target component of the pavement structure at the design service life according to the regression index model.

[0036] Further, the regression index model is expressed as:

[0037] y1 = A1 * exp(-x / t1) + y0 (2)

[0038] Wherein, y1 represents the pollutant leaching concentration (mg / L or μg / L), x is the soaking time (days), exp() represents the exponential function, and A1, t1, and y0 are fitting parameters.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] 1. The present invention can flexibly apply corresponding loads according to the actual stress characteristics of solid waste as subgrade filling in the highway subgrade structure, and simulate the mechanical boundary conditions matching the actual engineering situation.

[0041] 2. The present invention can prepare corresponding specimens for testing according to different solid materials used as subgrade filling, and has a wide range of application objects.

[0042] 3. The main body of the device of the present invention is composed of three parts: a collection device, a pressure device and a reaction force device, with a simple structure and low manufacturing cost.

[0043] 4. The present invention combines the current standard "Methods for Chemical Analysis of Gold" (GB / T 11066.11-2021), and uses inductively coupled plasma mass spectrometry to detect the manganese concentration in the leachate; according to the current standard "Water Quality - Determination of Ammonia Nitrogen - Nessler's Reagent Spectrophotometric Method" (HJ 535-2009), uses Nessler's reagent spectrophotometric method to detect the ammonia nitrogen concentration in the leachate, and has strong operability.

[0044] 5. The pressure device used in the present invention can be replaced by a jack with pressure display or an instrument with the same function, with a wide range of parts and low maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar components. The drawings generally illustrate various embodiments by way of example and not limitation, and are used together with the description and the claims to explain the disclosed embodiments. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and not intended to be an exhaustive or exclusive embodiment of the device or method.

[0046] Figure 1 FIG. shows a three-dimensional structural diagram of an evaluation device for leaching pollutants of solid waste used as subgrade filling according to an embodiment of the present invention. In the figure, 1 is a collection component, 101 is a cylinder, 102 is a sampling hole, 103 is a support, 104 is a reaction frame fixing hole, 2 is a pressure component, 201 is a pressure rod, 202 is a pressure mechanism, 203 is a pressure gauge, 204 is a pressure transmission gasket, 3 is a reaction force component, 301 is a reaction force rod, 302 is a reaction frame, 303 is a fixing bolt, 304 is a height adjustment hole, 305 is a reaction force rod fixing hole;

[0047] Figure 2 FIG. shows a flowchart of an evaluation method for leaching pollutants of solid waste used as subgrade filling according to an embodiment of the present invention;

[0048] Figure 3The flowchart shows the determination of the deviator stress of the layer where solid waste is used as subgrade filler in an evaluation method for leached pollutants of solid waste used as subgrade filler according to an embodiment of the present invention;

[0049] Figure 4 The flowchart shows the application of pressure to a standard specimen according to the determined pressure in an evaluation method for leached pollutants of solid waste used as subgrade filler according to an embodiment of the present invention;

[0050] Figure 5 The flowchart shows the evaluation of the environmental safety of road fill materials based on the target component concentration in an evaluation method for leached pollutants of solid waste used as subgrade filler according to an embodiment of the present invention;

[0051] Figure 6 The schematic diagram of the standard axle load according to an embodiment of the present invention is shown;

[0052] Figure 7 The schematic diagram of the stress point setting according to an embodiment of the present invention is shown;

[0053] Figure 8 The fitting curve graph of the manganese / ammonia nitrogen leaching concentration according to an embodiment of the present invention is shown. Detailed implementation manners

[0054] The following listed partial embodiments are only for better illustrating the present invention, but the content of the present invention is not limited to the applied embodiments. Therefore, those skilled in the art make non-essential improvements and adjustments to the implementation manners according to the above invention content and apply them to other embodiments, which are still within the protection scope of the present invention.

[0055] An embodiment of the present invention provides an evaluation device for leached pollutants of solid waste used as subgrade filler. As Figure 1 shown, the evaluation device includes a collection component 1, a pressure component 2 and a reaction force component 3.

[0056] The collection component 1 includes a cylinder body 101, a sampling hole 102 and a reaction force frame fixing hole 104. The sampling hole 102 and the reaction force frame fixing hole 104 are provided on the cylinder body 101. The collection component 1 is used to place a standard specimen 4, and the sampling hole 102 is used to take out the leachate. The standard specimen 4 can be prepared according to the compaction test operation process in the current standard "Code for Highway Geotechnical Tests" (JTG3430-2020) or other preparation methods such as static pressure forming.

[0057] The pressure component 2 includes a pressure application rod 201, a pressure mechanism 202, a pressure gauge 203 and a pressure transmission gasket 204. The pressure application rod 201, the pressure mechanism 202 and the pressure gauge 203 are arranged at the upper end of the pressure transmission gasket 204.

[0058] The pressure component 2 is used to apply corresponding pressure to the standard specimen 4, where the pressure application rod 201 and the pressure mechanism 202 are correspondingly connected. By operating the pressure application rod 201, the pressure mechanism 202 cooperates with the reaction force component 3 to generate corresponding pressure. For example, the pressure mechanism 202 can be a jack, and the pressure application rod 201 can be a component for operating the jack. By manually operating the pressure application rod 201, the jack cooperates with the reaction force component 3 to generate corresponding pressure on the standard specimen 4. The pressure value is read according to the pressure gauge 203. After reaching the preset pressure value, the operation of the pressure application rod 201 is stopped.

[0059] Of course, the pressure mechanism 202 can also be implemented as a telescopic assembly, such as a telescopic rod or a telescopic cylinder. Taking the telescopic rod as an example, the telescopic rod includes an outer rod and an inner rod. The pressure application rod 201 passes through the outer rod and is movably connected to the inner rod. The movable connection can be, for example, connected through a rack. The pressure application rod 201 is implemented as a rocker, so that the inner rod moves up and down within the outer rod, cooperating with the reaction force component 3 arranged above to generate corresponding pressure on the standard specimen 4. The pressure value is read according to the pressure gauge 203. After reaching the preset pressure value, the operation of the pressure application rod 201 is stopped.

[0060] The reaction force component 3 includes a reaction force rod 301, a reaction force frame 302, a fixing bolt 303, and a height adjustment hole 304; two reaction force frames 302 are provided. A plurality of height adjustment holes 304 are provided on the reaction force frame 302. The reaction force frame 302 is fixed to the upper end of the cylinder 101 through the fixing bolt 303 cooperating with the height adjustment hole 304 and the reaction force frame fixing hole 104. Both ends of the reaction force rod 301 are fixedly installed through one of the reaction force frames 302.

[0061] The reaction force component 3 cooperates with the pressure mechanism 202 through the reaction force rod 301 to generate pressure on the standard specimen 4. The plurality of height adjustment holes 304 cooperate with the fixing bolt 303 to make the distance between the reaction force rod 301 and the standard specimen 4 adjustable, so as to be applicable to standard specimens 4 of different heights.

[0062] In some embodiments, as Figure 1 shown, the collection component 1 further includes a support 103. A plurality of supports 103 are provided, and the plurality of supports 103 fixedly support the cylinder 101. The design of the support 103 makes the overall evaluation device easier to be placed stably, which is beneficial to the subsequent evaluation method and ensures the accuracy of the applied pressure.

[0063] In some embodiments, a specific installation method of the reaction force rod 301 is provided, as Figure 1 shown, a reaction force rod fixing hole 305 is provided on the reaction force frame 302. Both ends of the reaction force rod 301 are fixedly installed through the reaction force rod fixing hole 305 provided on one of the reaction force frames 302.

[0064] Based on the evaluation device for leached pollutants of solid waste used as subgrade filler described in each of the above embodiments, the embodiments of the present invention further provide an evaluation method for leached pollutants of solid waste used as subgrade filler. This evaluation method comprehensively considers boundary conditions such as different depths, different structural layers, and different stress states of solid waste used as subgrade filler, so as to evaluate its long-term leaching law of pollutants. By comparing with relevant standards (specifications) for the concentration of toxic and harmful substances in the leachate, the environmental safety of using this solid waste material as subgrade filler is judged. Specifically, as Figure 2 shown, this evaluation method starts from step S100, and determines the pressure applied by the pressure component according to the deviator stress of the layer where the solid waste is used as subgrade filler.

[0065] In some embodiments, as Figure 3 shown, the deviator stress of the layer where the solid waste is used as subgrade filler is determined by the following method:

[0066] Step S101, determine that the layer where the solid waste is used as subgrade filler is the stress calculation layer, and the stress calculation layer includes multiple stress calculation points.

[0067] It should be noted that the stress calculation layer described in this article is at least two of the road structure layers. The road structure layer is divided into six layers from top to bottom, namely the surface layer, the base layer, the upper roadbed, the lower roadbed, the upper embankment, and the lower embankment. The stress calculation layer is determined to be at least two of the surface layer, the base layer, the upper roadbed, the lower roadbed, the upper embankment, and the lower embankment according to the layer where the solid waste is used as subgrade filler. The stress calculation layer can be regarded as composed of multiple stress calculation points. In this article, each stress calculation layer is evenly divided into multiple stress calculation points for calculation to ensure the accuracy of the deviator stress calculation.

[0068] Step S102, calculate the vertical stress of the vehicle load acting on each stress calculation point based on the mechanics of the layered elastic system.

[0069] It should be noted that during the calculation based on the mechanics of the layered elastic system, it is assumed that the materials of each structural layer are isotropic and homogeneous linear elastic bodies; it is assumed that the subgrade is infinite in the horizontal direction and can extend infinitely in the vertical downward direction; it is assumed that there is complete continuity between each structural layer. Accordingly, the vertical stress of the vehicle load acting on each stress calculation point is calculated through the layered elastic system mechanics calculation program Bisar3.0.

[0070] Step S103, calculate the self-weight stress of the upper soil mass received by each stress calculation point according to formula (1):

[0071]

[0072] In the formula: the subscript i is the layer number of the subgrade stratified from top to bottom; n is the total number of layers; γ is the unit weight of soil (kN / m3 ); h is the soil layer thickness (m); F is the cross-sectional area of the soil column.

[0073] Step S104: Superimpose the vertical stress of the vehicle load acting on each stress calculation point on the self-weight stress of the upper soil body received by the corresponding stress calculation point to obtain the vertical total stress received by each stress calculation point.

[0074] Step S105: Subtract the horizontal stress received by the soil body caused by the load from the vertical total stress received by each stress calculation point to obtain the deviator stress received by each stress calculation point.

[0075] Step S106: Select the point with the maximum deviator stress in each stress calculation layer as the deviator stress of the layer where the solid waste is used as subgrade filler to explore the long-term leaching toxicity of the target components.

[0076] In some embodiments, the pressure F applied by the pressure component = p * A, where p is the deviator stress of the layer where the solid waste is used as subgrade filler, and A is the cross-sectional area of the pressure transmission gasket.

[0077] Only as an example, when the pressure transmission gasket is selected as a circular structure with a diameter of 152 mm, A = 181.5 cm 2 .

[0078] In step S200, place the standard specimen in the cylinder. With the sampling hole closed, add distilled water into the cylinder until it submerges the top of the standard specimen.

[0079] It should be noted that the purpose of adding distilled water into the cylinder until it submerges the top of the standard specimen is to soak the whole specimen to simulate the situation of the subgrade being completely immersed in water. The immersion depth is determined according to the situation of the subgrade being completely immersed in water to be simulated. For example, it can be 3 - 5 mm, and this embodiment does not limit it here.

[0080] In step S300, place the pressure transmission gasket on the top of the standard specimen and apply pressure to the standard specimen according to the determined pressure.

[0081] In some embodiments, as Figure 4 shown and in combination with Figure 1 , the placing the pressure transmission gasket on the top of the standard specimen and applying pressure to the standard specimen according to the determined pressure specifically includes:

[0082] Step S301: Pass the reaction rod through the two reaction frames in sequence.

[0083] Step S302: Adjust the reaction device to the preset height. At this time, pass the fixing bolts through the height adjustment holes and the reaction frame fixing holes in sequence and tighten them.

[0084] In step S303, adjust the pressure - applying rod to generate pressure on the pressure mechanism. When the reading of the pressure gauge reaches the determined pressure applied by the pressure component, stop the operation of the pressure - applying rod.

[0085] In step S400, after static pressure reaches the expected static - pressure time, take out the leachate through the sampling hole and detect the concentration of the target component in the leachate.

[0086] It should be noted that the target component can be determined according to the components of the solid waste used as subgrade filler, and the pollutants that may be leached during the use of the solid waste as subgrade filler theoretically are used as the target component.

[0087] Exemplarily, the concentration of the target component includes one or a combination of manganese concentration and ammonia - nitrogen concentration.

[0088] Finally, in step S500, evaluate the environmental safety of the materials used for road filling according to the concentration of the target component.

[0089] As Figure 5 shown, the evaluation of the environmental safety of the materials used for road filling according to the concentration of the target component specifically includes:

[0090] Step S501, construct a regression - index model according to the concentration of the target component in the leachate obtained under different expected static - pressure times.

[0091] In some embodiments, the regression - index model is expressed as:

[0092] y1 = A1*exp( - x / t1)+y0 (2)

[0093] Where y1 represents the leaching concentration of pollutants (mg / L or μg / L), x is the soaking time (days), exp() represents the exponential function, and A1, t1, and y0 are fitting parameters.

[0094] Step S502, calculate the leaching amount of the target component of the pavement structure at the design service life according to the regression - index model.

[0095] Next, the embodiments of the present invention will further illustrate the progressiveness of the present invention in combination with specific implementation cases.

[0096] Considering that under actual road - use conditions, subgrade soil is affected by factors such as self - weight, external loads, and intrusion of groundwater, etc., in this study, the long - term leaching toxicity study of the manganese - slag subgrade after special treatment was carried out using this invention patent. According to the current specification "Code for Design of Highway Asphalt Pavement" (JTGD50 - 2017), the standard design axle load for asphalt pavement design in China is a single - axle dual - wheel of 100 kN. The stress of the tire on the ground is simplified as two equivalent circles with a center - to - center distance of 319.5 mm and a diameter of 213 mm, and the tire pressure on the ground is 700 kPa. The schematic diagram of the axle load is shown inFigure 6 。

[0097] For the standard double - circle uniform load, analyze the internal stress of the manganese slag subgrade under static action, and solve the stress through Bisar3.0. Referring to the current specification "Code for Design of Highway Asphalt Pavement" (JTDG50 - 2017), set two benchmark pavement schemes for granular base course and inorganic binder stabilized base course. The stress calculation model is divided into 6 layers from top to bottom according to the road structure, namely surface course, base course, upper roadbed, lower roadbed, upper embankment, and lower embankment. The compaction degree and other parameters of each layer of the subgrade all refer to the standard parameters of the filled subgrade in the current specification "Code for Construction Technology of Highway Subgrade" (JTG / T3610 - 2019). The material parameters of each layer are shown in Tables 1 - 2. A total of 4 layers are set as stress calculation layers in the subgrade structure. The calculation points of each layer are 0.58m, 0.88m, 1.38m, and 2.08m from the top of the surface course from top to bottom, respectively, located within the upper roadbed, lower roadbed, upper embankment, and lower embankment structures. In each layer of the subgrade structure, 4 stress calculation points are taken. The 4 points of each layer are 0mm, 26.625mm, 53.25mm, and 159.75mm from the mid - point of the connection line of the two equivalent circle centers from left to right, totaling 16 stress points. The schematic diagram is shown in Figure 7 。

[0098] Table 1 Parameters of each structural layer of Scheme 1

[0099] Structural parameters Thickness (cm) Modulus (MPa) Poisson's ratio <![CDATA[Density (kg / m 3 )]]> Degree of compaction Surface course 18 8000.00 0.25 2.50 - Base course of granular material 40 400.00 0.35 2.30 - Upper roadbed 30 128.50 0.40 1.69 96％ Lower roadbed 50 128.50 0.40 1.69 96％ Upper embankment 70 119.50 0.40 1.62 94％ Lower embankment ∞ 115.30 0.40 1.59 93％

[0100] Table 2 Parameters of each structural layer of Scheme 2

[0101]

[0102] During the calculation process, it is assumed that the materials of each structural layer are isotropic and homogeneous linear elastic bodies; it is assumed that the subgrade is infinite in the horizontal direction and can extend infinitely in the vertical downward direction; it is assumed that there is complete continuity between each structural layer. Based on this, after calculating the vertical stress of the vehicle load acting on each stress calculation point through the layered elastic system mechanics calculation program Bisar3.0, according to the formula (1) for the self - weight stress of layered soil in soil mechanics, calculate the self - weight stress of the upper soil body corresponding to the calculation point. Superimpose the vertical stress generated by the vehicle load and the self - weight stress of the soil to obtain the vertical total stress received by each stress point. Then, subtract the horizontal stress of the soil caused by the load from the vertical total stress to obtain the deviator stress.

[0103]

[0104] In the formula: the subscript i is the layer number of the subgrade stratified from top to bottom; n is the total number of layers; γ is the unit weight of soil (kN / m 3 ); h is the thickness of the soil layer (m); F is the cross - sectional area of the soil column.

[0105] The additional stress caused by the vehicle load at each point and the deviator stress caused by the self-weight of the upper soil layer are shown in Table 3. The results show that in Plan 1, the point with the maximum stress appears at a depth of 2.08 m, which is 42.22 kPa, and the point with the minimum stress appears at a depth of 0.88 m, which is 31.01 kPa; in Plan 2, the point with the maximum stress appears at a depth of 2.08 m, which is 40.80 kPa, and the point with the minimum stress appears at a depth of 0.88 m, which is 12.15 kPa.

[0106] The long-term leaching toxicity of the manganese slag subgrade was explored using the device of this patent. According to the above calculation results, the point with the maximum deviator stress in each layer was taken. Due to space limitations, in this case, only the point a4 with the maximum deviator stress among the four points at the same layer of 2.08 m in Plan 1 (vertical depth of 2.08 m, horizontal distance from the center of the line connecting the centers of the two equivalent circles) was selected for elaboration. Standard static pressure forming specimens with a corresponding compaction degree (93%) were prepared from the specially treated manganese slag material and placed in the main body of the device. The device pressure was set to 42.22 kpa * 181.5 cm 2 = 726 N. Considering the most unfavorable conditions under actual road use conditions, the liquid level in the device was set to overflow the specimen by 3 - 5 mm, that is, the specimen was soaked as a whole to simulate the situation of the subgrade being completely immersed in water. Samples were taken on the 3rd, 7th, 11th, and 15th days after the device was left standing. According to the current standard "Methods for Chemical Analysis of Gold" (GB / T 11066.11 - 2021), the manganese concentration in the leachate was detected by inductively coupled plasma mass spectrometry (ICP-MS). According to the current standard "Water Quality - Determination of Ammonia Nitrogen - Nessler's Reagent Spectrophotometric Method" (HJ 535 - 2009), the ammonia nitrogen concentration in the leachate was detected by Nessler's reagent spectrophotometry. The results are shown in Figure 8 .

[0107] Table 3 Calculation Results of Stresses at Each Point

[0108]

[0109]

[0110] The upper limit requirement of the current specification "Integrated Wastewater Discharge Standard" (GB 8978 - 1996) for the manganese concentration in wastewater is 2 mg / L, and the upper limit requirement for the ammonia nitrogen concentration is 25 mg / L. The long-term experiment of this study is ongoing (30 d, 90 d, 180 d). Only the leaching concentration within 15 d is shown here. Subsequently, the long-term leaching situation is analyzed according to the exponential regression model and compared with the actual experiment. According to Figure 4It can be seen that the manganese concentration shows an upward trend within 15 days, and the upward rate gradually decreases. Its concentration is 36.64 μg / L at 15 days. The ammonia nitrogen concentration shows an upward trend within 15 days, and its variation law is approximately the same as that of the manganese concentration. The concentration reaches the maximum value of 13.92 mg / L at 15 days. According to the exponential regression model of formula (2), the regression fitting degrees of the leached manganese concentration and the leached ammonia nitrogen concentration reach 0.998 and 0.996 respectively, indicating a high correlation. In the current specification "Technical Standard for Highway Engineering" (JTG B01-2014), it is stipulated that the design service life of the pavement structure of expressways and first-class highways is 15 years. Through the calculation of the exponential regression model, the leaching amounts of manganese and ammonia nitrogen in the manganese slag subgrade after special treatment are 37.03 μg / L and 13.90 mg / L respectively at the 15th year. In summary, when the manganese slag after special treatment is used as a road filling material, the leaching concentrations of manganese and ammonia nitrogen are far lower than the upper limits of the relevant specifications, and the environmental safety meets the standards.

[0111] It should be noted that the above examples are merely examples. The present invention can also use the devices described in the above various embodiments to continue to detect the leaching toxicity of other stress points according to actual needs, and can comprehensively analyze the influence laws of different compaction degrees (depths), leaching times, and the magnitudes of applied stresses on toxicity leaching.

[0112] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more of their aspects) can be used in combination with each other. For example, those of ordinary skill in the art can use other embodiments when reading the above description. Additionally, in the above detailed description, various features can be grouped together to simplify the present disclosure. This should not be construed as an intention that the disclosed features not claimed are necessary for any claim. On the contrary, the subject matter of the present invention may be less than all the features of a particular disclosed embodiment. Thus, the following claims are incorporated into the detailed description as examples or embodiments, where each claim stands alone as a separate embodiment, and these embodiments can be combined with each other in various combinations or permutations. The scope of the present invention should be determined with reference to the appended claims and the full scope of the equivalents to which these claims are entitled.

Claims

1. An evaluation method for leached pollutants of solid waste used as subgrade filler, characterized in that, An evaluation device for leaching pollutants from solid waste used as subgrade filler, the evaluation device includes a collection component, a pressure component and a reaction force component; the collection component includes a cylinder body, a sampling hole and a reaction force frame fixing hole, and the sampling hole and the reaction force frame fixing hole are arranged on the cylinder body; the pressure component includes a pressure application rod, a pressure mechanism, a pressure gauge and a pressure transmission gasket, and the pressure application rod, the pressure mechanism and the pressure gauge are arranged at the upper end of the pressure transmission gasket; the reaction force component includes a reaction force rod, a reaction force frame, fixing bolts, height adjustment holes; two reaction force frames are provided, and a plurality of height adjustment holes are arranged on the reaction force frames. The reaction force frames are fixed to the upper end of the cylinder body through fixing bolts in cooperation with the height adjustment holes and the reaction force frame fixing holes, and both ends of the reaction force rod are fixedly installed through one of the reaction force frames respectively; The evaluation method includes: Determine the pressure applied by the pressure component according to the deviator stress at the layer where the solid waste is used as subgrade filler; Place the standard specimen in the cylinder body, and add distilled water into the cylinder body until it submerges the top of the standard specimen while closing the sampling hole; Place the pressure transmission gasket on the top of the standard specimen, and apply pressure to the standard specimen according to the determined pressure; After static pressure to the expected static pressure time, take out the leachate through the sampling hole and detect the concentration of the target component in the leachate; Evaluate the environmental safety of the material used for road filling according to the concentration of the target component; Determine the deviator stress at the layer where the solid waste is used as subgrade filler by the following method: Determine that the layer where the solid waste is used as subgrade filler is the stress calculation layer, and the stress calculation layer includes multiple stress calculation points; Based on the mechanics of layered elastic system, calculate the vertical stress of the vehicle load acting on each stress calculation point; Calculate the self-weight stress of the upper soil mass received by each stress calculation point according to formula (1): Where: the subscript i is the layer number of the subgrade from top to bottom; n is the total number of layers; γ is the unit weight of the soil, kN / m 3 ; h is the thickness of the soil layer, m; F is the cross-sectional area of the soil column; Superimpose the vertical stress of the vehicle load acting on each stress calculation point and the self-weight stress of the upper soil mass received by the corresponding stress calculation point to obtain the vertical total stress received by each stress calculation point; Subtract the horizontal stress caused by the load on the soil mass from the vertical total stress received by each stress calculation point to obtain the deviator stress received by each stress calculation point; Select the point with the maximum deviator stress in each stress calculation layer as the deviator stress at the layer where the solid waste is used as subgrade filler.

2. The evaluation method for leached pollutants of solid waste used as subgrade filler according to claim 1, characterized in that, The collection component further includes supports, and a plurality of supports are provided to fixedly support the cylinder body.

3. The evaluation method for leached pollutants of solid waste used as subgrade filler according to claim 1, characterized in that There is a reaction force rod fixing hole on the reaction force frame, and both ends of the reaction force rod are fixedly installed through the reaction force rod fixing holes arranged on one of the reaction force frames respectively.

4. The evaluation method for leached pollutants of solid waste used as subgrade filler according to claim 1, characterized in that, The pressure F applied by the pressure component = p * A, where p is the deviator stress at the layer where the solid waste is used as subgrade filler, and A is the cross-sectional area of the pressure transmission gasket.

5. The evaluation method for leached pollutants of solid waste used as subgrade filler according to claim 1, characterized in that, The step of placing the pressure transmission gasket on the top of the standard specimen and applying pressure to the standard specimen according to the determined pressure specifically includes: Pass the reaction force rod through the two reaction force frames in sequence; Adjust the reaction force device to the preset height, and at this time, pass the fixing bolts through the height adjustment holes and the reaction force frame fixing holes in sequence and tighten them; Adjust the pressure-applying rod to make the pressure mechanism generate pressure. When the reading of the pressure gauge reaches the determined pressure applied by the pressure component, stop the operation of the pressure-applying rod.

6. The evaluation method for leached pollutants of solid waste used as subgrade filler according to claim 1, characterized in that, The target component concentration includes one or a combination of manganese concentration and ammonia nitrogen concentration.

7. The evaluation method for leached pollutants of solid waste used as subgrade filler according to claim 6, characterized in that, Evaluating the environmental safety of the road filling material according to the target component concentration specifically includes: Construct a regression index model based on the target component concentration of the leachate obtained under different expected static pressure times; Calculate the leaching amount of the target component of the pavement structure at the design service life according to the regression index model.

8. The evaluation method for leached pollutants of solid waste used as subgrade filler according to claim 7, characterized in that The regression index model is expressed as: y1 = A1 * exp(-x / t1) + y0 (2) Where, y1 represents the pollutant leaching concentration, in mg / L or μg / L, x is the soaking time, in days, exp() represents the exponential function, and A1, t1 and y0 are fitting parameters.

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