Physical model test system for high-speed rail roadbed in severe cold water-rich environment

Abstract

The invention provides a severe cold water-rich environment high-speed railway subgrade physical model experiment testing system, and relates to the field of cold region high-speed railway subgrade research. A subgrade physical model subsystem is used for simulating a response rule to a dynamic load and a cold region environment in a high-speed railway operation process; the moisture field control monitoring subsystem is used for simulating the influence of environment change on the moisture content of a filling material in a roadbed and monitoring the content of unfrozen water in the roadbed, and the temperature field temperature control monitoring subsystem is used for simulating the temperature state of the service of the high-speed railway roadbed in a cold region environment; the simulation loading subsystem is used for simulating the physical change process of the high-speed railway roadbed under the train load effect in the cold region environment, and the physical process of the high-speed railway roadbed system under the train load effect in the cold region environment is scientifically restored and simulated; the change rule of the physical and mechanical properties of roadbed filling of the high-speed railway roadbed system in the cold region under the comprehensive influence of the moisture field, the temperature field and the dynamic load is accurately obtained, and the method has extremely high scientific research and application value.

Description

Technical Field

[0001] The invention relates to the field of cold region high-speed railway subgrade research, and in particular to a physical model test system for a high-speed railway subgrade in a severe cold and water-rich environment. Background Art

[0002] With the development of the national economy, my country's railway industry has also developed rapidly in the past decade. The frozen soil in northern my country has a huge impact on the practicality and durability of high-speed railway foundations. Therefore, it is very important to experimentally study the state of high-speed railway foundations in frozen soil areas during the working process.

[0003] At present, it is relatively rare to build a frozen soil high-speed railway subgrade model indoors in China. There are two types of existing test devices in China: one is a multifunctional frozen soil subgrade test box. Although it can provide low temperature and other conditions for the test soil and load it, due to its size limitation, it cannot fully simulate the overall working state of the subgrade under specific conditions, and it is difficult to meet the requirements of the coarse-grained soil filler used in high-speed railways for the size of the test sample. The other is an outdoor large-scale subgrade test model, which can meet the test conditions for loading the subgrade under standard size and fully reflect the overall working state of the subgrade. However, it cannot meet the conditions for temperature control and water replenishment of the test system, and cannot meet the experimental conditions for the working state of the high-speed railway subgrade in cold regions.

[0004] Based on the current important demand for developing high-speed railway projects in cold regions in my country, we urgently need a test model that can fully simulate the working conditions of the cold-region high-speed railway subgrade. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and to provide a physical model test system for high-speed railway subgrade in a severely cold and water-rich environment. The present invention systematically and scientifically restores and simulates the physical process of the cold-region high-speed railway subgrade system under the action of train loads, and accurately obtains the changing laws of the physical and mechanical properties of the subgrade fill of the cold-region high-speed railway subgrade system under the combined influence of moisture field, temperature field and dynamic load, and has extremely strong scientific research application value.

[0006] The present invention is achieved through the following technical solutions: A physical model test system for a high-speed railway subgrade in a severe cold and water-rich environment includes a subgrade physical model subsystem, a moisture field control and monitoring subsystem, a temperature field temperature control and monitoring subsystem, and a simulation loading subsystem. The subgrade physical model subsystem is used to simulate the response law of the high-speed railway to the dynamic load and the cold environment during the operation of the high-speed railway. The moisture field control and monitoring subsystem is used to simulate the influence of environmental changes on the moisture content of the filling material in the subgrade and monitor the unfrozen water content in the subgrade. The temperature field temperature control and monitoring subsystem is used to simulate the temperature state of the high-speed railway subgrade in the cold environment and monitor the temperature field change of the filling material in the subgrade. The simulation loading subsystem is used to simulate the physical change process of the high-speed railway subgrade under the train load in the cold environment, wherein: The roadbed physical model subsystem includes a rectangular retaining pit and a roadbed structure. The roadbed structure is arranged in the retaining pit. The roadbed structure includes tracks, track plates, mortar cushions, concrete bottom layers, roadbed layers, road base layers, and subsoil layers from top to bottom. The moisture field control and monitoring subsystem includes a moisture supply mechanism and a moisture monitoring mechanism. The moisture supply mechanism is used to simulate the moisture field changes of the cold-region high-speed railway subgrade affected by the surrounding environment during service. The moisture supply mechanism is arranged directly below the subgrade mechanism. The moisture monitoring mechanism is used to monitor the changes in the moisture content of the filling materials in the subgrade and the unfrozen water content in the subgrade. The temperature field control and monitoring subsystem includes a refrigeration mechanism and a temperature monitoring mechanism. The refrigeration mechanism is used to cool the roadbed physical model subsystem. The temperature monitoring mechanism monitors the temperature state of the high-speed railway roadbed in service in a simulated cold environment and the changes in the temperature field of the filling material in the roadbed.

[0007] It can be seen that in the above technical scheme, the present invention systematically and scientifically restores and simulates the physical process of the cold-region high-speed railway subgrade system under the action of train loads, accurately obtains the changing law of the physical and mechanical properties of the subgrade fill of the cold-region high-speed railway subgrade system under the comprehensive influence of moisture field, temperature field and dynamic load, and has extremely strong scientific research application value; it plays a certain guiding role in the anti-freezing design, construction and post-damage diagnosis and treatment of high-speed railway subgrades; the present invention can apply static loads and dynamic loads to simulate the different states of the high-speed railway subgrade in normal operation; the present invention can monitor the changes in the internal force of each layer inside the high-speed railway subgrade to explore the process and causes of problems during use; the present invention can achieve macroscopic monitoring of the harm of frozen soil changes to the high-speed railway subgrade, thereby obtaining prevention and control measures and improving the durability and stability of the high-speed railway subgrade in frozen soil areas; the present invention can monitor the content of unfrozen water in the subgrade to study the relationship between the unfrozen water content and mechanical properties of the high-speed railway subgrade under different freezing states in seasonal frozen soil areas.

[0008] According to the above technical scheme, preferably, the water supply mechanism includes a water replenishment tank top plate, a water replenishment tank body and a water replenishment tank bottom plate, the water replenishment tank body is provided with a plurality of groups of internal partition beams for support, the water replenishment holes connected to the roadbed mechanism are evenly distributed on the water replenishment tank top plate, and the water replenishment tank body is provided with a water inlet and an exhaust port connected to the outside world.

[0009] It can be seen that the above technical scheme can achieve the purpose of water migration and water replenishment during the freezing of the high-speed railway subgrade during the test, and complete the water replenishment of the roadbed structure from bottom to top by controlling the water level height in the water replenishment box and adjusting the size of the water replenishment hole; and the internal partition beam can ensure that the water replenishment box can meet the water replenishment function, greatly improving the bearing capacity of the water replenishment box; it can also simulate the changes in the moisture field caused by the change of groundwater runoff factors in the high-speed railway subgrade during service by controlling the opening position of the water replenishment hole on the top plate of the water replenishment tank; it can also simulate the process of the lower soil of the high-speed railway subgrade in cold areas rising through capillary water and replenishing water to the subgrade during the freezing of the high-speed railway subgrade in winter.

[0010] According to the above technical solution, preferably, the moisture monitoring mechanism includes multiple groups of humidity sensors and moisture monitoring processors arranged in the roadbed mechanism, the multiple groups of humidity sensors are signal-connected to the moisture monitoring processor, and the humidity sensors transmit the detected humidity data to the moisture monitoring processor in real time.

[0011] It can be seen that in the above technical solution, humidity sensors are arranged in each layer of soil, which can monitor the humidity changes of each layer inside the roadbed in real time.

[0012] According to the above technical solution, preferably, the refrigeration mechanism includes a condenser arranged in the soil of the roadbed mechanism and an external refrigeration device, and the refrigeration device cools the roadbed mechanism to a set temperature through the condenser.

[0013] According to the above technical solution, preferably, the refrigeration mechanism includes two groups of independently operated condensing tubes and an external refrigeration device, and the two groups of condensing tubes are symmetrically arranged on both sides of the roadbed mechanism.

[0014] According to the above technical solution, preferably, the refrigeration mechanism also includes a plurality of groups of cooling fans arranged on the left and right sides of the roadbed mechanism.

[0015] It can be seen that in the above technical solution, the cooling fan is used to assist in cooling the surface of the high-speed railway subgrade to improve the simulation authenticity.

[0016] According to the above technical solution, preferably, the temperature monitoring mechanism includes multiple groups of temperature sensors and temperature monitoring processors arranged in the roadbed mechanism, the multiple groups of temperature sensors are signal-connected to the temperature monitoring processor, and the temperature sensors transmit the detected temperature data to the temperature monitoring processor in real time.

[0017] According to the above technical solution, preferably, the simulation loading subsystem includes a gantry mechanism and a vertical loading mechanism, the gantry mechanism includes two groups of gantry tracks and a gantry frame body, the two groups of gantry tracks are symmetrically arranged on both sides of the tracks, the gantry frame body moves forward and backward along the gantry tracks, and the vertical loading mechanism includes two groups of vertical loading devices and a pressure beam, the fixed end of the vertical loading device is fixedly arranged on the gantry frame body, the pressure beam is erected on the track, and the free end of the vertical loading device presses down the pressure beam at a set frequency through a pressure column, and the pressure column directly bears the static load and dynamic load output by the vertical loading device.

[0018] According to the above technical solution, preferably, an energy isolation and shock absorption layer is provided around the enclosure pit, and the energy isolation and shock absorption layer includes an inner enclosure steel plate, a sliding plate, a reset spring block and an outer enclosure steel plate from the inside to the outside. The inner enclosure steel plate and the outer enclosure steel plate are both slidably connected to the sliding plate, and both sides of the reset spring block are against the inner enclosure steel plate and the outer enclosure steel plate.

[0019] It can be seen that in the above technical scheme, when there is interfering vibration in the soil around the test system, the inner and outer protective steel plates on the energy isolation and shock-absorbing layer slide relative to each other to prevent the interfering vibration from being transmitted to the inside of the test system, and at the same time, the reset spring block makes the sliding plate return to the equilibrium position; the energy isolation and shock-absorbing layer should be first arranged on the bottom and side walls of the retaining pit according to the plan before establishing the roadbed structure.

[0020] According to the above technical solution, preferably, the moisture monitoring mechanism further includes a plurality of resistivity probes buried in the roadbed mechanism; the resistivity probes include electrodes, temperature sensors, inclinometers, seismic detectors, pore pressure sensors, surface friction sensors and cone tips; the resistivity probes have a built-in unfrozen water content calculation model for calculating the unfrozen water content measured by the resistivity probes, as follows: First, the length of the microelement is taken as L (L=1), and the resistivity of the soil (s), water (e), and gas (g) in the roadbed structure in the experiment can be obtained from the resistivity probe and expressed as R s , R w , R g Considering the difference in unfrozen water content and the uneven distribution, the microelement a of the unfrozen water content is as follows: Figure 7 As shown; Assume that the conductivity coefficient of the soil is E, the porosity of the soil is n; Assume that the free water resistivity of the part connected in parallel with the soil is N, and the part connected in series is defined as M; Therefore, the following formula is obtained; (1) (2) (3) (4) (5) (6) in is the dry density of the microelement, is the solid length of the parallel part of the soil in the microelement, is the liquid length of the parallel part of the soil in the microelement, is the unfrozen length of the soil in the microelement, is the length of the liquid part in series with the soil in the microelement, is the solid length of the soil part in series in the microelement, is the gaseous length of the soil series part in the microelement, is the liquid density of the parallel part of the soil in the microelement, is the unfrozen water content measured by the resistivity probe; From formulas (1)-(6), we can get the following formula: (7) (8) (9) (10) (11) The total resistivity of microelement a is R a , then: (12) is the liquid resistivity of the parallel part of the soil in the microelement, It is the solid resistivity of the parallel part of the soil in the microelement; Substituting formula (7)-(11) into formula (12), we get: (13) In formula (13) is the density of the solid state; (14) is the density of the liquid; (15) (16) Combining formulas (13)-(16), we have: (17) (18) Finally, the unfrozen water content measured by the resistivity probe is obtained. .

[0021] The beneficial effects of the present invention are: (1) The present invention systematically and scientifically restores and simulates the physical process of the cold-region high-speed railway subgrade system under the action of train loads, accurately obtains the changing laws of the physical and mechanical properties of the subgrade fill of the cold-region high-speed railway subgrade system under the combined influence of moisture field, temperature field and dynamic load, and has extremely strong scientific research application value; (2) The present invention plays a certain guiding role in the antifreeze design, construction and post-damage diagnosis and treatment of high-speed railway subgrades; (3) The present invention can apply static loads and dynamic loads to simulate different states of the high-speed railway subgrade in normal operation; (4) The present invention can monitor the changes in the internal force of each layer inside the high-speed railway subgrade to explore the process and causes of problems that occur during use; (5) The present invention can achieve macroscopic monitoring of the harm of frozen soil changes to high-speed railway subgrades, thereby obtaining preventive measures and improving the durability and stability of high-speed railway subgrades in frozen soil areas; (6) The present invention can monitor the content of unfrozen water in the roadbed to study the relationship between the unfrozen water content and mechanical properties of the high-speed railway roadbed under different freezing conditions in seasonally frozen soil areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It shows an isometric structural schematic diagram according to an embodiment of the present invention; Figure 2 Another isometric structural diagram according to an embodiment of the present invention is shown; Figure 3 A schematic cross-sectional view of a roadbed physical model subsystem according to an embodiment of the present invention is shown; Figure 4 It shows an isometric structural schematic diagram of a water supply mechanism according to an embodiment of the present invention; Figure 5 A schematic cross-sectional structure diagram of an energy isolation and shock absorption layer according to an embodiment of the present invention is shown; Figure 6 A schematic diagram of the top view of the top plate of the water replenishment tank according to an embodiment of the present invention is shown; Figure 7 A schematic diagram of a microelement of unfrozen water content according to an embodiment of the present invention is shown; Description of reference numerals: 1. Pressure-bearing column; 2. Pressure-dividing beam; 3. Track; 4. Track plate; 5. Mortar cushion layer; 6. Concrete bottom layer; 7. Roadbed layer; 8. Roadbed layer; 9. Insulation board; 10. Condenser; 11. Water supply tank top plate; 12. Water supply mechanism; 13. Subsoil layer; 14. Containment pit; 15. Gantry track; 16. Vertical loading mechanism; 17. Gantry body; 18. Hydraulic oil interface; 19. Hydraulic oil pipeline; 20. Energy isolation and shock absorption layer; 21. Water supply tank bottom plate; 22. Inner partition beam; 23. Water inlet; 24. Exhaust port; 25. Water supply box; 26. Inner enclosure steel plate; 27. Sliding plate; 28. Reset spring block; 29. ​​Soil pressure sensor. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and the best embodiment. Based on the embodiments in the invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the invention.

[0024] In the description of the invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the invention.

[0025] like Figure 1-7 As shown, the present invention provides a physical model test system for high-speed railway subgrade in severe cold and water-rich environment, including a subgrade physical model subsystem, a moisture field control and monitoring subsystem, a temperature field temperature control and monitoring subsystem and a simulation loading subsystem. The subgrade physical model subsystem is used to simulate the response law of the high-speed railway to the dynamic load and the cold environment during the operation of the high-speed railway. The moisture field control and monitoring subsystem is used to simulate the influence of environmental changes on the moisture content of the filling material in the subgrade and monitor the unfrozen water content in the subgrade. The temperature field temperature control and monitoring subsystem is used to simulate the temperature state of the high-speed railway subgrade in service in the cold environment and monitor the temperature field change of the filling material in the subgrade. The simulation loading subsystem is used to simulate the physical change process of the high-speed railway subgrade under the action of the train load in the cold environment, wherein: The roadbed physical model subsystem includes a rectangular retaining pit 14 and a roadbed structure. The roadbed structure is arranged in the retaining pit 14. The roadbed structure includes a track 3, a track plate 4, a mortar cushion 5, a concrete bottom layer 6, a roadbed layer 7, a roadbed layer 8 and a subsoil layer 13 from top to bottom. The overall width of the roadbed physical model subsystem is 8.8m. In order to meet the soil column height converted by the track 3 and the train load required by the specification, the height of the roadbed 8 is 3.5m, the slope is 1:1.5, the thickness of the subgrade surface is 0.7m, and the subgrade surface meets the compaction standard required by the specification: ; ; ; The roadbed filling materials selected by the roadbed construction organization are group A and B filling materials; In order to meet the needs of various test simulations, the roadbed physical model subsystem is divided into two types: the cold region ballastless track model and the cold region ballasted track model; The moisture field control and monitoring subsystem includes a moisture supply mechanism 12 and a moisture monitoring mechanism. The moisture supply mechanism 12 is used to simulate the moisture field change of the cold region high-speed railway subgrade affected by the surrounding environment during service. The moisture supply mechanism 12 is arranged directly below the subgrade mechanism. The moisture monitoring mechanism is used to monitor the change of the moisture content of the filling material in the subgrade and the unfrozen water content in the subgrade. The water supply mechanism 12 includes a water supply tank top plate 11, a water supply tank body 25 and a water supply tank bottom plate 21. The water supply tank body 25 is provided with a plurality of groups of inner partition beams 22 for support. The water supply tank top plate 11 is evenly provided with water supply holes connected to the roadbed mechanism. The water supply tank body 25 is provided with a water inlet 23 and an exhaust port 24 connected to the outside world. It can achieve the purpose of water migration and water supply during the freezing of the high-speed railway subgrade during the test, and complete the water supply of the subgrade mechanism from bottom to top by controlling the water level height in the water supply tank body 25 and adjusting the size of the water supply holes; and the inner partition beam 22 can ensure that the water supply tank body 25 can meet the water supply function, and greatly improve the bearing capacity of the water supply tank body 25; it can also simulate the water field change caused by the change of groundwater runoff factors in the high-speed railway subgrade during service by controlling the opening position of the water supply hole on the top plate 11 of the water supply tank; it can also simulate the process in which the lower soil of the high-speed railway subgrade in the cold region rises through capillary water and replenishes water to the subgrade part during the freezing of the subgrade in winter; The moisture monitoring mechanism includes multiple groups of humidity sensors and moisture monitoring processors arranged in the roadbed mechanism. The multiple groups of humidity sensors are connected to the moisture monitoring processor signals. The humidity sensors transmit the detected humidity data to the moisture monitoring processor in real time. The humidity sensors are arranged in each layer of soil and can monitor the humidity changes of each layer inside the roadbed in real time. The temperature field control and monitoring subsystem includes a refrigeration mechanism and a temperature monitoring mechanism. The refrigeration mechanism is used to cool down the roadbed physical model subsystem. The temperature monitoring mechanism monitors the temperature state of the high-speed railway roadbed in service in a simulated cold region environment and the temperature field changes of the filling materials in the roadbed. The refrigeration mechanism includes a condenser pipe 10 arranged in the soil of the roadbed mechanism and an external refrigeration device, and the refrigeration device cools the roadbed mechanism to a set temperature through the condenser pipe; The temperature monitoring mechanism includes multiple groups of temperature sensors and temperature monitoring processors arranged in the roadbed mechanism, the multiple groups of temperature sensors are connected with the temperature monitoring processor signals, and the temperature sensors transmit the detected temperature data to the temperature monitoring processor in real time; The simulation loading subsystem includes a gantry mechanism and a vertical loading mechanism 16. The gantry mechanism includes two groups of gantry rails 15 and a gantry body 17. The two groups of gantry rails 15 are symmetrically arranged on both sides of the track 3. The gantry body 17 moves forward and backward along the gantry rails 15. The vertical loading mechanism 16 includes two groups of vertical loading devices and a pressure beam 2. The fixed end of the vertical loading device is fixedly arranged on the gantry body 17, and the pressure beam 2 is erected on the track 3. The free end of the vertical loading device presses down the pressure beam 2 at a set frequency through the pressure column 1, and the pressure column 1 directly bears the static load and dynamic load output by the vertical loading device.

[0026] The present invention systematically and scientifically restores and simulates the physical process of the cold-region high-speed railway subgrade system under the action of train loads, accurately obtains the changing laws of the physical and mechanical properties of the subgrade fill of the cold-region high-speed railway subgrade system under the comprehensive influence of moisture field, temperature field and dynamic load, and has extremely strong scientific research application value; it plays a certain guiding role in the anti-freezing design, construction and post-damage diagnosis and treatment of high-speed railway subgrades; the present invention can apply static loads and dynamic loads to simulate the different states of the high-speed railway subgrade in normal operation; the present invention can monitor the internal force changes of each layer inside the high-speed railway subgrade to explore the process and causes of problems during use; the present invention can achieve macroscopic monitoring of the harm of frozen soil changes to the high-speed railway subgrade, thereby obtaining prevention and control measures and improving the durability and stability of the high-speed railway subgrade in frozen soil areas; the present invention can monitor the content of unfrozen water in the subgrade to study the relationship between the unfrozen water content and mechanical properties of the high-speed railway subgrade under different freezing states in seasonal frozen soil areas.

[0027] Optionally, in a possible implementation, the refrigeration mechanism includes two groups of independently operated condensing tubes and an external refrigeration device, and the two groups of condensing tubes are symmetrically arranged on both sides of the roadbed mechanism.

[0028] Optionally, in a possible embodiment, an insulation plate 9 is provided on the outside of the condenser of the present invention, and the minimum test temperature of the test system is designed to be -20°C, and the test temperature can be set according to the target simulated ambient temperature or freeze-thaw rate requirements; since the condenser 10 is located between the roadbed structure and the insulation plate 9, the moisture in the air will condense into liquid water in the interlayer during operation. In order to prevent water accumulation in the interlayer from affecting the durability of the roadbed structure and the insulation plate 9, a drainage pipe is provided at the lower part of the interlayer.

[0029] Optionally, in a possible implementation, the refrigeration mechanism further includes a plurality of cooling fans arranged on the left and right sides of the roadbed mechanism, and the cooling fans are used to assist in cooling the surface of the high-speed railway roadbed to improve the simulation realism.

[0030] Optionally, in one possible embodiment, an energy isolation and shock absorption layer 20 is provided around the retaining pit 14, and the energy isolation and shock absorption layer 20 includes an inner retaining steel plate 26, a sliding plate 27, a reset spring block 28 and an outer retaining steel plate from the inside to the outside. The inner retaining steel plate 26 and the outer retaining steel plate are both slidably connected to the sliding plate 27, and the two sides of the reset spring block 28 are against the inner retaining steel plate 26 and the outer retaining steel plate. When there is interfering vibration in the soil around the test system, the inner retaining steel plate 26 and the outer retaining steel plate on the energy isolation and shock absorption layer 20 slide relative to each other to prevent the interfering vibration from being transmitted to the inside of the test system. At the same time, the reset spring block 28 makes the sliding plate 27 return to the equilibrium position; the energy isolation and shock absorption layer 20 should be first arranged on the bottom and side walls of the retaining pit 14 according to the plan before establishing the roadbed structure.

[0031] Optionally, in a possible implementation, the temperature sensor is a PT100 temperature sensor, which has the advantage that the temperature sensor is a contact temperature sensor. Compared with the same type of temperature sensors, it has higher accuracy and a wider applicable temperature range. The temperature sensor measurement range of this experimental platform is -200°C to 850°C, and the measurement accuracy is (0.15+0.002) degrees Celsius, which can meet the temperature measurement requirements in the experiment; the temperature sensors are arranged in double rows on the same horizontal plane, with a spacing of 4m between two adjacent ones; one layer is arranged on the roadbed layer 7, the roadbase layer 8, the subsoil layer 13 and the surface layer of the roadbed structure.

[0032] Optionally, in a possible implementation, in order to ensure the confining pressure conditions of the high-speed railway roadbed under normal working conditions required by the test system under loading conditions, a maintenance pit on the outside of the roadbed structure is filled with soil with a certain density, a hydraulic oil pipeline 19 with a diameter of 30 cm is buried in the maintenance pit, and multiple groups of hydraulic oil interfaces 18 are arranged in parallel on both sides to facilitate the operation of the hydraulically driven vertical loading mechanism 16 in the experiment.

[0033] Optionally, in a possible implementation, multiple groups of soil pressure sensors 29 are set in the concrete base layer 6, the road base layer 8 and the subsoil layer 13, with a total of 3 soil pressure sensors 29 in each layer, and the vertical distance between adjacent sensors from top to bottom is 1.0m, so as to meet the testing requirements of various indicators of model dynamic feedback in the experiment.

[0034] Optionally, in a possible implementation, the moisture monitoring mechanism further includes a plurality of groups of resistivity probes buried in the roadbed mechanism; the resistivity probes include electrodes, temperature sensors, inclinometers, seismic detectors, pore pressure sensors, surface friction sensors and cone tips; each group of resistivity probes can detect changes in soil resistivity within a range of 10m in the same soil layer, so resistivity probes are buried in the roadbed layer and the subsoil layer respectively; since the longitudinal dimension of the roadbed physical model subsystem is relatively large, two resistivity test areas are respectively set at both ends of the test platform, and each test area is divided into a roadbed layer and a subsoil layer, and a total of two groups of resistivity probes are tested; in order to eliminate mutual interference of the electric field between the resistivity probes, the horizontal spacing of the resistivity probes should be greater than 6m and they cannot be enabled at the same time during the test; in order to ensure that the electric field generated by the resistivity probes is not affected by the conductivity of the energy isolation layer material outside the model, an insulating polyethylene plate is attached to the inner side of the model energy isolation and shock absorption layer 20 to ensure the validity of the measured data; The resistivity probe has a built-in unfrozen water content calculation model, which is used to calculate the unfrozen water content measured by the resistivity probe, as follows: First, the length of the microelement is taken as L (L=1), and the resistivity of the soil (s), water (e), and gas (g) in the roadbed structure in the experiment can be obtained from the resistivity probe and expressed as R s , R w , R g Considering the difference in unfrozen water content and the uneven distribution, the microelement a of the unfrozen water content is as follows: Figure 7 As shown; Assume that the conductivity coefficient of the soil is E, the porosity of the soil is n; Assume that the free water resistivity of the part connected in parallel with the soil is N, and the part connected in series is defined as M; Therefore, the following formula is obtained; (1) (2) (3) (4) (5) (6) in is the dry density of the microelement, is the solid length of the parallel part of the soil in the microelement, is the liquid length of the parallel part of the soil in the microelement, is the unfrozen length of the soil in the microelement, is the length of the liquid part in series with the soil in the microelement, is the solid length of the soil part in series in the microelement, is the gaseous length of the soil series part in the microelement, is the liquid density of the parallel part of the soil in the microelement, is the unfrozen water content measured by the resistivity probe; From formulas (1)-(6), we can get the following formula: (7) (8) (9) (10) (11) The total resistivity of microelement a is R a , then: (12) is the liquid resistivity of the parallel part of the soil in the microelement, It is the solid resistivity of the parallel part of the soil in the microelement; Substituting formula (7)-(11) into formula (12), we get: (13) In formula (13) is the density of the solid state; (14) is the density of the liquid; (15) (16) Combining formulas (13)-(16), we have: (17) (18) Finally, the unfrozen water content measured by the resistivity probe is obtained. ; Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A physical model test system for high-speed railway subgrade in severe cold and water-rich environment, characterized in that: It includes a roadbed physical model subsystem, a moisture field control and monitoring subsystem, a temperature field temperature control and monitoring subsystem, and a simulated loading subsystem. The roadbed physical model subsystem is used to simulate the response law of the high-speed railway to the dynamic load and the cold environment during operation. The moisture field control and monitoring subsystem is used to simulate the influence of environmental changes on the moisture content of the filling material in the roadbed and monitor the unfrozen water content in the roadbed. The temperature field temperature control and monitoring subsystem is used to simulate the temperature state of the high-speed railway roadbed in the cold environment and monitor the temperature field changes of the filling material in the roadbed. The simulated loading subsystem is used to simulate the physical change process of the high-speed railway roadbed under the train load in the cold environment, wherein: The roadbed physical model subsystem includes a retaining pit and a roadbed structure of a rectangular parallelepiped structure. The roadbed structure is arranged in the retaining pit, and the roadbed structure includes a track, a track plate, a mortar cushion layer, a concrete bottom layer, a roadbed layer, a roadbed layer, and a subsoil layer in order from top to bottom; The moisture field control and monitoring subsystem includes a moisture supply mechanism and a moisture monitoring mechanism. The moisture supply mechanism is used to simulate the moisture field change of the cold region high-speed railway subgrade affected by the surrounding environment during service. The moisture supply mechanism is arranged directly below the subgrade mechanism. The moisture monitoring mechanism is used to monitor the change of the moisture content of the filling material in the subgrade and the unfrozen water content in the subgrade. The temperature field control and monitoring subsystem includes a refrigeration mechanism and a temperature monitoring mechanism. The refrigeration mechanism is used to cool the roadbed physical model subsystem. The temperature monitoring mechanism monitors the temperature state of the high-speed railway roadbed in service in a simulated cold environment and the temperature field changes of the filler in the roadbed.

2. According to the severe cold and water-rich environment high-speed railway subgrade physical model test system of claim 1, it is characterized by: The water replenishment mechanism includes a water replenishment tank top plate, a water replenishment tank body and a water replenishment tank bottom plate. The water replenishment tank body is provided with multiple groups of internal partition beams for support. Water replenishment holes connected to the roadbed mechanism are evenly distributed on the water replenishment tank top plate. The water replenishment tank body is provided with a water inlet and an exhaust port connected to the outside.

3. According to the severe cold and water-rich environment high-speed railway subgrade physical model test system of claim 2, it is characterized in that: The moisture monitoring mechanism includes multiple groups of humidity sensors and moisture monitoring processors arranged in the roadbed mechanism. The multiple groups of humidity sensors are signal-connected to the moisture monitoring processor. The humidity sensors transmit the detected humidity data to the moisture monitoring processor in real time.

4. The physical model test system for high-speed railway subgrade in severe cold and water-rich environment according to claim 1 is characterized in that: The refrigeration mechanism comprises a condenser arranged in the soil of the roadbed mechanism and an external refrigeration device, and the refrigeration device cools the roadbed mechanism to a set temperature through the condenser.

5. A physical model test system for high-speed railway subgrade in severe cold and water-rich environment according to claim 4, characterized in that: The refrigeration mechanism comprises two groups of independently operated condensing pipes and an external refrigeration device, and the two groups of condensing pipes are symmetrically arranged on both sides of the roadbed mechanism.

6. A physical model test system for high-speed railway subgrade in severe cold and water-rich environment according to claim 5, characterized in that: The refrigeration mechanism also includes a plurality of cooling fans arranged on the left and right sides of the roadbed mechanism.

7. The physical model test system for high-speed railway subgrade in severe cold and water-rich environment according to claim 1 is characterized in that: The temperature monitoring mechanism includes multiple groups of temperature sensors and a temperature monitoring processor arranged in the roadbed mechanism. The multiple groups of temperature sensors are connected to the temperature monitoring processor by signal. The temperature sensors transmit the detected temperature data to the temperature monitoring processor in real time.

8. The physical model test system for high-speed railway subgrade in severe cold and water-rich environment according to claim 1 is characterized in that: The simulation loading subsystem includes a gantry mechanism and a vertical loading mechanism. The gantry mechanism includes two groups of gantry tracks and a gantry frame body. The two groups of gantry tracks are symmetrically arranged on both sides of the tracks. The gantry frame body moves forward and backward along the gantry tracks. The vertical loading mechanism includes two groups of vertical loading devices and a pressure beam. The fixed end of the vertical loading device is fixedly arranged on the gantry frame body, and the pressure beam is set on the track. The free end of the vertical loading device presses the pressure beam down at a set frequency through a pressure column, and the pressure column directly bears the static load and dynamic load output by the vertical loading device.

9. The physical model test system for high-speed railway subgrade in severe cold and water-rich environment according to claim 1 is characterized in that: An energy isolation and shock absorption layer is provided around the enclosure pit, which includes an inner enclosure steel plate, a sliding plate, a reset spring block and an outer enclosure steel plate from the inside to the outside. The inner enclosure steel plate and the outer enclosure steel plate are both slidably connected to the sliding plate, and the two sides of the reset spring block are against the inner enclosure steel plate and the outer enclosure steel plate.

10. The physical model test system for high-speed railway subgrade in severe cold and water-rich environment according to claim 1 is characterized in that: The moisture monitoring mechanism also includes multiple groups of resistivity probes buried in the roadbed mechanism; the resistivity probes include electrodes, temperature sensors, inclinometers, seismic detectors, pore pressure sensors, surface friction sensors and cone tips; the resistivity probes have a built-in unfrozen water content calculation model for calculating the unfrozen water content measured by the resistivity probes, as follows: First, the length of the microelement is taken as L. The resistivity of the soil, water, and air in the roadbed structure in the experiment can be obtained from the resistivity probe and expressed as R s , R w , R g ; Assume that the conductivity coefficient of the soil is E, the porosity of the soil is n; Assume that the free water resistivity of the part connected in parallel with the soil is N, and the part connected in series is defined as M; Therefore, the following formula is obtained; （1） （2） （3） （4） （5） （6） in is the dry density of the microelement, is the solid length of the parallel part of the soil in the microelement, is the liquid length of the parallel part of the soil in the microelement, is the unfrozen length of the soil in the microelement, is the length of the liquid part in series with the soil in the microelement, is the solid length of the soil part in series in the microelement, is the gaseous length of the soil series part in the microelement, is the liquid density of the parallel part of the soil in the microelement, is the unfrozen water content measured by the resistivity probe; From formulas (1)-(6), we can get the following formula: （7） （8） （9） （10） （11） The total resistivity of microelement a is R a , then: （12） is the liquid resistivity of the parallel part of the soil in the microelement, is the solid resistivity of the parallel part of the soil in the microelement; Substituting formula (7)-(11) into formula (12), we get: （13） In formula (13) is the density of the solid state; （14） is the density of the liquid; （15） （16） Combining formulas (13)-(16), we have: （17） （18） Finally, the unfrozen water content measured by the resistivity probe is obtained. .

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