CN114965174A - Test device and test method for water vapor migration characteristics of unsaturated soil subgrade - Google Patents

Abstract

The application discloses a device and a method for testing moisture migration characteristics of unsaturated soil subgrade, and relates to the technical field of geotechnical engineering. The testing device comprises a model box, a moisture regulating assembly, a first temperature control assembly and a second temperature control assembly, wherein the moisture regulating assembly, the first temperature control assembly and the second temperature control assembly are arranged in the model box; still be provided with humiture measurement subassembly, drainage subassembly and displacement sensor in the model case, displacement sensor is used for detecting the altitude variation of sample, and humiture measurement subassembly is used for measuring the temperature and the humidity of sample in different positions department, and first temperature control subassembly is connected with the drainage subassembly including the device that absorbs water. The influence of water and air migration on the change conditions of the internal performance and the humidity of the roadbed under different working conditions can be simulated, so that the simulation effect is more in line with the engineering practice.

Description

Test device and test method for water vapor migration characteristics of unsaturated soil subgrade

technical field

The present application relates to the technical field of geotechnical engineering, and in particular, to a testing device and a testing method for water vapor migration characteristics of unsaturated soil roadbed.

Background technique

Moisture is the main factor that induces roadbed diseases and performance deterioration. In actual working conditions, the subgrade is affected by climate (rainfall, evaporation), groundwater level and pumping, and its internal water migration is often carried out by liquid and gaseous water simultaneously. On the one hand, groundwater migrates upwards into the subgrade soil in the form of liquid water under capillary action; on the other hand, the gaseous water in the soil also migrates in the soil pores and condenses into subgrade under the action of low temperature on the top surface of the subgrade. water.

At present, most of the research on the change of water occurrence in the subgrade is mainly based on the migration of single-phase liquid water. However, in some arid areas with deep groundwater burial, the influence of gaseous water migration on the subgrade fill is relatively large and cannot be ignored. At present, domestic researches have been carried out on the long-term performance evolution law of subgrade fill under the action of water and gas migration. Since there are many factors involved in theory, multi-field coupling numerical simulation and theoretical derivation are extremely complicated, and it is difficult to obtain better calculation results. Indoor experiments are carried out to study the law of water and vapor migration in roadbeds.

The existing test equipment mainly considers the change law of humidity and performance inside the subgrade soil during the water vapor migration process from two aspects: temperature (temperature difference) and groundwater (fluctuation), which has a certain deviation from the actual engineering conditions of the subgrade. It is impossible to accurately simulate the influence of gaseous moisture migration on the humidity and performance of subgrade under actual working conditions.

SUMMARY OF THE INVENTION

The purpose of this application is to provide a device for testing the water vapor migration characteristics of unsaturated soil roadbed and a testing method thereof, which can simulate the influence of water vapor migration under different working conditions on the internal performance and humidity changes of the roadbed, so that the simulation effect is more in line with Engineering practice.

The embodiments of the present application are implemented as follows:

In one aspect of the embodiments of the present application, there is provided an apparatus for testing water vapor migration characteristics of unsaturated soil roadbed, including a model box, and a moisture adjustment component, a first temperature control component, and a second temperature control component disposed in the model box , wherein the first temperature control component is used to be arranged on the top of the sample, the second temperature control component is used to be arranged on the bottom of the sample, and the moisture adjustment component is arranged on the second temperature control component ; The model box is also provided with a temperature and humidity measurement component, a drainage component and a displacement sensor, the displacement sensor is used to detect the height change of the sample, and the temperature and humidity measurement component is used to measure the sample at The temperature and humidity at different positions, the first temperature control assembly includes a water absorption device, and the water absorption device is connected with the drainage assembly.

Optionally, the first temperature control assembly includes a first temperature controller, and a first temperature adjustment plate connected to the first temperature controller, and the first temperature adjustment plate is connected with stacked heat transfer plates. baffles, the first temperature adjustment plate is connected with one of the heat transfer baffles through a rotatable adjustment support, the heat transfer baffles are respectively provided with through holes, and the two heat transfer baffles rotate with each other, In order to turn on or off the through hole, the first temperature adjustment plate and the rotatable adjustment support member form an accommodating cavity, and the water absorbing device is located in the accommodating cavity.

Optionally, the second temperature control assembly includes a second temperature controller, and a second temperature adjustment plate connected to the second temperature controller, the second temperature adjustment plate is connected to the bottom wall of the model box There are spacers in between.

Optionally, the moisture adjustment assembly includes a water storage tank, and a control valve connected to the water storage tank, the control valve is connected with a water outlet pipe, and the water outlet pipe is connected to the permeable stone arranged on the second temperature adjustment plate. The permeable stone is also connected with a first drainage pipe, the first drainage pipe is connected with the collection box, and the permeable stone is provided with a baffle plate, which is used to allow the passage of water vapor and restrict liquid water Through, the water baffle is used to place the sample.

Optionally, the temperature and humidity measurement assembly includes a data acquisition assembly, and a plurality of probes connected to the data acquisition assembly, and the plurality of probes are used to be inserted in different positions of the sample in the height direction. .

Optionally, the drainage assembly includes a second drainage pipe connected with the water absorbing device, and a condensate water collector connected with the second drainage pipe.

Optionally, the model box includes a box body, and a door body provided on one side of the box body, the door body is provided with a transparent observation port, the box body is provided with a heat insulation layer, and a through hole, The inner ring of the via hole is provided with a sealing ring, and a thermometer is also provided in the box for observing the temperature in the box.

Another aspect of the embodiments of the present application provides a method for testing water vapor transport characteristics of unsaturated soil roadbeds, using any one of the above-described water vapor transport characteristics testing devices for unsaturated soil roadbeds for testing, and the method includes: :

Prepare a roadbed model sample, and wrap the thermal insulation layer on the outer circle of the sample;

Insert the probe of the temperature and humidity test assembly into the sample;

placing the sample on a moisture conditioning assembly and placing a first temperature control assembly on top of the sample;

matching the displacement sensor with the first temperature control assembly;

respectively adjusting the first temperature control assembly, the second temperature control assembly and the moisture adjustment assembly;

Record the data changes of the displacement sensor and the temperature and humidity test assembly.

Optionally, the preparation of the roadbed model sample includes:

Take the soil sample to be tested and carry out an indoor light compaction test to determine the optimal water content and maximum dry density of the soil sample;

The samples are mixed according to the requirements for the compaction degree and water content of the subgrade filler in the actual project;

The soil samples were compacted in two layers.

Optionally, the separately adjusting the first temperature control assembly, the second temperature control assembly and the moisture adjustment assembly includes:

adjusting the temperature of the first temperature control assembly and the second temperature control assembly so that the top and bottom of the sample have a temperature difference;

Regulates the flow of water in the Moisture Conditioning Component, used to simulate water table heights.

The beneficial effects of the embodiments of the present application include:

The device for testing the water vapor migration characteristics of unsaturated soil roadbed and the testing method thereof provided in the embodiments of the present application, through the moisture adjustment component, the first temperature control component and the second temperature control component arranged in the model box, so as to facilitate the simulation of different working conditions. environmental conditions, such as the temperature difference between the surface and interior of the subgrade, and groundwater conditions. When collecting data, through the temperature and humidity measurement components and displacement sensors, while considering the internal humidity and temperature test of the soil during the water vapor migration process, the soil deformation test analysis is also added. Evolution law of performance of unsaturated soil subgrade. In addition, through the cooperation of the water absorption device and the drainage component, the influence of the droplet re-seepage on the experimental accuracy is avoided. By using the above form, the evolution law of subgrade performance under consideration of various working conditions can be accurately obtained, and the whole process simulation of water and gas migration of subgrade under the influence of various complex environments encountered in actual engineering can be carried out, and the unsaturated soil can be fully grasped. The subgrade takes into account the evolution laws of physics, mechanics, deformation and other properties during the two-way flow of water and gas, and provides a strong theoretical support for the later development of targeted subgrade treatment and comprehensive protection of subgrade service performance. And when simulating the influence of water vapor migration under different working conditions on the internal performance and humidity changes of the subgrade, the simulation effect is more in line with the actual engineering.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the following drawings will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic structural diagram of a device for testing the water vapor migration characteristics of an unsaturated soil roadbed provided by an embodiment of the application;

2 is a schematic structural diagram of a first temperature control assembly and a drainage assembly according to an embodiment of the present application;

3 is a schematic structural diagram of a first temperature control assembly provided by an embodiment of the present application;

4 is a schematic structural diagram of a model box provided by an embodiment of the present application;

FIG. 5 is a flowchart of a method for testing water vapor migration characteristics of an unsaturated soil roadbed provided in an embodiment of the present application.

Icon: 100-Testing device for water vapor migration characteristics of unsaturated soil subgrade; 110-Model box; 112-Box body; 114-Door body; 1142-Transparent observation port; 116-Insulation layer; circle; 120-moisture regulation assembly; 122-water storage tank; 124-control valve; 126-permeable stone; 127-first drain pipe; 128-collection box; 129-water baffle; 130-first temperature control assembly;132 - water absorption device; 134 - first temperature controller; 136 - first temperature adjustment plate; 137 - rotatable adjustment support; 138 - heat transfer baffle; 1382 - through hole; 140 - second temperature control assembly; 142 - The second temperature controller; 144 - the second temperature adjustment plate; 150 - the temperature and humidity measuring component; 152 - the data acquisition component; 154 - the probe; 160 - the drainage component; ; 170 - displacement sensor; 180 - spacer; 190 - thermometer.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of the present application, but not all of the embodiments. The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of this application, it should be noted that the orientation or positional relationship indicated by the terms "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or is usually placed when the product of the application is used. The orientation or positional relationship is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present application. In addition, the terms "first" and "second" are only used to differentiate the description and should not be construed as indicating or implying relative importance.

In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "arrangement" and "connection" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection, or It can be connected in one piece; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood in specific situations.

The existing test equipment mainly considers the change law of humidity and performance inside the subgrade soil during the water vapor migration process from two aspects: temperature (temperature difference) and groundwater (fluctuation), which has a certain deviation from the actual engineering conditions of the subgrade. It is impossible to accurately simulate the influence of gaseous moisture migration on the humidity and performance of subgrade under actual working conditions. In view of the above problems, the embodiments of the present application provide the following technical solutions to overcome the above problems.

Referring to FIG. 1 , the present embodiment provides an apparatus 100 for testing water vapor migration characteristics of unsaturated soil subgrade, including a model box 110 , and a moisture adjustment component 120 , a first temperature control component 130 and a second temperature control component 120 disposed in the model box 110 The temperature control assembly 140, wherein the first temperature control assembly 130 is used to be disposed on the top of the sample, the second temperature control assembly 140 is used to be disposed at the bottom of the sample, and the moisture adjustment assembly 120 is disposed on the second temperature control assembly 140 The model box 110 is also provided with a temperature and humidity measurement component 150, a drainage component 160 and a displacement sensor 170, the displacement sensor 170 is used to detect the height change of the sample, and the temperature and humidity measurement component 150 is used to measure the sample at different positions. For temperature and humidity, the first temperature control assembly 130 includes a water absorption device 132 , and the water absorption device 132 is connected with the drainage assembly 160 .

Specifically, the model box 110 is mainly used to ensure the technical performance and operational safety required in the experiment process to provide guarantee, and to avoid being affected by the external environment during the experiment process. By arranging the moisture adjustment component 120 in the model box 110, it is convenient to simulate groundwater to conduct experiments. The first temperature control component 130 and the second temperature control component 140 are mainly used to simulate a situation where there is a temperature difference in the roadbed under actual working conditions. In addition, the temperature and humidity measuring component 150 provided in the model box 110 is mainly used to measure the changes of temperature and humidity in the sample during the experiment. The displacement sensor 170 is used to detect the height change of the sample, so as to know the degree of influence of the temperature change on the shrinkage or expansion of the sample.

By connecting the water absorbing device 132 of the first temperature control assembly 130 to the drainage assembly 160 , in the experiment of water vapor migration characteristics, water vapor is prevented from infiltrating after the top layer condenses to form droplets, which is beneficial to ensure the stability of the experiment. At the same time, by connecting the water absorbing device 132 to the drainage assembly 160, the water in the water absorbing device 132 is prevented from seeping down after saturation. The water absorbing device 132 may be made of a water absorbing material, which is not specifically limited in this embodiment of the present application.

It should be noted that the embodiment of the present application does not specifically limit the number of groups of samples set in the model box 110 . For example, only one group may be set, or two or three groups may be set, as long as each set can be guaranteed The samples can be matched with corresponding devices. For example, when there are two groups of samples, the required first temperature control assembly 130 and the second temperature control assembly 140 also need to be set to two groups.

The device 100 for testing the water vapor transport characteristics of unsaturated soil roadbed provided in the embodiment of the present application uses the moisture adjustment component 120 , the first temperature control component 130 and the second temperature control component 140 arranged in the model box 110 to facilitate the simulation of different Working conditions, such as the temperature difference between the surface and the interior of the subgrade, and groundwater conditions. When collecting data, through the temperature and humidity measurement component 150 and the displacement sensor 170, while considering the internal humidity and temperature test of the soil during the water vapor migration process, the soil deformation test analysis is also added, and the water vapor migration can be obtained at the same time. The evolution law of performance of unsaturated soil subgrade during the process. In addition, by cooperating with the water absorbing device 132 and the drainage assembly 160, the influence of the droplet back infiltration on the experimental accuracy is avoided. By using the above form, the evolution law of subgrade performance under consideration of various working conditions can be accurately obtained, and the whole process simulation of water and gas migration of subgrade under the influence of various complex environments encountered in actual engineering can be carried out, and the unsaturated soil can be fully grasped. The subgrade takes into account the evolution laws of physics, mechanics, deformation and other properties during the two-way flow of water and gas, and provides a strong theoretical support for the later development of targeted subgrade treatment and comprehensive protection of subgrade service performance. And when simulating the influence of water vapor migration under different working conditions on the internal performance and humidity changes of the subgrade, the simulation effect is more in line with the actual engineering.

As shown in FIG. 1 , FIG. 2 and FIG. 3 , the first temperature control assembly 130 includes a first temperature controller 134 and a first temperature adjustment plate 136 connected to the first temperature controller 134 . The stacked heat transfer baffles 138 are connected. The first temperature adjustment plate 136 is connected to one of the heat transfer baffles 138 through a rotatable adjustment support 137. The heat transfer baffles 138 are respectively provided with through holes 1382. The partitions 138 are rotated mutually to make the through holes 1382 connected or closed. The first temperature adjusting plate 136 and the rotatable adjusting support 137 form an accommodating cavity, and the water absorbing device 132 is located in the accommodating cavity.

Specifically, the first temperature controller 134 is mainly used to control the temperature of the first temperature adjustment plate 136 so as to simulate the actual temperature under different working conditions. It can be understood that when the samples are set in two groups, two first temperature adjustment plates 136 can be set correspondingly, and the same first temperature control assembly 130 can be used for control. In addition, the drainage assembly 160 communicates with the water absorption device 132 through the rotatable adjustment support 137 , and a switch knob can be provided on the rotatable adjustment support 137 to control the conduction between the water absorption device 132 and the drainage assembly 160 .

By disposing a heat transfer baffle 138 on the first temperature adjustment plate 136, the heat on the first temperature adjustment plate 136 can be uniformly transferred to the top of the sample through heat transfer. At the same time, by setting the heat transfer baffles 138 in a stacked and mutually rotatable form, when simulating the actual working environment, the through holes 1382 of the heat transfer baffles 138 can be connected to each other, so that the The experimental simulation of the performance change of the subgrade under the closed condition (the subgrade is not closed for drainage or the subgrade is not closed and not drained). It can be understood that when the through holes 1382 of the heat transfer baffle 138 are dislocated to make them cut off, the experimental simulation of the performance change of the roadbed under the closed condition (the roadbed is closed without drainage or the roadbed is closed and drained) can be realized. In this way, the performance change laws such as the internal temperature and humidity of the subgrade fill under different drainage conditions of the upper pavement base can be considered, so that the simulation of the actual working conditions can be realized more comprehensively.

As shown in FIG. 1 , the second temperature control assembly 140 includes a second temperature controller 142 and a second temperature adjustment plate 144 connected with the second temperature controller 142 , and the second temperature adjustment plate 144 is connected to the bottom wall of the model box 110 . A spacer 180 is provided therebetween.

By disposing the spacer 180 between the second temperature adjustment plate 144 and the bottom wall of the model box 110 , the setting of the second temperature adjustment plate 144 is facilitated, and the influence of the model box 110 on the experimental accuracy can be avoided. In order to ensure the stability of the first temperature adjustment plate 136 and the second temperature adjustment plate 144 during use, other areas other than the opposite sides of the two are treated in the form of thermal insulation materials and rubber films to prevent the loss of temperature. to ensure the accuracy of the experiment. In addition, the temperature variation ranges of the first temperature control assembly 130 and the second temperature control assembly 140 are both -30°C to 60°C (the temperature deviation is ±0.01°C, and the temperature fluctuation does not exceed ±0.01°C). The first temperature controller 134 and the second temperature controller 142 externally connected through the model box 110 can set the target temperature, temperature duration and temperature change mode during the test, so as to better simulate the change of the working condition and environment. .

As shown in FIG. 1 , the moisture adjustment assembly 120 includes a water storage tank 122 and a control valve 124 connected to the water storage tank 122 . The control valve 124 is connected with a water outlet pipe, and the water outlet pipe is connected to the permeable stone arranged on the second temperature adjustment plate 144 126 is connected, the permeable stone 126 is also connected with a first drain pipe 127, the first drain pipe 127 is connected with the collection box 128, the permeable stone 126 is provided with a water baffle 129, and the water baffle 129 Liquid water passes through, and the sample is placed on the water baffle 129 .

Specifically, through the control valve 124 connected to the water storage tank 122, it is convenient to control the water replenishment amount, the water replenishment speed, the water replenishment time, and the controllable water replenishment intermittent time. The whole water supply adopts the method of unpressurized water supply. When the water in the water storage tank 122 is insufficient, water can be replenished into the water storage tank 122 . By connecting the water outlet pipe to the permeable stone 126 so as to wet the permeable stone 126, the groundwater situation is simulated. In addition, the water blocking plate 129 is provided on the permeable stone 126 to allow the water vapor to pass through and restrict the passage of liquid water, so as to better simulate the water vapor migration characteristics of the unsaturated soil roadbed. During the experiment, there is water overflowing from the lower part of the sample, which can be drained through the first drain pipe 127 connected to the permeable stone 126 .

It can be understood that the water blocking plate 129 may not be provided on the permeable stone 126, so as to realize the separate migration and joint migration process of water and gas at the bottom of the sample through different setting forms. The above-mentioned form provides conditions for simulating the actual situation of the water vapor migration law in areas with aridity, little rainfall, and deep groundwater burial, and is convenient to provide basic data support for the study of the water vapor migration law.

As shown in FIG. 1 , the temperature and humidity measurement assembly 150 includes a data acquisition assembly 152 and a plurality of probes 154 connected to the data acquisition assembly 152 , and the plurality of probes 154 are used to be inserted in different positions of the sample in the height direction.

For example, when performing an experiment, a probe 154 may be arranged on the sample from top to bottom every 5 cm in the height direction, and the probe 154 may use an anti-corrosion electrode to ensure the reliability of the measurement. In addition, the displacement sensor 170 can also be connected to the data acquisition component 152, so that the real-time monitoring of temperature, humidity and displacement changes can be collected through the data acquisition component 152, so as to facilitate sorting and analysis.

As shown in FIG. 2 , the drainage assembly 160 includes a second drainage pipe 162 connected with the water absorbing device 132 , and a condensed water collector 164 connected with the second drainage pipe 162 to collect moisture absorbed by the water absorbing device 132 .

As shown in FIG. 4 , the model box 110 includes a box body 112 and a door body 114 provided on one side of the box body 112 . The door body 114 is provided with a transparent observation port 1142 , and the box body 112 is provided with a heat insulation layer 116 . As well as the via hole 118 , the inner ring of the via hole 118 is provided with a sealing ring 119 , and a thermometer 190 is also provided in the box body 112 for observing the temperature in the box body 112 .

Specifically, the model box 110 should meet the required technical performance and operational safety protection goals, and realize the functions of heat insulation, heat preservation and moisture retention. For heat insulation and heat preservation, a steel plate can be used to wrap the heat preservation material (ie, a heat insulation layer 116 is provided on the box body 112 ) as a measure to isolate the temperature exchange between the temperature of the test model box 110 and the outside temperature. In addition, in order to meet the visualization requirements during the experiment, the transparent observation port 1142 can be made of transparent resin, aerogel plate and glass, so as to meet the visualization requirements under the condition of ensuring sealing.

In addition, through the door body 114 provided on one side of the box body 112, it is convenient to open and close the door on the side, and to facilitate the taking and placing of the sample. By arranging the via hole 118 on the box body 112, it is convenient for various data collection lines to enter the test box, so as to facilitate the simulation of working conditions and the collection of data. The thermometer 190 provided in the box body 112 can observe the ambient temperature in the box body 112 , so as to avoid affecting the accuracy of the experimental results due to the fluctuation of the ambient temperature in the box body 112 . For example, in order to eliminate the influence of temperature on the experimental results, the temperature in the box 112 can be kept at 25° C., and the thermometer 190 is used to observe whether the ambient temperature in the box 112 meets the requirements.

As shown in FIG. 5 , the embodiment of the present application also discloses a method for testing the water vapor migration characteristics of unsaturated soil roadbed, using the device 100 for testing the water vapor migration characteristics of unsaturated soil roadbed in the foregoing embodiment, and the method includes:

S100, preparing a roadbed model sample, and wrapping a thermal insulation layer on the outer circle of the sample.

Specifically, the roadbed model sample can be prepared into a cylindrical shape. In order to save the test time and allow for comparative observation, two groups of parallel tests were carried out. The column with a height of 35 cm can also be set to other sizes according to actual needs, which is not specifically limited in the embodiment of the present application. When setting the thermal insulation layer, a layer of rubber film can be wrapped around the cylindrical sample first, followed by a layer of flexible thermal insulation material, and the outermost layer can be wrapped with a layer of rubber film. By adopting the above method, the influence of the air temperature inside the model box 110 on the sample temperature can be reduced, and one-way temperature control can be achieved to the greatest extent. At the same time, the double-layer rubber film can effectively ensure the smoothness and full contact of the thermal insulation material, soften and compress the thermal insulation material, and achieve a better thermal insulation effect. The three-layer sandwich arrangement of the rubber film, the flexible thermal insulation material and the rubber film can better achieve thermal insulation and one-way temperature control, and has good experimental results.

S200, insert the probe 154 of the temperature and humidity test assembly into the sample.

S300, placing the sample on the moisture adjustment component 120, and placing the first temperature control component 130 on top of the sample.

S400 , match the displacement sensor 170 with the first temperature control assembly 130 correspondingly.

S500 , adjust the first temperature control assembly 130 , the second temperature control assembly 140 and the moisture adjustment assembly 120 respectively.

S600, record the data variation of the displacement sensor 170 and the temperature and humidity test component.

Using the above method, the internal water vapor migration process of the actual subgrade project can be better simulated, and the water vapor migration law of the subgrade under different temperature gradients, different groundwater conditions, different unsaturated soil subgrade fillings, and initial filling conditions can be obtained intuitively. In addition, the test cost is low and the economic benefit is huge, which is beneficial to obtain the distribution of humidity, deformation and temperature of unsaturated soil subgrade under various water vapor migration conditions, which can effectively guide the construction design of subgrade engineering and improve engineering safety.

In an optional embodiment of the present application, preparing a roadbed model sample includes:

S110, take the soil sample to be tested, and perform an indoor light compaction test to determine the optimal water content and maximum dry density of the soil sample.

S120, the sample is mixed according to the required standards for the compaction degree and water content of the subgrade filler in the actual project.

S130, the soil sample is divided into upper and lower layers and compacted.

Specifically, after determining the optimal water content and maximum dry density of the soil sample, it is convenient for the sample to achieve the best compaction degree, so as to ensure the effect of the experiment. During the compaction process, the soil samples were compacted at the upper and lower sides to facilitate the simulation of roadbeds and embankments, and to ensure that the experimental process matched the actual working conditions.

In an optional embodiment of the present application, adjusting the first temperature control assembly 130, the second temperature control assembly 140 and the moisture adjustment assembly 120 respectively includes:

S510, adjust the temperature of the first temperature control assembly 130 and the second temperature control assembly 140, so that the top and the bottom of the sample have a temperature difference;

S520. Adjust the flow rate of water in the moisture adjustment component 120 for simulating the height of the groundwater level.

Specifically, in practical projects, a drainage layer is generally set below the pavement structure and above the top layer of the subgrade. The existing test instruments do not consider the change and difference of soil moisture at the top of the subgrade with and without drainage. In order to make the experiment closer to the engineering practice, the present application uses the form of the water baffle 129 to prevent the migration of underground liquid water generated by capillary action, and does not block the migration of gaseous water, and the first temperature control assembly 130 and the second temperature control assembly. 140 to independently and effectively obtain the law of the influence of gaseous moisture migration on the humidity and performance of the roadbed. In addition, the first temperature control assembly 130 is combined with the water absorbing device 132 through the heat transfer baffle 138, and communicates with the drainage assembly 160 to monitor the water output. At the same time, by adjusting the flow rate of water in the moisture adjustment component 120, it is used to simulate the height of the groundwater level, so as to simulate different working conditions.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (10)

1. an unsaturated soil roadbed water vapor migration characteristic testing device, is characterized in that, comprises model box, and is arranged in the moisture regulation assembly, the first temperature control assembly and the second temperature control assembly in described model box, wherein, The first temperature control assembly is used to be disposed on the top of the sample, the second temperature control assembly is used to be disposed at the bottom of the sample, and the moisture adjustment assembly is disposed on the second temperature control assembly; the The model box is also provided with a temperature and humidity measurement component, a drainage component and a displacement sensor, the displacement sensor is used to detect the height change of the sample, and the temperature and humidity measurement component is used to measure the sample at different positions. temperature and humidity, the first temperature control assembly includes a water absorption device, and the water absorption device is connected with the drainage assembly. 2 . The device for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 1 , wherein the first temperature control component comprises a first temperature controller, and a first temperature controller connected to the first temperature controller. 3 . A temperature adjustment plate, the first temperature adjustment plate is connected with heat transfer baffles arranged in layers, the first temperature adjustment plate is connected with one of the heat transfer baffles through a rotatable adjustment support, and the heat transfer baffle is connected to the first temperature adjustment plate. Through holes are respectively provided on the heat baffles, and the two heat transfer baffles are rotated mutually to make the through holes conduct or cut off, and the first temperature adjustment plate and the rotatable adjustment support are formed to accommodate a cavity, and the water absorbing device is located in the accommodating cavity. 3. The device for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 1 or 2, wherein the second temperature control assembly comprises a second temperature controller, and is connected to the second temperature controller The second temperature adjustment plate is provided with a cushion block between the second temperature adjustment plate and the bottom wall of the model box. 4 . The device for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 3 , wherein the moisture regulating assembly comprises a water storage tank, and a control valve connected to the water storage tank, the control valve is connected to the There is a water outlet pipe, the water outlet pipe is connected with the permeable stone arranged on the second temperature adjustment plate, the permeable stone is also connected with a first drainage pipe, the first drainage pipe is connected with the collection box, and the permeable stone is arranged on There is a water baffle, which is used to allow water vapor to pass through and restrict the passage of liquid water, and is used to place the sample on the water baffle. 5. The device for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 1 or 2, wherein the temperature and humidity measurement component comprises a data acquisition component, and a plurality of probes connected to the data acquisition component , a plurality of the probes are used to be inserted in different positions of the sample in the height direction. 6 . The device for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 1 or 2 , wherein the drainage assembly comprises a second drainage pipe connected with the water absorbing device, and a second drainage pipe connected with the second drainage device. 7 . Tube-connected condensate collector. 7. The device for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 1 or 2, wherein the model box comprises a box body, and a door body provided on one side of the box body, the door body A transparent observation port is provided on the top, a heat insulating layer is provided on the box body, and a via hole is provided on the inner ring of the via hole, and a sealing ring is provided in the inner ring of the via hole. temperature. 8. A method for testing water vapor migration characteristics of unsaturated soil roadbed, characterized in that, the test device for water vapor migration characteristics of unsaturated soil roadbed described in any one of claims 1-7 is used for testing, and the method comprises: Prepare a roadbed model sample, and wrap the thermal insulation layer on the outer circle of the sample; Insert the probe of the temperature and humidity test assembly into the sample; placing the sample on a moisture conditioning assembly and placing a first temperature control assembly on top of the sample; matching the displacement sensor with the first temperature control assembly; respectively adjusting the first temperature control assembly, the second temperature control assembly and the moisture adjustment assembly; Record the data changes of the displacement sensor and the temperature and humidity test assembly. 9. The method for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 8, wherein the preparation of the roadbed model sample comprises: Take the soil sample to be tested and carry out an indoor light compaction test to determine the optimal water content and maximum dry density of the soil sample; The samples are mixed according to the requirements for the compactness and water content of the subgrade filler in the actual project; The soil samples were compacted in two layers. 10. The method for testing water vapor migration characteristics of unsaturated soil roadbed according to claim 8 or 9, wherein the adjusting the first temperature control assembly, the second temperature control assembly and the moisture adjustment assembly respectively comprises: adjusting the temperature of the first temperature control assembly and the second temperature control assembly so that the top and bottom of the sample have a temperature difference; Regulates the flow of water in the Moisture Conditioning Component, used to simulate water table heights.

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