A centripetal permeation model device

Abstract

The application provides a centripetal infiltration model device and relates to the technical field of vacuum preloading model tests, and comprises a steel frame mechanism, the inside of the steel frame mechanism is 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; the inside of the rigid-flexible combined lining is sequentially provided with a vacuum control system, an air pressure test system and a water pressure test system from top to bottom, and the outside of the steel frame mechanism is provided with a soil pressure and soil sample deformation monitoring system. The rigid-flexible combined lining can be used for eliminating the side wall friction force, can be used for researching the vacuum preloading evolution mechanism and testing new vacuum preloading materials and technologies, and through the centripetal infiltration model device, the vacuum degree attenuation mechanism in the vacuum preloading process can be simulated and researched, and new technologies for improving the clogging condition of the drainage plate can be tested.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vacuum preloading model test, in particular, to a centripetal infiltration model device. BACKGROUND

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

[0003] The problem of limited vacuum preloading reinforcement depth seriously restricts the application of vacuum preloading technology. There are problems such as large settlement and insufficient deep bearing capacity in the completed vacuum preloading treatment sites. Indoor small-size models have some limitations in revealing drainage consolidation rules, drainage board clogging mechanisms, and deep bearing capacity development mechanisms, mainly including the following aspects:

[0004] 1. Size effect: Indoor small-size models usually cannot truly simulate the mechanical property changes of actual soil layers and cannot completely eliminate the influence of size effect on model test results. When it comes to problems such as excessive settlement or insufficient deep bearing capacity, size effect may cause large differences between model test results and actual conditions.

[0005] 2. Geological condition differences: Indoor small-size models usually cannot completely replicate real geological conditions, such as stratum heterogeneity, nonlinearity, and groundwater effects. These geological conditions may not be fully reflected in indoor small-size models.

[0006] 3. Boundary condition limitations: Indoor small-size models are usually limited by laboratory conditions, such as limited model size and boundary condition settings, which may cause model test results to be affected by boundary conditions, resulting in additional shear stress and shear strain, and unable to fully reflect the complex conditions in actual engineering.

[0007] 4. Unable to accurately consider time effect: In actual engineering, excessive settlement and insufficient deep bearing capacity usually develop gradually over time, while indoor small-size models usually cannot simulate the changes and evolution process of actual engineering in the time scale.

[0008] In view of the problems in the related art, no effective solutions have been proposed so far. SUMMARY

[0009] Therefore, the present application provides a centripetal infiltration model device to solve the above-mentioned problems.

[0010] In order to solve the above problems, the specific technical scheme adopted by the present application is as follows:

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

[0012] Further, in order to realize the reduction of the friction of the side wall, the rigid-flexible combined lining is composed of a plurality of rigid rings and a plurality of flexible rings, and the rigid rings and the flexible rings are arranged in an alternating staggered manner, the flexible ring is made of nylon fabric material, and the rigid ring is made of stainless steel; the adjacent two groups of rigid-flexible combined linings are connected by water stop flanges.

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

[0014] Further, the soil consolidation analysis system comprises a data receiving unit, a pore space evolution analysis unit, a water and gas transport model construction unit and a soil consolidation evaluation unit.

[0015] The data receiving unit is used to acquire the motion data of the airflow and the water flow in the air pressure test system and the water pressure test system and the monitoring data of the soil pressure and the 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 the soil under the interaction of the airflow and the water flow based on the multiple fractal theory according to the monitoring data of the soil pressure and the soil sample deformation.

[0017] The water and gas transport model construction unit is used to simulate the water and gas transport process in the pore space of the soil based on the motion data of the airflow and the water flow, and analyze the influence of the water and gas transport on the soil consolidation.

[0018] Further, the analysis of the pore space evolution of the soil under the interaction of the airflow and the water flow based on the multiple fractal theory according to the monitoring data of the soil pressure and the soil sample deformation comprises:

[0019] The monitoring data of the soil pressure and the soil sample deformation are preprocessed, and the preprocessed monitoring data are sorted according to the time stamp to obtain the time series data of the soil pressure and the soil sample deformation;

[0020] The time series data of the soil pressure and the soil sample deformation are divided into a plurality of windows by 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, the multifractal spectrum curve is established according to the calculation result, and 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] Further, the time series data of the soil pressure and the soil sample deformation are divided into a plurality of windows by using the swing window algorithm, and the local weight of each window is calculated, which includes:

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

[0024] The upper swing window and the lower swing window of the soil pressure and the soil sample deformation are calculated by using the swing window algorithm and according to the pre-set window width;

[0025] The time series data of the soil pressure and the soil sample deformation are traversed, and the time series data of the soil pressure and the soil sample deformation are divided 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 the soil sample deformation;

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

[0027] Further, according to the local weight of each window, the singularity index of each window is calculated, the multifractal spectrum curve is established according to the calculation result, and 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, which includes:

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

[0029] The singularity indexes of all windows are counted, and the frequency of the same singularity index window subset is determined, and the fractal dimension is calculated according to the frequency;

[0030] The multifractal spectrum curve is drawn by using the fractal dimension, and the characteristics of the pore space evolution are extracted by analyzing the spectrum width and the curve shape of the multifractal spectrum curve;

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

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

[0033] The physical experimental data of the soil and the three-dimensional structure of the soil pores are collected, and a soil pore structure model is established;

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

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

[0036] The influence of water-air transport on soil consolidation is analyzed by combining the water-air transport results with the soil consolidation theory. Further, the expression of Darcy's law is:

[0037] Q = K x A x (h2-h1) / L

[0038] V = K x I

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

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

[0041] K represents the permeability coefficient;

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

[0043] L represents the seepage path length;

[0044] I represents the hydraulic slope;

[0045] V represents the seepage velocity.

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

[0047] According to the water-air transport results, the seepage parameters in the water-air transport results are extracted and used as the initial conditions for the consolidation analysis, including the pore pressure distribution, water-air saturation and permeability coefficient, and used as the initial conditions for the consolidation analysis;

[0048] According to the seepage parameters in the water-air transport results, a coupled model of water-air transport and consolidation process is constructed by combining the consolidation theory;

[0049] The coupling model is used for simulating the consolidation process of the soil body, calculating the settlement, consolidation rate and pore pressure dissipation, and analyzing the dynamic influence of water and gas transportation on the consolidation process, and the variation and stability of the consolidation rate of the soil body under different water and gas transportation conditions are evaluated according to the analysis result.

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

[0051] 1、The centripetal infiltration model device adopts a 1:1 model size, and the side wall friction force is ingeniously eliminated through the rigid-flexible combined lining, so that the evolution mechanism of vacuum preloading can be researched, and new materials and new technologies of vacuum preloading can be tested.

[0052] 2、The present application can comprehensively consider air pressure, water pressure, soil pressure and soil sample deformation and other factors, and can analyze the soil consolidation in all directions, improve the accuracy and comprehensiveness of the analysis, reduce manual intervention through the automatic data receiving and processing process, improve the analysis efficiency, use the multi-fractal theory to analyze the pore space evolution, and more accurately reveal the pore structure change of the soil body under the interaction of air flow and water flow, and through the analysis of the dynamic influence of water and gas transportation on the consolidation process, the mechanism and law of soil consolidation can be more deeply understood. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. In the drawings:

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

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

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

[0057] Figure 4 is a principle block diagram of 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 body consolidation analysis system in a centripetal infiltration model device according to an embodiment of the present application.

[0058] Fig. 1 is a schematic diagram of a centripetal infiltration model device according to an embodiment of the present application.

[0059] 1. Steel frame mechanism; 101, steel frame; 102, vertical roller guide groove; 2, rigid-flexible combined liner; 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 for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

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

[0062] The present application will be further described in combination with the accompanying drawings and specific embodiments. Figures 1-4 As shown in the drawings, the centripetal infiltration model device according to the embodiment of the present application comprises a steel frame mechanism 1, the inside of the steel frame mechanism 1 is provided with a rigid-flexible combined liner 2, the top end of the steel frame mechanism 1 is provided with a load loading system 3, and the bottom end of the steel frame mechanism 1 is provided with a sand collecting pool 4; the inside of the rigid-flexible combined liner 2 is sequentially provided from top to bottom with a vacuum control system 5, an air pressure test system 6 and a water pressure test system 7, and the outside of the steel frame mechanism 1 is provided with a soil pressure and soil sample deformation monitoring system 8; 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 with a soil consolidation analysis system 9 in an electrically connected manner.

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

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

[0065] 2. Research on the vacuum degree attenuation law in vacuum preloading: researches the change of the permeability of the drainage plate caused by the starting and entering of the fine-grained soil into the drainage plate, thereby affecting the transmission of the vacuum degree.

[0066] 3. Evaluation of permeability: by simulating the permeation process under the condition of vacuum preloading, the permeability and other mechanical properties of new materials in the vacuum preloading environment can be evaluated.

[0067] 4. Process optimization: With the centripetal infiltration model device, the vacuum preloading process can be optimized, including preloading parameters, material selection, and process flow, to improve the efficiency and reliability of the new vacuum preloading technology.

[0068] In summary, the centripetal infiltration model device can provide a reliable experimental platform for the research and application of new materials and new technologies in vacuum preloading, helping engineers and researchers better understand and optimize the vacuum preloading process, and promoting the application and development of new materials and new 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 rings 202, and the rigid rings 201 and the flexible rings 202 are arranged in an alternating staggered manner. The flexible ring 202 is made of nylon fabric material, and the rigid ring 201 is made of stainless steel material. The adjacent two groups of rigid-flexible combined lining 2 are connected by a water stop flange.

[0070] Specifically, the present application successfully solves the problem of large-size model sidewall friction force of traditional rigid boundary by using rigid-flexible combined lining 2. The rigid-flexible combined lining 2 uses rigid rings 201 for lateral constraint and flexible rings 202 for vertical free deformation. The rigid rings 201 and the flexible rings 202 are arranged at intervals, which can convert the lateral friction force caused by the vertical settlement of large-size vacuum preloading model up to 1m into a lateral limited vertical free deformation experimental device, achieving more than 90% reduction of the influence of sidewall friction on soil stress conditions.

[0071] In addition, it should be noted that the stainless steel material is used to make steel rings with a wall thickness of 1cm, a height of 5cm, and different diameters of 1m and 1.2m as rigid rings 201. Because steel has high tensile strength and tensile stiffness, the rigid ring 201 can provide sufficient lateral constraint when the soil sample has lateral earth pressure, achieving a lateral limited boundary condition. However, only rigid constraint cannot solve the problem of sidewall friction, because the rigid sidewall cannot achieve vertical free deformation. The rigid-flexible combined lining 2 can cleverly solve the problem of lateral limited constraint and vertical free deformation. The flexible ring 202 made of nylon fabric material is arranged at intervals with the rigid ring 201 to form the model sidewall. By using the folding deformation characteristics of the flexible ring 202, the vertical free deformation of the model soil sample is realized without generating vertical friction. At the same time, the flexible ring 202 also has good tensile strength and tensile stiffness, and is not easy to produce horizontal deformation. The flexible ring 202 and the rigid ring 201 are connected by a micro-hole reserved on the edge of the rigid ring 201, and are treated to be water-tight.

[0072] In addition, the rigid-flexible combined liner has two types of inner diameters of 1 m and 1.2 m. The centripetal infiltration model has a height of 10 m, of which 4 m is above ground, 2 m is a platform, and 6 m is underground. The working range of the pore water pressure is -100 kPa to 300 kPa, the working range of the pore gas pressure is -100 kPa to 0 kPa, and the working range of the earth pressure is 0 kPa to 300 kPa.

[0073] Thirdly, the rigid-flexible combined material is arranged as the side wall of the model with a vertical spacing 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 lateral limited boundary condition can be achieved while greatly reducing or even eliminating the friction between the side wall and the soil sample.

[0074] Proper stress or displacement conditions are set at the boundary of the model to ensure that the model does not exert additional lateral pressure on the soil sample when achieving the lateral limited boundary condition. Regarding the stress condition and the displacement condition, the following is described:

[0075] The stress condition refers to setting a zero lateral stress condition and a free lateral displacement limited condition on the side wall of the model, i.e., at the boundary. The zero lateral stress condition means that no lateral constraint or pressure is applied in the horizontal direction of a certain material (such as soil, structural members, etc.), so that the stress in that direction is zero. The free lateral displacement limited condition means that the displacement of the material in the horizontal direction is limited or constrained in some form, but not completely fixed. This limitation can be elastic constraint, rigid constraint or other forms of constraint. In this way, it can be ensured that the side wall of the model does not exert additional lateral pressure on the soil sample, while achieving the lateral limited boundary condition of the soil sample, simulating the infiltration behavior of the effective working zone soil under vacuum preloading.

[0076] The load loading mode adopts an axisymmetric loading mode, such as applying pressure downward or outward through the central axis direction, to simulate vacuum preloading or surcharge 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 liner is connected to the surrounding steel frame through a wheel groove system to achieve horizontal support. The rigid ring with a spacing of 1 m refers to a vertical roller arranged outwardly, which is embedded in a vertical wheel groove provided on the steel frame, to achieve horizontal support and avoid torsional constraint while providing a vertical free deformation boundary condition. The rigid frame and the rigid-flexible combined liner are correspondingly sectioned to achieve detachable and combined use. The rigid frame sections are connected by bolts. The rigid-flexible combined liner sections are connected by water stop flanges.

[0079] In the embodiment, the vertical steel frame is used as the model horizontal support system, and the steel frame 101 is arranged on the base 10. The rigid-flexible combined liner 2 is provided with fixed vertical rollers at intervals of 1 m, and the roller bodies are embedded in the vertical roller guide grooves 102 fixed to the steel frame 101. There are four vertical roller guide grooves, which are symmetrically fixed to the steel frame 101 by bolt connection.

[0080] As a preferred embodiment, the soil consolidation analysis system 9 comprises a data receiving unit 901, a pore space evolution analysis unit 902, a water-gas transport model construction unit 903, and a soil consolidation evaluation unit 904.

[0081] The data receiving unit 901 is used to acquire the motion data of the gas flow and the water flow in the air pressure test system 6 and the water pressure test system 7, respectively, and the monitoring data of the soil pressure and the soil sample deformation in the soil pressure and soil sample deformation monitoring system 8.

[0082] Specifically, the motion data of the gas flow describes the flow characteristics of the gas in the soil pores. The motion data of the gas flow includes the gas flow pressure, the gas flow rate, the air pressure gradient, etc.

[0083] The gas flow pressure is the pressure distribution of the gas in the soil, which records the air pressure values at different positions.

[0084] The gas flow rate is the velocity distribution of the gas flow, which reflects the speed of the gas flow through the soil pores.

[0085] The air pressure gradient is the driving force of the gas flow, which is usually calculated by measuring the air pressure difference.

[0086] The motion data of the water flow describes the seepage characteristics of the water flow in the soil porous medium. The motion data of the water flow includes the water flow pressure, the seepage flow rate, the hydraulic gradient, etc.

[0087] The water flow pressure records the water pressure values at different positions of the soil, reflecting the water head distribution in the seepage process.

[0088] The seepage flow rate is the flow rate of the water flow through the soil, which is an important parameter of the seepage characteristics.

[0089] The hydraulic gradient is calculated according to the water head difference and the seepage path length.

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

[0091] The pore pressure is the water pressure in the soil pores, reflecting the change of the pore pressure in the seepage process.

[0092] The soil deformation is the settlement amount, deformation rate, and cumulative deformation amount of the soil sample, reflecting the behavior of soil consolidation.

[0093] Stress state of soil: distribution and variation of total stress and effective stress.

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

[0095] As a preferred embodiment, the analysis of the pore space evolution of the soil under the interaction of air flow and water flow based on the multi-fractal theory according to the monitoring data of the earth pressure and the soil sample deformation includes:

[0096] The monitoring data of the earth pressure and the soil sample deformation are preprocessed, and the preprocessed monitoring data are sorted according to the time stamps to obtain time series data of the earth pressure and the soil sample deformation.

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

[0098] The preprocessed data are sorted according to the time stamps to ensure the continuity and consistency of the time series. First, check the time stamps of all monitoring data, sort the data in ascending order according to the time stamps, and ensure that the data are arranged in chronological order. If there are multiple device data time alignment problems:

[0099] Use interpolation method to align data of different sampling frequencies;

[0100] Use linear interpolation or nearest neighbor interpolation to fill the data gap between time stamps;

[0101] Use the swing window algorithm to divide the time series data of the earth pressure and the soil sample deformation into several windows, and calculate the local weight of each window.

[0102] As a preferred embodiment, the use of the swing window algorithm to divide the time series data of the earth pressure and the soil sample deformation into several windows, and calculate the local weight of each window includes:

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

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

[0105] Suppose the time series data are as follows:

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

[0107] The time series of soil sample deformation: 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 pre-set window width W, the boundary values of the upper swing window and the lower swing window of the soil pressure and the 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 soil pressure and the deformation in the current window.

[0111] For the soil pressure sequence P:

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

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

[0114] For the soil sample deformation sequence D:

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

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

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

[0118] For the soil pressure sequence P:

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

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

[0121] For the soil sample deformation sequence D:

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

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

[0124] The time series data of the earth pressure and the soil sample deformation are divided into a plurality of windows according to the boundary values of the upper and lower swing windows of the earth pressure and the 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 it meets the condition, the data point belongs to the current window; if it does not meet the condition, the current window is closed, and a new window is opened from this data point.

[0126] The specific division process of the division is as follows:

[0127] Step 1: initial window definition;

[0128] Set the start point of the first window (e.g. the first point t = 1 of the time series);

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

[0130] Step 2: check the data point;

[0131] For each data point:

[0132] If the earth pressure value pi and the soil sample deformation value di are both within the upper and lower swing window boundary range of the current window, the data point is assigned to the current window;

[0133] If pi or di exceeds the boundary value, the current window is ended, and a new window is started from the 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 window.

[0136] Calculate the cumulative change amount of the earth pressure and the deformation in each window of the earth pressure and the soil sample deformation, and obtain the local weight of each window by normalizing the cumulative change amount.

[0137] Specifically, in each time window, the cumulative change amount of the earth pressure and the 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 change amount of the earth pressure and the soil sample deformation is calculated respectively.

[0139] The cumulative change amount reflects the total change amplitude of the earth pressure in the current window. The calculation method is the difference between the maximum and minimum values of the earth pressure in the window:

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

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

[0142] According to the local weight of each window, the singularity index of each window is calculated, the multifractal spectrum curve is established according to the calculation result, and 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 embodiment, according to the local weight of each window, the singularity index of each window is calculated, the multifractal spectrum curve is established according to the calculation result, and 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, including:

[0144] According to the local weight of each window, and combined with the pre-set window width, the singularity index of each window is calculated by logarithmic transformation;

[0145] The singularity indexes of all windows are counted, and the frequency of the same singularity index window subset is determined, and the fractal dimension is calculated according to the frequency;

[0146] The multifractal spectrum curve is drawn by using the fractal dimension, and the characteristics of the pore space evolution are extracted by analyzing the spectrum width and the curve shape of the multifractal spectrum curve;

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

[0148] It should be noted that the singularity index reflects the intensity of the local change 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] In the formula, 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 ) is calculated by the singularity index and the weight of each window:

[0152] f(α k )=-αk lnW(k)

[0153] Where, 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, reflecting 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 represents the dominant singularity intensity of the multifractal spectrum; it reflects the main characteristics of the evolution of the pore space.

[0159] Spectral symmetry:

[0160] Compare f(α) in α peak Whether the distribution on the left and right is symmetrical; if the spectrum is asymmetrical, it indicates that the evolutionary process is biased.

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

[0162] Pore ​​heterogeneity: The complexity of pore structure is judged by the spectral width Δα. Pore spaces with high heterogeneity may have a significant impact on fluid flow or mass migration.

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

[0164] Evolutionary dynamics: If the spectral width gradually decreases over time, it indicates that the pore space tends to be stable; if the spectral width increases over time, it indicates that the pore space is more susceptible to external influences, and the evolutionary process becomes more complex.

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

[0166] As a preferred embodiment, based on the motion data of air flow and water flow, the water-air transport process in the pore space of soil is simulated, and the influence of water-air transport on soil consolidation is analyzed by analyzing the influence of water-air transport on soil consolidation, including:

[0167] Collecting physical experimental data of soil and three-dimensional structure of soil pores, and establishing a soil pore structure model;

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

[0169] Soil basic properties: particle size distribution; porosity; permeability coefficient; specific gravity; water content.

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

[0171] Water-air characteristics: saturation; capillary pressure; water-air phase 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 pores; and the three-dimensional structure is reconstructed by image processing algorithm.

[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, and the coupling model of water-air two-phase flow is formed;

[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 flow per unit time; A represents the water section area; K represents the permeability coefficient; h2-h1 represents the upstream and downstream water head difference; L represents the seepage path length; I represents the hydraulic slope; V represents the seepage velocity.

[0178] Specifically, for gas flow, it is usually assumed that the gas in the pore space follows a flow behavior similar to Darcy's law. The flow rate of gas flow is related to the pressure gradient and the gas permeability of the medium. The basic equation of 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 the gas, represents the flow capacity of the gas in the pore, μ g represents the dynamic viscosity of the gas, represents the gas pressure gradient.

[0181] The coupled model of water-air 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 influenced by saturation, pore structure, and interaction. Here are the basic equations of water-air two-phase flow: w +S g = 1; P c = P g - P w ;

[0182] where S w is the saturation of the water phase, S g is the saturation of the gas phase, P c is the capillary pressure representing the pressure difference between water and gas, P w is the pressure of the water phase, and P g is the pressure of the gas phase.

[0183] Combining these relationships of water-air 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 between water and gas flow: Changes in saturation of water and gas phases affect the permeability coefficient and flow path; the flow of gas may increase the drainage pressure in the pore, thereby driving the flow of water.

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

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

[0187] Use numerical simulation software to solve the coupled model of water-air two-phase flow, calculate the distribution of water and gas in the pore space, pressure field, and saturation change, and obtain the water-air transport results;

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

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

[0190] The iterative solution of numerical simulation includes:

[0191] Solver configuration: Configure appropriate solvers in the software for iterative solution of the discretized equation set. 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 computation: Start the solver and begin the iterative computation process. During this process, the software continuously adjusts the water-gas distribution, pressure field, and saturation within the pore space to gradually approach the true physical state.

[0193] Convergence check: During the iterative process, it is necessary to regularly check the convergence of the solution. When the change in the solution is less than the pre-set threshold, it can be considered that the iteration has converged, and the simulation results are reliable.

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

[0195] Result visualization: Use the visualization tools provided by the software to visually display the water-gas transport in the pore space.

[0196] Combine the water-gas transport results with the soil consolidation theory to analyze the influence of water-gas transport on soil consolidation.

[0197] As a preferred embodiment, combining the water-gas transport results with the soil consolidation theory to analyze the influence of water-gas transport on soil consolidation includes:

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

[0199] According to the permeability parameters in the water-gas transport results, combine the consolidation theory to construct a coupling model of water-gas transport and consolidation process.

[0200] Specifically, based on the obtained water-gas transport parameters, these parameters need to be combined with the soil consolidation theory. This usually involves substituting the permeability parameters into the consolidation equation to construct a coupling model that can reflect both water-gas transport and soil consolidation processes. The construction of the coupling model needs to consider the migration law of water-gas in the soil, the stress-strain relationship of the soil, and the change of pore pressure, etc. Through reasonable assumptions and simplifications, a coupling model that is both physically realistic and easy to numerically solve can be obtained.

[0201] Use the coupling model 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. According to the analysis results, evaluate the changes and stability of the soil consolidation rate under different water-gas transport conditions.

[0202] It is important to note that the extracted water vapor transport results, such as pore pressure distribution, water vapor saturation, and permeability coefficient, are used as initial conditions in the coupled model. Appropriate numerical methods (such as finite element method, finite difference method, etc.) are used to solve the coupled model. This usually involves iterative calculations until the convergence condition is met. After the simulation ends, the settlement amount, consolidation rate, and pore pressure distribution of the soil at different time steps are output.

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

[0204] The dynamic influence of water vapor transport on the consolidation process is analyzed, including:

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

[0206] Saturation and consolidation rate: Analyze the influence of water vapor saturation on the 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 simulation results at different time steps, reveal how water vapor transport dynamically affects the consolidation process of the soil.

[0208] Evaluate the changes and stability of the consolidation rate of the soil under different water vapor 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 respectively.

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

[0211] Stability evaluation: According to the simulation results, evaluate the stability of the soil under different water vapor transport conditions. Pay special attention to conditions that may cause soil instability or abnormal changes in the consolidation rate.

[0212] Sensitivity analysis: Perform 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, by means of the technical scheme of the present application, the centripetal infiltration model device adopts a 1:1 model size, and the lateral wall friction force is ingeniously eliminated by the rigid-flexible combined lining 2, which can be used to study the vacuum preloading evolution mechanism and test new materials and new technologies of vacuum preloading. Through the centripetal infiltration model device, the vacuum degree decay mechanism in the vacuum preloading process can also be simulated and studied, and new technologies to improve the drainage plate clogging condition can be tested. The present application can comprehensively consider factors such as air pressure, water pressure, soil pressure and soil sample deformation, and perform all-around analysis on soil consolidation, thereby improving the accuracy and comprehensiveness of the analysis. Through the automatic data receiving and processing process, manual intervention is reduced, and the analysis efficiency is improved. The pore space evolution is analyzed by using the multi-fractal theory, which can more accurately reveal the change of the pore structure of the soil under the interaction of air flow and water flow. By analyzing the dynamic influence of water and air transport on the consolidation process, the mechanism and rules of soil consolidation can be more deeply understood.

[0214] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage and the like) embodying computer usable program code.

[0215] The above-described specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely specific embodiments of the present application and are not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An in vitro centripetal permeation model device, characterized in that, The application relates to a steel frame mechanism (1) which is internally provided with a rigid-flexible combined lining (2), the top end of the steel frame mechanism (1) is provided with a load loading system (3), and the bottom end of the steel frame mechanism (1) is provided with a sand collecting pool (4). The rigid-flexible combined lining (2) is internally sequentially provided with a vacuum control system (5), an air pressure test system (6) and a water pressure test system (7) from top to bottom, and the outer side of the steel frame mechanism (1) is provided with a soil pressure and soil sample deformation monitoring system (8). 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 connected with a soil body consolidation analysis system (9) in an electrically connected mode. The rigid-flexible combined lining (2) is composed of a plurality of rigid rings (201) and a plurality of flexible ring belts (202), the rigid rings (201) and the flexible ring belts (202) are sequentially arranged in an interlaced mode, the flexible ring belts (202) are made of nylon fabric material, and the rigid rings (201) are made of stainless steel. Two groups of adjacent rigid-flexible combined linings (2) are connected through water stop flanges.

2. A centripetal permeation model device according to claim 1, characterized in that The steel frame mechanism (1) is composed of a plurality of steel frames which are sequentially connected in the vertical direction and are fixedly connected through bolts.

3. The centripetal permeation model device of claim 1, wherein, The soil body consolidation analysis system (9) comprises a data receiving unit (901), a pore space evolution analysis unit (902), a water and gas transport model construction unit (903) and a soil body consolidation evaluation unit (904). The data receiving unit (901) is used for acquiring the motion data of air flow and water flow in the air pressure test system (6) and the water pressure test 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 for analyzing the pore space evolution of the soil body under the interaction of air flow and water flow based on the monitoring data of soil pressure and soil sample deformation and the multi-fractal theory. The water and gas transport model construction unit (903) is used for simulating the water and gas transport process in the pore space of the soil body based on the motion data of air flow and water flow and analyzing the influence of water and gas transport on soil body consolidation.

4. A centripetal permeation model device according to claim 3, wherein The method comprises the following steps: The monitoring data of soil pressure and soil sample deformation is pretreated, and the pretreated monitoring data is sorted according to time stamps to obtain time sequence data of soil pressure and soil sample deformation. The time sequence data of soil pressure and soil sample deformation is divided into a plurality of windows by using a swing window algorithm, and the local weight of each window is calculated. The singularity index of each window is calculated according to the local weight of each window, a multi-fractal spectrum curve is established according to the calculation result, pore space evolution characteristics are extracted according to the multi-fractal spectrum curve, and the evolution law of the pore space is analyzed according to the pore space evolution characteristics.

5. A centripetal permeation model device according to claim 4, wherein The step of dividing the time series data of the soil pressure and the soil sample deformation into a plurality of windows by using the swing window algorithm and calculating a local weight of each window comprises: According to the time series data of the soil pressure and the soil sample deformation, an initial time and corresponding soil pressure value and soil sample deformation value at the initial time are determined respectively, and the soil pressure value and the soil sample deformation value at the initial time are taken as a starting point; The swing window algorithm is used to calculate the boundary values of the upper swing window and the lower swing window of the soil pressure and the soil sample deformation according to a pre-set window width; The time series data of the soil pressure and the soil sample deformation are traversed, and the time series data of the soil pressure and the soil sample deformation are divided 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 the soil sample deformation; The cumulative change amount of the soil pressure and the deformation is calculated in each window of the soil pressure and the soil sample deformation respectively, and the local weight of each window is obtained by normalizing the cumulative change amount.

6. A centripetal permeation model device according to claim 4, wherein The step of calculating the singularity index of each window according to the local weight of each window, establishing a multifractal spectrum curve according to the calculation result, extracting the pore space evolution characteristics according to the multifractal spectrum curve, and analyzing the evolution law of the pore space according to the pore space evolution characteristics comprises: The singularity index of each window is calculated by logarithmic transformation according to the local weight of each window and in combination with the pre-set window width; The singularity indexes of all windows are counted, and the frequency of a subset of windows with the same singularity index is determined, and the fractal dimension is calculated according to the frequency; The multifractal spectrum curve is drawn by using the fractal dimension, and the characteristics of the pore space evolution are extracted by analyzing the spectrum width and the curve shape of the multifractal spectrum curve; The dynamic change law and trend of the pore space are analyzed by comparing the multifractal spectrum curves under different times or conditions according to the characteristics of the pore space evolution.

7. The centripetal permeation model apparatus according to claim 3, wherein The step of simulating the water-gas transport process in the pore space of the soil body based on the motion data of the air flow and the water flow and analyzing the influence of the water-gas transport on the soil body consolidation comprises: Physical experimental data of the soil body and a three-dimensional structure of the soil body pores are collected, and a soil body pore structure model is established; Based on Darcy's law, the seepage characteristics of the water flow in the porous medium are simulated in combination with the soil body pore structure model and the experimental data, a gas flow equation is introduced to describe the air flow behavior, and a coupled model of the water-gas two-phase flow is formed; The coupled model of the water-gas two-phase flow is solved by using a numerical simulation software, the water-gas distribution, the pressure field and the saturation change in the pore space are calculated, and the water-gas transport result is obtained; The influence of the water-gas transport on the soil body consolidation is analyzed in combination with the water-gas transport result and the soil body consolidation theory.

8. A centripetal permeation model device according to claim 7, 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 unit time seepage flow; A represents the water passing section area; K represents the permeability coefficient; h2-h1 represents the upstream and downstream water head difference; L represents the seepage path length; I represents the hydraulic slope; V represents the seepage velocity.

9. A centripetal permeation model device according to claim 8, wherein The step of analyzing the influence of the water-gas transport on the soil body consolidation in combination with the water-gas transport result and the soil body consolidation theory comprises: According to the water vapor transport result, the permeation parameters including the pore pressure distribution, water vapor saturation and permeation coefficient in the water vapor transport result are extracted and used as the initial conditions of the consolidation analysis; According to the permeation parameters in the water vapor transport result, a coupling model of water vapor transport and consolidation process is constructed in combination with the consolidation theory; The coupling model is used to simulate the consolidation process of the soil body, calculate the settlement, consolidation rate and pore pressure dissipation, analyze the dynamic influence of the water vapor transport on the consolidation process, and evaluate the change and stability of the consolidation rate of the soil body under different water vapor transport conditions according to the analysis result.

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