Instrument for simulating corrosion effect of acid rain on soil structure and corrosion simulation method

Abstract

The invention relates to an instrument for simulating the corrosion effect of acid rain on a soil structure. The instrument comprises a transparent corrosion cylinder, a water storage device, a water pump, and a first filtering piece, a second filtering piece and a third filtering piece which are sequentially arranged in the corrosion cylinder from top to bottom and divide the corrosion cylinder into a first area, a second area, a third area and a fourth area, a water inlet of the water pump is communicated with the water storage device, and a water outlet of the water pump is communicated with the corrosion cylinder. Functional areas are clearly divided through the layered design of the transparent corrosion cylinder and the three layers of filtering pieces, natural permeation simulation of an acid rain solution from top to bottom is achieved, meanwhile, precise separation and enrichment of corrosion products of different sizes are completed by means of graded filtering, and a pure sample is provided for subsequent targeted analysis; the water storage device can pre-prepare a simulated acid rain solution with a specific pH value and components, so that the stability of an acid rain source is ensured, and the requirements of different experimental working conditions are met.

Description

Technical Field

[0001] This invention relates to the field of soil microstructure testing and analysis, and more specifically, to an instrument and method for simulating the dissolving effect of acid rain on soil structure. Background Technology

[0002] With the continuous development of soil science, geotechnical engineering, and environmental science, the need to deeply explore the changes in soil microstructure and damage mechanisms under the influence of complex and variable environmental factors is becoming increasingly urgent. Among the various environmental factors affecting soil structure, soil dissolution damage caused by acid rain and landfill leachate is particularly significant and has become a hot and difficult issue in current academic research and engineering practice.

[0003] Acid rain, due to its acidic nature, can chemically react with various minerals in the soil, damaging the original soil structure and leading to a decrease in soil strength and stability. Landfill leachate, with its complex composition and various harmful substances, can also cause severe erosion damage to the soil during long-term infiltration, greatly affecting the engineering properties and environmental safety of the soil. Therefore, there is an urgent need to use more advanced instruments and equipment to investigate the erosion damage effects of the above factors on soil structure.

[0004] While research on soil dissolution damage has made some progress, many problems still need to be addressed in terms of experimental methods and monitoring techniques. At the level of experimental methods, existing room-temperature soil dissolution tests do not comprehensively and deeply consider key factors such as osmotic pressure, pH value, and leachate type, making it difficult to accurately simulate the soil dissolution process under complex actual environments, resulting in discrepancies between experimental results and actual conditions. At the level of monitoring techniques, traditional methods rely heavily on testing the physical properties of the soil before and after the test (such as particle analysis and density measurement). While these methods can obtain basic information before and after dissolution, they cannot monitor the subtle changes in the internal structure of the soil during the dissolution process in real time (such as the dynamic evolution of pores and cracks, and the gradual change of cementitious materials), making it difficult to reveal the intrinsic mechanisms of soil dissolution damage. Summary of the Invention

[0005] The primary objective of this invention is to provide an instrument for simulating the erosive effect of acid rain on soil structures. This instrument allows for pre-adjustment of osmotic pressure and ensures uniform solution penetration. Furthermore, it can be combined with digital imaging technology, ion probes, and high-precision electronic balances. During the experiment, acoustic emission and digital imaging technology are used in the middle section to monitor wave velocity, acoustic emission, and changes in pore size and fissures in real time. At the bottom, a high-precision electronic balance and ion probes are used to analyze clay particles and ion concentration, thereby exploring the soil erosion rate and changes in cementitious materials.

[0006] To achieve the above-mentioned objectives, the technical solution adopted is as follows: An instrument simulating the erosive effect of acid rain on soil structures includes a transparent erosion cylinder, a water storage device, a water pump, and a first filter element, a second filter element, and a third filter element arranged sequentially from top to bottom within the erosion cylinder to divide the erosion cylinder into a first region, a second region, a third region, and a fourth region; the inlet of the water pump is connected to the water storage device, and the outlet of the water pump is connected to the erosion cylinder.

[0007] In the above scheme, the water storage device serves as a storage unit for the simulated acid rain solution. It can be pre-configured with a simulated acid rain solution of a specific pH value and composition that meets the experimental requirements, providing a stable "acid rain source" for the dissolution process. The water pump, as the power core, can extract the simulated acid rain solution from the device through its inlet-to-water connection with the water storage device. By connecting the outlet to the dissolution cylinder, the extracted solution is stably injected into the first area at the top of the dissolution cylinder, thereby constructing a top-down solution flow dynamic system to simulate the process of acid rain settling and infiltrating the soil in the natural environment.

[0008] The dissolution chamber is divided into four functional zones by three filters arranged from top to bottom, with the second zone being the core dissolution zone. When the simulated acid rain solution enters the first zone, it first undergoes preliminary filtration by the first filter to remove any large particles that may be present in the solution, preventing these impurities from interfering with the accuracy of the subsequent soil dissolution reaction. The purified solution then evenly penetrates into the soil sample in the second zone, undergoing physical penetration and chemical dissolution. The acidic components in the solution react chemically with the minerals in the soil, disrupting the original soil structure and causing some particles (such as clay particles) to detach and mix with the solution to form leachate.

[0009] The leachate is sequentially filtered through second and third filters to separate dissolution products of different sizes. The second filter intercepts larger soil particles in the leachate, allowing only the leachate containing fine clay particles and dissolved substances to enter the third zone, making the third zone a clay particle enrichment area. Subsequently, the third filter further filters the clay particles in the leachate, allowing only the clarified leachate containing dissolved soil minerals to enter the fourth zone, completing the graded separation of "large particles - clay particles - dissolved substances".

[0010] Through the aforementioned layered dissolution and graded filtration process, the instrument concentrates the dissolution products in the third region (clay particles) and the fourth region (clarified leachate), respectively. The transparent dissolution cylinder structure facilitates observation of the entire dissolution and infiltration process. Simultaneously, it allows direct sampling of clay particles in the third region to analyze their particle size, content, and other data, reflecting the impact of acid rain dissolution on soil particle migration. Sampling of the clarified leachate in the fourth region allows for analysis of its pH value, ion concentration, chemical composition, and other data, quantifying the degree of acid rain-soil dissolution reaction. Ultimately, this enables a systematic study of the dissolution patterns of soil structures under the influence of acid rain.

[0011] Preferably, the inlet and outlet of the water pump are connected to the water storage device and the dissolution cylinder via pipes, respectively; valves are installed on the pipes connecting the inlet and outlet. Through the combined action of the valves and the water pump, the pre-adjustment of the osmotic pressure is achieved, controlling the flow rate and osmotic pressure of the solution.

[0012] Preferably, the top of the etch cylinder is provided with a protective cover, and the outlet of the water pump is connected to the space inside the etch cylinder through the protective cover.

[0013] Preferably, the first filter element includes a permeable stone layer and a filter paper arranged sequentially from top to bottom, and the edges of the permeable stone layer and the filter paper are connected to the inner wall of the etching cylinder.

[0014] Preferably, the second filter element includes filter paper and filter screen arranged sequentially from top to bottom, and the edges of the filter paper and filter screen are connected to the inner wall of the etching cylinder.

[0015] Preferably, the third filter element includes filter paper and filter screen arranged sequentially from top to bottom, and the edges of the filter paper and filter screen are connected to the inner wall of the etching cylinder.

[0016] Preferably, it also includes an ion probe for detecting the leachate at the bottom of the etching cylinder.

[0017] Preferably, it also includes a sampling box, which is connected to the bottom of the etching cylinder. An ion probe is positioned above the sampling box and is moved up and down by a rocker arm to penetrate into or move away from the sampling box.

[0018] Preferably, it also includes a data logger, which is electrically connected to the ion probe.

[0019] The second objective of this invention is to provide a method for simulating the dissolving effect of acid rain on soil structures, which utilizes the aforementioned instrument: A method for simulating the dissolution effect of acid rain on soil structures includes the following steps: Prepare soil samples; The prepared soil sample is placed into the second area of ​​the leaching cylinder; Start the water pump to draw the solution from the water storage device and inject it into the first area of ​​the dissolution cylinder; After the solution enters the first area, it passes through the first filter element and then enters the soil sample in the second area to dissolve the soil sample. The leachate containing soil and solution enters the third area after being filtered by the second filter element. The leachate containing soil and solution enters the fourth area after being filtered by the third filter element. Data was collected and analyzed for clay particles in the third region; data was collected and analyzed for leachate in the fourth region.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1) Through the layered design of transparent etching cylinder and three-layer filter, functional areas are clearly defined to realize the natural infiltration simulation of acid rain solution from top to bottom. At the same time, the graded filtration completes the precise separation and enrichment of etching products of different sizes, providing pure samples for subsequent targeted analysis. The water storage device can be pre-mixed with simulated acid rain solution with specific pH value and composition to ensure the stability of the "acid rain source" and meet the needs of different experimental conditions.

[0021] 2) By coordinating the water pump with the valves of the inlet and outlet water pipelines, the osmotic pressure can be pre-adjusted and the solution flow rate can be precisely controlled, effectively solving the problems of unstable osmotic pressure and uneven solution osmosis in traditional simulation devices, ensuring that the dissolution process is closer to the natural acid rain osmosis law, and improving the reliability and accuracy of experimental data.

[0022] 3) The instrument can be combined with multiple technologies such as digital imaging technology, ion probes, high-precision electronic balances, and acoustic emission equipment to achieve real-time dynamic monitoring of wave velocity, acoustic emission, and changes in pores and fissures during the dissolution process. At the same time, the ion probe and high-precision electronic balance can be used to accurately analyze the ion concentration of clay particles and leachate, comprehensively capturing the soil dissolution rate and cementation changes, providing rich data support for in-depth research on the dissolution mechanism. The sampling box design with a data logger and a movable ion probe further improves the convenience and continuity of data acquisition. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1A schematic diagram of an instrument used to simulate the dissolving effect of acid rain on soil structures. Detailed Implementation

[0025] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Example

[0026] The structural diagram of the instrument provided by this invention is as follows: Figure 1 As shown, this embodiment is based on the instrument for simulating the erosive effect of acid rain on soil structures described in this invention. It focuses on illustrating the assembly method and collaborative working process of each component of the instrument. The specific implementation is as follows: First, the instrument components were inspected and prepared. A comprehensive check was performed on all components of the simulation instrument, confirming that the transparent etching cylinder 1, water storage device 2, water pump 3, first filter element 4, second filter element 5, third filter element 6, protective cover 7, valve 8, sampling box 9, ion probe 10, and data logger 11 were all intact and undamaged, with no damage or blockage at any connection interface. Simultaneously, the connection lines of each monitoring component were checked to ensure reliable electrical connection between the ion probe 10 and the data logger 11, laying the foundation for subsequent instrument assembly and experimental execution. In addition, a simulated acid rain solution with a specific pH value and composition was pre-prepared according to experimental requirements and kept ready for use.

[0027] Following this, the core instrument assembly work commenced. Using the transparent etching cylinder 1 as the main body, the components were installed sequentially from bottom to top, dividing the cylinder into four functional areas. First, the third filter element 6, composed of filter paper and a filter screen, was installed at the bottom of the etching cylinder 1, sealing it to the inner wall. Below this element, the fourth area (clarified leachate collection area) was formed. Above the third filter element 6, the second filter element 5, also composed of filter paper and a filter screen, was installed, its edges tightly fitted to the inner wall of the etching cylinder 1. Below this element, the third area (clay particle enrichment area) was formed. Above the second filter element 5 was the second area (core etching area), where soil samples would be placed later. Above the second area, the first filter element 4, composed of a permeable stone layer and filter paper, was installed, its edges tightly connected to the inner wall of the etching cylinder 1, ensuring a level installation for uniform filtration. Finally, the protective cover 7 was installed on top of the etching cylinder 1, above the first filter element 4, ensuring a stable installation and leaving space for solution containment. After completing the installation of the internal components of the etching cylinder 1, the inlet of the water pump 3 is connected to the water storage device 2, and the outlet is connected to the protective cover 7 of the etching cylinder 1 through a pipe. Valves 8 are installed on the pipes connecting the inlet and outlet of the water pump 3 to construct a complete solution delivery path. Finally, the sampling box 9 is connected to the fourth area of ​​the etching cylinder 1 to collect the clarified leachate. The ion probe 10 is placed above the sampling box 9, and the rocker arm 12 is used to adjust the ion probe 10 to move it up and down, ensuring that it can penetrate deep into the sampling box 9 for detection. At the same time, the data recorder 11 is electrically connected to the ion probe 10 to realize the real-time acquisition and recording of detection data.

[0028] After the instrument is assembled, it is debugged and tested to verify the function of each component and the effect of their coordinated operation. A pre-prepared simulated acid rain solution is injected into the water storage device 2, and the water pump 3 is started. By adjusting the valves 8 on the inlet and outlet pipes, and in conjunction with the operating parameters of the water pump 3, the permeation pressure is pre-adjusted to control the flow rate and velocity of the solution. The solution is observed to flow smoothly from the water storage device 2 through the pipes and protective cover 7 into the reserved space at the top of the dissolution cylinder 1, and then permeates evenly through the first filter element 4. At this point, it is confirmed that there is no leakage, the permeation is uniform, and the adjustment functions of each valve 8 are normal. Subsequently, a pre-prepared soil sample is placed in the second area of ​​the dissolution cylinder 1, and the water pump 3 is started again, allowing the simulated acid rain solution to enter the second area after being filtered through the first filter element 4, contacting the soil sample and initiating the dissolution process. During the process, it was observed that after the leachate produced by dissolution was filtered by the second filter element 5, larger soil particles were intercepted, and the leachate containing fine clay particles entered the third area; subsequently, the leachate was further filtered by the third filter element 6, and clay particles were intercepted and enriched in the third area. The clarified leachate entered the fourth area and flowed into the sampling box 9. The functions of each area were all performed normally.

[0029] Based on this, the combined application effect of the instrument and monitoring technology was verified. In the middle of the second region where the soil sample was located, acoustic emission technology and digital imaging technology equipment were used to achieve real-time monitoring of changes in soil wave velocity, acoustic emission signals, and the evolution of pores and fissures during the dissolution process. The mass of clay particles enriched in the third region was monitored using a high-precision electronic balance to analyze the soil dissolution rate. The ion concentration of the clarified leachate in the sampling box 9 was detected by an adjustable ion probe 10, and the detection data was collected and stored in real time by a data recorder 11. Throughout the trial operation, all components of the instrument worked together stably, and solution delivery, stratified dissolution, graded filtration, and data monitoring were all successfully achieved, verifying the rationality and reliability of the instrument's structural design and its ability to meet the needs of simulation experiments on the dissolution effect of acid rain on soil structures. Example

[0030] This embodiment is used to simulate the erosive effect of acid rain on soil structures. The simulation erosion method described in this invention is employed, and the specific implementation process is as follows: First, the experiment preparation and soil sample preparation were carried out. Naturally air-dried red soil was selected as the raw material according to the experimental requirements. It was crushed and sieved to remove impurities and large particles. Then, the required mass of soil and additives was accurately weighed, and the soil mixture was prepared according to the preset moisture content and dry density. A cylindrical mold meeting the experimental requirements was selected. After lubricating the inner wall of the mold, the prepared soil mixture was filled into the mold in one go. During the filling process, appropriate vibration was used to remove air from the soil, ensuring uniform distribution. The mold containing the soil was placed under the pressure head of a pressure testing machine, and a preset pressure was slowly applied and maintained for the specified holding time to compact the soil. After molding, the pressure was slowly released, and the soil sample was demolded using a demolding device. The demolded soil sample was wrapped with a moisture-retaining material and placed in a moisture-retaining tank for standard curing. After curing for the preset time, it was removed for use. At the same time, a comprehensive inspection of the simulation instruments used in the experiment was carried out to confirm that the water storage device 2, water pump 3, erosion cylinder 1 and other components were undamaged and unblocked, and that all connection parts were well sealed; the acoustic emission equipment, digital image technology equipment, high-precision electronic scale, ion probe 10 and other monitoring instruments were inspected to ensure that they could be turned on and calibrated normally, that the connection lines were correct and the data transmission was stable.

[0031] Next, the experimental parameters were adjusted and the dissolution process was carried out. A simulated acid rain solution with a specific pH value and composition that met the experimental requirements was pre-prepared and stored in the water storage device 2. To eliminate the influence of solution osmotic pressure on soil sample dissolution, the inflow rate of the solution was controlled by the water pump 3 and valve 8 before the experiment, and the osmotic pressure was slowly adjusted to ensure that the simulated acid rain solution flowed smoothly into the reserved gap of the dissolution cylinder 1, avoiding excessive fluctuations in the liquid level and ensuring a stable start to the dissolution process. After the solution entered the dissolution cylinder 1, it was initially filtered by the first filter element 4 to remove impurities, and then it permeated evenly into the soil sample, undergoing physical osmosis and chemical dissolution with the soil sample to form a leachate containing soil particles and solution. The leachate continued to permeate downwards, and after being filtered by the second filter element 5, larger soil particles were intercepted, and the leachate containing fine clay particles and dissolved substances entered the reserved clay particle storage gap; it was then further filtered by the third filter element 6, where clay particles were intercepted and enriched, and the clarified leachate entered the bottom of the dissolution cylinder 1 and was introduced into the sampling box 9.

[0032] In the central region of the soil sample, acoustic emission and digital imaging technologies were used to monitor and record in real time the changes in wave velocity, acoustic ringing number, and the evolution of pores and fissures during the dissolution process. A high-precision electronic balance was used to record the mass of enriched clay particles in real time to analyze the soil dissolution rate. A movable ion probe 10 was inserted into the sampling box 9 to continuously detect changes in ion concentration in the leachate. The detection data was collected and stored in real time using a data logger 11.

[0033] When the experiment reaches the preset time or obvious dissolution and damage characteristics are observed in the soil sample, water pump 3, valve 8, and all monitoring equipment are turned off in sequence to stop the experiment. Carefully remove the dissolved soil sample, observe and record its final morphology, dissolution damage, and other external characteristics. Systematically organize and summarize the clay particle mass data, leachate ion concentration data, acoustic emission signal data, and digital image monitoring data collected during the experiment. Use professional data analysis software to analyze these data, exploring the soil dissolution rate and cementitious material changes under acid rain, thus completing the entire simulation experiment.

[0034] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An instrument for simulating the dissolving effect of acid rain on soil structures, characterized in that: It includes a transparent etching cylinder, a water storage device, a water pump, and a first filter element, a second filter element, and a third filter element arranged sequentially from top to bottom inside the etching cylinder to divide the etching cylinder into a first region, a second region, a third region, and a fourth region; the water inlet of the water pump is connected to the water storage device, and the water outlet of the water pump is connected to the etching cylinder.

2. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 1, characterized in that: The water pump's inlet and outlet are connected to the water storage device and the dissolving cylinder via pipes, respectively; valves are installed on the pipes connecting the inlet and outlet.

3. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 2, characterized in that: The top of the erosion cylinder is equipped with a protective cover, and the outlet of the water pump is connected to the space inside the erosion cylinder through the protective cover.

4. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 3, characterized in that: The first filter element includes a permeable stone layer and a filter paper arranged sequentially from top to bottom, and the edges of the permeable stone layer and the filter paper are connected to the inner wall of the etch cylinder.

5. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 4, characterized in that: The second filter element includes filter paper and filter screen arranged sequentially from top to bottom, with the edges of the filter paper and filter screen connected to the inner wall of the etching cylinder.

6. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 5, characterized in that: The third filter element includes filter paper and filter screen arranged sequentially from top to bottom, with the edges of the filter paper and filter screen connected to the inner wall of the etching cylinder.

7. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 6, characterized in that: It also includes an ion probe, which is used to detect the leachate at the bottom of the etching cylinder.

8. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 7, characterized in that: It also includes a sampling box, which is connected to the bottom of the etching cylinder. An ion probe is positioned above the sampling box and is moved up and down by a rocker arm to penetrate into or move away from the sampling box.

9. The instrument for simulating the dissolving effect of acid rain on soil structures according to claim 8, characterized in that: It also includes a data logger, which is electrically connected to the ion probe.

10. A method for simulating the dissolving effect of acid rain on soil structures, using the instrument described in any one of claims 1-9, characterized in that: Includes the following steps: Prepare soil samples; Place the prepared soil sample into the second area of ​​the leaching cylinder; Start the water pump to draw the solution from the water storage device and inject it into the first area of ​​the dissolution cylinder; After the solution enters the first area, it passes through the first filter element and then enters the soil sample in the second area to dissolve the soil sample. The leachate containing soil and solution enters the third area after being filtered by the second filter element. The leachate containing soil and solution enters the fourth area after being filtered by the third filter element. Data was collected and analyzed for clay particles in the third region; data was collected and analyzed for leachate in the fourth region.

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