Model system based on soil frost heaving rule
By establishing a soil frost heave law model system and using data collection and sensor optimization models, the problem of soil frost heave simulation was solved, soil frost heave prediction and risk control in construction environments were achieved, and construction safety was ensured.
Patent Information
- Application Number
- CN202510815253.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-18
- Publication Date
- 2025-09-12
AI Technical Summary
Existing technologies cannot effectively simulate soil frost heave, which affects the stability and safety of underground engineering construction.
A model system based on the law of soil frost heave is provided, which includes a soil detection module, a model optimization module and a model detection module. Temperature, moisture and displacement data are collected through a data acquisition system and sensors, a similarity criterion optimization model is established, and an engineering simulation model is constructed.
It can simulate soil frost heave in different construction environments, predict and control potential risks, and ensure construction safety.
Smart Images
Figure CN120633520A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of soil frost heave simulation, and in particular to a model system based on soil frost heave law. Background Art
[0002] With the rapid development of urban infrastructure construction, underground engineering is increasingly used in urban transportation, river crossings and other fields. The pipe curtain method forms a temporary support structure by constructing a steel pipe curtain wall around the soil, which can effectively control stratum displacement and water flow. Therefore, the pipe curtain method is combined with the artificial freezing method to form a "pipe curtain freezing method", that is, a frozen soil curtain is formed on the outside of the pipe curtain through artificial freezing, which can give full play to the advantages of both: the high-rigidity support of the pipe curtain method and the water-sealing effect of the artificial freezing method.
[0003] However, during underground engineering construction, especially in tunnel construction using freezing technology, frost heave has become a key issue affecting project stability and construction safety. For example, within the frost heave area, vertical displacement not only affects the foundation of ground buildings but can also cause deformation of underground pipelines and even cracks or damage. Therefore, vertical displacement simulation of frost heave can provide an important reference for engineering design and construction, helping to reasonably predict and control potential risks. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the defects of the existing technology and provide a model system based on the law of soil frost heave, which mainly solves the problem that the existing technology cannot form a simulation system for soil frost heave construction to prevent construction safety.
[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: The invention provides a model system based on the law of soil frost heave. The model system comprises: a soil detection module, comprising a soil temperature measuring unit and a soil cooling unit, for testing the cooling performance of sampled target soil and establishing a preliminary linear system model; a model optimization module, comprising a data acquisition system, a model test box and a freezing refrigeration box, wherein the data acquisition system is connected to the model test box and the freezing refrigeration box respectively, and the preliminary linear system model is optimized by unifying the temperature field, the moisture field and the displacement field to a similarity criterion according to a dimensional analysis method based on the data acquisition system; a model detection module, comprising a temperature sensor, a displacement sensor, a freezing pipe and a liquid separation pipe, and after establishing an engineering model consisting of the freezing pipe and the soil, the temperature sensor and the displacement sensor collect corresponding data; and a model system for combining the sampled target soil and the model optimization module so that the optimized preliminary linear system model forms a modeled system, obtains the cyclic frost heave law of the target soil, confirms the proportional relationship between temperature, displacement, time and geometric dimensions, and finally constructs a model system with an engineering simulation effect.
[0006] Preferably, the soil temperature measurement unit includes a thermal constant analyzer for detecting the thermal conductivity and specific heat capacity of the target soil at room temperature; the soil cooling unit includes a freezing low-temperature box for cooling the target soil and measuring the elastic modulus and Poisson's ratio in low-temperature scenarios.
[0007] Preferably, the temperature field is uniformly expressed according to the similarity criterion for the area where the freezing process has not started, the frozen soil area not affected by the frozen soil cold source, and the temperature boundary of the outer wall of the freezing pipe, so as to finally obtain a dimensionless similarity criterion: the temperature field distribution inside the soil, the surface temperature of the freezing pipe, the radius of the outward expansion of the frozen soil area, the spacing distance of the freezing pipe, the length of the freezing pipe, the thermal conductivity coefficient of the unfrozen soil, the volume specific heat capacity of the unfrozen soil, the duration of freezing, and the phase change latent heat released per unit volume of soil during the soil freezing process.
[0008] Preferably, the moisture field forms a similarity criterion for the frozen moisture field based on the soil moisture content and soil permeability coefficient, and the factors related to the moisture boundary in the frozen soil area where the freezing process has not started and is not affected by the frozen soil cold source, and the similarity criterion data of the moisture field is linked to the temperature field.
[0009] Preferably, the displacement field is derives a dimensionless similarity criterion based on the similarity criterion: strain, displacement, stress, soil density, gravitational acceleration, outer diameter of the pipe curtain surrounding structure, Poisson's ratio, overburden thickness, and steel pipe thickness.
[0010] Preferably, the model system further comprises: steel pipes constituting the pipe curtain, pipeline ball valves of the cold junction pipes, and refrigerant.
[0011] Preferably, the target soil includes a strong freezing zone and a weak freezing zone, wherein the strong freezing zone and the weak freezing zone are distinguished by the refrigeration intensity of the freezing liquid in the freezing pipe.
[0012] Preferably, the temperature sensor has no less than five characteristic temperature monitoring points in the strong freezing area and no less than two characteristic temperature monitoring points in the weak freezing area, which are used to collect temperature data of different areas of the model system.
[0013] Preferably, the displacement sensor is arranged with no less than five displacement monitoring points on the midline of the reinforced end surface of the target soil, and a monitoring path is arranged on the upper surface of the target soil for collecting data on the vertical frost heave interval of the target soil and the frost heave interval of the surface lifting displacement.
[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a corresponding calculation model, collects preliminary field data, optimizes the target model, and finally constructs a model system. All of these are model systems formed according to the on-site construction environment. In addition, this system is reproducible based on the calculation model and can cope with soil frost heave simulation under different construction environments. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 Schematic diagram of the frozen soil thickness and cooling rate change curve of the present invention; Figure 2 Schematic diagram of the displacement and uplift change curve of the monitoring point inside the soil body of the present invention; Figure 3 It is a schematic diagram of the spatiotemporal variation curve of the surface uplift displacement of the present invention. DETAILED DESCRIPTION
[0016] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0017] The present invention provides a model system based on soil frost heave law, the model system comprising: The soil detection module includes a soil temperature measurement unit and a soil cooling unit, which are used to test the cooling performance of the sampled target soil and establish a preliminary linear system model; The model optimization module includes a data acquisition system, a model test box, and a freezing refrigeration box. The data acquisition system is connected to the model test box and the freezing refrigeration box respectively. The data acquisition system optimizes the preliminary linear system model based on the temperature field, moisture field, and displacement field by unifying them to a similarity criterion according to a dimensional analysis method. The model detection module includes a temperature sensor, a displacement sensor, a freezing pipe, and a liquid dispensing pipe. After establishing an engineering model consisting of the freezing pipe and soil, the temperature sensor and the displacement sensor collect corresponding data. It is used to combine the sampled target soil and the model optimization module to make the optimized preliminary linear system model form a modeled system, obtain the cyclic frost heave law of the target soil, confirm the proportional relationship between temperature, displacement, time and geometric dimensions, and ultimately build a model system with engineering simulation effect.
[0018] The model optimization module further shows that the freezing process of soil is a three-dimensional heat conduction problem, involving water migration and phase change phenomena, and the process is accompanied by the release of latent heat of phase change. The heat conduction process can be expressed by the following equation: ; For frozen soil areas where the freezing process has not yet begun and the influence of frozen soil cold sources has not yet been received, the boundary conditions related to temperature can be expressed as: ; ; ; The temperature boundary condition of the outer wall of the freezing pipe can be expressed as: ; The temperature boundary condition at the freezing interface can be expressed by the heat balance equation: ; In the above formula: represents the time variable, Represents thermal conductivity, unit: , ; Unfrozen soil, It is frozen soil; Represents the phase change latent heat released per unit volume of soil during the freezing process, unit: ; represents the initial soil temperature, unit: °C; Represents the freezing temperature of soil, unit: ℃; represents the outer diameter coordinate of the circular freezing pipe, unit: m; r represents the soil coordinate, unit: m; Represents the frozen soil development interface, unit: m; Indicates thermal diffusivity, unit: m 2 / s, Indicates the density of the material, unit: kg / m 3 , Indicates the specific heat capacity of the material, unit: J / (kg·K).
[0019] Since there is no other cold source inside the soil except the surface temperature of the freezing pipe, the influencing factors are as follows:
[0020] Where, Represents the temperature field distribution inside the soil, unit: ℃; Represents the surface temperature of the circular freezing tube, unit: ℃; Represents the duration of freezing, unit: s; Represents the volume specific heat capacity of unfrozen soil, unit: ; Represents the volume specific heat capacity of frozen soil, unit: ; Represents the spacing distance of the freezing pipes, unit: m; Represents the length of the circular freezing pipe, unit: m; Represents the radius of the permafrost area, unit: m; is the outer diameter of the circular freezing pipe, unit: m.
[0021] Among the parameters involved in the above equation, , , and The four dimensionally independent standard parameters are used as basic parameters, and the following similarity criteria can be further derived using the method of dimensional analysis: , , , , , , , , ; Furthermore, the similarity criterion of the moisture field indicates that during the freezing process, the development of the frozen wall will cause the migration of moisture in the soil, thereby affecting the distribution of the moisture field in the soil. Therefore, in order to describe the migration phenomenon of moisture in the soil, the diffusion equation is introduced to construct a mathematical model of the moisture field, which can be expressed as: ; Where, Represents the moisture content of the soil, Permeability coefficient of soil For frozen soil areas where the freezing process has not yet begun and the influence of frozen soil cold sources has not yet been received, the boundary conditions related to moisture can be expressed as: ; ; ; Where, is the initial moisture content of the soil; According to the above process, the equations of influencing factors are listed: ; represents the water diffusion coefficient, represents the freezing rate; Using the method of dimensional analysis, we can obtain the similarity criterion: Fourier criterion: ; Moisture field criteria: ; ; Geometric criteria: ; Therefore, the similarity criterion equation of the frozen water field is: ; The mathematical model of moisture migration in soil is similar to the heat conduction during freezing, and both processes conform to Fourier's law of diffusion. Therefore, by simply satisfying the similarity conditions of the temperature field in the physical model test, the similarity of the moisture field can be simultaneously ensured. Furthermore, the similarity criterion of displacement field is mainly based on the specific actual conditions of the project, and the main influencing factors are listed as follows: ; Where, Represents stress, unit: MPa; represents strain, dimensionless; Represents elastic modulus, unit: MPa; stands for Poisson's ratio, dimensionless; Represents the density of the steel pipe, unit: kg / m 3 ; Represents soil density, unit: Kg / m 3 ; Represents the acceleration due to gravity, unit: m / s 2 ; Represents the thickness of the overlying soil, unit: m; Represents displacement, unit: m; Represents the outer diameter of the pipe curtain surrounding structure, unit: m; Represents the thickness of the steel pipe, unit: m; Represents the length of the circular freezing pipe, unit: m; Combining actual projects and applying dimensional analysis methods, the following similarity criteria are further derived: , , , , , , , , ; From the above similarity principles, it can be seen that various major influencing factors have been unified in the model optimization module. The model system can be further optimized on this basis. At the same time, the required materials are determined based on the optimized preliminary linear system model, and freezing pipes and steel pipes with materials similar to those of the target project are selected as auxiliary model materials. The soil density is unified to be the same as that in the actual geological survey.
[0022] Before the actual construction of a project in a certain place, the model system is actually constructed according to the model detection module, and the environmental variables are determined based on the above process. Then the target project soil is collected and processed to achieve the same soil density and moisture content conditions; finally, freezing pipes and sensors are buried in the strong freezing zone and weak freezing zone respectively, and the cooling loss test is completed simultaneously, and the final result is as follows. Figure 1-3 the result; like Figure 1 As shown in the figure, before the freezing liquid temperature reaches 0°C, no frozen ground forms on either the west or east side, and its thickness is zero. Because there is a slight difference in the amount of cold on both sides, the results show a certain difference in cooling rate, with an average cooling rate of 0.483°C / min on the west side and 0.476°C / min on the east side. After the freezing liquid temperature reaches 0°C, the frozen wall continues to develop, and the frozen ground thickness shows a rapid and continuous increase. After 1.2 hours of freezing, the average thickness of the frozen soil reached 0.098m on the west side and 0.089m on the east side. This difference is due to the presence of more severely frozen areas on the west side. During this period, the average cooling rate continued to increase due to changes in the soil's thermophysical parameters, reaching 0.571°C / min on the west side and 0.543°C / min on the east side. As freezing continued, the frozen soil thickness continued to increase in the next period, but the rate of increase slowed, reaching an average thickness of 0.157m on the west side and 0.135m on the east side. At this point, the frozen soil thickness reached the design thickness requirements for the project, demonstrating that it meets the simulation requirements for actual projects and can effectively simulate the expansion thickness of frozen soil.
[0023] Furthermore, the displacement change data of the soil internal uplift displacement monitoring points Point 1 to 5 during the freezing process and the spatiotemporal change data of the surface uplift displacement monitoring points Point 5L2, Point 5L1, Point 5, Point 5R1, and Point 5R2 are extracted, as shown in Figure 2. Figure 2 As shown in the figure, in the early stage of phase change, the soil in the surface area is affected by all the freezing pipes. Under the superposition of frost heave in the soil below, the soil in the upper surface area will experience a large uplift displacement. Point 1 is affected by the cluster of freezing pipes in the bottom plate freezing zone, resulting in a 5.5mm displacement uplift during the entire freezing test process. Point 2 is affected by the superposition of freezing zones on the east and west sides, resulting in a 7.6mm displacement during the entire freezing process. Compared with the bottom plate freezing zone, the freezing zones on both sides have a smaller impact on the centerline and do not cause a large uplift displacement increment. The displacement changes at Points 1 and 3 indicate that the frozen zones of the top and bottom plates can cause an incremental displacement of 6 to 7 mm, which has a major impact on the overall vertical frost heave of the soil. The displacement changes at Points 3 and 4 show a significant incremental displacement, indicating that the frozen soil curtain has developed into this region, producing a phase change frost heave effect.
[0024] From the data collected by the model system, we can know that different points are subject to different freezing displacements, which proves that engineering construction design and engineering plans can be made. It also shows that even if the same material is used, different degrees of changes will occur when the freezing time and freezing area are different.
[0025] from Figure 3 It can be seen that when the freezing liquid in the freezing tube reaches 0°C, there is no significant surface displacement. When the freezing time reaches 1.2 hours, a phase change is evident in the soil, resulting in a significant incremental displacement. At 1.8 hours, the soil displacement also undergoes a significant change compared to the previous period, but the incremental change then begins to decrease, indicating that the dramatic phase change and frost heave effect primarily occur between 0.6 and 1.8 hours. The increase in frost heave displacement continues to decrease thereafter. This is because, in the later stages of the freezing test, most of the free water surrounding the frozen soil curtain has transformed into ice, leaving little moisture in the soil that can further freeze. Furthermore, the temperature gradient decreases significantly in the later stages of the test, reducing the driving force for water migration toward the outer edges of the frozen wall. Ice crystal growth enters a stable equilibrium phase, and the increase in frost heave displacement slows. Furthermore, the maximum surface displacement is approximately between Point 5L1 and Point 5R1, which is located towards the center of the frozen soil curtain. It can be seen that good simulation performance can also be achieved for the displacement of ground uplift, and in subsequent actual working conditions, the model system produced based on the scheme of the present invention can also correspond to it; the system of the present invention can realize the simulation before soil frost heave construction, which is convenient for advance planning of the construction process and can also ensure safety during construction.
[0026] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.
Claims
1. A model system based on soil frost heave law, characterized in that: The model system includes: The soil detection module includes a soil temperature measurement unit and a soil cooling unit, which are used to test the cooling performance of the sampled target soil and establish a preliminary linear system model; The model optimization module includes a data acquisition system, a model test box, and a freezing refrigeration box. The data acquisition system is connected to the model test box and the freezing refrigeration box respectively. The data acquisition system optimizes the preliminary linear system model based on the temperature field, moisture field, and displacement field by unifying them to a similarity criterion according to a dimensional analysis method. The model detection module includes a temperature sensor, a displacement sensor, a freezing pipe, and a liquid dispensing pipe. After establishing an engineering model consisting of the freezing pipe and soil, the temperature sensor and the displacement sensor collect corresponding data. It is used to combine the sampled target soil and the model optimization module to make the optimized preliminary linear system model form a modeled system, obtain the cyclic frost heave law of the target soil, confirm the proportional relationship between temperature, displacement, time and geometric dimensions, and ultimately build a model system with engineering simulation effect.
2. A model system based on soil frost heave law according to claim 1, characterized in that: The soil temperature measurement unit includes a thermal constant analyzer for detecting the thermal conductivity and specific heat capacity of the target soil at room temperature; the soil cooling unit includes a freezing low-temperature box for cooling the target soil and measuring the elastic modulus and Poisson's ratio in low-temperature scenarios.
3. A model system based on soil frost heave law according to claim 1, characterized in that: The temperature field, based on a similarity criterion, uniformly expresses the temperature boundary of areas where the freezing process has not yet begun, frozen areas not affected by frozen soil cooling sources, and the outer wall of the freezing pipe, ultimately deriving a dimensionless similarity criterion: the temperature field distribution inside the soil, the surface temperature of the freezing pipe, the radius of the outward expansion of the frozen area, the spacing between the freezing pipes, the length of the freezing pipes, the thermal conductivity of the unfrozen soil, the volume specific heat capacity of the unfrozen soil, the duration of freezing, and the phase change latent heat released per unit volume of soil during the freezing process.
4. A model system based on soil frost heave law according to claim 3, characterized in that: According to the similarity criterion, the moisture field forms a similarity criterion of the frozen moisture field based on the soil moisture content and the soil permeability coefficient, and the factors related to the moisture boundary in the frozen soil area where the freezing process has not started and is not affected by the frozen soil cold source, and the similarity criterion data of the moisture field is linked to the temperature field.
5. A model system based on soil frost heave law according to claim 4, characterized in that: The displacement field is converted into a dimensionless similarity criterion based on the similarity criterion: strain, displacement, stress, soil density, gravitational acceleration, outer diameter of the pipe curtain surrounding structure, Poisson's ratio, overburden thickness, and steel pipe thickness.
6. A model system based on soil frost heave law according to claim 5, characterized in that: The model system also includes: steel pipes constituting the pipe curtain, pipeline ball valves of the cold junction pipes, and refrigerant.
7. A model system based on soil frost heave law according to claim 6, characterized in that: The target soil includes a strong freezing zone and a weak freezing zone, wherein the strong freezing zone and the weak freezing zone are distinguished by the refrigeration intensity of the freezing liquid in the freezing pipe.
8. A model system based on soil frost heave law according to claim 7, characterized in that: The temperature sensor has no less than five characteristic temperature monitoring points in the strong freezing area and no less than two characteristic temperature monitoring points in the weak freezing area, and is used to collect temperature data of different areas of the model system.
9. The model system based on soil frost heave law according to claim 6, characterized in that: The displacement sensor is arranged with no less than five displacement monitoring points on the midline of the reinforced end surface of the target soil, and a monitoring path is arranged on the upper surface of the target soil, for collecting data on the vertical frost heave interval of the target soil and the frost heave interval of the surface lifting displacement.