Centripetal permeation model device

Abstract

The invention provides a centripetal permeation model device, and relates to the technical field of vacuum preloading model tests, the centripetal permeation model device comprises a steel frame mechanism, the steel frame mechanism is internally provided with a rigid-flexible combined lining, the top end of the steel frame mechanism is provided with a load loading system, and the bottom end of the steel frame mechanism is provided with a sand collecting pool; a vacuum control system, an air pressure testing system and a water pressure testing system are sequentially arranged in the rigid-flexible combined lining from top to bottom, and a soil pressure and soil sample deformation monitoring system is arranged on the outer side of the steel frame mechanism. According to the device, the friction force of the side wall is ingeniously eliminated through rigid-flexible combination of the lining, the device can be used for researching a vacuum preloading evolution mechanism and testing a new vacuum preloading material and a new technology, and through the centripetal permeation model device, a vacuum degree attenuation mechanism in the vacuum preloading process can be simulated and researched, and the new technology can be tested to improve the clogging condition of the drainage plate.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum preloading model test, in particular to a centripetal infiltration model device. Background Art

[0002] Current vacuum preloading test research is mainly based on indoor small-scale models and field tests. The former is difficult to simulate actual conditions, and the latter is difficult to accurately control and measure hydraulic and gas pressure conditions.

[0003] The limited depth of vacuum preloading seriously restricts the application of vacuum preloading technology. The completed vacuum preloading treatment sites generally have problems such as large settlement and insufficient deep bearing capacity. The indoor small-scale model has some limitations in revealing the drainage consolidation law, drainage board clogging mechanism, deep bearing capacity development mechanism, etc., mainly including the following aspects:

[0004] 1. Size effect: Indoor small-scale models usually cannot truly simulate the changes in the mechanical properties of the actual soil layer, and cannot completely eliminate the impact of the size effect on the model test results. When it comes to problems such as excessive settlement or insufficient deep bearing capacity, the size effect may cause a large difference between the model test results and the actual situation.

[0005] 2. Differences in geological conditions: Indoor small-scale models are usually difficult to fully replicate real geological conditions, such as the heterogeneity and nonlinearity of the strata and the role of groundwater. The impact of these geological conditions on settlement and bearing capacity may not be fully reflected in indoor small-scale models.

[0006] 3. Boundary condition limitations: Indoor small-scale models are usually limited by laboratory conditions, such as limited model size and boundary condition settings, which may cause the model test results to be affected by boundary conditions, resulting in additional shear stress and shear strain, and cannot fully reflect the complex situations in actual engineering.

[0007] 4. Unable to accurately consider the time effect: In actual projects, excessive settlement and insufficient deep bearing capacity usually develop gradually over time, while small-scale indoor models are usually difficult to simulate the changes and evolution of actual projects on a time scale.

[0008] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention

[0009] In view of this, the present invention provides a centripetal infiltration model device to solve the above-mentioned problems.

[0010] In order to solve the above problems, the specific technical solutions adopted by the present invention are as follows:

[0011] A centripetal infiltration model device comprises a steel frame mechanism, a rigid-flexible composite lining is arranged inside the steel frame mechanism, a load loading system is arranged at the top of the steel frame mechanism, and a sand collecting pool is arranged at the bottom of the steel frame mechanism; a vacuum control system, an air pressure test system and a water pressure test system are arranged inside the rigid-flexible composite lining from top to bottom, and a soil pressure and soil sample deformation monitoring system is arranged outside the steel frame mechanism; the load loading system, the air pressure test system, the water pressure test system and the soil pressure and soil sample deformation monitoring system are all connected to a soil consolidation analysis system by means of electrical connection.

[0012] Furthermore, in order to reduce the friction against the side wall, the rigid-flexible combined lining is composed of a number of rigid rings and a number of flexible ring belts, and the rigid rings and the flexible ring belts are arranged in a staggered manner in sequence. The flexible ring belts are made of nylon fabric material, and the rigid rings are made of stainless steel. Two adjacent groups of rigid-flexible combined linings are connected by a water-stop flange.

[0013] Furthermore, in order to realize the detachable and combined use of the steel frame mechanism, the steel frame mechanism is composed of a plurality of steel frames connected in sequence in the vertical direction, and the steel frames are fixedly connected by bolts.

[0014] Furthermore, the soil consolidation analysis system includes: a data receiving unit, a pore space evolution analysis unit, a water vapor transport model building unit and a soil consolidation evaluation unit;

[0015] A data receiving unit, used to respectively obtain the movement data of air flow and water flow in the air pressure test system and the water pressure test system and the monitoring data of soil pressure and soil sample deformation in the soil pressure and soil sample deformation monitoring system;

[0016] The pore space evolution analysis unit is used to analyze the pore space evolution of soil under the interaction of air and water flow based on the monitoring data of soil pressure and soil sample deformation and multi-fractal theory;

[0017] The water vapor transport model building unit is used to simulate the water vapor transport process in the pore space of soil based on the movement data of air and water flow, and to analyze the influence of water vapor transport on soil consolidation.

[0018] Furthermore, based on the monitoring data of soil pressure and soil deformation, the evolution of pore space in soil under the interaction of air and water flow is analyzed based on multifractal theory, including:

[0019] Preprocessing the monitoring data of soil pressure and soil sample deformation, and sorting the preprocessed monitoring data according to timestamps to obtain time series data of soil pressure and soil sample deformation;

[0020] The time series data of soil pressure and soil sample deformation are divided into several windows using the swing window algorithm, and the local weight of each window is calculated.

[0021] According to the local weight of each window, the singularity index of each window is calculated, and the multifractal spectrum curve is established according to the calculation results. The pore space evolution characteristics are extracted according to the multifractal spectrum curve, and the evolution law of the pore space is analyzed according to the pore space evolution characteristics.

[0022] Furthermore, the swing window algorithm is used to divide the time series data of soil pressure and soil sample deformation into several windows, and the local weight of each window is calculated including:

[0023] According to the time series data of soil pressure and soil sample deformation, the initial moment and the soil pressure value and soil sample deformation value corresponding to the initial moment are determined respectively, and the soil pressure value and soil sample deformation value corresponding to the initial moment are taken as the starting point;

[0024] Using the swing window algorithm and according to the preset window width, the boundary values ​​of the upper swing window and the lower swing window of the earth pressure and soil sample deformation are calculated respectively;

[0025] Traversing the time series data of soil pressure and soil sample deformation, and dividing the time series data of soil pressure and soil sample deformation into a plurality of windows according to the boundary values ​​of the upper swing window and the lower swing window of the soil pressure and soil sample deformation;

[0026] The cumulative changes of soil pressure and deformation are calculated in each window of soil pressure and soil sample deformation, and the local weight of each window is obtained by normalizing the cumulative changes.

[0027] Furthermore, according to the local weight of each window, the singularity index of each window is calculated, and a multifractal spectrum curve is established according to the calculation results. The pore space evolution characteristics are extracted according to the multifractal spectrum curve. The evolution law of the pore space is analyzed according to the pore space evolution characteristics, including:

[0028] According to the local weight of each window and the preset window width, the singularity index of each window is calculated by logarithmic transformation;

[0029] Count the singularity index of all windows, determine the frequency of window subsets with the same singularity index, and calculate the fractal dimension based on the frequency;

[0030] The fractal dimension is used to draw the multifractal spectrum curve, and the characteristics of pore space evolution are extracted by analyzing the spectrum width and curve shape of the multifractal spectrum curve.

[0031] According to the characteristics of pore space evolution, the multi-fractal spectrum curves under different times or conditions are compared to analyze the dynamic change law and trend of pore space.

[0032] Furthermore, based on the movement data of air and water flow, the water vapor transport process in the pore space of the soil is simulated, and the influence of water vapor transport on soil consolidation is analyzed, including:

[0033] Collect physical experimental data of soil and the three-dimensional structure of soil pores, and establish a soil pore structure model;

[0034] Based on Darcy's law, combined with the soil pore structure model and experimental data, the seepage characteristics of water flow in porous media are simulated, and the gas flow equation is introduced to describe the gas flow behavior, integrating to form a coupled model of water-gas two-phase flow;

[0035] The numerical simulation software is used to solve the water-gas two-phase flow coupling model, calculate the water-gas distribution, pressure field and saturation changes in the pore space, and obtain the water-gas transport results;

[0036] Combining the results of water vapor transport with soil consolidation theory, the influence of water vapor transport on soil consolidation is analyzed. Furthermore, the expression of Darcy's law is:

[0037] Q=K×A×(h2-h1) / L

[0038] V=K×I

[0039] In the formula, Q represents the seepage rate per unit time;

[0040] A represents the cross-sectional area of ​​water flow;

[0041] K represents the permeability coefficient;

[0042] h2-h1 represents the upstream and downstream head difference;

[0043] L represents the length of the seepage path;

[0044] I represents the hydraulic slope;

[0045] V represents the seepage velocity.

[0046] Furthermore, by combining the results of water-gas transport with the theory of soil consolidation, the influence of water-gas transport on soil consolidation is analyzed, including:

[0047] According to the water-gas transport results, the permeability parameters in the water-gas transport results are extracted and used as the initial conditions for consolidation analysis. The permeability parameters include pore pressure distribution, water-gas saturation and permeability coefficient, and are used as the initial conditions for consolidation analysis.

[0048] According to the permeability parameters in the water vapor transport results and combined with the consolidation theory, a coupling model of water vapor transport and consolidation process is constructed;

[0049] The coupled model is used to simulate the soil consolidation process, calculate the settlement, consolidation rate and pore pressure dissipation, and analyze the dynamic influence of water-gas transport on the consolidation process. Based on the analysis results, the change and stability of soil consolidation rate under different water-gas transport conditions are evaluated.

[0050] The beneficial effects of the present invention are:

[0051] 1. The centripetal infiltration model device proposed in the present invention adopts a 1:1 model size and cleverly eliminates the side wall friction through a rigid-flexible combination lining. It can be used to study the evolution mechanism of vacuum preloading and test new materials and technologies for vacuum preloading. Through the centripetal infiltration model device, the vacuum attenuation mechanism during vacuum preloading can also be simulated and studied, and new technologies can be tested to improve the clogging of drainage plates.

[0052] 2. The present invention can comprehensively consider multiple factors such as air pressure, water pressure, earth pressure and soil sample deformation, conduct a comprehensive analysis of soil consolidation, improve the accuracy and comprehensiveness of the analysis, reduce manual intervention and improve analysis efficiency through automated data reception and processing procedures, and use multi-fractal theory to analyze the evolution of pore space, which can more accurately reveal the changes in the pore structure of soil under the interaction of air and water flow. By analyzing the dynamic influence of water and gas transport on the consolidation process, the mechanism and law of soil consolidation can be more deeply understood. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0054] Figure 1 is a structural schematic diagram of a centripetal infiltration model device according to an embodiment of the present invention;

[0055] Figure 2 is a schematic diagram of the assembly of a steel frame mechanism and a rigid-flexible combined lining in a centripetal infiltration model device according to an embodiment of the present invention;

[0056] Figure 3 is a schematic diagram of assembling a rigid ring and a flexible ring belt in a centripetal infiltration model device according to an embodiment of the present invention;

[0057] Figure 4 It is a principle block diagram among a load loading system, an air pressure testing system, a water pressure testing system, a soil pressure and soil sample deformation monitoring system and a soil consolidation analysis system in a centripetal infiltration model device according to an embodiment of the present invention.

[0058] In the figure:

[0059] 1. Steel frame structure; 101. Steel frame; 102. Vertical roller guide groove; 2. Rigid-flexible composite lining; 201. Rigid ring; 202. Flexible ring belt; 3. Load loading system; 4. Sand collecting pool; 5. Vacuum control system; 6. Air pressure test system; 7. Water pressure test system; 8. Soil pressure and soil sample deformation monitoring system; 9. Soil consolidation analysis system; 10. Base. DETAILED DESCRIPTION

[0060] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0061] According to an embodiment of the present invention, a centripetal infiltration model device is provided.

[0062] The present invention is further described with reference to the accompanying drawings and specific embodiments. Figure 1-Figure 4 As shown, the centripetal infiltration model device according to an embodiment of the present invention includes a steel frame mechanism 1, a rigid-flexible composite lining 2 is arranged inside the steel frame mechanism 1, a load loading system 3 is arranged at the top of the steel frame mechanism 1, and a sand collecting pool 4 is arranged at the bottom of the steel frame mechanism 1; a vacuum control system 5, an air pressure test system 6 and a water pressure test system 7 are arranged in sequence inside the rigid-flexible composite lining 2 from top to bottom, and a soil pressure and soil sample deformation monitoring system 8 is arranged on the outside of the steel frame mechanism 1; the load loading system 3, the air pressure test system 6, the water pressure test system 7 and the soil pressure and soil sample deformation monitoring system 8 are all connected to the soil consolidation analysis system 9 by electrical connection.

[0063] Specifically, the centripetal infiltration model device can be used for the following research:

[0064] 1. Research on the evolution law of unsaturated zone under vacuum preloading: mainly studies the evolution of soil pore space and water vapor transport under the interaction of air and water flow and its influence on soil consolidation.

[0065] 2. Study on the attenuation law of vacuum preloading: Study the fine-grained soil starting and entering the drainage board, causing the permeability of the drainage board to change, thereby affecting the vacuum transfer.

[0066] 3. Permeability performance evaluation: By simulating the permeability process under vacuum preloading conditions, the permeability performance and other mechanical properties of new materials under vacuum preloading conditions can be evaluated.

[0067] 4. Process optimization: The centripetal infiltration model device can be used to optimize the vacuum prepressing process, including prepressing parameters, material selection and process flow, so as to improve the efficiency and reliability of the new vacuum prepressing technology.

[0068] In general, the centripetal infiltration model device can provide a reliable experimental platform for the research and development and application of new materials and technologies for vacuum preloading, help engineers and researchers better understand and optimize the vacuum preloading process, and promote the application and development of new materials and technologies.

[0069] As a preferred embodiment, the rigid-flexible combined lining 2 is composed of a plurality of rigid rings 201 and a plurality of flexible ring belts 202, and the rigid rings 201 and the flexible ring belts 202 are arranged in a staggered manner in sequence, the flexible ring belts 202 are made of nylon fabric material, and the rigid rings 201 are made of stainless steel; two adjacent groups of rigid-flexible combined liners 2 are connected by a water-stop flange.

[0070] Specifically, the present invention proposes for the first time to use a rigid-flexible composite liner 2, which successfully solves the problem of side wall friction of traditional large-scale rigid boundary models. The rigid-flexible composite liner 2 uses a rigid ring 201 for lateral constraints and a flexible ring belt 202 to achieve vertical unconstrained deformation. The rigid ring 201 and the flexible ring 202 are arranged with intervals, which can transform the lateral friction caused by the vertical settlement of a large-scale vacuum preloading model that may be as high as 1m into a laterally restricted vertical free deformation experimental device, thereby reducing the side wall friction and thus reducing the influence of the side wall friction on the stress conditions of the soil sample by more than 90%.

[0071] In addition, it should be noted that stainless steel is used to make steel rings of different models with a wall thickness of 1 cm, a height of 5 cm, a diameter of 1 m and 1.2 m as the rigid ring 201. Since steel has a large tensile strength and tensile stiffness, when the soil sample has a lateral earth pressure, the rigid ring 201 can provide sufficient lateral constraints to achieve lateral restricted boundary conditions. However, only rigid constraints cannot solve the problem of side wall friction, because the rigid side wall cannot achieve vertical free deformation. The rigid-flexible composite lining 2 can cleverly solve the problems of lateral restricted constraints and vertical free deformation at the same time. The use of nylon fabric material to form a ring belt and the rigid ring 201 to form the side wall of the model is to use the characteristics of the flexible ring belt 202 that can be wrinkled and deformed to achieve vertical free deformation of the model soil sample without generating vertical friction. At the same time, the flexible ring belt 202 still has good tensile strength and tensile stiffness, and is also not easy to produce horizontal deformation. The flexible ring belt 202 and the rigid ring 201 are sewn together by preserving micro-holes on the edge of the rigid ring 201 and are waterproofed.

[0072] In addition, the rigid-flexible combination lining has two models with inner diameters of 1m and 1.2m. The centripetal permeability model is 10m high, including 4m above ground, a 2m platform, and 6m underground. The pore water pressure working range is: -100kPa to 300kPa, the pore gas pressure working range is: -100kPa to 0kPa, and the soil pressure working range is: 0kPa to 300kPa.

[0073] Again, rigid-flexible composite materials are used as the side walls of the model at vertical intervals of 5 cm. The rigid material well constrains the lateral deformation of the soil, and the flexible material allows vertical compression. In this way, the friction between the side wall and the soil sample can be greatly reduced or even eliminated while achieving the lateral restricted boundary condition.

[0074] Appropriate stress or displacement conditions are set at the boundary of the model to ensure that no additional lateral pressure is applied to the soil sample when the model realizes the lateral restricted boundary conditions. The stress conditions and displacement conditions are described as follows:

[0075] Stress conditions refer to the setting of zero lateral stress conditions and free lateral displacement restriction conditions on the side walls (i.e., boundaries) of the model. The zero lateral stress condition means that no lateral constraints or pressure are applied to a certain material (such as soil, structural components, etc.) in a horizontal direction, so that the stress in this direction is zero. The free lateral displacement restriction condition means that the displacement of the material in the horizontal direction is subject to some form of restriction or constraint, but it is not completely fixed. This restriction can be an elastic constraint, a rigid constraint, or other forms of constraint. This ensures that the side walls of the model do not exert additional lateral pressure on the soil sample, while realizing the lateral restricted boundary conditions of the soil sample, simulating the permeability behavior of the soil in the effective working area under vacuum preloading.

[0076] The load loading method adopts an axisymmetric loading method, such as applying pressure downward or outward through the central axis to simulate vacuum preloading or heap load preloading conditions.

[0077] As a preferred embodiment, the steel frame mechanism 1 is composed of a plurality of steel frames 101 connected in sequence in the vertical direction.

[0078] Specifically, the rigid-flexible lining is connected to the surrounding steel frame through a wheel groove system to achieve horizontal support. The rigid rings are arranged at 1m intervals and are vertical rollers that point to the outside. They are embedded in the vertical wheel grooves set on the steel frame to achieve horizontal support and avoid torsional constraints while providing boundary conditions for vertical free deformation. The rigid frame and the rigid-flexible composite lining are manufactured in sections to achieve detachable combination use. Bolts are used to connect the rigid frame sections. Water-stop flanges are used to connect the rigid-flexible composite lining sections.

[0079] A vertical steel frame is used as the horizontal support system of the model, and the steel frame 101 is set on the base 10. The rigid-flexible composite liner 2 is provided with fixed vertical rollers at intervals of 1m, and the roller body is embedded in the vertical roller guide groove 102 fixed to the steel frame 101. There are 4 vertical roller guide grooves in total, which are symmetrically fixed to the steel frame 101 by bolt connection.

[0080] As a preferred embodiment, the soil consolidation analysis system 9 includes: a data receiving unit 901, a pore space evolution analysis unit 902, a water vapor transport model building unit 903 and a soil consolidation evaluation unit 904;

[0081] The data receiving unit 901 is used to obtain the movement data of the air flow and water flow in the air pressure test system 6 and the water pressure test system 7 and the monitoring data of the soil pressure and soil sample deformation in the soil pressure and soil sample deformation monitoring system 8 respectively;

[0082] Specifically, the movement data of airflow is obtained to describe the flow characteristics of gas in the soil pores. The movement data of airflow includes: airflow pressure, airflow velocity, air pressure gradient, etc.

[0083] Air flow pressure: the pressure distribution of gas in the soil, recording the air pressure values ​​at different locations;

[0084] Air flow rate: The velocity distribution of gas flow, reflecting the speed of air flow through the soil pores;

[0085] Pressure gradient: The driving force for gas flow, usually calculated by measuring differences in air pressure.

[0086] Obtain water flow movement data to describe the seepage characteristics of water flow in porous soil media. Water flow movement data include: water flow pressure, seepage flow, hydraulic gradient, etc.

[0087] Water flow pressure: record the water pressure values ​​at different positions of the soil, reflecting the water head distribution during the seepage process;

[0088] Infiltration flow: The flow rate of water through the soil, which is an important parameter of infiltration characteristics;

[0089] Hydraulic Gradient: Calculates the hydraulic gradient within a soil mass based on the hydraulic head difference and the infiltration path length.

[0090] By monitoring the pore pressure and deformation characteristics of soil under the action of water and air flow, the pore pressure, soil deformation and stress state can be obtained.

[0091] Pore ​​pressure: water pressure in soil pores, reflecting the change of pore pressure during seepage;

[0092] Soil deformation: the settlement, deformation rate and cumulative deformation of soil samples reflect the consolidation behavior of soil;

[0093] Soil stress state: distribution and changes of total stress and effective stress.

[0094] The pore space evolution analysis unit 902 is used to analyze the pore space evolution of the soil under the interaction of air flow and water flow based on the monitoring data of soil pressure and soil sample deformation and multi-fractal theory;

[0095] As a preferred implementation, based on the monitoring data of soil pressure and soil sample deformation, the pore space evolution of soil under the interaction of air flow and water flow is analyzed based on multi-fractal theory, including:

[0096] Preprocessing the monitoring data of soil pressure and soil sample deformation, and sorting the preprocessed monitoring data according to timestamps to obtain time series data of soil pressure and soil sample deformation;

[0097] Specifically, the purpose of data preprocessing is to ensure the accuracy and consistency of monitoring data and provide reliable input for subsequent time series analysis. Data preprocessing includes: data cleaning, data completion and normalization;

[0098] Sort the preprocessed data by timestamp to ensure the continuity and consistency of the time series. First, check the timestamps of all monitoring data and sort the data in ascending order according to the timestamp to ensure that the data is arranged in chronological order. If there is a time alignment problem with multiple device data:

[0099] Use interpolation methods to align data with different sampling frequencies;

[0100] Use linear interpolation or nearest neighbor interpolation to fill the data gaps between timestamps;

[0101] The time series data of soil pressure and soil sample deformation are divided into several windows using the swing window algorithm, and the local weight of each window is calculated.

[0102] As a preferred implementation, the time series data of soil pressure and soil sample deformation are divided into several windows using the swing window algorithm, and the local weight of each window is calculated, including:

[0103] According to the time series data of soil pressure and soil sample deformation, the initial moment and the soil pressure value and soil sample deformation value corresponding to the initial moment are determined respectively, and the soil pressure value and soil sample deformation value corresponding to the initial moment are taken as the starting point;

[0104] Specifically, according to the time series data of soil pressure and soil sample deformation, the initial time and the soil pressure value and soil sample deformation value corresponding to the initial time are determined, and these initial values ​​are used as the starting point.

[0105] Assume the time series data is as follows:

[0106] Earth pressure time series: P = {p1, p2, …, pn};

[0107] Soil sample deformation time series: D = {d1, d2, …, dn};

[0108] At the initial time t=1, the corresponding soil pressure value is p1 and the soil sample deformation value is d1.

[0109] Using the swing window algorithm and according to the preset window width W, the boundary values ​​of the upper swing window and the lower swing window of the earth pressure and soil sample deformation are calculated respectively;

[0110] It should be noted that the boundary value of the upper swing window is the maximum value of the earth pressure and deformation in the current window.

[0111] For the earth pressure series P:

[0112] The window range at time point t is [t, t+W-1];

[0113] Calculate the boundary value of the upper swing window UpperP(t)=max(pt,pt+1,…,pt+W-1).

[0114] For soil sample deformation sequence D:

[0115] The window range at time point t is [t, t+W-1];

[0116] Calculate the boundary value of the upper swing window UpperD(t)=max(dt,dt+1,…,dt+W-1).

[0117] The boundary value of the lower swing window is the minimum value of earth pressure and deformation in the current window.

[0118] For the earth pressure series P:

[0119] The window range at time point t is [t, t+W-1];

[0120] Calculate the boundary value of the lower swing window LowerP(t)=min(pt,pt+1,…,pt+W-1).

[0121] For soil sample deformation sequence D:

[0122] The window range at time point t is [t, t+W-1];

[0123] Calculate the boundary value of the lower swing window LowerD(t)=min(dt,dt+1,…,dt+W-1).

[0124] Traversing the time series data of soil pressure and soil sample deformation, and dividing the time series data of soil pressure and soil sample deformation into a plurality of windows according to the boundary values ​​of the upper swing window and the lower swing window of the soil pressure and soil sample deformation;

[0125] Specifically, starting from the first data point of the time series, each data point is checked in turn to see if it meets the swing window condition of the current window. If the condition is met, the data point belongs to the current window; if the condition is not met, the current window is closed and a new window is opened from this data point.

[0126] The specific division process:

[0127] Step 1: Initial window definition;

[0128] Set the starting point of the first window (such as the first point of the time series t=1);

[0129] Calculate the upper and lower swing window boundary values ​​of the current window.

[0130] Step 2: Check the data points;

[0131] For each data point:

[0132] If the soil pressure value pi and the soil sample deformation value di are both within the upper and lower swing window boundaries of the current window, the data point is included in the current window;

[0133] If pi or di exceeds the boundary value, the current window ends and a new window starts from that data point.

[0134] Step 3: Repeat the above steps;

[0135] Repeat the above process for all data points in the time series until all data points are assigned to the corresponding windows.

[0136] The cumulative changes of soil pressure and deformation are calculated in each window of soil pressure and soil sample deformation, and the local weight of each window is obtained by normalizing the cumulative changes.

[0137] Specifically, in each time window, the cumulative changes of soil pressure and soil sample deformation can be obtained by calculating the data change amplitude in the window. Subsequently, the local weight of each window can be calculated by normalization processing.

[0138] For each window, the cumulative changes of earth pressure and soil sample deformation are calculated respectively.

[0139] The cumulative change reflects the total change in soil pressure in the current window. It is calculated as the difference between the maximum and minimum soil pressure in the window:

[0140] The cumulative change of soil sample deformation is calculated by the difference between the maximum and minimum values ​​of soil sample deformation in the window:

[0141] In order to compare the changes between different windows, the cumulative changes in each window can be normalized. A common normalization method is to scale the changes in each window by the maximum change in the window. For the cumulative changes in soil pressure and soil deformation in each window, the local weights are obtained after normalization.

[0142] According to the local weight of each window, the singularity index of each window is calculated, and the multifractal spectrum curve is established according to the calculation results. The pore space evolution characteristics are extracted according to the multifractal spectrum curve, and the evolution law of the pore space is analyzed according to the pore space evolution characteristics.

[0143] As a preferred implementation, the singularity index of each window is calculated according to the local weight of each window, a multifractal spectrum curve is established according to the calculation result, and the pore space evolution characteristics are extracted according to the multifractal spectrum curve. The evolution law of the pore space is analyzed according to the pore space evolution characteristics, including:

[0144] According to the local weight of each window and the preset window width, the singularity index of each window is calculated by logarithmic transformation;

[0145] Count the singularity index of all windows, determine the frequency of window subsets with the same singularity index, and calculate the fractal dimension based on the frequency;

[0146] The fractal dimension is used to draw the multifractal spectrum curve, and the characteristics of pore space evolution are extracted by analyzing the spectrum width and curve shape of the multifractal spectrum curve.

[0147] According to the characteristics of pore space evolution, the multi-fractal spectrum curves under different times or conditions are compared to analyze the dynamic change law and trend of pore space.

[0148] It should be noted that the singularity index reflects the intensity of local changes in each window. Let the local weight of the kth window be W(k), and the singularity index of the window be α k Defined as:

[0149] α k =-lnW(k) / lnδt

[0150] Where δt is the time span of the window.

[0151] In order to analyze the evolution characteristics of the pore space, the fractal dimension is introduced. The fractal dimension f(α k ):

[0152] f(α k )=-αk lnW(k)

[0153] Among them, f(α k ) represents the singularity index α k The corresponding fractal dimension.

[0154] The multifractal spectrum curve is the relationship curve between f(α) and α, which reflects the distribution characteristics of different singularity intensities. The following characteristic parameters are extracted from the multifractal spectrum curve:

[0155] Spectral width (Δα): Δα=αmax-αmin;

[0156] Δα represents the range of local variation intensity within the pore space; the larger the value, the more complex the variation in the pore space.

[0157] Peak position (α peak ): α peak = argmaxf(α);

[0158] The peak position indicates the strength of the dominant singularity of the multifractal spectrum; it reflects the main characteristics of the pore space evolution.

[0159] Spectral symmetry:

[0160] Compare f(α) at ​​α peak Whether the distribution on the left and right is symmetrical. If the spectrum is asymmetrical, it means that the evolutionary process is biased.

[0161] In addition, the evolution law of the pore space can be analyzed based on the multifractal spectrum curve and the extracted characteristic parameters:

[0162] Pore ​​heterogeneity: The complexity of the pore structure is determined by the spectrum width Δα. Pore spaces with large heterogeneity may have a significant impact on fluid flow or material migration.

[0163] Pore ​​evolution trend: peak position α peak The symmetry of the spectrum can reveal whether the pore structure tends to be uniform (symmetrical) or differentiated (asymmetrical).

[0164] Evolutionary dynamics: If the spectrum width decreases gradually over time, it means that the pore space tends to be stable. If the spectrum width increases over time, it means that the pore space is increasingly affected by the outside world and the evolution process becomes more complicated.

[0165] The water vapor transport model building unit 903 is used to simulate the water vapor transport process in the pore space of the soil based on the movement data of air flow and water flow, and analyze the influence of water vapor transport on soil consolidation.

[0166] As a preferred implementation, based on the movement data of air and water flow, the water vapor transport process in the pore space of the soil is simulated, and the influence of water vapor transport on soil consolidation is analyzed, including:

[0167] Collect physical experimental data of soil and the three-dimensional structure of soil pores, and establish a soil pore structure model;

[0168] Specifically, the following key physical parameters are collected, which are usually obtained through laboratory testing:

[0169] Basic properties of soil: particle size distribution; porosity; permeability coefficient; specific gravity; water content.

[0170] Mechanical parameters: compression modulus; shear strength parameters.

[0171] Water vapor characteristics: saturation; capillary pressure; water vapor permeability.

[0172] Among them, the three-dimensional structure of soil pores can be obtained by using laser technology to obtain two-dimensional slice images of the pores; and the three-dimensional structure can be reconstructed through image processing algorithms.

[0173] Based on Darcy's law, combined with the soil pore structure model and experimental data, the seepage characteristics of water flow in porous media are simulated, and the gas flow equation is introduced to describe the gas flow behavior, integrating to form a coupled model of water-gas two-phase flow;

[0174] As a preferred embodiment, the expression of Darcy's law is:

[0175] Q=K×A×(h2-h1) / L

[0176] V=K×I

[0177] In the formula, Q represents the seepage rate per unit time; A represents the water flow cross-sectional area; K represents the permeability coefficient; h2-h1 represents the upstream and downstream head difference; L represents the length of the seepage path; I represents the hydraulic gradient; and V represents the seepage velocity.

[0178] Specifically, for gas flow, it is usually assumed that the gas follows a flow behavior similar to Darcy's law in the pore space. The flow rate of the gas flow is related to the pressure gradient and the gas permeability of the medium. The basic equation for gas flow can be expressed as:

[0179]

[0180] In the formula, v g represents the gas flow rate, k rg Represents the relative permeability of gas, which indicates the flow capacity of gas in pores, μ g is the dynamic viscosity of the gas, Represents the gas pressure gradient.

[0181] The coupled model of water-gas two-phase flow mainly describes the co-flow behavior of water and gas in the pore space. The flow of water and gas phases is affected by saturation, pore structure and interaction. The following is the basic equation of water-gas two-phase flow: S w +S g =1;P c =P g -P w ;

[0182] Among them, S w is the saturation of the water phase, S g is the saturation of the gas phase, P c is the capillary pressure, which represents the pressure difference between water and gas, P w is the pressure of the water phase, P g is the pressure of the gas phase.

[0183] Combining these relationships for water-gas two-phase flow, a complete coupled model can be formed to describe the co-flow behavior of water and gas in porous media:

[0184] Interaction of water and gas flow: Changes in the saturation of the water and gas phases affect the permeability coefficient and flow path; the flow of gas may increase the drainage pressure in the pores, thereby driving water flow.

[0185] Constraints of flow dynamics: Water flow is mainly controlled by head difference and permeability coefficient; body flow is affected by pressure gradient, gas relative permeability and dynamic viscosity.

[0186] Dynamic equilibrium: When the system reaches dynamic equilibrium, the distribution, pressure field, and saturation of the water phase and gas phase interact with each other, presenting a stable flow state.

[0187] The numerical simulation software is used to solve the water-gas two-phase flow coupling model, calculate the water-gas distribution, pressure field and saturation changes in the pore space, and obtain the water-gas transport results;

[0188] Specifically, in numerical simulation software, the continuous water-gas two-phase flow coupling model equations need to be discretized, which usually involves finite difference, finite element or finite volume methods.

[0189] According to the specific research scenario, reasonable boundary conditions and initial conditions are set for the model. These conditions will serve as the starting point of the simulation and guide the development of the entire simulation process.

[0190] The iterative solution of numerical simulation includes:

[0191] Solver configuration: Configure the appropriate solver in the software to iteratively solve the discretized system of equations. The choice of solver will be based on the complexity of the problem, the availability of computing resources, and the accuracy requirements of the solution.

[0192] Iterative calculation: Start the solver and start the iterative calculation process. During this process, the software will continuously adjust the water vapor distribution, pressure field and saturation in the pore space to gradually approach the real physical state.

[0193] Convergence check: During the iteration process, the convergence of the solution needs to be checked regularly. When the change in the solution is less than the preset threshold, it can be considered that the iteration has converged and the simulation result is reliable.

[0194] Data export: Export calculated water vapor distribution, pressure field, saturation and other data from numerical simulation software.

[0195] Result visualization: The visualization tools provided by the software can be used to intuitively display the water vapor transport in the pore space.

[0196] Combining the water vapor transport results with soil consolidation theory, the influence of water vapor transport on soil consolidation is analyzed.

[0197] As a preferred implementation method, combining the water-gas transport results with the soil consolidation theory, the analysis of the influence of water-gas transport on soil consolidation includes:

[0198] According to the water-gas transport results, the permeability parameters in the water-gas transport results are extracted and used as the initial conditions for consolidation analysis. The permeability parameters include pore pressure distribution, water-gas saturation and permeability coefficient, and are used as the initial conditions for consolidation analysis.

[0199] According to the permeability parameters in the water vapor transport results and combined with the consolidation theory, a coupling model of water vapor transport and consolidation process is constructed;

[0200] Specifically, based on the water vapor transport parameters that have been obtained, it is necessary to combine these parameters with the soil consolidation theory. This usually involves substituting the permeability parameters into the consolidation equation to construct a coupled model that can simultaneously reflect the water vapor transport and soil consolidation processes. The construction of the coupled model requires comprehensive consideration of factors such as the migration law of water vapor in the soil, the stress-strain relationship of the soil, and the change of pore pressure. Through reasonable assumptions and simplifications, a coupled model that is both in line with physical reality and easy to solve numerically can be obtained.

[0201] The coupled model is used to simulate the soil consolidation process, calculate the settlement, consolidation rate and pore pressure dissipation, and analyze the dynamic influence of water-gas transport on the consolidation process. Based on the analysis results, the change and stability of soil consolidation rate under different water-gas transport conditions are evaluated.

[0202] It should be noted that the permeability parameters (such as pore pressure distribution, water vapor saturation and permeability coefficient) extracted from the water vapor transport results are input into the coupling model as initial conditions, and the coupling model is solved using appropriate numerical methods (such as finite element method, finite difference method, etc.). This usually involves iterative calculations until the convergence conditions are met. After the simulation is completed, the settlement, consolidation rate and pore pressure distribution of the soil at different time steps are output;

[0203] According to the simulation results, the change of settlement over time at the soil surface or at a specific depth is calculated, and the consolidation rate of the soil is obtained by calculating the change rate of settlement over time. It helps to understand the speed of soil consolidation and analyze the change of pore pressure during the consolidation process, including the reduction rate of pore pressure and the final stable value.

[0204] Analyze the dynamic effects of water vapor transport on the consolidation process, including:

[0205] Water vapor migration and pore pressure: Study how the migration of water vapor in soil affects the distribution and change of pore pressure. The flow of water vapor may cause a local increase or decrease in pore pressure, thus affecting the consolidation behavior of the soil.

[0206] Saturation and consolidation rate: Analyze the effect of water vapor saturation on consolidation rate. Changes in saturation may change the permeability and mechanical properties of the soil, thereby affecting the consolidation rate.

[0207] Dynamic process analysis: By comparing the simulation results at different time steps, it is revealed how water vapor transport dynamically affects the consolidation process of the soil.

[0208] Evaluate the change in soil consolidation rate and stability under different water-gas transport conditions, including:

[0209] Condition setting and simulation: Set different water vapor transport conditions (such as different saturation, permeability coefficient or water vapor flow rate) and simulate them separately.

[0210] Comparison of consolidation rates: Compare the consolidation rates of soil under different conditions and analyze the specific impact of water vapor transport conditions on the consolidation rate.

[0211] Stability assessment: Based on the simulation results, the stability of the soil under different water and gas transport conditions is evaluated. Special attention is paid to conditions that may cause soil instability or abnormal changes in consolidation rate.

[0212] Sensitivity analysis: Conduct sensitivity analysis to determine which water vapor transport parameters have the greatest impact on soil consolidation and stability, providing key parameters for engineering design and construction.

[0213] In summary, with the help of the above technical scheme of the present invention, the centripetal infiltration model device proposed by the present invention adopts a 1:1 model size, and cleverly eliminates the side wall friction through the rigid-flexible combined lining 2, which can be used to study the evolution mechanism of vacuum preloading and test new materials and technologies for vacuum preloading. Through the centripetal infiltration model device, it is also possible to simulate and study the vacuum attenuation mechanism during vacuum preloading and test new technologies to improve the clogging of drainage plates. The present invention can comprehensively consider multiple factors such as air pressure, water pressure, earth pressure and soil sample deformation, conduct a comprehensive analysis of soil consolidation, improve the accuracy and comprehensiveness of the analysis, reduce manual intervention through automated data reception and processing procedures, and improve analysis efficiency. The multi-fractal theory is used to analyze the evolution of pore space, which can more accurately reveal the changes in the pore structure of soil under the interaction of air flow and water flow. By analyzing the dynamic influence of water and gas transport on the consolidation process, the mechanism and law of soil consolidation can be more deeply understood.

[0214] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program code.

[0215] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A centripetal infiltration model device, characterized in that: It comprises a steel frame structure (1), wherein a rigid-flexible composite lining (2) is arranged inside the steel frame structure (1), a load loading system (3) is arranged at the top end of the steel frame structure (1), and a sand collecting pool (4) is arranged at the bottom end of the steel frame structure (1); The interior of the rigid-flexible composite lining (2) is provided with a vacuum control system (5), an air pressure test system (6) and a water pressure test system (7) in order from top to bottom, and the outer side of the steel frame structure (1) is provided with a soil pressure and soil sample deformation monitoring system (8); The load application system (3), the air pressure testing system (6), the water pressure testing system (7) and the soil pressure and soil sample deformation monitoring system (8) are all connected to the soil consolidation analysis system (9) by means of electrical connection.

2. A centripetal infiltration model device according to claim 1, characterized in that: The rigid-flexible combined lining (2) comprises a plurality of rigid rings (201) and a plurality of flexible ring belts (202), and the rigid rings (201) and the flexible ring belts (202) are arranged in a staggered manner in sequence, the flexible ring belts (202) are made of nylon fabric material, and the rigid rings (201) are made of stainless steel; Two adjacent groups of rigid-flexible combined linings (2) are connected by a water-stop flange.

3. A centripetal infiltration model device according to claim 1, characterized in that: The steel frame mechanism (1) is composed of a plurality of steel frames connected in sequence in the vertical direction, and the steel frames are fixedly connected by bolts.

4. A centripetal infiltration model device according to claim 1, characterized in that: The soil consolidation analysis system (9) comprises: a data receiving unit (901), a pore space evolution analysis unit (902), a water vapor transport model construction unit (903) and a soil consolidation evaluation unit (904); The data receiving unit (901) is used to respectively obtain the movement data of air flow and water flow in the air pressure testing system (6) and the water pressure testing system (7) and the monitoring data of soil pressure and soil sample deformation in the soil pressure and soil sample deformation monitoring system (8); The pore space evolution analysis unit (902) is used to analyze the pore space evolution of the soil under the interaction of air flow and water flow based on the monitoring data of soil pressure and soil sample deformation and multi-fractal theory; The water vapor transport model building unit (903) is used to simulate the water vapor transport process in the pore space of the soil based on the movement data of air flow and water flow, and analyze the influence of water vapor transport on soil consolidation.

5. A centripetal infiltration model device according to claim 4, characterized in that: The above-mentioned analysis of the evolution of the pore space of the soil under the interaction of air flow and water flow based on the monitoring data of soil pressure and soil sample deformation and multi-fractal theory includes: Preprocessing the monitoring data of soil pressure and soil sample deformation, and sorting the preprocessed monitoring data according to timestamps to obtain time series data of soil pressure and soil sample deformation; The time series data of earth pressure and soil sample deformation are divided into several windows using the swing window algorithm, and the local weight of each window is calculated. According to the local weight of each window, the singularity index of each window is calculated, and the multifractal spectrum curve is established according to the calculation results. The pore space evolution characteristics are extracted according to the multifractal spectrum curve, and the evolution law of the pore space is analyzed according to the pore space evolution characteristics.

6. A centripetal infiltration model device according to claim 5, characterized in that: The method of using the swing window algorithm to divide the time series data of soil pressure and soil sample deformation into a number of windows and calculating the local weight of each window includes: According to the time series data of soil pressure and soil sample deformation, the initial moment and the soil pressure value and soil sample deformation value corresponding to the initial moment are determined respectively, and the soil pressure value and soil sample deformation value corresponding to the initial moment are taken as the starting point; Using the swing window algorithm and according to the preset window width, the boundary values ​​of the upper swing window and the lower swing window of the earth pressure and soil sample deformation are calculated respectively; Traversing the time series data of soil pressure and soil sample deformation, and dividing the time series data of soil pressure and soil sample deformation into a plurality of windows according to the boundary values ​​of the upper swing window and the lower swing window of the soil pressure and soil sample deformation; The cumulative changes of soil pressure and deformation are calculated in each window of soil pressure and soil sample deformation, and the local weight of each window is obtained by normalizing the cumulative changes.

7. A centripetal infiltration model device according to claim 5, characterized in that: The singularity index of each window is calculated according to the local weight of each window, a multifractal spectrum curve is established according to the calculation result, and the pore space evolution characteristics are extracted according to the multifractal spectrum curve. The evolution law of the pore space is analyzed according to the pore space evolution characteristics, including: According to the local weight of each window and the preset window width, the singularity index of each window is calculated by logarithmic transformation; Count the singularity index of all windows, determine the frequency of window subsets with the same singularity index, and calculate the fractal dimension based on the frequency; The fractal dimension is used to draw the multifractal spectrum curve, and the characteristics of pore space evolution are extracted by analyzing the spectrum width and curve shape of the multifractal spectrum curve. According to the characteristics of pore space evolution, the multi-fractal spectrum curves under different times or conditions are compared to analyze the dynamic change law and trend of pore space.

8. A centripetal infiltration model device according to claim 4, characterized in that: The motion data of air and water flow are used to simulate the water vapor transport process in the pore space of the soil, and the influence of water vapor transport on soil consolidation is analyzed, including: Collect physical experimental data of soil and the three-dimensional structure of soil pores, and establish a soil pore structure model; Based on Darcy's law, combined with the soil pore structure model and experimental data, the seepage characteristics of water flow in porous media are simulated, and the gas flow equation is introduced to describe the gas flow behavior, integrating to form a coupled model of water-gas two-phase flow; The numerical simulation software is used to solve the water-gas two-phase flow coupling model, calculate the water-gas distribution, pressure field and saturation changes in the pore space, and obtain the water-gas transport results; Combining the water vapor transport results with soil consolidation theory, the influence of water vapor transport on soil consolidation is analyzed.

9. A centripetal infiltration model device according to claim 8, characterized in that: The expression of Darcy's law is: Q=K×A×(h2-h1) / L V=K×I In the formula, Q represents the seepage rate per unit time; A represents the cross-sectional area of ​​water flow; K represents the permeability coefficient; h2-h1 represents the upstream and downstream head difference; L represents the length of the seepage path; I represents the hydraulic slope; V represents the seepage velocity.

10. A centripetal infiltration model device according to claim 9, characterized in that: The above analysis of the influence of water-gas transport on soil consolidation by combining the water-gas transport results with soil consolidation theory includes: According to the water-gas transport results, permeability parameters are extracted from the water-gas transport results and used as initial conditions for consolidation analysis. The permeability parameters include pore pressure distribution, water-gas saturation and permeability coefficient and used as initial conditions for consolidation analysis. According to the permeability parameters in the water vapor transport results and combined with the consolidation theory, a coupling model of water vapor transport and consolidation process is constructed; The coupled model is used to simulate the soil consolidation process, calculate the settlement, consolidation rate and pore pressure dissipation, and analyze the dynamic influence of water-gas transport on the consolidation process. Based on the analysis results, the change and stability of soil consolidation rate under different water-gas transport conditions are evaluated.

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