A device and method for testing stress-dependent water storage parameters in peat soil

Abstract

This invention belongs to the field of hydrogeological parameter testing technology, and relates to a device and method for testing stress-dependent water storage parameters in peat soil. The device includes an undisturbed peat column support component, a variable head drive and control component, a macroscopic flow-force multi-field synchronous monitoring component, and a microscopic acoustic emission non-destructive monitoring component. The variable head drive and control component is connected to the bottom of the undisturbed peat column support component; the macroscopic flow-force multi-field synchronous monitoring component is installed on the undisturbed peat column support component. This invention solves the problem of the failure of traditional constant parameter models in peat soil; it eliminates the need to introduce exogenous substances such as chemical tracers and isotopes, while preserving the natural micro-fibrous structure of peat soil to the greatest extent; this invention establishes a stress-dependent dynamic inversion model of specific water storage coefficient based on acoustic emission energy, which can accurately characterize the nonlinear decay law of aquifer water storage capacity in high-altitude peatlands during complex hydrological cycles, with testing accuracy far exceeding that of traditional methods.

Description

Technical Field

[0001] This invention belongs to the field of hydrogeological parameter testing technology, specifically relating to a device and method for testing peat soil stress-dependent water storage parameters. Background Technology

[0002] High-altitude peat bogs are crucial terrestrial water reservoirs in watersheds and core regulators of regional hydrological cycles. Their aquifer specific yield and specific storage coefficient are fundamental parameters for revealing surface water-groundwater transformation patterns, assessing peatland water conservation capacity, and constructing watershed hydrological models. However, peat soils possess extremely high porosity, strong compressibility, and a unique plant fiber network structure, exhibiting fundamental differences in physical and mechanical properties compared to conventional sands and clays. This leads to limitations in existing water storage parameter testing methods for this type of medium, as detailed below: (1) In the classical groundwater dynamics theory, the specific water storage coefficient of the aquifer is usually regarded as a constant. However, in the process of water supply and drainage in peatland, a small change in effective stress can trigger a violent and irreversible consolidation compression of the peat fiber skeleton. Its compression coefficient decreases significantly and nonlinearly with the decrease of the void ratio. This makes the specific water storage coefficient of peat soil essentially a variable that evolves dynamically with effective stress, rather than a constant value. When using the traditional constant parameter model for hydrological calculation, serious deviations of orders of magnitude will occur, making it impossible to accurately depict the hydrological regulation process of peatland. (2) Due to the limitations of the implementation conditions and ecological protection requirements of field projects in high-altitude peatlands, large-scale hydrochemical or isotope tracer tests are often not possible. At the same time, conventional field pumping tests will produce large fluctuations in water head, which will seriously damage the original micro-fiber structure and pore characteristics of peat, resulting in the test results failing to reflect the in-situ natural characteristics of peat soil. (3) Conventional Darcy permeameters can only test the permeability coefficient and cannot obtain the compression deformation parameters of the soil. Conventional consolidation instruments can only obtain the final settlement and average compression coefficient of the soil and cannot simultaneously monitor the transient pore water pressure evolution during the seepage process. Furthermore, neither type of instrument can capture the dynamic evolution of microscopic damage such as fiber skeleton misalignment and microfracture during peat release. This results in a serious disconnect between the microstructural damage, macroscopic deformation and hydraulic parameters of the medium on the time scale, making it impossible to establish a quantitative coupling relationship between the three and even more impossible to achieve dynamic inversion of water storage parameters.

[0003] Therefore, developing a testing device and method that can non-destructively and synchronously monitor microscopic damage and macroscopic fluid-force response during peat seepage consolidation, and accurately invert stress-dependent water storage parameters, has become an urgent problem to be solved in the field of hydrogeological research in high-altitude peatlands. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention provides a solution. This invention provides a device and method for testing stress-dependent water storage parameters in peat soil.

[0005] In a first aspect, the present invention provides a peat stress-dependent water storage parameter testing device, including an undisturbed peat column bearing component, a variable head driving and control component, a macroscopic flow-force multi-field synchronous monitoring component, and a microscopic acoustic emission non-destructive listening component. The undisturbed undisturbed peat core bearing assembly is used to accommodate the undisturbed undisturbed peat core, providing a closed bearing space for one-dimensional vertical seepage and consolidation deformation of peat. The variable head drive and control component is connected to the bottom of the original peat column bearing component, and is used to drive the peat soil drainage consolidation water release and water expansion rebound. The macroscopic flow-force multi-field synchronous monitoring component is installed on the undisturbed peat column bearing component to synchronously collect the macroscopic pore water pressure and vertical strain of peat during the seepage consolidation process. The microscopic acoustic emission non-destructive monitoring component is coupled and installed on the outer wall of the original peat column bearing component. It is used to capture the acoustic emission elastic wave signal generated by the misalignment and micro-fracture of the fiber skeleton during the drainage consolidation process of peat soil in real time, and to perform non-destructive dynamic monitoring of skeleton damage.

[0006] Secondly, the present invention provides a method for testing stress-dependent water storage parameters in peat soil, comprising: Water is injected from bottom to top into the original peat column bearing component to fully saturate the original peat core. An overburden load corresponding to the in-situ burial depth is applied to the saturated peat core and left to stand until the deformation data of the macro-fluid-force multi-field synchronous monitoring component is stable and the background noise of the micro-acoustic emission non-destructive listening component is zero. The variable head drive and control components are activated to continuously lower the water level at a preset rate, simulating the drainage, consolidation and release process of the groundwater level in peatlands. During the continuous decline of water level, the micro-accumulated acoustic emission absolute energy, macro-vertical strain, and pore water pressure drop depth data of peat cores were simultaneously and continuously collected using macro-fluid-force multi-field synchronous monitoring components and micro-acoustic emission non-destructive listening components. Based on the effective stress principle, the real-time effective stress increment is calculated, and combined with the collected macroscopic vertical strain data, the dynamic compression coefficient of peat soil under the current effective stress state is determined. By mathematically fitting the absolute energy of micro-accumulated acoustic emission with the dynamic compressibility coefficient, an acoustic energy-skeleton damage compression constitutive model for peat soil is established. Substituting the acoustic energy-skeleton damage compression constitutive model into the specific water storage coefficient definition formula, a stress-dependent dynamic inversion model of specific water storage coefficient based on acoustic emission energy is obtained. The cumulative acoustic emission energy signal during peat release is acquired in real time, and the dynamic specific water storage coefficient under effective stress state is obtained by inverting the stress-dependent specific water storage coefficient dynamic inversion model.

[0007] In some optional embodiments, the undisturbed peat column support assembly includes a transparent solid outer cylinder, a top permeable stone, a bottom permeable stone, and a top pressure-bearing permeable plate; the transparent solid outer cylinder is a cylindrical structure with openings at both ends; the top permeable stone and the bottom permeable stone are respectively sealed and installed at the top and bottom ends of the transparent solid outer cylinder; the top pressure-bearing permeable plate is stacked on the upper surface of the top permeable stone; the interior of the transparent solid outer cylinder forms a sealed sample cavity for accommodating the undisturbed peat core.

[0008] In some optional embodiments, the undisturbed peat core bearing assembly further includes an axial load application assembly; the axial load application assembly is drivenly connected to the top pressure-bearing permeable plate and is used to apply an effective overburden stress to the undisturbed peat core that matches the in-situ burial depth.

[0009] In some optional embodiments, the variable head drive and control components employ a CNC horizontal flow pump or a micro-stepping Marshall bottle; the outlet of the CNC horizontal flow pump or micro-stepping Marshall bottle is connected to the bottom of the undisturbed peat column support component through a sealed pipeline, for controlling the rate of rise and fall of water level with a set precision, simulating the continuous hydrological fluctuation process in nature.

[0010] In some optional embodiments, the macroscopic fluid-force multi-field synchronous monitoring component includes a micro-pore water pressure array and a deformation monitoring meter; the micro-pore water pressure array includes at least three micro-pore water pressure gauges, each of which is inserted into the sample chamber through a sealed puncture at different elevations along the sidewall of the undisturbed peat column bearing component, for real-time acquisition of transient water head and pore water pressure data at different depths of the peat core; the high-precision deformation monitoring meter uses a laser displacement sensor; the laser displacement sensor is coaxially mounted at the center of the top pressure-bearing permeable plate of the undisturbed peat column bearing component, for real-time acquisition of one-dimensional vertical strain of the peat core.

[0011] In some optional embodiments, the microscopic acoustic emission non-destructive listening component includes at least three sets of broadband piezoelectric acoustic emission sensors, each set of broadband piezoelectric acoustic emission sensors being coupled and fixed to the outer wall of the undisturbed peat column support component.

[0012] In some optional embodiments, the microscopic acoustic emission lossless monitoring component also includes a preamplifier and a high-frequency acoustic emission full waveform acquisition instrument; the signal output terminals of each broadband piezoelectric acoustic emission sensor are electrically connected to the input terminal of the preamplifier; the output terminal of the preamplifier is electrically connected to the input terminal of the high-frequency acoustic emission full waveform acquisition instrument.

[0013] In some optional embodiments, based on the effective stress principle, the real-time effective stress increment is calculated, and combined with the collected macroscopic vertical strain, the dynamic compressibility coefficient of peat soil under the current effective stress state is determined, including: assuming the macroscopic vertical strain is... The change in the macroscopic vertical dependent variable is The dynamic compression ratio is pore water pressure is The total stress is The effective stress increment is , For effective stress, The dynamic compression coefficient is then expressed as: .

[0014] In some optional embodiments, an acoustic energy-skeleton damage compression constitutive model of peat is established, including: setting the dynamic compressibility coefficient as... The density of water is The acceleration due to gravity is Porosity is The compressibility of water is , To accumulate absolute energy for acoustic emission, The constitutive mapping function obtained by fitting is, and the water storage coefficient is Then the acoustic energy-skeleton damage compression constitutive model is expressed as: ; Substituting the acoustic energy-skeleton damage compression constitutive model into the definition formula of the specific water storage coefficient, we obtain a stress-dependent dynamic inversion model of the specific water storage coefficient based on acoustic emission energy, which is expressed as: .

[0015] The beneficial effects of this invention are: (1) Based on the rigorous principles of groundwater dynamics and geotechnical mechanics, this invention utilizes the clear causal relationship between pore water pressure, effective stress and elastic waves in peat soil to ensure the reliability of the inversion model and solve the problem of failure of traditional constant parameter models in peat soil. (2) The present invention adopts the method of non-destructive acoustic emission monitoring, which does not require the introduction of chemical tracers and isotopes or other exogenous substances, nor does it require destructive pumping tests. It not only meets the ecological protection requirements of high-altitude peatlands, but also preserves the natural micro-fiber structure of peat soil to the greatest extent. The test results can truly reflect the in-situ hydrological characteristics of peat soil. (3) This invention breaks through the limitation of the traditional hydrological model that treats the specific storage coefficient as a constant, and establishes a stress-dependent dynamic inversion model of the specific storage coefficient based on acoustic emission energy. Only the acoustic emission cumulative energy signal needs to be obtained to invert and derive the dynamic specific storage coefficient under a specific effective stress state in real time. It can accurately depict the nonlinear decay law of the aquifer water storage capacity of the high-altitude peatland in the complex hydrological cycle, and the test accuracy is much higher than that of the traditional method. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structural principle of a peat soil stress-dependent water storage parameter testing device provided in Embodiment 1 of the present invention; Figure 2 This is a structural principle diagram of a specific implementation of a peat soil stress-dependent water storage parameter testing device provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of a peat soil stress-dependent water storage parameter testing method provided in Embodiment 2 of the present invention.

[0017] In the diagram: 1-Original peat column bearing component; 101-Transparent solid outer cylinder; 102-Top permeable stone; 103-Bottom permeable stone; 104-Top pressure-bearing permeable plate; 2-Variable head drive and control component; 3-Macroscopic flow-force multi-field synchronous monitoring component; 301-Micro pore water pressure array; 302-Deformation monitoring meter; 4-Microscopic acoustic emission non-destructive listening component; 401-Wideband piezoelectric acoustic emission sensor; 402-Preamplifier; 403-High-frequency acoustic emission full waveform acquisition instrument. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Example 1 As an example, in order to solve the problems existing in the prior art, this embodiment provides a peat soil stress-dependent water storage parameter testing device.

[0020] The implementation details of the apparatus in this embodiment will be described in detail below. The following implementation details are provided for ease of understanding only and are not necessary for implementing this solution.

[0021] As attached Figure 1As shown in the figure, this embodiment provides a peat stress-dependent water storage parameter testing device, which includes an undisturbed peat column bearing component 1, a variable head driving and control component 2, a macroscopic flow-force multi-field synchronous monitoring component 3, and a microscopic acoustic emission non-destructive listening component 4. The undisturbed undisturbed peat core bearing component 1 is used to accommodate the undisturbed undisturbed peat core, providing a closed bearing space for the one-dimensional vertical seepage and consolidation deformation of the peat. The variable head drive and control component 2 is connected to the bottom of the original peat column bearing component 1, and is used to drive the peat soil to drain, consolidate, release water and expand and rebound when exposed to water. The macroscopic flow-force multi-field synchronous monitoring component 3 is installed on the original peat column bearing component 1 to synchronously collect the macroscopic pore water pressure and vertical strain of peat during the seepage consolidation process. The microscopic acoustic emission non-destructive monitoring component 4 is coupled and installed on the outer wall of the original peat column bearing component 1. It is used to capture the acoustic emission elastic wave signal generated by the fiber skeleton misalignment and micro fracture during the peat drainage consolidation process in real time, and to perform non-destructive dynamic monitoring of skeleton damage.

[0022] In some alternative embodiments, as shown in the appendix Figure 2 As shown, the undisturbed peat column support assembly 1 includes a transparent solid outer cylinder 101, a top permeable stone 102, a bottom permeable stone 103, and a top pressure-bearing permeable plate 104; the transparent solid outer cylinder 101 is a cylindrical structure with openings at both ends; the top permeable stone 102 and the bottom permeable stone 103 are respectively sealed and installed at the top and bottom ends of the transparent solid outer cylinder 101; the top pressure-bearing permeable plate 104 is stacked on the upper surface of the top permeable stone 102; the interior of the transparent solid outer cylinder 101 forms a sealed sample cavity for accommodating the undisturbed peat core.

[0023] In some optional embodiments, the undisturbed peat core bearing assembly 1 further includes an axial load application assembly; the axial load application assembly is drivenly connected to the top pressure-bearing permeable plate and is used to apply an effective overburden stress matching the in-situ burial depth to the undisturbed peat core.

[0024] In some optional embodiments, the variable head drive and control component 2 adopts a CNC horizontal flow pump or a micro-stepping Marshall bottle; the outlet of the CNC horizontal flow pump or the micro-stepping Marshall bottle is connected to the bottom of the original peat column support component 1 through a sealed pipeline, which is used to control the rate of rise and fall of water level with a set accuracy, simulating the continuous falling and rising process in nature.

[0025] In some alternative embodiments, as shown in the appendix Figure 2As shown, the macroscopic flow-force multi-field synchronous monitoring component includes a micro-pore water pressure array 301 and a deformation monitoring meter 302. The micro-pore water pressure array 301 includes at least three micro-pore water pressure gauges, each of which is inserted into the sample chamber through a sealed puncture at a different elevation along the side wall of the undisturbed peat column bearing component 1, for real-time acquisition of transient water head and pore water pressure data at different depths of the peat core. The high-precision deformation monitoring meter 302 uses a laser displacement sensor. The laser displacement sensor is coaxially installed at the center of the top pressure-bearing permeable plate 104 of the undisturbed peat column bearing component 1, for real-time acquisition of one-dimensional vertical strain of the peat core.

[0026] Specifically, the micro-pore water pressure array 301 includes three micro-pore water pressure gauges with a range of 0~0.2MPa. The three micro-pore water pressure gauges are inserted into the sample cavity through sealed joints at elevations of 50mm, 100mm and 150mm from the bottom of the soil sample along the side wall of the transparent rigid outer cylinder, respectively, to make close contact with the undisturbed peat core. This is used to collect transient water head and pore water pressure data at different depths of the peat core in real time. The high-precision deformation monitoring meter 302 uses a laser displacement sensor with a range of 0~50mm and an accuracy of 1μm. It is coaxially installed at the center of the upper surface of the top pressure-bearing permeable plate 104 to collect one-dimensional vertical settlement data of the peat core in real time and convert it into vertical strain data.

[0027] In some optional embodiments, the microscopic acoustic emission non-destructive monitoring component includes at least three sets of broadband piezoelectric acoustic emission sensors 401, each set of broadband piezoelectric acoustic emission sensors 401 being coupled and fixed to the outer wall of the undisturbed peat column support component 1. Optionally, the installation height of each set of broadband piezoelectric acoustic emission sensors 401 corresponds one-to-one with the installation height of each micropore water pressure gauge.

[0028] In some alternative embodiments, as shown in the appendix Figure 2 As shown, the microscopic acoustic emission lossless monitoring component also includes a preamplifier 402 and a high-frequency acoustic emission full waveform acquisition instrument 403; the signal output terminals of each broadband piezoelectric acoustic emission sensor 401 are electrically connected to the input terminal of the preamplifier 402; the output terminal of the preamplifier 402 is electrically connected to the input terminal of the high-frequency acoustic emission full waveform acquisition instrument 403.

[0029] Specifically, the microscopic acoustic emission lossless monitoring component uses a wideband piezoelectric acoustic emission sensor 401 with a response frequency of 100kHz / 1MHz. Three sets of wideband piezoelectric acoustic emission sensors 401 are coupled and fixed to the outer wall of the transparent rigid outer cylinder by a coupling agent. The preamplifier 402 has a gain of 40dB and a bandwidth of 10kHz / 2MHz. The sampling frequency of the acquisition instrument is 10MHz. It is used to amplify, acquire and store the acoustic emission elastic wave signal, and analyze the characteristic parameters such as the cumulative absolute energy of acoustic emission, the number of impacts, the amplitude and the rise time.

[0030] Example 2 Based on the peat soil stress-dependent water storage parameter testing device of Example 1, as shown in the attached... Figure 3 As shown in the figure, this embodiment provides a method for testing peat soil stress-dependent water storage parameters, including steps 110-160.

[0031] Step 110: Inject water from bottom to top into the undisturbed peat core bearing component to fully saturate the undisturbed peat core. Apply an overburden load corresponding to the in-situ burial depth to the saturated peat core and let it stand until the deformation data of the macroscopic flow-force multi-field synchronous monitoring component is stable and the background noise of the microscopic acoustic emission non-destructive listening component returns to zero.

[0032] Specifically, water saturation is carried out using a slow, bottom-up saturation method with a hydraulic gradient of no more than 0.05 to avoid the peat fiber structure being destroyed by water flow during the saturation process. The criteria for determining static stability are: the fluctuation of the laser displacement sensor reading is no more than 0.1% of the full scale within 12 consecutive hours, and there is no effective impact event triggered by the acoustic emission system to ensure that the peat soil reaches a stress equilibrium state and to eliminate the interference of initial background noise on the test results.

[0033] An effective overburden stress of 50 kPa is applied to the saturated peat core using an axial load application component to match the in-situ burial depth conditions of the peat core.

[0034] Step 120: Activate the variable head drive and control components to continuously lower the water level at a preset rate, simulating the drainage, consolidation, and water release process of the peatland groundwater level drop.

[0035] Specifically, the water level drop rate is controlled within the range of 0.1-5 cm / h, and the simulated hydraulic gradient range is 0.001-0.1, strictly matching the extremely low hydraulic gradient conditions of natural hydrological fluctuations in alpine peatlands, ensuring that the test process is consistent with the in-situ hydrological processes in peatlands.

[0036] A high-precision CNC horizontal flow pump was started to continuously lower the water level at a rate of 1 cm / h to simulate the natural groundwater level drop process in peatlands. The hydraulic gradient was controlled to be no greater than 0.05 throughout the test process to match the extremely low hydraulic gradient conditions of natural hydrological fluctuations in high-altitude peatlands, thereby driving the one-dimensional vertical drainage consolidation and release of water from the peat soil.

[0037] Step 130: During the continuous decline of water level, the absolute energy of micro-accumulated acoustic emission, macro-vertical strain, and pore water pressure drop depth of peat cores are collected synchronously and continuously using the macro-fluid-force multi-field synchronous monitoring component and the micro-acoustic emission non-destructive listening component.

[0038] Specifically, pore water pressure drop data at different depths are collected in real time using three miniature pore water pressure gauges, vertical settlement data of peat cores are collected in real time using a laser displacement sensor and converted into vertical strain data, and cumulative absolute energy data of acoustic emission damage to peat fiber skeleton is collected and analyzed in real time using a broadband piezoelectric acoustic emission sensor, a preamplifier and a high-frequency acoustic emission full waveform acquisition instrument.

[0039] Specifically, the synchronous acquisition frequency of multi-source physical data is no less than 1MHz, and all acquired data have a unified timestamp to achieve precise alignment of microscopic acoustic emission events with macroscopic seepage and deformation data on the time scale, providing a unified time dimension benchmark for subsequent coupled modeling.

[0040] Step 140: Based on the effective stress principle, calculate the real-time effective stress increment, and combine it with the collected macroscopic vertical strain data to determine the dynamic compression coefficient of peat soil under the current effective stress state.

[0041] Specifically, based on the effective stress principle, the real-time effective stress increment is calculated, and combined with the collected macroscopic vertical strain, the dynamic compressibility coefficient of peat soil under the current effective stress state is determined, including: assuming the macroscopic vertical strain is... The change in the macroscopic vertical dependent variable is The dynamic compression ratio is pore water pressure is The total stress is The effective stress increment is , For effective stress, The dynamic compression coefficient is then expressed as: .

[0042] Step 150: Mathematically fit the micro-accumulated acoustic emission absolute energy with the dynamic compression coefficient to establish an acoustic energy-skeleton damage compression constitutive model for peat soil. Substitute the acoustic energy-skeleton damage compression constitutive model into the specific water storage coefficient definition formula to obtain a stress-dependent dynamic inversion model of specific water storage coefficient based on acoustic emission energy.

[0043] Specifically, an acoustic energy-skeleton damage compression constitutive model for peat soil is established, including: setting the dynamic compressibility coefficient as... The density of water is The acceleration due to gravity is Porosity is The compressibility of water is , To accumulate absolute energy for acoustic emission, The constitutive mapping function obtained by fitting is, and the water storage coefficient is Then the acoustic energy-skeleton damage compression constitutive model is expressed as: ; Substituting the acoustic energy-skeleton damage compression constitutive model into the definition formula of the specific water storage coefficient, we obtain a stress-dependent dynamic inversion model of the specific water storage coefficient based on acoustic emission energy, which is expressed as: .

[0044] Step 160: Acquire the cumulative acoustic emission energy signal during peat medium water release in real time, and obtain the dynamic specific water storage coefficient under effective stress state by using a stress-dependent specific water storage coefficient dynamic inversion model.

[0045] In some optional embodiments, after the drainage and water release test is completed, the water level is continuously raised at a preset rate by a variable head drive and control component to simulate the water expansion process of peatland groundwater recharge. Acoustic emission energy, vertical rebound strain and pore water pressure rise data are collected simultaneously during the water level rise process to verify the applicability of the dynamic inversion model in the peat soil expansion and rebound process, and to complete the water storage parameter evolution test of the entire peat soil water release-recharge cycle.

[0046] This invention is based on rigorous groundwater dynamics and geotechnical mechanics principles. The dissipation of pore water pressure in peat soil inevitably leads to an increase in effective stress, and the compression displacement and microfracture of the fiber skeleton inevitably release elastic waves. There is a clear causal relationship among the three, which fundamentally ensures the reliability of the inversion model and completely solves the problem of the failure of traditional constant parameter models in peat soil.

[0047] This invention employs a non-destructive acoustic emission monitoring method, which eliminates the need for the introduction of exogenous substances such as chemical tracers and isotopes, as well as the need for destructive pumping tests. It not only meets the ecological protection requirements of alpine peatlands but also preserves the natural micro-fibrous structure of peat soil to the greatest extent. The test results can accurately reflect the in-situ hydrological characteristics of peat soil.

[0048] This invention breaks through the limitation of traditional hydrological models that treat the specific storage coefficient as a constant, and establishes a stress-dependent dynamic inversion model of the specific storage coefficient based on acoustic emission energy. In subsequent monitoring, only the cumulative acoustic emission energy signal needs to be acquired to derive the dynamic specific storage coefficient under a specific effective stress state in real time. This model can accurately characterize the nonlinear decay law of aquifer water storage capacity in high-altitude peatlands during complex hydrological cycles, and the testing accuracy is far higher than that of traditional methods.

[0049] It is understood that the detailed description of the method in the foregoing embodiments also applies to the various units in this device embodiment, and for the sake of simplicity, it has not been described in detail.

[0050] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A peat stress-dependent water storage parameter testing device, characterized by, It includes an original peat column bearing component (1), a variable head drive and control component (2), a macroscopic flow-force multi-field synchronous monitoring component (3), and a microscopic acoustic emission non-destructive listening component (4). The original peat column bearing component (1) is used to accommodate the undisturbed original peat core, providing a closed bearing space for the one-dimensional vertical seepage and consolidation deformation of peat soil; The variable head drive and control component (2) is connected to the bottom of the original peat column bearing component (1) to drive the peat soil to drain, consolidate, release water and expand and rebound under water. The macroscopic flow-force multi-field synchronous monitoring component (3) is installed on the original peat column bearing component (1) to synchronously collect the macroscopic pore water pressure and vertical strain of peat during the seepage consolidation process; The microscopic acoustic emission non-destructive monitoring component (4) is coupled and installed on the outer wall of the original peat column bearing component (1) to capture the acoustic emission elastic wave signal generated by the fiber skeleton misalignment and micro fracture during the peat drainage consolidation process in real time, and to perform non-destructive dynamic monitoring of skeleton damage. The variable head drive and control component (2) is used to: continuously reduce the water level at a preset rate to simulate the drainage, consolidation and release process of the peatland groundwater level drop; Based on the effective stress principle, the real-time effective stress increment is calculated. Combined with the collected macroscopic vertical strain data, the dynamic compressibility coefficient of peat soil under the current effective stress state is determined, including: assuming the macroscopic vertical strain is... The change in the macroscopic vertical dependent variable is The dynamic compression ratio is pore water pressure is The total stress is The effective stress increment is , For effective stress, The dynamic compression coefficient is then expressed as: A constitutive model of acoustic energy-skeleton damage compression for peat soil is established by mathematically fitting the absolute energy of microscopic cumulative acoustic emission with the dynamic compressibility coefficient, including: setting the dynamic compressibility coefficient as... The density of water is The acceleration due to gravity is Porosity is The compressibility coefficient of water is , Accumulate absolute energy for acoustic emission. The constitutive mapping function obtained by fitting is, and the water storage coefficient is Then the acoustic energy-skeleton damage compression constitutive model is expressed as: Substituting the acoustic energy-skeleton damage compression constitutive model into the definition formula of the specific water storage coefficient, a stress-dependent dynamic inversion model of the specific water storage coefficient based on acoustic emission energy is obtained, expressed as: Substituting the acoustic energy-skeleton damage compression constitutive model into the specific water storage coefficient definition formula, a stress-dependent dynamic inversion model of specific water storage coefficient based on acoustic emission energy is obtained; the acoustic emission cumulative energy signal during peat medium water release is acquired in real time, and the dynamic specific water storage coefficient under effective stress state is obtained through the stress-dependent dynamic inversion model of specific water storage coefficient. The macroscopic flow-force multi-field synchronous monitoring component (3) and the microscopic acoustic emission non-destructive listening component (4) are used to: synchronously and continuously collect data on the microscopic cumulative acoustic emission absolute energy, macroscopic vertical strain and pore water pressure drop depth of peat cores during the continuous decline of water level.

2. The peat soil stress-dependent water storage parameter testing device according to claim 1, characterized in that, The original peat column support assembly (1) includes a transparent solid outer cylinder (101), a top permeable stone (102), a bottom permeable stone (103), and a top pressure-bearing permeable plate (104); the transparent solid outer cylinder (101) is a cylindrical structure with openings at both ends; the top permeable stone (102) and the bottom permeable stone (103) are respectively sealed and installed at the top and bottom ends of the transparent solid outer cylinder (101); the top pressure-bearing permeable plate (104) is stacked on the upper surface of the top permeable stone (102); the interior of the transparent solid outer cylinder (101) forms a sealed sample cavity for accommodating the original peat core.

3. The peat soil stress-dependent water storage parameter testing device according to claim 2, characterized in that, The original peat column bearing assembly (1) also includes an axial load application assembly; the axial load application assembly is connected to the top pressure permeable plate (104) for applying an effective overburden stress matching the in-situ burial depth to the original peat core.

4. The peat soil stress-dependent water storage parameter testing device according to claim 1, characterized in that, The variable head drive and control component (2) adopts a numerically controlled horizontal flow pump or a micro-stepping Marshall bottle; the outlet of the numerically controlled horizontal flow pump or the micro-stepping Marshall bottle is connected to the bottom of the original peat column support component (1) through a sealed pipeline, which is used to control the rate of rise and fall of water level with a set accuracy, and simulate the continuous hydrological fluctuation process in nature.

5. The peat soil stress-dependent water storage parameter testing device according to claim 2, characterized in that, The macroscopic flow-force multi-field synchronous monitoring component (3) includes a micro pore water pressure array (301) and a deformation monitoring meter (302); the micro pore water pressure array (301) includes at least three micro pore water pressure gauges, each of which is inserted into the sample cavity through a sealed puncture along different elevations of the sidewall of the undisturbed peat column bearing component (1) to collect transient water head and pore water pressure data at different depths of the peat core in real time; the deformation monitoring meter (302) uses a laser displacement sensor; the laser displacement sensor is coaxially installed at the center of the top pressure permeable plate (104) of the undisturbed peat column bearing component (1) to collect one-dimensional vertical strain of the peat core in real time.

6. The peat soil stress-dependent water storage parameter testing device according to claim 1, characterized in that, The microscopic acoustic emission non-destructive listening component (4) includes at least three sets of broadband piezoelectric acoustic emission sensors (401), each set of broadband piezoelectric acoustic emission sensors (401) being coupled and fixed to the outer wall of the undisturbed peat column support component (1).

7. The peat soil stress-dependent water storage parameter testing device according to claim 6, characterized in that, The microscopic acoustic emission lossless monitoring component (4) also includes a preamplifier (402) and a high-frequency acoustic emission full waveform acquisition instrument (403); the signal output terminals of each broadband piezoelectric acoustic emission sensor (401) are electrically connected to the input terminal of the preamplifier (402); the output terminal of the preamplifier (402) is electrically connected to the input terminal of the high-frequency acoustic emission full waveform acquisition instrument (403).

8. A method for testing stress-dependent water storage parameters in peat soil, characterized in that, include: Water is injected from bottom to top into the original peat column bearing component (1) to fully saturate the original peat core. An overburden load corresponding to the in-situ burial depth is applied to the saturated peat core. The system is left to stand until the deformation data of the macro-fluid-force multi-field synchronous monitoring component (3) is stable and the background noise of the micro-acoustic emission non-destructive listening component (4) is zero. Start the variable head drive and control component (2) to continuously lower the water level at a preset rate to simulate the drainage, consolidation and release process of the peatland groundwater level drop; During the continuous decline of water level, the micro-accumulated acoustic emission absolute energy, macro-vertical strain and pore water pressure drop data of peat cores are collected synchronously and continuously through the macro-fluid-force multi-field synchronous monitoring component (3) and the micro-acoustic emission non-destructive listening component (4). Based on the effective stress principle, the real-time effective stress increment is calculated. Combined with the collected macroscopic vertical strain data, the dynamic compressibility coefficient of peat soil under the current effective stress state is determined, including: assuming the macroscopic vertical strain is... The change in the macroscopic vertical dependent variable is The dynamic compression ratio is pore water pressure is The total stress is The effective stress increment is , For effective stress, The dynamic compression coefficient is then expressed as: ; A constitutive model of acoustic energy-skeleton damage compression for peat soil is established by mathematically fitting the absolute energy of microscopic cumulative acoustic emission with the dynamic compressibility coefficient. This model includes: setting the dynamic compressibility coefficient as... The density of water is The acceleration due to gravity is Porosity is The compressibility coefficient of water is , Accumulate absolute energy for acoustic emission. The constitutive mapping function obtained by fitting is, and the water storage coefficient is Then the acoustic energy-skeleton damage compression constitutive model is expressed as: Substituting the acoustic energy-skeleton damage compression constitutive model into the definition formula of the specific water storage coefficient, a stress-dependent dynamic inversion model of the specific water storage coefficient based on acoustic emission energy is obtained, expressed as: Substituting the acoustic energy-skeleton damage compression constitutive model into the specific water storage coefficient definition formula, a stress-dependent dynamic inversion model of the specific water storage coefficient based on acoustic emission energy is obtained. The cumulative acoustic emission energy signal during peat release is acquired in real time, and the dynamic specific water storage coefficient under effective stress state is obtained by inverting the stress-dependent specific water storage coefficient dynamic inversion model.

Images