A testing device and method for coupling deformation of porous media and migration of non-aqueous phase liquids

Abstract

The application belongs to the technical field of indoor hydrogeological experiment, and provides a testing device for coupling of deformation of porous medium and migration of heavy non-aqueous phase liquid, which comprises a split device main body, a fluid control system for controlling water phase and non-aqueous phase in a split mode, and a multi-dimensional synchronous monitoring system integrated with deformation monitoring, inter-well resistivity imaging, pore water pressure monitoring and flow monitoring. The deformation monitoring module non-destructively exports the internal settlement of the sample through an integrated carbon fiber transmission rod, the inter-well resistivity imaging module acquires dynamic resistivity distribution by using symmetrically arranged sealed insulation monitoring electrodes on the sidewall, and the data acquisition module synchronously collects displacement, water pressure and flow data under the same time reference. The application breaks through the ideal assumption of no deformation of traditional porous medium, can truly reproduce the coupling evolution process of deformation of porous medium and migration of heavy non-aqueous phase liquid, and provides experimental support for collaborative mechanism research.

Description

Technical Field

[0001] This application belongs to the field of indoor hydrogeological experimental technology, and in particular relates to a test device and method for coupling the deformation of porous media with the migration of heavy non-aqueous liquids. Background Technology

[0002] In the fields of hydrogeology and environmental hydrology, the migration and transformation of heavy non-aqueous phase liquids (DNAPLs) in underground media has always been a core research focus. DNAPLs typically refer to organic liquids with a density greater than water and immiscible with water, such as chlorinated hydrocarbon solvents and coal tar. Once these pollutants leak into the underground environment, they will migrate downwards under the influence of gravity, crossing the vadose zone until they encounter low-permeability layers or reach the bedrock surface to form a contamination pool. This migration process often spans decades or even centuries. On such a long timescale, as the excess pore water pressure gradually dissipates, the porous media of the aquifer undergoes significant compression and consolidation deformation. This long-term and slow skeletal deformation not only changes the dominant migration pathways of pollutants but also inversely affects the mechanical properties and seepage field distribution of the medium, resulting in a complex co-evolutionary relationship between DNAPL migration and porous media deformation. However, current macroscopic-scale experiments exploring the migration patterns of DNAPLs mostly rely on traditional rigid one-dimensional seepage columns or two-dimensional and three-dimensional sandbox models. These devices typically use rigid containers to fill porous media samples, with inlets and outlets at the bottom to control the seepage boundary, and sampling holes or observation windows on the side walls to obtain fluid information. The experimental process is always based on the ideal assumption that the porous media skeleton does not deform.

[0003] However, current methods are unable to accurately reproduce the coupled evolution process between the migration of non-aqueous liquids and the deformation of the medium while fully considering the deformation of the porous media framework. This makes it difficult to quantitatively reveal the spatiotemporal synergistic mechanism between the flow field, displacement field, and chemical field, which severely restricts the ability to gain a deeper understanding and predict the long-term migration behavior of groundwater pollutants. Summary of the Invention

[0004] This application provides a testing device and method for coupling the deformation of porous media with the migration of heavy non-aqueous liquids. This method can solve the problem that current methods cannot fully reproduce the coupling evolution process between the migration of heavy non-aqueous liquids and the deformation of the medium while taking into full account the deformation of the porous media skeleton. This makes it difficult to quantitatively reveal the spatiotemporal synergistic mechanism between the flow field, displacement field and chemical field, which seriously restricts the ability to gain a deeper understanding and predict the long-term migration behavior of groundwater pollutants.

[0005] In a first aspect, embodiments of this application provide a testing device for the coupling of porous media deformation and heavy non-aqueous phase liquid migration, comprising a device body, a fluid control system, and a monitoring system; the device body includes a first device body and a second device body, the first device body being located below the second device body and having a test chamber and pores for accommodating the porous media; the second device body is connected to the upper part of the first device body; the fluid control system includes an aqueous phase control system and a non-aqueous phase control system; the aqueous phase control system includes multiple water level control valves disposed on the second device body, and a peristaltic pump, multiple first pipelines, a water tank, and a tailwater recovery system disposed outside the device body. The peristaltic pump is connected to the water level control valve and the water tank via the first pipeline, and the water level control valve and the tailwater recovery tank are connected via the first pipeline; the non-aqueous phase control system includes a non-aqueous phase point source release device installed in the test chamber, and a high-precision injection pump and a second pipeline installed outside the main body of the device; the high-precision injection pump is connected to the non-aqueous phase point source release device via the second pipeline; the monitoring system includes a deformation monitoring module, an inter-well resistivity imaging monitoring module, a pore water pressure monitoring module, a flow monitoring module, and a data acquisition module; the deformation monitoring module includes at least one integrated carbon fiber transmission rod, a permeable plate, and The integrated carbon fiber transmission rod is connected at one end to the permeable plate and at the other end to the digital micrometer. The well resistivity imaging monitoring module includes multiple sealed and insulated monitoring electrodes, wires, and a high-density resistivity monitoring system. Multiple sealed and insulated monitoring electrodes are embedded and fixed within the side wall of the main body of the first device, with the detection end face of each electrode extending 2mm beyond the inner wall of the test chamber. The sealed and insulated monitoring electrodes are connected to the high-density resistivity monitoring system via the wires. The pore water pressure monitoring module includes pore water pressure monitoring valves and pore water pressure monitoring probes. The multiple pore water pressure monitoring valves respectively... Located at different heights on the side wall of the first device body, with its layout axis perpendicular to the side wall electrode cross-section; the pore water pressure monitoring probe is connected to the pore water pressure monitoring valve; the flow monitoring module includes an outlet valve, an outlet pipeline, a digital electronic balance, and a beaker, with the outlet valve located at the lower part of the first device body; one end of the outlet pipeline is connected to the outlet valve, and the other end is placed in the beaker; the data acquisition module is connected to the digital dial indicator, the pore water pressure monitoring probe, and the digital electronic balance respectively, for synchronously acquiring and storing displacement data, pore water pressure data, and flow change data of the porous medium under the same time reference.

[0006] In one possible implementation of the first aspect, the aforementioned plurality of water level control valves are respectively installed at different heights of the second device body to serve as inlets and outlets for the aqueous fluid to limit different test water level heights.

[0007] Optionally, in another possible implementation of the first aspect, the permeable plate is pre-positioned at a predetermined height in the porous medium within the test chamber during the porous medium loading process; the other end of the integrated carbon fiber transfer rod extends upward through the main body of the second device and abuts against the probe of the digital dial indicator.

[0008] Optionally, in another possible implementation of the first aspect, multiple sealed and insulated monitoring electrodes are divided into two rows and symmetrically distributed along the sidewall of the main body of the first device.

[0009] Optionally, in another possible implementation of the first aspect, the lower part of the first device body has a detachable base plate, which is connected to the first device body via a flange; a rubber plate is placed under the base plate.

[0010] Optionally, in another possible implementation of the first aspect, a temperature sensor is provided inside the beaker to monitor the ambient water temperature in order to correct the liquid phase density.

[0011] Optionally, in another possible implementation of the first aspect, the aforementioned sealed and insulated monitoring electrode includes a hollow fastener, a conductive core, and an insulating sealing filler; the hollow fastener has a through axial inner hole and an external thread provided on its outer sidewall for screwing into the main body of the first device; the conductive core is coaxially inserted in the axial inner hole, the outer peripheral cylindrical portion of the conductive core is covered with an insulating layer, and its two ends are exposed to form a detection end face and a signal terminal; the insulating sealing filler fills the space between the axial inner hole and the insulating layer; after assembly, the common cross-section of the inner end face of the hollow fastener, the end of the insulating layer, and the insulating sealing filler is flush, and the detection end face of the conductive core extends 2 mm beyond the common cross-section.

[0012] Optionally, in another possible implementation of the first aspect, an initial water level valve is also provided on the side wall of the main body of the first device to maintain the initial water level in the test chamber during the initial stage of the test.

[0013] Secondly, this application provides a testing method for the coupling of porous media deformation and heavy non-aqueous phase liquid migration, applied to the above-mentioned device, including: S1, sample model construction: connecting the main body of the first device to the base plate and placing it on a rubber plate; S2, sensor installation: installing a pore water pressure monitoring probe and a sealed and insulated monitoring electrode at a preset position on the main body of the first device, and closing all valves in the main body of the first device; S3, model filling: filling at least one porous media as a sample in the test chamber of the main body of the first device, and placing at least one permeable plate connected to the integrated carbon fiber transfer rod at a preset height during the filling process; S4, model saturation and stabilization: saturating the sample in the test chamber, and after the saturation treatment is completed, adding water to the initial water level valve of the main body of the first device to make the sample reach the initial saturated and stable state; S5. Device Assembly: Slide the second device body onto the top of the integrated carbon fiber transfer rod and connect it to the first device body via a flange; install the digital micrometer, ensuring the probe of the digital micrometer abuts against the upper end of the integrated carbon fiber transfer rod; connect the pipelines and wires used for the fluid control system and monitoring system; test the inter-well resistivity imaging monitoring module to obtain the initial value of resistivity distribution; S6. Coupling Process Monitoring: Open the outlet valve and pore water pressure monitoring valve of the first device body to begin monitoring operations and test the operating status of the monitoring system; S7. Coupling Evolution Activation: Run the fluid control system, control the upstream water head through a peristaltic pump, and inject non-aqueous phase fluid into the non-aqueous phase point source release device through a high-precision injection pump; S8. Device Disassembly: After the experiment, disassemble and clean the device sequentially from top to bottom, process soil and water samples, and complete data processing.

[0014] In one possible implementation of the second aspect, a coupling analysis step is included after step S8, as follows:

[0015] The acquired dynamic resistivity data were subjected to time-step inversion calculations to extract the three-dimensional resistivity distribution field inside the porous medium, and then transformed into a non-aqueous fluid spatial saturation distribution image based on the rock physics model.

[0016] Based on a unified timestamp, the spatial saturation of non-aqueous fluid, the pore water pressure dissipation rate, and the skeleton sedimentation at different depths are extracted at the same evolution time to quantitatively assess the spatial synergistic relationship between the migration morphology of heavy non-aqueous liquid and the non-uniform deformation of porous media.

[0017] Beneficial Effects: The scheme provided in this application realizes the coupling process between porous media deformation and the migration of heavy non-aqueous liquids, breaking the ideal assumption of a fixed skeleton in traditional heavy non-aqueous liquid migration and transformation experiments. This design completely overcomes the limitation of assuming the soil skeleton is absolutely undeformed in previous multiphase flow physics simulation experiments, making the test scenario more closely resemble the real environment. Simultaneously, it highly integrates a carbon fiber transfer rod, a pore water pressure monitoring probe, a flow monitoring module, and a high-density resistivity monitoring system. Through the data acquisition module, under a unified time reference, it achieves simultaneous acquisition of multi-dimensional, multi-source data such as porous media deformation, pore water pressure changes, and macroscopic multiphase fluid distribution, providing solid data support for quantitatively revealing the laws of co-evolution. Furthermore, the introduction of high-density electrical resistivity tomography between wells can also accurately characterize the strong spatial heterogeneity and nonlinearity caused by fingering effects during the migration of non-aqueous fluids. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a test device for coupling the deformation of porous media with the migration of heavy non-aqueous liquids according to an embodiment of this application;

[0020] Figure 2 This is a front view of the main body of the first device provided in an embodiment of this application;

[0021] Figure 3 This is a side view of the main body of the first device provided in an embodiment of this application;

[0022] Figure 4 This is a schematic diagram of the flange connection between the first device body and the second device body according to an embodiment of this application;

[0023] Figure 5 This is a schematic diagram of a sealed and insulated monitoring electrode structure provided in one embodiment of this application;

[0024] Figure 6 This is a schematic flowchart of a test method for coupling the deformation of porous media with the migration of heavy non-aqueous liquids according to an embodiment of this application;

[0025] Figure 7 This is a schematic diagram of the structure of the testing device provided in one embodiment of this application after the sample is loaded;

[0026] Explanation of reference numerals in the attached figures:

[0027] 1-Second device main body; 2-Digital dial gauge; 3-Water level control valve; 4-Integrated carbon fiber transmission rod; 5-Flange connection screw; 6-Initial water level valve; 7-First device main body; 8-Sealed and insulated monitoring electrode; 9-Permeable plate; 10-Non-aqueous phase point source release device; 11-Outlet pipe; 12-Pore water pressure monitoring valve; 13-Outlet valve; 14-Base plate; 15-First pipe; 16-Peristaltic pump; 17-First pipe; 18-First pipe; 19-Water bucket; 20-Tailwater recovery bucket; 21-Second pipe; 22-High-precision injection pump; 23-Wire; 24-High-density resistivity monitoring system; 25-Temperature sensor; 26-Beaker; 27-Digital electronic balance; 28-Hollow fastener; 29-Insulating sealing filler; 30-Conductive core; 31-Nut; 32-Silicone anti-seepage gasket; 33-Large particle quartz sand; 34-Sample. Detailed Implementation

[0028] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0029] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0030] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0031] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0032] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0033] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0034] The following is a detailed description of a testing apparatus and method for coupling the deformation of porous media with the migration of heavy non-aqueous liquids, provided in this application, with reference to the accompanying drawings.

[0035] like Figure 1-3 As shown, the test device for coupling the deformation of porous media with the migration of heavy non-aqueous liquid includes a main body, a fluid control system, and a monitoring system.

[0036] The main body of the device includes a first device body 7 and a second device body 1. The first device body 7 is located below the second device body 1 and has a test chamber and pores for accommodating porous media. The second device body 1 is connected to the upper part of the first device body 7.

[0037] The fluid control system includes an aqueous phase control system and a non-aqueous phase control system. The aqueous phase control system includes multiple water level control valves 3 installed on the main body 1 of the second device, a peristaltic pump 16, multiple first pipelines (15, 17, 18), a water tank 19, and a tailwater recovery tank 20 installed outside the main body of the device. The peristaltic pump 16 connects the water level control valves 3 and the water tank 19 through the first pipelines 15 and 17, and the water level control valves 3 and the tailwater recovery tank 20 are connected through the first pipeline 18. The non-aqueous phase control system includes a non-aqueous phase point source release device 10 installed inside the test chamber, a high-precision injection pump 22 installed outside the main body of the device, and a second pipeline 21. The high-precision injection pump 22 is connected to the non-aqueous phase point source release device 10 through the second pipeline 21.

[0038] For example, the high-precision syringe pump 22 has a flow accuracy of ≤±0.35% and a repeatability of ≤±0.03%.

[0039] The monitoring system includes a deformation monitoring module, an inter-well resistivity imaging monitoring module, a pore water pressure monitoring module, a flow rate monitoring module, and a data acquisition module;

[0040] The deformation monitoring module includes at least one integrated carbon fiber transmission rod 4, a permeable plate 9, and a digital dial gauge 2. One end of the integrated carbon fiber transmission rod 4 is connected to the permeable plate 9, and the other end is connected to the digital dial gauge 2.

[0041] The well-to-well resistivity imaging monitoring module includes multiple sealed and insulated monitoring electrodes 8, wires 23, and a high-density resistivity monitoring system 24; the multiple sealed and insulated monitoring electrodes 8 are embedded and fixed in the side wall of the main body 7 of the first device, and the detection end face of each sealed and insulated monitoring electrode 8 extends 2 mm out of the inner wall of the test chamber; the sealed and insulated monitoring electrodes 8 are connected to the high-density resistivity monitoring system 24 through wires 23.

[0042] The pore water pressure monitoring module includes a pore water pressure monitoring valve 12 and a pore water pressure monitoring probe; multiple pore water pressure monitoring valves 12 are located at different heights on the side wall of the main body 7 of the first device, and their arrangement axis is perpendicular to the side wall electrode cross-section; the pore water pressure monitoring probe is connected to the pore water pressure monitoring valve 12.

[0043] The flow monitoring module includes a water outlet valve 13, a water outlet pipe 11, a digital electronic balance 27, and a beaker 26. The water outlet valve 13 is located at the lower part of the main body 7 of the first device. One end of the water outlet pipe 11 is connected to the water outlet valve 13, and the other end is placed in the beaker 26.

[0044] The data acquisition module is connected to the digital dial gauge 2, the pore water pressure monitoring probe, and the digital electronic balance 27, respectively, to synchronously acquire and store displacement data, pore water pressure data, and flow rate change data of the porous medium under the same time reference.

[0045] Furthermore, in this embodiment, the aforementioned plurality of water level control valves 3 are respectively disposed at different heights of the second device body 1, serving as inlet and outlet ports for the aqueous fluid to limit different test water level heights.

[0046] Furthermore, in this embodiment, the permeable plate 9 is pre-positioned at a predetermined height in the porous medium within the test chamber during the porous medium loading process; the other end of the integrated carbon fiber transfer rod 4 extends upward through the main body 1 of the second device and abuts against the probe of the digital micrometer 2.

[0047] Furthermore, in this embodiment, the plurality of sealed and insulated monitoring electrodes 8 are divided into two rows and are symmetrically distributed along the sidewall of the first device body 7.

[0048] Furthermore, in this embodiment of the application, the lower part of the first device body 7 has a detachable base plate 14, and the base plate 14 is connected to the first device body 7 through a flange; a rubber plate is placed under the base plate 14.

[0049] It should be noted that, as Figure 4 As shown, the flange connection is secured by multiple flange connection screws 5 and nuts 31, and a silicone gasket 32 ​​is clamped in place to prevent leakage at the connection.

[0050] Furthermore, in this embodiment, a temperature sensor 25 is provided inside the beaker 26 to monitor the ambient water temperature in order to correct the liquid phase density.

[0051] Furthermore, in the embodiments of this application, such as Figure 5 As shown, the aforementioned sealed and insulated monitoring electrode 8 includes a hollow fastener 28, a conductive core 30, and an insulating sealing filler 29. The hollow fastener 28 has a through axial inner hole and an external thread on its outer sidewall for screwing into the first device body 7. The conductive core 30 is coaxially inserted into the axial inner hole, and the outer cylindrical portion of the conductive core 30 is covered with an insulating layer, with its two ends exposed to form a detection end face and a signal terminal. The insulating sealing filler 29 fills the space between the axial inner hole and the insulating layer. After assembly, the common cross-section of the inner end face of the hollow fastener 28, the end of the insulating layer, and the insulating sealing filler 29 is flush, and the detection end face of the conductive core 30 extends 2 mm beyond the common cross-section.

[0052] In this embodiment, after assembly, the insulating and sealing filler prevents the conductive core 30 from contacting the hollow fastener 28, thus preventing current from being transmitted to the hollow fastener 28 and affecting the measurement results. Furthermore, the probe end face of the electrode extends precisely 2mm beyond the inner wall of the test chamber. This specific extension not only pierces the water film on the side wall to ensure electrical contact but also avoids the probe from excessively penetrating and physically obstructing the migration trajectory of the non-aqueous phase fluid.

[0053] Furthermore, in this embodiment of the application, the first device body 7 is also provided with an initial water level valve 6 on its side wall, which is used to maintain the initial water level in the test chamber during the initial stage of the test.

[0054] It should be noted that the main body of the device, from top to bottom, includes a second device body 1, a first device body 7, and a base plate 14. The second device body 1 primarily serves as a bearing space for the overlying hydrostatic pressure, maintaining overall hydraulic stability during the multiphase fluid injection test. The first device body 7 contains a test chamber for accommodating porous media, mainly responsible for constructing the aquifer physical model; different positions on its sidewalls include an initial water level valve 6, a sealed and insulated monitoring electrode 8, a pore water pressure monitoring valve 12, and an outlet valve 13 for monitoring and implementing the test process. The base plate 14 is a sheet material, primarily used to create a closed boundary. A shock-absorbing rubber sheet is placed beneath the base plate 14 to isolate the precision instruments from external environmental interference and minor vibrations.

[0055] It should be noted that the fluid control system consists of two independently operating loops: an aqueous phase control system and a non-aqueous phase control system. In the aqueous phase control system, multiple sets of water level control valves 3, longitudinally arranged on the side wall of the second device body 1, are used to flexibly limit and maintain different test water levels. An external peristaltic pump 16 continuously pumps the aqueous fluid from the water tank 19 into the water level control valves 3 through the first pipelines (15, 17). Simultaneously, excess water flows back to the tailwater recovery tank 20 through the first pipeline 18 connected to the water level control valves 3, thereby achieving precise maintenance of the upper boundary constant head. The non-aqueous phase control system utilizes an external high-precision injection pump 22 connected to a non-aqueous phase point source release device 10 located at a preset position inside the test chamber via the second pipeline 21. The high precision and continuity of the injection pump simulate the continuous release of point source contamination. This design can accurately simulate specific point source leakage and spatial injection processes of heavy non-aqueous phase fluid (DNAPL) in deep porous media.

[0056] It should be noted that the monitoring system mainly includes a deformation monitoring module, an inter-well resistivity imaging monitoring module, a pore water pressure monitoring module, a flow rate monitoring module, and a data acquisition module. The deformation monitoring module is primarily used to obtain the true skeletal deformation of the deep porous media.

[0057] The addition of the well-to-well resistivity imaging monitoring module is primarily to address the nonlinear characteristics and strong heterogeneity of the spatial evolution of non-aqueous fluids. In one embodiment, 30 sealed and insulated monitoring electrodes 8 are longitudinally arranged at equal intervals on one side wall of the device, for a total of 60 electrodes on both sides; and the center-to-center distance between adjacent electrodes is set to 2 cm. Through this high-density array, and connected to a high-density resistivity monitoring system 24 via wire 23, extremely high-resolution dynamic resistivity data can be acquired, accurately capturing heterogeneous changes within the sample.

[0058] The pore water pressure monitoring module utilizes multiple pore water pressure monitoring valves 12 installed at different heights on the sidewall of the main body 7 of the first device as monitoring points. The axis of the pore water pressure monitoring valves 12 is perpendicular to the cross-section of the sidewall electrode to prevent physical interference between sensor positions. The pore pressure probe is connected to each valve to monitor the microscopic pore pressure dissipation process and is connected to a computer to record and save real-time pore water pressure changes.

[0059] The flow monitoring module primarily utilizes the outlet valve 13 and outlet pipe 11 located at the bottom of the main body 7 of the first device. The liquid flowing from the bottom of the sample is collected in a beaker 26, and the flow rate is recorded in real-time by a digital electronic balance 27 at the bottom. An independent temperature sensor 25 is also installed externally to record the ambient water temperature, thereby correcting for the liquid phase density. Furthermore, based on computer and digital technologies, this device connects each module of the monitoring system to a computer via RS485 communication, ensuring that data from each module is recorded and stored in the computer in real time, providing comprehensive and detailed data support for subsequent research.

[0060] This application provides a testing device coupling porous media deformation and heavy non-aqueous phase fluid migration, realizing the coupling process between porous media deformation and heavy non-aqueous phase fluid migration, breaking the ideal assumption of a fixed skeleton in traditional heavy non-aqueous phase fluid migration and transformation experiments. This design completely overcomes the limitation of assuming absolute non-deformation of the soil skeleton in previous multiphase flow physics simulation experiments, making the test scenario more closely resemble the real environment. It also highly integrates a carbon fiber transfer rod, a pore water pressure monitoring probe, a flow monitoring module, and a high-density resistivity monitoring system. Through the data acquisition module, under a unified time reference, it achieves simultaneous acquisition of multi-dimensional, multi-source data such as porous media deformation, pore water pressure changes, and macroscopic multiphase fluid distribution, providing solid data support for quantitatively revealing the co-evolution law. Furthermore, the introduction of high-density electrical resistivity tomography between wells can accurately characterize the strong spatial heterogeneity and nonlinearity caused by fingering effects during non-aqueous phase fluid migration.

[0061] like Figure 6 The diagram shows a test method for coupling the deformation of porous media with the migration of heavy non-aqueous liquids. This method is applied to the aforementioned device and specifically includes the following steps:

[0062] S1. Sample model construction: Connect the main body of the first device to the base plate and place it on the rubber plate;

[0063] S2. Sensor installation: Install the pore water pressure monitoring probe and the sealed and insulated monitoring electrode at the preset position on the main body of the first device, and close all valves in the main body of the first device.

[0064] S3, Model loading: At least one porous medium is filled into the test chamber of the main body of the first device as a sample. During the filling process, at least one permeable plate connected to the integrated carbon fiber transfer rod is placed at a preset height.

[0065] S4. Model Saturation and Stability: The sample in the test chamber is saturated. After the saturation treatment is completed, water is added to the initial water level valve of the main body of the first device to make the sample reach the initial saturated stable state.

[0066] S5. Device Assembly: Slide the second device body onto the top of the integrated carbon fiber transfer rod and connect it to the first device body via a flange; install the digital micrometer and make the probe of the digital micrometer abut against the upper end of the integrated carbon fiber transfer rod; connect the pipelines and wires used for the fluid control system and monitoring system; test the inter-well resistivity imaging monitoring module to obtain the initial value of resistivity distribution.

[0067] S6. Coupling process monitoring: Open the outlet valve and pore water pressure monitoring valve of the main body of the first device to start the monitoring operation and test the operating status of the monitoring system;

[0068] S7. Coupled Evolution Excitation: The fluid control system operates, controls the upstream head through a peristaltic pump, and injects non-aqueous phase fluid into the non-aqueous phase point source release device through a high-precision injection pump.

[0069] S8. Device disassembly: After the experiment, the device is disassembled and cleaned from top to bottom, and the soil and water samples are processed to complete the data processing.

[0070] Furthermore, in this embodiment of the application, after step S8, the following steps are also included:

[0071] The acquired dynamic resistivity data were subjected to time-step inversion calculations to extract the three-dimensional resistivity distribution field inside the porous medium, and then transformed into a non-aqueous fluid spatial saturation distribution image based on the rock physics model.

[0072] Based on a unified timestamp, the spatial saturation of non-aqueous fluid, the pore water pressure dissipation rate, and the skeleton sedimentation at different depths are extracted at the same evolution time to quantitatively assess the spatial synergistic relationship between the migration morphology of heavy non-aqueous liquid and the non-uniform deformation of porous media.

[0073] This application provides a testing method for the coupling of porous media deformation and heavy non-aqueous phase liquid migration, achieving synchronous monitoring of the multi-physics coupling process. Specifically, by utilizing the coordinated arrangement of a pore water pressure monitoring probe, a sealed and insulated monitoring electrode, and an inter-well resistivity imaging module, pore water pressure, heavy non-aqueous phase liquid migration distribution, and resistivity field changes can be acquired in real time during porous media deformation, overcoming the shortcomings of traditional separate testing methods that result in missing coupling information. Simultaneously, the design of sample saturation and stabilization, peristaltic pump head control, and high-precision injection pump point source release realistically simulates groundwater level fluctuations and fixed-point infiltration of pollutants. An integrated carbon fiber transfer rod, combined with a digital dial gauge for contact measurement, accurately captures media settlement and deformation, while the pre-set position of the permeable plate ensures balanced pore water pressure transmission. Furthermore, the modular flange connection facilitates disassembly, cleaning, and reuse. The overall process logic is clear and the operation is standardized, providing a high-precision and reproducible experimental method for similar studies on the coupling of porous media deformation and heavy non-aqueous phase liquid migration.

[0074] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0075] The following is combined with Figure 7 This paper will specifically describe the test operation process of coupling the deformation of porous media with the migration of heavy non-aqueous liquids provided in this application.

[0076] In conjunction with the above-described apparatus, this embodiment uses large-particle quartz sand 33 as the base material and small-particle quartz sand as the sample 34 in the embodiment, with the sample height set at 50 cm. The test operation procedure is as follows:

[0077] Sample model construction: Connect the main body 7 of the first device to the base plate 14, place it on the rubber plate, install the pore water pressure sensor and the sealed and insulated monitoring electrode 8 at the preset position, and then inject water into the cavity to check the overall sealing performance. After confirming that there is no leakage, drain the water and apply Vaseline to the inner wall to eliminate the sidewall effect.

[0078] Porous media filling: First, large-particle quartz sand 33 is filled to the preset height and compacted to ensure its stability in subsequent testing. Then, a filter screen is laid on top of the cushion layer, with degreased cotton used to supplement the edges to prevent leakage. The main purpose of laying the filter screen here is that, because the particle size of the cushion layer material is large while the particle size of the sample is small, leakage and damage can easily occur under the impact of water flow from top to bottom, affecting the sample structure. Therefore, to ensure the stability of the sample structure, a filter screen with a pore size slightly smaller than the particle size of the quartz sand in the sample needs to be laid downstream of the sample to prevent structural damage. Then, a layered filling method is adopted, using dry density as the control index and 2 cm as the single filling height. Height and mass are used as control standards to fill the sample 34 layer by layer. During the filling process, the mass of quartz sand required for the predetermined dry density is first weighed using an electronic balance. Then, distilled water equal to 10% of the mass of quartz sand is added and thoroughly stirred to prevent quartz sand spillage and dust from affecting the sample filling process. During the layered sample loading process, the amount and height of quartz sand in each layer must be controlled. After reaching the preset height, the sample surface is roughened using tools such as scrapers and brushes to prevent the formation of layered walls that would affect the infiltration process. The roughening depth is approximately 1-2 mm. During the filling process, constant attention must be paid to the connection between the sample sidewalls and the test chamber to avoid large voids. When the preset height is reached, the permeable plate 9, connected to the integrated carbon fiber rod 4, is horizontally and smoothly placed into the soil. After sample 34 is filled, large-particle quartz sand 33 is continued to be laid to prevent erosion by subsequent water flow.

[0079] Sample Saturation: The quartz sand used in the sample in this embodiment is medium sand, which has a relatively high permeability coefficient and can be saturated by natural head saturation. Therefore, this embodiment uses head saturation to saturate the sample. During the saturation process, the outlet valve 13 at the bottom of the main body 7 of the first device is used as the saturation inlet. An external water bucket is connected by a pipeline, and the height of the water bucket is gradually increased at unit intervals of more than 2 hours and height intervals of 3 cm, so that the sample gradually becomes saturated from bottom to top until water comes out from the top surface of the upper cushion layer. The water level is then stabilized at the initial water level valve 6.

[0080] System Assembly: The second device body 1 is slid into place along the top of the integrated carbon fiber rod 4, and the flanges of the two main body sections are fastened. All pipelines are connected, and the digital dial indicator 2 is installed and zeroed, completing the deformation monitoring module assembly. The high-density resistivity monitoring system 24 is connected via wire 23 to check connectivity and obtain the initial background resistivity value before fluid injection. The pore water pressure monitoring probe is connected via the pore water pressure monitoring valve, completing the pore water pressure monitoring module assembly. The outlet valve is connected via the outlet pipe 11, and the other end is extended to the top of the beaker 26. The beaker 26 is placed on the top of the digital electronic balance 27, completing the flow monitoring module assembly. The water level control valve 3 and the water tank 19 are connected via the first pipe 15 and the peristaltic pump 16 as the water inlet system; the tailwater recovery tank 20 is connected via the first pipe 18 as the return water system, completing the aqueous phase control system assembly; the high-precision injection pump 22 and the non-aqueous phase point source release device 10 are connected via the second pipe 21 as the non-aqueous phase control system. The monitoring module's sensors are connected to the computer via RS485 communication, and the data acquisition quality is checked.

[0081] Coupled evolution dynamic test: Close the initial water level valve 6, open the water level control valve 3, outlet valve 13, and pore water pressure monitoring valve 12 of the connecting pipeline, and start monitoring. Turn on the peristaltic pump 16 and increase its power to accelerate the water inflow rate and begin raising the water head. After the water head reaches the predetermined water level, reduce the power of the peristaltic pump 16 to stabilize the water level. Turn on the high-precision injection pump 22 and inject the heavy non-aqueous phase fluid into the sample at a constant rate through the non-aqueous phase point source release device 10. During the test, the high-density resistivity distribution between wells is measured at 1-hour intervals.

[0082] Multi-field data decoupling analysis: During injection and subsequent evolution, the data acquisition module synchronously extracts displacement, flow rate, water pressure, and high-density electrical resistivity data based on a unified timestamp. The dynamic resistivity distribution within the porous medium is obtained through time-step inversion calculations, and the rock physics model is parameter-corrected using measured layered skeleton settlement at a unified timestamp. This effectively eliminates resistivity disturbances caused by non-uniform skeleton deformation and quantitatively assesses the spatial synergy between non-aqueous fluid migration and medium skeleton deformation.

[0083] Sample Removal: After the experiment, turn off the peristaltic pump 16, syringe pump 22, etc., close all valves, open the initial water level valve 6 and the outlet valve 13 to begin drainage. After the water has drained, remove all external equipment and pipelines, and close all valves; remove the second device body 1 and the digital micrometer 2 on it, then remove all probes on the first device body 7, and pour out the sample and bedding layer. Properly place the test water and soil sample.

[0084] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 this application, and should all be included within the protection scope of this application.

Claims

1. A testing device for coupling the deformation of porous media with the migration of heavy non-aqueous liquids, characterized in that, This includes the main body of the device, the fluid control system, and the monitoring system; The device body includes a first device body and a second device body. The first device body is located below the second device body and has a test chamber and pores for accommodating porous media. The second device body is connected to the upper part of the first device body. The fluid control system includes an aqueous phase control system and a non-aqueous phase control system. The aqueous phase control system includes multiple water level control valves mounted on the main body of the second device, as well as a peristaltic pump, multiple first pipelines, a water tank, and a tailwater recovery tank located outside the main body of the device. The peristaltic pump connects the water level control valves and the water tank via the first pipelines, and the water level control valves and the tailwater recovery tank are connected via the first pipelines. The non-aqueous phase control system includes a non-aqueous phase point source release device located inside the test chamber, as well as a high-precision injection pump and a second pipeline located outside the main body of the device. The high-precision injection pump is connected to the non-aqueous phase point source release device via the second pipeline. The monitoring system includes a deformation monitoring module, an inter-well resistivity imaging monitoring module, a pore water pressure monitoring module, a flow rate monitoring module, and a data acquisition module; The deformation monitoring module includes at least one integrated carbon fiber transmission rod, a permeable plate, and a digital dial indicator. One end of the integrated carbon fiber transmission rod is connected to the permeable plate, and the other end is connected to the digital dial indicator. The well-to-well resistivity imaging monitoring module includes multiple sealed and insulated monitoring electrodes, wires, and a high-density resistivity monitoring system; the multiple sealed and insulated monitoring electrodes are embedded and fixed in the side wall of the main body of the first device, and the detection end face of each sealed and insulated monitoring electrode extends 2 mm out of the inner wall of the test chamber; the sealed and insulated monitoring electrodes are connected to the high-density resistivity monitoring system through the wires; The pore water pressure monitoring module includes pore water pressure monitoring valves and pore water pressure monitoring probes; multiple pore water pressure monitoring valves are located at different heights on the side wall of the main body of the first device, and their arrangement axis is perpendicular to the side wall electrode cross-section; the pore water pressure monitoring probe is connected to the pore water pressure monitoring valves; The flow monitoring module includes a water outlet valve, a water outlet pipe, a digital electronic balance, and a beaker. The water outlet valve is located at the lower part of the main body of the first device. One end of the water outlet pipe is connected to the water outlet valve, and the other end is placed in the beaker. The data acquisition module is connected to the digital dial gauge, the pore water pressure monitoring probe, and the digital electronic balance, respectively, and is used to synchronously acquire and store displacement data, pore water pressure data, and flow rate change data of the porous medium under the same time reference.

2. The apparatus as claimed in claim 1, characterized in that, The multiple water level control valves are respectively installed at different heights of the second device body to serve as inlets and outlets for the aqueous fluid, thereby limiting different test water level heights.

3. The apparatus as described in claim 1, characterized in that, The permeable plate is pre-positioned at a predetermined height in the porous medium within the test chamber during the porous medium loading process; the other end of the integrated carbon fiber transfer rod extends upward through the main body of the second device and abuts against the probe of the digital micrometer.

4. The apparatus as claimed in claim 1, characterized in that, The multiple sealed and insulated monitoring electrodes are divided into two rows and are symmetrically distributed along the side wall of the main body of the first device.

5. The apparatus as claimed in claim 1, characterized in that, The lower part of the first device body has a detachable base plate, which is connected to the first device body via a flange; a rubber plate is placed under the base plate.

6. The apparatus as claimed in claim 1, characterized in that, A temperature sensor is installed inside the beaker to monitor the ambient water temperature and correct the liquid phase density.

7. The apparatus as claimed in claim 4, characterized in that, The sealed and insulated monitoring electrode includes a hollow fastener, a conductive core, and an insulating sealing filler. The hollow fastener has a through axial inner hole and an external thread on its outer sidewall for screwing into the main body of the first device. The conductive core is coaxially inserted into the axial inner hole, and the outer cylindrical portion of the conductive core is covered with an insulating layer, with its two ends exposed to form the detection end face and signal terminal, respectively. The insulating sealing filler fills the space between the axial inner hole and the insulating layer. After assembly, the common cross-section of the inner end face of the hollow fastener, the end of the insulating layer, and the insulating sealing filler is flush, and the detection end face of the conductive core extends 2 mm beyond this common cross-section.

8. The apparatus as claimed in claim 1, characterized in that, The first device body is also provided with an initial water level valve on its side wall, which is used to maintain the initial water level in the test chamber during the initial stage of the test.

9. A test method for the coupling of porous media deformation and heavy non-aqueous phase liquid migration, applied to the apparatus described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Sample model construction: Connect the main body of the first device to the base plate and place it on the rubber plate; S2. Sensor installation: Install the pore water pressure monitoring probe and the sealed and insulated monitoring electrode at the preset position on the main body of the first device, and close all valves in the main body of the first device. S3, Model loading: At least one porous medium is filled into the test chamber of the main body of the first device as a sample. During the filling process, at least one permeable plate connected to the integrated carbon fiber transfer rod is placed at a preset height. S4. Model Saturation and Stability: The sample in the test chamber is saturated. After the saturation treatment is completed, water is added to the initial water level valve of the main body of the first device to make the sample reach the initial saturated stable state. S5. Device Assembly: Slide the second device body onto the top of the integrated carbon fiber transfer rod and connect it to the first device body via a flange; install the digital micrometer and make the probe of the digital micrometer abut against the upper end of the integrated carbon fiber transfer rod; connect the pipelines and wires used for the fluid control system and monitoring system; test the inter-well resistivity imaging monitoring module to obtain the initial value of resistivity distribution. S6. Coupling process monitoring: Open the outlet valve and pore water pressure monitoring valve of the main body of the first device to start the monitoring operation and test the operating status of the monitoring system; S7. Coupled Evolution Excitation: The fluid control system operates, controls the upstream head through a peristaltic pump, and injects non-aqueous phase fluid into the non-aqueous phase point source release device through a high-precision injection pump. S8. Device disassembly: After the experiment, the device is disassembled and cleaned from top to bottom, and the soil and water samples are processed to complete the data processing.

10. The method as described in claim 9, characterized in that, Following step S8, a coupling analysis step is also included, as follows: The acquired dynamic resistivity data is subjected to time-step inversion calculation to extract the three-dimensional resistivity distribution field inside the porous medium, and is converted into a non-aqueous fluid spatial saturation distribution image based on the rock physics model. Based on a unified timestamp, the spatial saturation of the non-aqueous phase fluid, the pore water pressure dissipation rate, and the skeleton sedimentation at different depths are extracted at the same evolution time to quantitatively evaluate the spatial synergistic relationship between the migration morphology of the non-aqueous phase liquid and the non-uniform deformation of the porous medium.

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