Oxidation-seepage experimental method for simulating process of infiltrating oxidized surface water into filler

Abstract

The invention relates to the technical field of pyrite-containing filler experiments, in particular to an oxidation-seepage experimental device and method for simulating the process of infiltrating oxidized surface water into filler, the experimental device comprises a reaction kettle for containing a sample, a water adding device for providing a seepage solution for the sample and a pressurizing device for constructing a controllable oxidation reaction environment for the reaction kettle, mineral phase change sequences and particle migration distribution characteristics of the filler under different oxidation-seepage coupling conditions can be obtained; the dynamic association rule of the oxidation reaction rate, the seepage velocity and the filler component evolution is quantitatively analyzed, then the association mechanism of the oxidation-seepage effect and the filler component change is disclosed, technical support is provided for analysis of the disaster-causing mechanism of the upward arch deformation of the pyrite-containing roadbed, and the stability of roads and buildings is further guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of pyrite-containing filler experiments, in particular to an oxidation-seepage experimental device and method for simulating a process in which oxidized surface water infiltrates into a filler. Background Art

[0002] The stability and load transfer efficiency of roadbed structures are core foundations for the safe operation of transportation projects. With the rapid development of high-grade highways and heavy-haul railways, the engineering durability of filler materials faces increasingly stringent requirements. Pyrite, a common associated component in natural fillers, has become a key hazard factor inducing progressive roadbed failure through its oxidation and expansion effects. Although current regulations have set thresholds for pyrite content in fillers, the discrete nature of the mineral's occurrence and the insufficient resolution of detection technology make accurate identification and risk warning of pyrite difficult in actual projects. Under oxidative surface water infiltration conditions, pyrite aggregates undergo complex water-rock-gas multiphase reactions under the action of oxidation and seepage, leading to the formation of secondary minerals and volume expansion effects, which in turn trigger chemical-mechanical synergistic degradation of the roadbed structure. This type of disease is characterized by long-term cumulative deformation, manifested as a continuously increasing, nonconvergent arching displacement. Its irreversibility and time-varying expansion force significantly increase the difficulty of engineering treatment and seriously threaten the full-life service performance of transportation roads.

[0003] A Chinese patent application (CN 106442172 A) discloses a multiphase flow-stress coupled core shear test apparatus and method. This apparatus utilizes specially designed shear plates and soft mortar to achieve a secure seal for high-pressure fluids, and utilizes matrix suction from a permeable baffle to control the multiphase flow. This makes it suitable for rock mechanics experiments under complex conditions. However, the apparatus's complex structure and cumbersome operation increase production costs and complicate quality control. Multiphase flow control relies on specially designed shear plates and soft mortar seals, but repeated compression and deformation of the mortar over long periods of use can degrade its sealing performance, affecting the accuracy of experimental data. A Chinese patent application (CN 110108750 A) discloses a cross-fracture seepage heat transfer test apparatus and method. These apparatus can simulate heat source distribution and determine the temporal distribution of the temperature and flow fields within a specimen under different heat source distributions. However, this apparatus is complex and requires high operator skill; even the slightest misoperation can affect the accuracy of experimental data. It relies on heating pads and resistance wires to simulate heat source distribution, but this simulation method may not fully reflect the actual heat source conditions under complex geological conditions. Furthermore, the device's insulation layer utilizes insulating cotton made from organosilicon fiber. Over time, this material aging may degrade the insulation, impacting experimental reliability. A Chinese patent (CN 109342150 A) discloses an experimental device and method for consolidation and permeability testing of aerated soil samples. Suitable for experiments with aerated soil, this device improves measurement accuracy and enables simultaneous consolidation and permeability testing. However, the device is complex to operate, expensive, and requires high operator skill, increasing the difficulty and cost of the experiment. It utilizes multiple sealing rings and complex piping connections. Over time, these rings may wear out, leading to a loss of sealing performance and impacting the reliability of the experimental results. Furthermore, while the device's computer data processing system improves data accuracy, it places extremely high demands on the system's stability and accuracy, and any failure could impact the entire experimental process.

[0004] Existing technologies for processing fillers face significant bottlenecks: First, some methods are complex, involving the pretreatment and modification of multiple materials, which is cumbersome to operate, increasing production costs and the difficulty of quality control, significantly impacting construction efficiency. Second, existing methods are sensitive to the construction environment, and changes in temperature, humidity, pH, etc. significantly affect filler quality. Third, most existing methods lack sufficient verification of long-term performance and durability, and more actual engineering cases are needed to demonstrate their stability and durability. These methodological deficiencies severely restrict the refined modeling of fillers in the oxidation-seepage coupled process, resulting in a lack of theoretical and technical support for disease prevention and control. Therefore, there is an urgent need to construct an experimental platform capable of reproducing water-rock interactions and to develop multi-parameter collaborative monitoring and cross-scale numerical simulation technologies to reveal the degradation mechanism of pyrite-containing fillers in dynamic seepage environments, provide a scientific basis for the durability design and intelligent maintenance of roadbed projects, and provide theoretical support for the performance assurance of transportation infrastructure throughout its life cycle. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an oxidation-seepage experimental device and method for simulating the process of oxidized surface water infiltration into fillers, revealing the mineral formation sequence and particle migration characteristics of pyrite-containing fillers under different oxidizing environments and seepage conditions, and further revealing the correlation mechanism between oxidation-seepage effect and filler composition changes.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] An oxidation-seepage experimental method for simulating the process of oxidizing surface water infiltrating into a filler, the method using an oxidation-seepage experimental device for simulating the process of oxidizing surface water infiltrating into a filler, the experimental device comprising a reactor, a water adding device, and a pressurizing device, the bottom of the reactor being connected to a drain pipe with a valve; the reactor having a hollow bottom plate, a sample base being placed above the bottom plate, a permeable stone being placed within the sample base, and an acrylic tube being placed above the permeable stone;

[0008] The method comprises the following steps:

[0009] S1: After the dried pyrite-containing filler sample is ground to less than 150 mesh, the sample is layered into an acrylic tube. During the loading process, the weight moisture content and packing density of the sample are set according to the experimental requirements;

[0010] S2: Place the acrylic tube containing the sample on the permeable stone, place the detection device (such as temperature sensor, photoelectric displacement sensor, weight moisture content probe, etc.) as needed, and close and seal the reactor;

[0011] S3: Open the pressurizing device and the water adding device to keep the internal pressure of the reactor consistent with the internal pressure of the water adding device so that the solution in the water adding device can flow smoothly into the sample and finally flow out from the drain pipe;

[0012] S4: By changing the type and flow rate of the solution in the water adding device and the type of gas in the pressurizing device, different oxidation environments and seepage conditions are simulated. Based on Darcy's seepage theory, the permeability coefficient K of the porous medium and the pressure gradient are mastered. , a quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample was constructed to achieve dynamic characterization of the fluid migration rate in the pyrite reaction zone under different oxidation-seepage conditions.

[0013] Furthermore, in the method, the operation of constructing the quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample is as follows: based on the Darcy seepage constitutive relationship, the dynamic permeability K calculated and the pressure gradient measured experimentally are used to calculate the relationship between the permeability K and the experimental pressure gradient. , combined with the detected fluid dynamic viscosity , a quantitative calculation model of the seepage rate q was constructed to understand the changes in the seepage rate of the sample in the oxidation-seepage experiment, which was used to characterize the changes in the internal pore structure. Specifically:

[0014] After completing the above experiment, calculate the percolation rate in the oxidation-percolation device ,in,

[0015] Since the main oxidative acid corrosion of pyrite in the sample, the oxidation reaction of pyrite under acidic conditions is expressed as:

[0016] ;

[0017] The pyrite oxidation rate was calculated according to the pyrite oxidation kinetic equation:

[0018] ;

[0019] where r Pyrite is the oxidation rate of pyrite; M0 is the mass of the sample before the experiment; M is the mass of the sample after the experiment; A Pyrite is the specific surface area of ​​pyrite; M Pyrite is the molar mass of pyrite; t is the reaction time;

[0020] The pore volume change coefficient is calculated based on the pore volume change caused by pyrite dissolution:

[0021] ;

[0022] ;

[0023] v Pyrite is the coefficient of variation of pore volume; In order to determine the change of pore volume before and after the reaction by nitrogen adsorption method, , V pore is the pore volume after reaction; V pore0 is the pore volume before reaction; is the number of moles of pyrite dissolved;

[0024] Permeability K varies with porosity The change of porosity is described by the modified Kozeny-Carman equation. The change in is driven solely by pyrite dissolution:

[0025] ;

[0026] ;

[0027] Where K0 is the initial permeability; is the initial porosity; n is the empirical index;

[0028] The pressure gradient ∇P of the sample before and after the reaction was indirectly calculated using Darcy's law using a gas adsorption analyzer;

[0029] ;

[0030] Where: Q is the gas flow rate of the gas adsorption analyzer; k g is the gas permeability coefficient; A is the cross-sectional area of ​​the sample.

[0031] Furthermore, the water adding device includes a hose, with a diverter and an external water tank connected to both ends of the hose respectively. The diverter is fixed above the sample through a movable bracket to ensure that the liquid in the water tank can enter the sample.

[0032] Furthermore, the water adding device is also provided with a flow meter and a flow switch.

[0033] Furthermore, the water tank is provided with a water tank pressure relief valve, a water tank pressure gauge and a water tank pressurizing device.

[0034] Furthermore, the pressurizing device includes a kettle pressure relief valve, a kettle pressure gauge and a gas cylinder.

[0035] Furthermore, the gas cylinder is connected to the reactor body through the gas inlet, and the gas in the gas cylinder is nitrogen, oxygen or a mixed gas of 50% nitrogen + 50% oxygen.

[0036] Furthermore, the reactor body is provided with a temperature sensor and a photoelectric displacement sensor. According to actual needs, other detection devices including a weight moisture content probe can be inserted into the sample for real-time detection. The filler is monitored in real time by the temperature sensor, the photoelectric displacement sensor and the weight moisture content probe, wherein the photoelectric displacement sensor records the height of the sample in the sample.

[0037] The present invention has the following advantages and beneficial effects:

[0038] The present invention provides an innovative oxidation-seepage experimental device, constructing a multi-field coupled oxidation-seepage experimental system with an innovative integrated hydraulic-mechanical-chemical dynamic interaction module. This device can effectively simulate the process of oxidized surface water infiltration into fillers, providing a reliable experimental platform for studying pyrite-containing roadbed fillers. The device is equipped with a temperature sensor, a photoelectric displacement sensor, and a gravimetric moisture content probe to achieve real-time monitoring of the filler's physical changes and moisture status, thereby obtaining more accurate experimental data. By regulating the gas environment and pressure, controlling the flow rate, and configuring fluids with different pH values, it can accurately reproduce complex working conditions such as dry-wet cycles and acid rain erosion. It deeply analyzes the mineral formation sequence and particle migration characteristics of pyrite-containing roadbed fillers under different oxidizing environments and seepage conditions, revealing the correlation mechanism between oxidation-seepage and filler composition changes, providing an important scientific basis for the design and construction of railway subgrades, and improving the safety and durability of railways. The experimental method and device design are highly adaptable and can be adjusted according to different research needs, making it suitable for the study of various types of fillers and seepage conditions. In addition, the present invention provides theoretical support and experimental basis for solving the problems of filler arch deformation and disease in high-speed railway construction, has important practical application value, and promotes the application of environmentally friendly materials in railway engineering, which is in line with the concept of sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the oxidation-seepage experimental device for simulating the process of oxidizing surface water infiltration into fillers in an embodiment of the present invention;

[0040] Figure 2 A top view of a reactor of an oxidation-seepage experimental device for simulating the process of oxidizing surface water infiltrating into a filler according to an embodiment of the present invention;

[0041] Figure 3 A top view of the sample base of the oxidation-seepage experimental device for simulating the process of oxidizing surface water infiltration into fillers in an embodiment of the invention;

[0042] Figure numerals: 1-reactor body, 2-kettle body handle, 3-hose, 4-movable bracket, 5-hollow bottom plate, 6-drain pipe, 7-sample base, 8-permeable stone, 9-acrylic tube, 10-sensor fixing position, 11-diverter, 12-kettle body pressure relief valve, 13-kettle body pressure gauge, 14-kettle body air inlet, 15-gas cylinder, 16-temperature sensor, 17-photoelectric displacement sensor, 18-weight moisture content probe, 19-flow meter, 20-flow switch, 21-water tank pressure relief valve, 22-water tank pressure gauge, 23-water tank pressurizing device, 24-sample, 25-water tank. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0044] like Figure 1 As shown, an oxidation-seepage experimental device for simulating the process of oxidized surface water infiltration into filler material includes a reactor, a water supply device, and a pressurizing device. The reactor is the main container for encapsulating pyrite-containing filler samples and implementing water-rock reaction. The water supply device provides seepage solution for the sample in the reactor, and the pressurizing device provides a reaction gas environment for the reactor. In this embodiment, the size of the reactor body 1 is set to , the internal size design of acrylic tube 9 , the size of the sample 24 is filled in To reduce the impact of the size effect on the experiment, the dried pyrite-containing filler sample 24 was ground to less than 150 mesh using a grinder. A certain amount of distilled water was added to the ground sample 24 to simulate the weight moisture content Wg of the sample 24 under a real environment. The sample 24 was then filled into the acrylic tube 9 according to a certain density ρ.

[0045] The reactor includes a reactor handle 2 and a reactor body 1. The bottom of the reactor body 1 has a downwardly concave arc to guide the solution to a drain pipe 6 equipped with a valve. The reactor body 1 has a hollow bottom plate 5, on which six sample bases 7 are evenly placed. Permeable stones 8 are placed within the sample bases 7, and an acrylic tube 9 containing the sample is placed above the permeable stones 8. To achieve the detection of relevant indicators, the experimental device in this embodiment also includes a temperature sensor 16, a photoelectric displacement sensor 17, and a weight moisture content probe 18. The temperature sensor 16 and the photoelectric displacement sensor 17 are mounted on the sensor fixing position 10 provided inside the reactor body 1, respectively used to monitor the changes in temperature and height of the sample during the reaction in real time. The weight moisture content probe 18 is inserted into the sample and, by real-time monitoring the changes in the weight moisture content of the sample, adjusts the water intake to stabilize the weight moisture content of the sample within the range required for the experiment.

[0046] The water supply device includes a hose 3, whose ends are respectively connected to the diverter 11 and the external water tank 25. The diverter 11 is fixed above the sample 24 by a movable bracket 4 to ensure that the liquid in the water tank 25 can enter the sample. The water tank 25 is equipped with a water tank pressure relief valve 21, a water tank pressure gauge 22, and a water tank pressurizing device 23. A flow meter 19 and a flow switch 20 are installed at the connection between the water tank 25 and the kettle body 1 to control and monitor the flow rate of the solution.

[0047] The pressurizing device includes a kettle body pressure relief valve 12, a kettle body pressure gauge 13 and a gas cylinder 15, wherein the gas cylinder 15 can be a nitrogen cylinder, an oxygen cylinder and a mixed gas cylinder according to experimental requirements, wherein the gas in the oxygen cylinder is pure oxygen, the gas in the nitrogen cylinder is pure nitrogen, and the gas in the mixed gas cylinder is 50% nitrogen + 50% oxygen, and the gas cylinder is connected to the reactor body 1 through the air inlet 14.

[0048] In the present invention, when collecting liquid and filler samples, the kettle 1 and the water tank 25 must be depressurized first to ensure safety during the experiment. Then, the above-mentioned device is used to conduct filler mineral composition testing and chemical composition testing on the collected samples before and after corrosion, specifically:

[0049] A method for conducting an experiment using the above-mentioned oxidation-seepage experimental device for simulating the process of oxidizing surface water infiltration into a filler comprises the following steps:

[0050] S1: In order to reduce the influence of size effect on the experiment, the dried pyrite filler sample was ground to less than 150 mesh by a grinder, and the sample mass was recorded as M0. A certain amount of distilled water was added to the ground sample to simulate the weight moisture content W of sample 24 under real environment. g Then, the sample is divided into 5 layers and loaded into the acrylic tube 9 according to a certain density ρ. The layers are scraped and evenly compacted during filling. The weight moisture content W g The calculation formula of density ρ is as follows:

[0051] ;

[0052] ;

[0053] Where: W g is the weight moisture content of the sample; G W is the amount of distilled water added; G S is the weight of the dry sample, ρ is the density of the sample 24 in the acrylic tube 9, m is the weight of the loaded sample, and v is the volume of the sample;

[0054] S2: Place the acrylic tube 9 containing the sample on the permeable stone 8, then insert the weight moisture content probe 18 into the sample 24, and close and seal the reactor body 1.

[0055] S3: Open the gas cylinder 15, the kettle air inlet 14, the flow switch 20, the water tank pressurizing device 23, and the drain pipe 6 with a valve. Observe the kettle pressure gauge 13 and the water tank pressure gauge 22 at the same time to ensure that the pressure inside the kettle is consistent with the pressure inside the water tank so that the solution in the water tank 25 can flow smoothly into the sample 24 and finally flow out of the drain pipe 6 with a valve.

[0056] S4: The flow rate of the solution in the water tank 25 through the sample is controlled by adjusting the flow switch. Different gas environments are set by replacing the gas cylinder 15, including 100% oxygen cylinder, 100% nitrogen cylinder, and 50% oxygen + 50% nitrogen cylinder. Multiple parallel experiments are conducted to analyze the mineral formation sequence and particle migration characteristics of pyrite filler under different oxidation environments and seepage conditions, thereby revealing the correlation mechanism between oxidation-seepage effect and filler composition change;

[0057] S5: The filler is monitored in real time by the temperature sensor 16, the photoelectric displacement sensor 17, and the weight moisture content probe 18. Since temperature has a significant impact on the expansion rate and fluid dynamic viscosity, the temperature is monitored in real time by the temperature sensor 16. The photoelectric displacement sensor 17 records the filler height during the experiment to observe the change in the expansion rate during the experiment. The expansion rate δ of the filler is calculated based on the initial height H0 of the sample 24 before the reaction and the filler height H after the reaction:

[0058] ;

[0059] The pore volume V of the sample 24 before and after the reaction was measured by nitrogen adsorption method using a gas adsorption analyzer. pore0 and V pore At the same time, the gas adsorption analyzer is used to indirectly calculate the pressure gradient of the sample 24 before and after the reaction through Darcy's law. ;

[0060] ;

[0061] ;

[0062] in: is the change in pore volume before and after the reaction; V pore is the pore volume after reaction; V pore0 is the pore volume before the reaction; Q is the gas flow rate of the gas adsorption analyzer; k g is the gas permeability coefficient; A is the cross-sectional area of ​​the rock and soil sample;

[0063] S6: During the first seven days of the experiment, the reaction solution was sampled at one-day intervals for water quality analysis, which may include testing for pH, conductivity, and major element ion concentrations. In the later stages of the experiment, the reaction solution was sampled at seven-day intervals and water quality analysis was also performed. At different reaction stages (e.g., once a month), the kettle and water tank were depressurized using the kettle pressure relief valve 12 and the water tank pressure relief valve 21. The kettle handle 2 was lifted, and a portion of the filler in one of the samples 24 was removed from the reactor. Mineral and chemical composition tests were performed on the filler before and after corrosion, and the sample 24 was dried to measure its mass M.

[0064] S7: After completing the above experiment, in order to calculate the seepage rate q in the oxidation-seepage device, since the oxidation and acid corrosion of pyrite are the main factors in the sample 24 in the device, the oxidation reaction of pyrite under acidic conditions can be expressed as:

[0065] ;

[0066] The pyrite oxidation rate was calculated according to the pyrite oxidation kinetic equation:

[0067] ;

[0068] where r Pyrite is the oxidation rate of pyrite; M0 is the mass of sample 24 before the experiment; M is the mass of sample 24 after the experiment; A Pyrite is the specific surface area of ​​pyrite, which was calculated using the BET formula based on the adsorption isotherm data; M Pyrite is the molar mass of pyrite; t is the reaction time;

[0069] The pore volume change coefficient is calculated based on the pore volume change caused by pyrite dissolution:

[0070] ;

[0071] ;

[0072] v Pyrite is the coefficient of variation of pore volume; To determine the pore volume change before and after the reaction by nitrogen adsorption method; is the number of moles of pyrite dissolved;

[0073] Permeability K varies with porosity The change of porosity is described by the modified Kozeny-Carman equation. The change in is driven solely by pyrite dissolution:

[0074] ;

[0075] ;

[0076] Where K0 is the initial permeability; is the initial porosity; n is the empirical index;

[0077] Based on the Darcy constitutive relationship for seepage, a quantitative calculation model for the seepage rate q was constructed by combining the calculated dynamic permeability K with the experimentally measured pressure gradient ∇P, in combination with the fluid dynamic viscosity μ (measured by a rotational viscometer). This model allowed us to understand the changes in the seepage rate of the sample during the oxidation-seepage experiment and to characterize the changes in the internal pore structure.

[0078] .

[0079] The following is an example of an oxidation-percolation experiment;

[0080] The purpose of this experiment is to study the changes in the physical and chemical properties of the filler under specific conditions, especially its behavior during the seepage process. The dry density of the filler is set to 1.45g / cm 3 The gravimetric water content was set to 5%, distilled water was used as the experimental fluid, and a temperature sensor was used to monitor the reactor temperature in real time. The rock samples were weighed using a balance before and after the experiment, and their pore volumes were measured using a gas adsorption analyzer. Basic rock sample and fluid data are shown in Table 1.

[0081] Table 1 Basic data of rock samples and fluids

[0082]

[0083] According to the above method, simulation experiments were carried out, and the experimental data were systematically analyzed and processed to finally obtain the calculation results. The detailed data are listed in Table 2 and Table 3 respectively;

[0084] Table 2 Test results

[0085]

[0086] Table 3 Calculation results

[0087]

[0088] After the above tests and calculations, the expansion rate δ and seepage rate q of this rock sample can be obtained as shown in Table 4;

[0089] Table 4 Expansion rate δ and seepage rate q of rock samples

[0090]

[0091] The results of this experiment only cover the initial phase of the oxidation-percolation experiment. To fully understand the dynamic changes in the sample during the oxidation-percolation process, subsequent experiments should conduct separate measurements and calculations at different stages of the reaction, recording the changes in the expansion ratio δ and the percolation rate q, thereby effectively characterizing the evolution of the sample's internal pore structure. This process is crucial for a deeper understanding of the oxidation-percolation mechanism.

[0092] The above is only an embodiment of the present invention, and common knowledge such as the specific technical solutions or characteristics in the solution is not described in detail here. For those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. An oxidation-seepage experimental method for simulating the infiltration of oxidizing surface water into a filler. The method utilizes an oxidation-seepage experimental apparatus for simulating the infiltration of oxidizing surface water into a filler. The experimental apparatus comprises a reactor, a water supply device for providing a seepage solution to a sample, and a pressurizing device for creating a controllable oxidation reaction environment for the reactor. A drain pipe with a valve is connected to the bottom of the reactor. The reactor has a hollow bottom plate, a sample base is placed above the bottom plate, a permeable stone is placed within the sample base, and an acrylic cylinder is placed above the permeable stone. The method comprises the following steps: S1: After the dried pyrite-containing filler sample is ground to less than 150 mesh, the sample is layered into an acrylic tube. During the loading process, the weight moisture content and packing density of the sample are set according to the experimental requirements; S2: Place the acrylic tube containing the sample on the permeable stone, place the detection device as needed, and close and seal the reactor; S3: Open the pressurizing device and the water adding device to keep the internal pressure of the reactor consistent with the internal pressure of the water adding device so that the solution in the water adding device can flow smoothly into the sample and finally flow out from the drain pipe; S4: By changing the type and flow rate of the solution in the water adding device and the type of gas in the pressurizing device, different oxidation environments and seepage conditions are simulated. Based on Darcy's seepage theory, the permeability coefficient K of the porous medium and the pressure gradient are mastered. , a quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample was constructed to achieve dynamic characterization of the fluid migration rate in the pyrite reaction zone under different oxidation-seepage conditions.

2. The method according to claim 1, characterized in that In the method, the operation of constructing the quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample is as follows: based on the Darcy seepage constitutive relationship, the dynamic permeability K calculated and the pressure gradient measured experimentally are used to calculate the relationship between the permeability K and the experimental pressure gradient. , combined with the detected fluid dynamic viscosity μ, a quantitative calculation model for the seepage rate q was constructed to understand the changes in the seepage rate of the sample in the oxidation-seepage experiment and to characterize the changes in the internal pore structure. Specifically: After the experiment is completed, calculate the percolation rate in the oxidation-percolation device ,in, Since the main oxidative acid corrosion of pyrite in the sample, the oxidation reaction of pyrite under acidic conditions is expressed as: ； The pyrite oxidation rate was calculated according to the pyrite oxidation kinetic equation: ； where r Pyrite is the oxidation rate of pyrite; M0 is the mass of the sample before the experiment; M is the mass of the sample after the experiment; A Pyrite is the specific surface area of ​​pyrite; M Pyrite is the molar mass of pyrite; t is the reaction time; The pore volume change coefficient is calculated based on the pore volume change caused by pyrite dissolution: ； ； v Pyrite is the coefficient of variation of pore volume; In order to determine the change of pore volume before and after the reaction by nitrogen adsorption method, , is the pore volume after reaction; is the pore volume before reaction; is the number of moles of pyrite dissolved; Permeability K varies with porosity The change of porosity is described by the modified Kozeny-Carman equation. The change in is driven solely by pyrite dissolution: ； ； in initial permeability; is the initial porosity; n is the empirical index; The pressure gradient of the sample before and after the reaction is indirectly calculated using Darcy's law using a gas adsorption analyzer. ; ； Where: Q is the gas flow rate of the gas adsorption analyzer; k g is the gas permeability coefficient; A is the cross-sectional area of ​​the sample.

3. The method according to claim 1, characterized in that The detection device includes a temperature sensor and a photoelectric displacement sensor placed inside the kettle body for real-time monitoring of temperature and height changes, and a weight moisture content probe for detecting the weight moisture content of the sample.

4. The method according to claim 1, wherein The water adding device includes a hose, with a diverter and an external water tank connected to both ends of the hose, and the diverter is fixed above the sample by a movable bracket to ensure that the liquid in the water tank can enter the sample; and / or The water adding device is further provided with a flow meter and a flow switch; and / or The water tank is provided with a water tank pressure relief valve, a water tank air pressure gauge and a water tank pressurizing device; and / or The pressurizing device includes a kettle pressure relief valve, a kettle pressure gauge and a gas cylinder; and / or The gas cylinder is connected to the reactor body through the gas inlet, and the gas in the gas cylinder is nitrogen, oxygen or a mixed gas of 50% nitrogen + 50% oxygen.

Images