CN110749517B - Model test method for dynamic characteristics of roadbed soil under circulating humidification effect - Google Patents
Model test method for dynamic characteristics of roadbed soil under circulating humidification effect Download PDFInfo
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0236—Other environments
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
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Abstract
The invention discloses a model test device and a method for dynamic characteristics of roadbed soil under the action of circulating humidification, wherein the simulation test device comprises: assembling a model box; the roadbed model is filled in the combined mould box; the rainfall simulation system is used for carrying out spray humidification on the upper part of the roadbed model; the evaporation drying simulation system is used for dehumidifying the roadbed model; the water level control system is used for supplying water to the interior of the roadbed model and controlling the height of the water level in the roadbed model; the roadbed humidity monitoring system is used for monitoring the roadbed soil humidity at different depths in the roadbed model; the power loading system is used for carrying out power loading on the roadbed model; and the dynamic stress and dynamic deformation testing system is used for detecting the dynamic stress and dynamic deformation conditions of the roadbed model under the dynamic loading condition. The model test device and the method can analyze the change rule of the dynamic characteristics of the roadbed soil under the humidity cyclic change, and provide a theoretical basis for guaranteeing the long-term performance of the roadbed in the damp and hot area.
Description
Technical Field
The invention relates to the technical field of road and railway roadbed engineering, in particular to a model test device and a method for dynamic characteristics of roadbed soil under the action of circulating humidification caused by rainfall evaporation and water level elevation.
Background
After the construction of the roadbed, the roadbed is exposed to the natural environment for a long time, particularly in the humid and hot rainy areas in the south, and due to the alternate action of rainfall and evaporation and the continuous rising and falling of underground water level, the interior of the roadbed is subjected to a cyclic humidification process of humidification and dehumidification. The strength and deformation of the roadbed soil can change along with the humidity in each circulation process, and the roadbed soil can show certain performance decay after undergoing a plurality of circulating humidification paths. Meanwhile, as the scale of the constructed expressway and the scale of the expressway and the expressway tend to be high-speed and heavy-load, the dynamic characteristic of the roadbed soil has more and more obvious influence on the service performance of the roadbed structure. In recent years, due to the combined action of humidity cycle change and traffic dynamic load, the problems of uneven settlement, longitudinal crack, settlement and the like of a roadbed in a hot and humid region in south are increasingly prominent, the workload of road maintenance is increased greatly, and the driving safety and the comfort degree are seriously influenced.
Based on this, many researchers have developed triaxial tests and model test studies on the static and dynamic characteristics of roadbed soil. For triaxial test research, at present, samples with different humidity are mostly prepared directly for testing, and the humidity change of the samples is not consistent with actual engineering, so that the authenticity of a test result is influenced. In the roadbed model test, the research on the influence of the humidification and dehumidification cycle on the roadbed mostly focuses on the static characteristic, mainly relating to the evolution of roadbed surface cracks, the attenuation of shear strength, the stability of side slopes and the like. The model test of the road base dynamic characteristics by considering the humidity change mainly has the following problems: (1) how to ensure that the moisture content of the road foundation soil after multiple humidification and dehumidification cycles is the same as that of the road foundation soil during the first cycle; (2) how to reduce the subgrade cracking caused by uneven reduction of the humidity on the subgrade surface and inside the subgrade; (3) how to accurately measure the dynamic stress and dynamic deformation of the roadbed, the research on the dynamic characteristics of the roadbed usually does not consider the influence of humidity change.
Therefore, it is necessary to develop a model test apparatus and method capable of simulating the influence of the circulating humidification caused by the evaporation of rainfall and the rise and fall of the groundwater level on the dynamic characteristics (acceleration, moving soil pressure and moving displacement) of the roadbed soil.
Disclosure of Invention
The invention mainly aims to provide a model test device and a method for roadbed soil dynamic characteristics under the action of circulating humidification.
In order to achieve the above object, according to one aspect of the present invention, there is provided a model test apparatus for dynamic characteristics of roadbed soil under the action of circulation humidification, the simulation test apparatus comprising:
the bottom of the combined mould box is provided with a water outlet;
the roadbed model is filled in the combined mould box;
the rainfall simulation system is erected at the upper part of the combined model box and is used for carrying out spray humidification on the upper part of the roadbed model;
the evaporation drying simulation system is used for evaporating the moisture in the roadbed model to dehumidify the roadbed model;
the water outlet end of the water level control system extends into the roadbed model, and the water level control system is used for supplying water to the interior of the roadbed model and controlling the water level height of the interior of the roadbed model;
the roadbed humidity monitoring system is buried in the roadbed model and is used for monitoring the roadbed soil humidity at different depths in the roadbed model;
the power loading system is arranged on the roadbed model and is used for carrying out power loading on the roadbed model;
and the dynamic stress and dynamic deformation testing system is arranged on the upper part and inside the roadbed model and is used for detecting the dynamic stress and dynamic deformation conditions of the roadbed model under the dynamic loading condition.
Further, the split mold box is composed of a steel plate on the outer side and an aluminum plate arranged on the inner side of the steel plate.
Further, the evaporation drying simulation system comprises an electric heating plate, and the electric heating plate is arranged between the steel plate and the aluminum plate.
Furthermore, the rainfall simulation system comprises a support erected on the upper portion of the combined model box, a plurality of rainfall simulation water inlet pipes are mounted on the support, a plurality of atomization nozzles are mounted on the rainfall simulation water inlet pipes, and a water meter and a water valve switch are arranged on the rainfall simulation water inlet pipes.
Further, evaporation drying analog system still includes a plurality of sun lamps, and the sun lamp is installed on rainfall simulation inlet tube, and sun lamp and atomizer interval setting in turn.
Furthermore, the water level control system comprises a sand tank buried in the roadbed model, a water pipe with a yarn winding hole is buried in the sand tank, one end of the water pipe with the yarn winding hole is connected with a water supply tank through a pipeline, and a water level control switch is mounted on the pipeline.
Further, the roadbed model comprises a cement stabilized gravel layer, a gray soil layer and a red clay layer which are sequentially filled in the combined model box from top to bottom, and a drainage ditch is arranged on the toe side of the roadbed model.
Further, dynamic stress and dynamic deformation test system includes displacement sensor, accelerometer, moves soil pressure cell and moves the displacement meter, and displacement sensor and accelerometer install the upper surface at cement stabilization gravel layer, and the quantity that moves soil pressure cell and move the displacement meter is a plurality of, and a plurality of move soil pressure cells and move the displacement meter and install between cement stabilization gravel layer and grey soil layer, between grey soil layer and the red clay layer and the different degree of depth department on red clay layer.
Furthermore, the roadbed humidity monitoring system comprises a plurality of humidity sensors buried at different depths of the roadbed model; the power loading system is an MTS electro-hydraulic servo system.
According to another aspect of the invention, a model test method for dynamic characteristics of roadbed soil under the action of circulation humidification is provided, a simulation test is carried out by adopting the model test device for dynamic characteristics of roadbed soil, and the model test method comprises the following steps:
s1: determining the required soil amount according to the size of the combined model box, filling roadbed fillers in each layer by adopting a layered compaction method, burying a roadbed humidity monitoring system, a dynamic stress and dynamic deformation testing system and a water level control system in a pre-buried position until reaching a preset height, and completing roadbed model filling to form a roadbed model;
s2: starting a water level control system to inject water into the roadbed model, and stopping injecting water when the water level in the roadbed model reaches a preset lowest water level; meanwhile, starting a rainfall simulation system to perform spray humidification on the upper part of the roadbed model;
s3: assembling the thermal infrared imager, and placing a lens of the thermal infrared imager in an area where the roadbed model is located to perform infrared thermal imaging; starting a power loading system, setting loading parameters according to the actual traffic level on site, simulating traffic loads with different frequencies and amplitudes, and completing the power loading of the preset minimum water level working condition;
s4: repeating the step S2 and the step S3, completing the power loading of each working condition from the lowest preset water level to the highest preset water level, and simulating the influence of the underground water level on the power characteristics of the roadbed;
s5: after the highest water level power loading is completed, a water outlet is opened to discharge water in the roadbed model; according to the actually measured temperature and the actually measured evaporation capacity, an evaporation drying simulation system is started to carry out evaporation drying on the inner part and the upper surface of the roadbed model, so that the inner part and the upper surface temperature are close to the actually measured temperature; when the reading of the roadbed humidity monitoring system reaches the actual humidity, closing the evaporation drying simulation system, standing until the reading of the roadbed humidity monitoring system does not change any more, and finishing the roadbed dehumidification process;
s6: the roadbed model finishes a primary humidification and dehumidification cycle from the highest preset water level to the evaporation and drying process, the step S2 and the step S5 are repeated from the second humidification and dehumidification cycle without considering the high influence of the water level, the multiple alternate cycle process is finished, and the reading of the roadbed humidity monitoring system is monitored in real time after each cycle is finished to ensure that the roadbed model is the same as the roadbed model in the first cycle;
s7: repeating the steps S3 and S4 after the specified humidification and dehumidification cycle number is reached, and simulating the influence of the humidification and dehumidification cycle on the road-based power characteristics;
s8: by comparing a thermal imaging image obtained by the thermal infrared imager with a test result of the dynamic stress and dynamic deformation test system, a mathematical relationship between the thermal imaging image and the test result is established, and then the change rule of the dynamic characteristic of the whole roadbed part under the humidity cyclic change is analyzed.
By applying the technical scheme of the invention, the road foundation soil is humidified through the water level control system and the rainfall simulation system; the humidity of the roadbed soil can be reduced through the water level control system and the evaporation drying simulation system; monitoring the change of the water content of the soil body in real time by utilizing a roadbed humidity monitoring system; monitoring the change rule of dynamic stress, dynamic acceleration and accumulated deformation of roadbed soil by a dynamic stress and dynamic deformation test system; the model test device can analyze the change rule of the dynamic characteristics of the roadbed soil under the humidity cyclic change, and provides a theoretical basis for long-term performance guarantee of the roadbed in the damp and hot area.
The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic structural diagram of a model testing apparatus according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a rainfall simulation system in the model testing apparatus according to the embodiment of the present invention.
Fig. 3 is a schematic layout view of sand tanks of a water level control system in the model test apparatus according to the embodiment of the present invention.
FIG. 4 is a schematic diagram of the change of the humidification and dehumidification circulating water level of the model test device in the embodiment of the invention.
Wherein the figures include the following reference numerals:
10. assembling a model box; 11. a water outlet; 12. a steel plate; 13. an aluminum plate; 20. a roadbed model; 21. a cement stabilized rubble layer; 22. a grey soil layer; 23. a red clay layer; 24. a drainage ditch; 30. a rainfall simulation system; 31. a support; 32. a rainfall simulation water inlet pipe; 33. an atomizing spray head; 34. a water meter; 35. a water valve switch; 41. an electrical heating plate; 42. a sun lamp; 50. a water level control system; 51. a sand tank; 52. a pipeline; 53. a water supply tank; 54. a water level control switch; 60. a humidity sensor; 70. A power loading system; 81. a displacement sensor; 82. an accelerometer; 83. moving soil pressure cell; 84. a dynamic displacement meter.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The use of the words "a" or "an" and the like in the description and claims of the present patent application do not denote a limitation of quantity, but rather denote the presence of at least one.
Referring to fig. 1 to 3, a model test device for dynamic characteristics of roadbed soil under the action of circulation humidification according to an embodiment of the invention mainly comprises: the device comprises a combined mould box 10, a roadbed model 20, a rainfall simulation system 30, an evaporation drying simulation system, a water level control system 50, a roadbed humidity monitoring system, a power loading system 70 and a dynamic stress and dynamic deformation testing system. Wherein, the bottom of the combined mould box 10 is provided with a water outlet 11; the roadbed model 20 is filled in the combined mould box 10; a rainfall simulation system 30 is erected on the upper part of the combined model box 10, and the rainfall simulation system 30 is used for performing spray humidification on the upper part of the roadbed model 20; the evaporation drying simulation system is used for evaporating the moisture in the roadbed model 20 so as to dehumidify the roadbed model 20; the water outlet end of the water level control system 50 extends into the interior of the roadbed model 20, and the water level control system 50 is used for supplying water to the interior of the roadbed model 20 and controlling the water level height of the interior of the roadbed model 20; the roadbed humidity monitoring system is buried in the roadbed model 20 and is used for monitoring the roadbed soil humidity at different depths in the roadbed model 20; the power loading system 70 is arranged on the roadbed model 20 and is used for carrying out power loading on the roadbed model 20; the dynamic stress and dynamic deformation testing system is arranged on the upper part and inside the roadbed model 20 and is used for detecting the dynamic stress and dynamic deformation of the roadbed model 20 under the dynamic loading condition.
The model test device for the dynamic characteristics of the roadbed soil under the circulating humidification effect humidifies the roadbed soil (the roadbed model 20) through the water level control system 50 and the rainfall simulation system 30; the humidity of the roadbed soil can be reduced through the water level control system 50 and the evaporation drying simulation system; monitoring the change of the water content of the soil body in real time by utilizing a roadbed humidity monitoring system; monitoring the change rule of dynamic stress, dynamic acceleration and accumulated deformation of roadbed soil by a dynamic stress and dynamic deformation test system; the model test device can analyze the change rule of the dynamic characteristics of the roadbed soil under the humidity cyclic change, and provides a theoretical basis for long-term performance guarantee of the roadbed in the damp and hot area.
Specifically, referring to fig. 1, 2 and 3, in the present embodiment, the split mold box 10 is composed of a steel plate 12 on the outer side and an aluminum plate 13 disposed on the inner side of the steel plate 12. The evaporation drying simulation system includes an electric heating plate 41, the electric heating plate 41 being disposed between the steel plate 12 and the aluminum plate 13; the evaporation drying simulation system further comprises a plurality of solar lamps 42, the solar lamps 42 are connected with a temperature control switch (not shown in the figure), the solar lamps 42 are installed on the rainfall simulation water inlet pipe 32, and the solar lamps 42 and the atomizing nozzles 33 are alternately arranged at intervals. So set up, be divided into two parts with evaporation drying analog system, partly for being located the sun lamp 42 of road bed model 20 top, another part is for being located the electric heating board 41 between steel sheet 12 and the aluminum plate 13, carries out evaporation drying to road bed model 20 through sun lamp 42 and electric heating board 41 together, can reduce the inside and outside humidity of road bed soil and reduce the inhomogeneous road bed fracture that causes, can accelerate the dehumidification speed of road bed soil simultaneously.
Referring to fig. 1 and 2, in the present embodiment, the rainfall simulation system 30 includes a support 31 erected on the upper portion of the composite model box 10, a plurality of rainfall simulation inlet pipes 32 are installed on the support 31, a plurality of atomizing nozzles 33 are installed on each rainfall simulation inlet pipe 32, a water meter 34 and a water valve switch 35 are further installed on each rainfall simulation inlet pipe 32, and a water supply source adopts tap water. Thus, the atomized water can be uniformly atomized and humidified on the upper surface of the roadbed model 20, and the amount of atomized water can be conveniently controlled.
Referring to fig. 1 and 3, in the present embodiment, the water level control system 50 includes a sand tank 51 buried inside the roadbed model 20, a yarn-entangled perforated water pipe buried in the sand tank 51, one end of the yarn-entangled perforated water pipe being connected to a water supply tank 53 through a pipe 52, and a water level control switch 54 installed on the pipe 52. Specifically, the sand grooves 51 are formed in multiple layers, and the multiple sand grooves 51 are buried at different depths inside the roadbed model 20. Thus, water can be conveniently and rapidly injected into the roadbed model 20. When burying sand groove 51 underground, the buried depth of control sand groove 51 and the position of burying underground of the foraminiferous water pipe of kinking yarn make the clay can't get into the inslot water pipe, like this, can accelerate the moisture injection and can guarantee that the roadbed soil absorbs water evenly.
Referring to fig. 1, in the present embodiment, a roadbed model 20 includes a cement stabilized gravel layer 21, a soil layer 22 and a red clay layer 23 which are sequentially filled in a combination mold 10 from top to bottom, and a drainage ditch 24 is provided on a toe side of the roadbed model 20. The subgrade slope rate of the subgrade model is set to be 1: 1.5.
Referring to fig. 1, in the present embodiment, the dynamic stress and dynamic deformation testing system includes a displacement sensor 81, an accelerometer 82, a dynamic soil pressure cell 83, and a dynamic displacement meter 84; wherein, displacement sensor 81 and accelerometer 82 install the upper surface at cement stabilized rubble layer 21, move soil pressure cell 83 and move the quantity of displacement meter 84 and be a plurality ofly, and a plurality of move soil pressure cells 83 and move the displacement meter 84 and install between cement stabilized rubble layer 21 and grey soil layer 22, between grey soil layer 22 and red clay layer 23 and the different degree of depth department in red clay layer 23. So set up, be favorable to accurate survey road bed soil's dynamic stress and dynamic deformation.
Referring to fig. 1, in the present embodiment, the roadbed humidity monitoring system includes a plurality of humidity sensors 60 buried at different depths of the roadbed model 20, and the moisture content of the roadbed soil after multiple humidification and dehumidification cycles is the same as that during the first cycle through the combined action of the humidity sensors 60, the water level control system 50 and the evaporation and drying simulation system; the power loading system 70 employs a set of MTS electro-hydraulic servo systems.
The model test method for the dynamic characteristics of the roadbed soil under the combined action of rainfall evaporation and water level elevation by adopting the model test device comprises the following steps:
step one, determining the required soil amount according to the size of a model, and filling roadbed fillers of all layers by adopting a soil layering compaction method, wherein the filling height of each layer is controlled to be 20cm, and the compaction degree is controlled to be 96%; when the sand tank 51 is buried, the depth of the sand tank 51 is 20cm, the diameter of the water pipe with the yarn winding hole is 6cm, and the sand tank is buried in the middle position, namely 7cm above and below the sand tank 51, so that the water injection can be accelerated, and the uniform water absorption of the roadbed soil can be ensured; embedding other test elements at the pre-embedding position until the pre-embedding position reaches a preset height, and completing model filling; wherein the thickness of the cement stabilized rubble layer 21 is 20cm, the thickness of the gray soil layer is 40cm, and the thickness of the red clay layer is 245 cm;
step two, starting a water level control switch 54 to inject water, keeping the water level of a water supply tank 53 unchanged in the water injection process, and starting a rainfall simulation system 30 to humidify the upper part of the roadbed model 20; specifically, the water injection is stopped when the reading conversion value of the water meter 34 reaches the actual rainfall by controlling the water valve switch 35 and reaches the preset water level of-2.55 m, and the spraying is stopped when the reading of the humidity sensor 60 above the preset water level is basically consistent with the reading of the humidity sensor 60 below the water level, and the water meter is kept still for 12 hours;
step three, assembling the thermal infrared imager, placing a lens in the area where the roadbed model 20 is located, adjusting the distance, the angle and the focal length to ensure that the instrument is fixed and started after the imaging effect reaches the best; starting an MTS electro-hydraulic servo system, setting a cyclic loading parameter, and finishing the power loading of a preset water level of-2.55 m as shown in a table 2;
step four, repeating the step two and the step three, completing the dynamic loading of each working condition shown in the table 1, and simulating the influence of the underground water level on the dynamic characteristic of the roadbed;
step five, after the power loading of the water level of-0.6 m is completed, firstly opening a water outlet 11 of the combined mould box 10, discharging underground water, simultaneously starting a solar lamp 42 to irradiate and an electric heating plate 41 to heat according to the situation of temperature and humidity actually measured on site, controlling the temperature of the solar lamp 42 and the temperature of the electric heating plate 41 to be about 30 ℃, when the reading of a dry-humidity sensor 60 reaches the actual humidity, closing an evaporation-drying simulation system, standing for 24 hours until the reading of the dry-humidity sensor 60 is not changed any more, and then completing the roadbed dehumidification process;
step six, after the roadbed soil is subjected to the process from the highest preset water level to the evaporation drying process, completing a primary humidification and dehumidification cycle, starting from a secondary humidification and dehumidification cycle, directly raising the underground water level to-0.6 m in each cycle, then carrying out evaporation drying, not carrying out power loading under other two water level working conditions, repeating the step two and the step five, and completing a multiple alternating cycle process;
step seven, after the specified humidification and dehumidification cycle times are reached, repeating the step three, and simulating the influence of the humidification and dehumidification cycle on the road-based power characteristics; the change of the humidification and dehumidification circulating water level is shown in figure 4;
and step eight, result analysis, namely establishing a mathematical relation between the thermal imaging graph and the power test system result by comparing the thermal imaging graph and the power test system result, and further analyzing the change rule of the power characteristic of the whole roadbed under the humidity cyclic change.
TABLE 1 Water level rise and humidifying dehumidifying cycle test working condition
TABLE 2 different load conditions
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A model test method for dynamic characteristics of roadbed soil under the action of circulating humidification is characterized in that a model test device for dynamic characteristics of roadbed soil is adopted for model test, and the model test device comprises:
the combined model box (10), the bottom of the combined model box (10) is provided with a water outlet (11);
a roadbed model (20) filled in the combined model box (10);
a rainfall simulation system (30) which is erected at the upper part of the combined model box (10), wherein the rainfall simulation system (30) is used for carrying out spray humidification on the upper part of the roadbed model (20);
the evaporation drying simulation system is used for evaporating moisture in the roadbed model (20) to dehumidify the roadbed model (20);
the water level control system (50), the water outlet end of the water level control system (50) extends into the roadbed model (20), and the water level control system (50) is used for supplying water to the interior of the roadbed model (20) and controlling the water level height of the interior of the roadbed model (20);
the roadbed humidity monitoring system is buried in the roadbed model (20) and is used for monitoring the roadbed soil humidity at different depths in the roadbed model (20);
the power loading system (70) is arranged on the roadbed model (20) and is used for carrying out power loading on the roadbed model (20);
the dynamic stress and dynamic deformation testing system is arranged at the upper part and inside the roadbed model (20) and is used for detecting the dynamic stress and dynamic deformation conditions of the roadbed model (20) under the dynamic loading condition;
the model test method comprises the following steps:
s1: determining the required soil amount according to the size of a preset roadbed model (20), filling roadbed fillers of each layer by adopting a layered compaction method, burying the roadbed humidity monitoring system, the dynamic stress and dynamic deformation testing system and the water level control system (50) at a pre-buried position until reaching a preset height, and completing roadbed model filling to form the roadbed model (20);
s2: starting the water level control system (50) to inject water into the roadbed model (20), and stopping injecting water when the water level in the roadbed model (20) reaches a preset lowest water level; simultaneously starting the rainfall simulation system (30) to perform spray humidification on the upper part of the roadbed model (20);
s3: assembling a thermal infrared imager, and placing a lens of the thermal infrared imager in an area where the roadbed model (20) is located to perform infrared thermal imaging; starting the power loading system (70), setting loading parameters according to the actual traffic level on site, simulating traffic loads with different frequencies and amplitudes, and completing the power loading of the preset lowest water level working condition;
s4: repeating the step S2 and the step S3, completing the power loading of each working condition from the lowest preset water level to the highest preset water level, and simulating the influence of the rising of the underground water level on the power characteristics of the roadbed;
s5: after the highest water level power loading is completed, opening the water outlet (11) to discharge water in the roadbed model (20); according to the actually measured temperature and the actually measured evaporation capacity, the evaporation drying simulation system is started to evaporate and dry the inner part and the upper surface of the roadbed model (20), so that the inner part and the upper surface temperature are close to the actually measured temperature; when the reading of the roadbed humidity monitoring system reaches the actual humidity, closing the evaporation drying simulation system, standing until the reading of the roadbed humidity monitoring system does not change any more, and finishing the roadbed dehumidification process;
s6: the roadbed model (20) finishes a primary humidification and dehumidification cycle from the highest preset water level to the evaporation and drying process, the step S2 and the step S5 are repeated from the second humidification and dehumidification cycle without considering the influence of the height of the water level, the multiple alternate cycle process is finished, and after each cycle is finished, the reading of the roadbed humidity monitoring system is monitored in real time to ensure that the roadbed humidity monitoring system is the same as that in the first cycle;
s7: repeating the steps S3 and S4 after the specified humidification and dehumidification cycle number is reached, and simulating the influence of the humidification and dehumidification cycle on the road-based power characteristics;
s8: and establishing a mathematical relationship between a thermal imaging image acquired by the thermal infrared imager and the test result of the dynamic stress and dynamic deformation test system, and further analyzing the change rule of the dynamic characteristic of the whole roadbed part under the humidity cyclic change.
2. The model test method of dynamic characteristics of roadbed soil under the action of circulation humidification as claimed in claim 1, wherein the combined model box (10) is composed of an outer steel plate (12) and an inner aluminum plate (13) arranged on the inner side of the steel plate (12).
3. The model test method of dynamic characteristics of roadbed soil under the action of circulation humidification according to claim 2, wherein the evaporation drying simulation system comprises an electric heating plate (41), and the electric heating plate (41) is arranged between the steel plate (12) and the aluminum plate (13).
4. The model test method for the dynamic characteristics of the roadbed soil under the action of the circulating humidification as claimed in claim 1, wherein the rainfall simulation system (30) comprises a support (31) erected on the upper portion of the combined model box (10), a plurality of rainfall simulation water inlet pipes (32) are installed on the support (31), a plurality of atomization nozzles (33) are installed on the rainfall simulation water inlet pipes (32), and a water meter (34) and a water valve switch (35) are arranged on the rainfall simulation water inlet pipes (32).
5. The model test method for road foundation soil dynamic characteristics under the action of circulation humidification as claimed in claim 4, wherein the evaporation drying simulation system further comprises a plurality of sun lamps (42), the sun lamps (42) are installed on the rainfall simulation water inlet pipe (32), and the sun lamps (42) and the atomizing nozzles (33) are alternately arranged at intervals.
6. The model test method for the dynamic characteristics of the subgrade soil under the action of circulating humidification as claimed in claim 1, wherein the water level control system (50) comprises a sand tank (51) buried inside the subgrade model (20), a water pipe with a yarn winding hole is buried in the sand tank (51), one end of the water pipe with the yarn winding hole is connected with a water supply tank (53) through a pipeline (52), and a water level control switch (54) is mounted on the pipeline (52).
7. The model test method for the dynamic characteristics of the roadbed soil under the action of the circulating humidification as claimed in claim 1, wherein the roadbed model (20) comprises a cement-stabilized gravel layer (21), a lime soil layer (22) and a red clay layer (23) which are sequentially filled in the combined model box (10) from top to bottom, and a drainage ditch (24) is arranged on the toe side of the roadbed model (20).
8. The model test method for the dynamic characteristics of roadbed soil under the action of circulating humidification according to claim 7, wherein the dynamic stress and dynamic deformation test system comprises a displacement sensor (81), an accelerometer (82), a dynamic soil pressure box (83) and a dynamic displacement meter (84), wherein the displacement sensor (81) and the accelerometer (82) are installed on the upper surface of the cement-stabilized gravel layer (21), the number of the dynamic soil pressure box (83) and the dynamic displacement meter (84) is multiple, and the multiple dynamic soil pressure box (83) and the dynamic displacement meter (84) are installed between the cement-stabilized gravel layer (21) and the lime soil layer (22), between the lime soil layer (22) and the red clay layer (23) and at different depths of the red clay layer (23).
9. The model test method of the dynamic characteristics of the roadbed soil under the action of the circulating humidification as claimed in claim 1, wherein the roadbed humidity monitoring system comprises a plurality of humidity sensors (60) buried at different depths of the roadbed model (20); the power loading system (70) is an MTS electro-hydraulic servo system.
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