Intelligent roadbed soil moisture content self-adaptive control system and method based on hydrothermal coupling

Abstract

The invention discloses an intelligent roadbed soil moisture content self-adaptive control system and method based on hydrothermal coupling. Comprising a vegetation layer, a silt layer, a wicking geotextile layer and a gravel layer which are sequentially laid from top to bottom; the roadbed inner wicking geotextile layer is embedded in the lower part of the roadbed, and the roadbed inner wicking geotextile layer is connected with the wicking geotextile layer; the part, paved in the drying chamber, of the wicking geotextile layer forms a drying part, the drying module conducts drying treatment on the drying part through an air pump and a heater, and the temperature and humidity of the drying part are monitored in real time through an air temperature and humidity sensor; the soil body temperature and humidity sensors are arranged above the roadbed inner core geotextile layer; and the solar panel is used for supplying power to the self-adaptive control system. The device is suitable for various climates and soil conditions, and external moisture can be prevented from entering the roadbed in rainy weather.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering, and particularly to an intelligent subgrade soil moisture content adaptive control system and method. Background Art

[0002] In the field of road construction and maintenance, effectively reducing the soil moisture content in the subgrade is crucial for ensuring the stability and durability of the road. However, traditional methods mainly remove water in the road surface system through drainage ditches, which are only effective for gravity water flow following Darcy's law under saturated or near-saturated conditions. Under unsaturated conditions, the soil may still contain excessive moisture. In this case, traditional drainage methods are difficult to effectively remove the excessive moisture in the soil under unsaturated conditions, resulting in problems such as easy softening and settlement of the subgrade. This will not only affect the service life of the road, but may also cause serious safety hazards and environmental problems.

[0003] The capillary barrier layer is a structure that regulates water migration by restricting soil capillary action. Its working principle is based on introducing specific physical barrier structures or hydrophilic-hydrophobic property gradients in the covering layer to form an effective barrier to water infiltration. In humid climate regions, the anti-seepage effect of traditional capillary barrier layers is not good. At the same time, the wicking geotextile, as a new material, has a wide application prospect in the field of civil engineering due to its good water absorption performance. However, using the wicking geotextile alone still has problems such as slow drainage speed, incomplete drainage, and possible water backflow, and cannot meet the requirements for reducing the soil moisture content in the subgrade in road engineering. Therefore, there is an urgent need to propose an innovative system aimed at preventing water from entering, improving the drainage efficiency of the subgrade, reducing the soil moisture content in the subgrade, and protecting the stability of the road structure. Summary of the Invention

[0004] The present invention provides an intelligent subgrade soil moisture content adaptive control system and method based on hydrothermal coupling, aiming to solve the problems of high soil moisture content in the traditional subgrade and low drainage efficiency of the traditional drainage system. The present invention uses the energy provided by solar energy, combined with components such as a capillary barrier layer, a wicking geotextile, a drying module, and a temperature and humidity sensor, to achieve adaptive adjustment and control of the subgrade water content. Thereby reducing the water content in the road surface layer, improving the stability and water resistance of the subgrade, extending the service life of the road, and at the same time having environmental and economic benefits, bringing important technical breakthroughs and practical application prospects to the field of road engineering.

[0005] The technical solution adopted by the present invention is as follows:

[0006] 1. An intelligent subgrade soil moisture content adaptive control system based on hydrothermal coupling

[0007] The adaptive control system includes:

[0008] The capillary barrier cover layer is laid on the slope surface of the subgrade and includes a vegetation layer, a silt layer, a wicking geotextile layer, and a gravel layer laid in sequence from top to bottom;

[0009] The wicking geotextile layer in the subgrade is buried in the lower part of the subgrade, and the wicking geotextile layer in the subgrade is connected to the wicking geotextile layer;

[0010] The drying module includes a drying chamber, an air pump with adjustable speed, a heater with adjustable temperature, and an air temperature and humidity sensor. The part of the wicking geotextile layer paved in the drying chamber forms a drying section. The drying module dries the drying section through the air pump and the heater, and monitors the temperature and humidity of the drying section in real time through the air temperature and humidity sensor;

[0011] A plurality of soil temperature and humidity sensors are arranged above the wicking geotextile layer in the subgrade;

[0012] The solar panel is used to convert solar energy into electrical energy and supply power to the adaptive control system.

[0013] Specifically, the capillary barrier cover layer is used to regulate, block, and drain the infiltration of water caused by rainfall by utilizing the difference in hydrophilic and hydrophobic properties between layers; the difference in hydrophilic and hydrophobic properties between layers specifically means that the water retention performance relationships of each layer meet the following requirements: the air entry value of the silt layer is greater than or equal to the water entry value of the wicking geotextile layer, and the air entry value of the wicking geotextile layer is greater than or equal to the water entry value of the gravel layer.

[0014] Specifically, the thickness of the silt layer is set according to the following formula:

[0015]

[0016] In the formula, d slit is the thickness of the silt layer; x max is the maximum value of the continuous rainfall in the area where the subgrade is located under the preset safety probability; θ wick is the volumetric water content of the silt layer corresponding to the matrix suction water entry value of the wicking geotextile layer; α is the slope of the capillary barrier cover layer.

[0017] Among them, the maximum value x of the continuous rainfall in the area where the subgrade is located max is obtained through the following process: Summarize and sort out the rainfall data of previous years in the area where the subgrade is located, count the rainfall of continuous rainfall with a day as the minimum scale, calculate the statistical distribution of the rainfall, the statistical distribution includes the average value and the standard deviation, check the distribution type of the statistical distribution, and calculate the maximum value x of the continuous rainfall in the area where the subgrade is located according to the statistical distribution and the preset safety probability max .

[0018] Among them, the volumetric water content of the silt layer corresponding to the matrix suction water intake value of the wicking geotextile layer means that: the silt has a water retention characteristic curve, that is, there is a corresponding relationship between its matrix suction value and the volumetric water content. According to the water retention performance relationship of each layer above, when the matrix suction reaches the water intake value of the lower layer, it means that water is about to break through into the lower layer. At this time, calculate the amount of water that can be stored in the upper layer (silt layer), that is, use the matrix suction when the lower layer is about to intake water, and calculate the volumetric water content in the upper silt according to the water retention characteristic curve of the silt.

[0019] The thickness of the wicking geotextile layer is set according to the following formula:

[0020]

[0021] In the formula, d wick is the thickness of the wicking geotextile layer; k silt is the saturated permeability coefficient of the silt layer; B is the covering width; k wick is the permeability coefficient of the wicking geotextile layer.

[0022] Specifically, each layer in the capillary barrier cover layer is laid from the top of the subgrade slope surface to the bottom of the subgrade slope surface along the slope direction. The wicking geotextile layer in the subgrade is laid horizontally, and one end of the outer side is connected to the wicking geotextile layer in the capillary barrier cover layer to form a continuous water transmission channel, realizing the directional migration of water from the high water content part to the low water content part; the drying module is arranged in the slope section corresponding to the connection of the wicking geotextile layer and the wicking geotextile layer in the subgrade. After the wicking geotextile layer extends outward from the connection to the subgrade, it is spread in the drying chamber of the drying module along the subgrade slope surface direction; the gravel layer extends 3-5 times the thickness of the capillary barrier cover layer along the horizontal direction from the connection of the wicking geotextile layer and the wicking geotextile layer in the subgrade into the subgrade, and the extended part of the gravel layer is arranged on both the upper and lower sides of the wicking geotextile layer in the subgrade.

[0023] Specifically, the adaptive control system further includes a control module. The control module can receive the real-time temperature and humidity data of the drying part from the air temperature and humidity sensor, receive the real-time temperature and humidity data of the corresponding acquisition points from each soil temperature and humidity sensor by communicating with the air pump, heater, air temperature and humidity sensor of the drying module and each soil temperature and humidity sensor respectively, send a target wind speed command to the air pump, and send a target temperature command to the heater. The output wind speed of the air pump and the output temperature of the heater can be adjusted according to the target wind speed command and the target temperature command respectively.

[0024] Specifically, the control module can also determine whether the humidity inside the subgrade exceeds the limit according to the real-time temperature and humidity data of all collection points. When the humidity inside the subgrade exceeds the limit, after calculating the target temperature and target wind speed based on the received data, the control module sends the target temperature command and the target wind speed command to the heater and the air pump of the drying module respectively. When the humidity inside the subgrade does not exceed the limit, there is no need to perform the processes of calculating the target temperature and target wind speed and sending commands to the drying module.

[0025] Specifically, the way for the control module to determine whether the humidity inside the subgrade exceeds the limit is as follows: The control module obtains the real-time moisture content distribution inside the subgrade according to the real-time temperature and humidity data of all collection points, extracts the moisture content characteristic data from the real-time moisture content distribution, obtains the deviation of the moisture content characteristic data from the preset moisture content characteristic data threshold, and compares the deviation with the preset deviation threshold. If the deviation is greater than the preset deviation threshold, the humidity inside the subgrade exceeds the limit; otherwise, the humidity inside the subgrade does not exceed the limit.

[0026] Furthermore, the adaptive control system further includes a drainage ditch and an angle adjustment mechanism; the solar panel is connected to the angle adjustment mechanism, the angle adjustment mechanism can adjust the angle of the solar panel, and the angle adjustment mechanism is controlled by the control module.

[0027] II. An intelligent subgrade soil moisture content adaptive control method based on the above intelligent subgrade soil moisture content adaptive control system

[0028] The adaptive control method includes the following steps:

[0029] Step S1: Use each soil temperature and humidity sensor to obtain the real-time temperature and humidity data of the corresponding collection point respectively.

[0030] Step S2: In the control module, use the control equation based on hydrothermal coupling, and according to the real-time temperature and humidity data collected in Step S1, obtain the real-time moisture content distribution inside the subgrade, and extract the moisture content characteristic data from the real-time moisture content distribution.

[0031] Specifically, the moisture content characteristic data is mainly composed of the real-time values of at least one moisture content characteristic such as the average moisture content, the moisture content in the key control area, and the peak moisture content.

[0032] Step S3: In the control module, obtain the deviation of the moisture content characteristic data obtained in Step S2 from the preset moisture content characteristic data threshold.

[0033] Step S4: In the control module, compare the deviation with the preset deviation threshold:

[0034] If the offset situation is greater than the preset offset threshold, the humidity inside the subgrade exceeds the limit. According to the real-time moisture content distribution obtained in step S2 and the real-time temperature and humidity data of the drying section received from the air temperature and humidity sensor, after calculating the target temperature and target wind speed, the target temperature instruction and the target wind speed instruction are respectively sent to the heater and the air pump of the drying module. The heater and the air pump deliver hot air with the target temperature and target wind speed to the drying chamber, promoting the evaporation and discharge of the moisture in the drying section;

[0035] Otherwise, the humidity inside the subgrade does not exceed the limit, and there is no need to perform the processes of calculating the target temperature and target wind speed and sending instructions to the drying module.

[0036] The specific comparison of the offset situation with the preset offset threshold is as follows: when the offset corresponding to any moisture content feature is greater than the preset offset threshold, the offset situation is greater than the preset offset threshold.

[0037] In step S4, the process of calculating the target temperature and target wind speed is specifically as follows:

[0038] Step S41: Combine the real-time moisture content distribution obtained in step S2 and the control equation based on hydrothermal coupling to obtain the real-time maximum flow velocity of the core geotextile layer inside the subgrade;

[0039] Step S42: Process the real-time maximum flow velocity of the core geotextile layer inside the subgrade through the following formula to obtain the target evaporation rate:

[0040]

[0041] In the formula, E is the target evaporation rate; v max is the real-time maximum flow velocity of the core geotextile layer inside the subgrade; D wick is the thickness of the core geotextile layer inside the subgrade; L wick is the effective paving length of the drying section of the core geotextile layer inside the drying module;

[0042] Step S43: Process the target evaporation rate through the following formula to obtain the target temperature and target wind speed:

[0043]

[0044] In the formula, E is the target evaporation rate; Γ is the slope of the saturation vapor pressure-temperature curve; k is the equivalent forced convection heat transfer coefficient; T a is the target temperature; T wick is the surface temperature of the core geotextile layer inside the subgrade; ν is the humidity constant; u is the target wind speed; h a is the relative air humidity on the surface of the drying section of the core geotextile layer; A is the reciprocal of the relative humidity on the surface of the core geotextile layer inside the subgrade; m, n are fitting constants; among them, the relative air humidity h on the surface of the drying section of the core geotextile layera is the real-time humidity data collected by the air temperature and humidity sensor; the surface temperature T of the wick geotextile layer inside the subgrade wick and the reciprocal A of the relative humidity on the surface of the wick geotextile layer inside the subgrade can be calculated from the real-time temperature and humidity data collected in step S1 by using the control equation based on hydrothermal coupling.

[0045] The control equation based on hydrothermal coupling is specifically as follows:

[0046]

[0047] In the formula, C T , K T , are equation coefficients; is the matrix suction; T is the temperature; K w is the permeability coefficient; ρ l is the density of liquid water; t is the time variable, is the nabla operator, is the partial derivative symbol.

[0048] Step S5: Continuously run steps S1 to S4 to achieve adaptive control of the water content of the subgrade soil.

[0049] The beneficial effects of the present invention are as follows:

[0050] 1. The adaptive control system in the present invention is driven by solar energy. Through the coordinated action of components such as the capillary barrier cover layer, wick geotextile, and drying module, precise regulation of the water content of the subgrade is achieved. When the humidity of the subgrade is too high, the drying module starts to accelerate the evaporation and release of water; when the external humidity is too high, the drying module closes to prevent the entry of external water. Thus, the water content in the road surface layer is overall reduced, and the stability and water resistance of the subgrade are improved.

[0051] 2. The adaptive control system in the present invention combines an adaptive control method, which can quickly and accurately adjust the water content of the subgrade, improving the stability and water resistance of the subgrade.

[0052] 3. The adaptive control system in the present invention is equipped with temperature and humidity sensors and an intelligent control system, which can monitor the humidity of the subgrade in real time and automatically adjust the operating state of the drying module. Using solar panels as the energy source and converting solar energy into electrical energy not only saves energy costs but also has the advantages of environmental protection and sustainability.

[0053] 4. The adaptive control system in the present invention can reduce the water content in the road surface layer, thereby reducing the incidence of problems such as subgrade softening and settlement, prolonging the service life of the road, improving traffic safety, and enhancing the road traffic efficiency. Description of the Drawings

[0054] Figure 1 It is a schematic structural view of the slope covering layer;

[0055] Figure 2 It is a schematic structural view of the connection between the drying module and the capillary barrier covering layer;

[0056] Figure 3 It is a schematic cross-sectional view of the subgrade;

[0057] Figure 4 It is a schematic internal structural view of the drying module.

[0058] In the figures: 1 - vegetation layer; 2 - silt layer; 3 - wicking geotextile layer; 4 - gravel layer; 5 - drying module; 6 - solar panel; 7 - drainage ditch; 8 - soil temperature and humidity sensor; 9 - air pump; 10 - heater; 11 - air temperature and humidity sensor; 12 - subgrade internal wicking geotextile layer. Detailed Embodiment

[0059] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0060] The first aspect of the present invention provides an intelligent subgrade soil moisture content adaptive control system based on hydrothermal coupling.

[0061] The soil moisture content adaptive control system of the present invention includes a capillary barrier covering layer, a subgrade internal wicking geotextile layer 12, a drying module 5, a plurality of soil temperature and humidity sensors 8, and a solar panel 6. Under the power supply of the solar panel 6, the control module uses the soil temperature and humidity sensors 8 to monitor the soil humidity in real time, analyzes and calculates to obtain the moisture content distribution, and realizes efficient evaporation by precisely controlling the operation of the drying module 5, thereby forming a moisture gradient force to continuously discharge the internal moisture, significantly improving the stability and water resistance of the subgrade. And by using the groove structure and capillary action on the surface of the capillary barrier covering layer and the wicking geotextile, while blocking the external moisture from entering, it quickly guides the internal moisture of the subgrade to the surface.

[0062] For the capillary barrier covering layer, as Figure 1 shown, the capillary barrier covering layer is laid on the subgrade slope surface, and includes a vegetation layer 1, a silt layer 2, a wicking geotextile layer 3, and a gravel layer 4 laid in sequence from top to bottom. The capillary barrier covering layer is laid from the top of the subgrade slope surface to the bottom of the subgrade slope surface along the slope direction. The capillary barrier covering layer is used to regulate, block, and drain the infiltration of moisture caused by rainfall by utilizing the difference in hydrophilic and hydrophobic properties between layers.

[0063] Specifically, the vegetation layer 1 and the silt layer 2 serve as water storage and regulation layers, which can intercept water in the soil when the rainfall is less; the wick geotextile layer 3 is a lateral drainage layer, which can conduct the excess water laterally to the drainage ditch 7 when the rainfall is large; the gravel layer 4 is a capillary barrier layer, and its permeability coefficient is less than that of the wick geotextile layer in the low suction stage (i.e., the matrix suction is greater than the "intake value"), forming anisotropy of the permeability coefficient and blocking the infiltration of water into the subgrade. Since the gravel layer 4 has a low permeability coefficient, the intake value of its matrix suction is higher than the water absorption value of the wick geotextile layer 3, thus forming a preferential path for lateral drainage.

[0064] Therefore, for each layer of the capillary barrier cover layer, to ensure the full play of the water storage capacity and the lateral drainage capacity, the water holding performance relationship needs to meet the following requirements: for two adjacent soil layers, the intake value of the matrix suction of the upper soil layer should be greater than or equal to the intake value of the lower soil layer, so as to give full play to the water storage and lateral drainage functions. This requirement can be expressed by the following formula:

[0065] AEV up ≥WEV low

[0066] In the formula, AEV up is the intake value of the upper soil layer, with the unit of kPa; WEV low is the intake value of the lower soil layer, with the unit of kPa.

[0067] Preferably, the water holding performance relationship of each layer meets the following requirements: the intake value of the silt layer 2 is greater than or equal to the intake value of the wick geotextile layer 3, and the intake value of the wick geotextile layer 3 is greater than or equal to the intake value of the gravel layer 4. That is, the water holding performance relationship of each layer meets the following formula:

[0068] AEV silt ≥WEV wick ,AEV wick ≥WEV gravel

[0069] In the formula, AEV silt ,AEV wick are respectively the intake values of the silt layer 2 and the wick geotextile layer 3, with the unit of kPa; WEV wick ,WEV gravel are respectively the intake values of the wick geotextile layer 3 and the gravel layer 4, with the unit of kPa.

[0070] Preferably, the thickness of the silt layer 2 is set according to the following formula:

[0071]

[0072] In the formula, d slitis the thickness of the silt layer 2, with the unit of m; x max is the maximum value of the continuous rainfall in the area where the subgrade is located under the preset safety probability, with the unit of m; θ wick is the volumetric water content of the silt layer 2 corresponding to the matrix suction water intake value of the wicking geotextile layer 3, with the unit of 1; α is the slope of the capillary barrier covering layer, with the unit of °.

[0073] Among them, the maximum value x of the continuous rainfall in the area where the subgrade is located max can be obtained through the following process: Summarize and sort out the rainfall data of previous years in the area where the subgrade is located, count the rainfall of continuous rainfall with the day as the minimum scale, calculate the statistical distribution of the rainfall, the statistical distribution includes the mean value and the standard deviation, and test the distribution type of the statistical distribution. Determine the appropriate safety probability as needed, and calculate the maximum value x of the continuous rainfall in the area where the subgrade is located according to the statistical distribution and the preset safety probability max .

[0074] Preferably, the thickness of the wicking geotextile layer 3 can be adjusted as needed to improve the lateral drainage capacity of the capillary barrier covering layer and improve the applicability under humid climate conditions. The thickness of the wicking geotextile layer 3 is set according to the following formula:

[0075]

[0076] In the formula, d wick is the thickness of the wicking geotextile layer 3, with the unit of m; k silt is the saturated hydraulic conductivity of the silt layer 2, with the unit of m / s; B is the covering width, as Figure 3 shown, that is, the length from the top of the subgrade slope to the installation position of the drying module 5, with the unit of m; k wick is the hydraulic conductivity of the wicking geotextile layer 3, with the unit of m / s.

[0077] The thickness of the wicking geotextile layer 3 can be adjusted according to the above formula as needed to improve the lateral drainage capacity of the capillary barrier covering layer and improve the applicability under humid climate conditions.

[0078] In specific implementation, the material parameters of each layer in the adaptive control system can be adjusted according to different soil and climate conditions to meet different engineering requirements. For example, the particle distribution of the silt layer can be optimized to have a higher water holding rate, and the groove size and material thickness of the wicking geotextile can be designed to meet specific drainage speed requirements.

[0079] For the wicking geotextile layer 12 inside the subgrade, as Figure 3 shown, the wicking geotextile layer 12 inside the subgrade is buried in the lower part of the subgrade. The wicking geotextile layer 12 inside the subgrade is connected to the wicking geotextile layer 3 to form a continuous water transmission channel, realizing the directional migration of water from high water content to low water content.

[0080] Furthermore, as Figure 2 shown, the wick geotextile layer 3 is laid along the roadbed slope surface, the wick geotextile layer 12 inside the roadbed is laid horizontally, and one end of the outer side is connected to the wick geotextile layer 3 in the capillary barrier covering layer. The gravel layer 4 extends horizontally 3 - 5 times the thickness length L of the capillary barrier covering layer from the connection of the wick geotextile layer 3 and the wick geotextile layer 12 inside the roadbed, and the extended part of the gravel layer 4 is arranged on both the upper and lower sides of the wick geotextile layer 12 inside the roadbed. The length L of the extended part of the gravel layer 4 can be adjusted within this preferred range as needed to prevent rainwater infiltration at the connection.

[0081] Both the wick geotextile layer 12 inside the roadbed and the wick geotextile layer 3 are made of wick geotextile. One or both surfaces of the wick geotextile have surface structures. The surface structure is a microscopic groove structure, which can quickly draw the water infiltrated from the slope surface and the water inside the roadbed to the geotextile through capillary action. At the same time, its excellent permeability enables it to quickly form a water seepage channel when one end is relatively dry, thus realizing the directional migration of water from a high water content to a low water content. In specific implementation, the width and depth of the microscopic groove structure can be adjusted as needed to control the water attraction and concentration efficiency. For the wick geotextile layer 3, its outer surface should be provided with a surface structure, and there is no restriction on the other surface.

[0082] The thickness of the wick geotextile layer 12 inside the roadbed does not need to be the same as that of the wick geotextile layer 3, and its thickness can be selected as needed.

[0083] For the drying module 5, as Figure 4 shown, the drying module 5 includes a drying chamber, an air pump 9 with adjustable speed, a heater 10 with adjustable temperature, and an air temperature and humidity sensor 11. The wick geotextile layer 3 extends from its connection with the wick geotextile layer 12 inside the roadbed to the outside of the roadbed and into the drying chamber, and the part laid in the drying chamber forms a drying section. The drying module 5 dries the drying section of the wick geotextile layer 3 through the air pump 9 and the heater 10, and real - time monitors the temperature and humidity of the drying section of the wick geotextile layer 3 through the air temperature and humidity sensor 11. In addition, at the same time, in case of high external humidity such as rainfall, the drying module can also effectively protect the outer end (drying section) of the wick geotextile from absorbing water and prevent the capillary action from causing water to migrate into the roadbed.

[0084] Specifically, the wick geotextile layer 3 is laid along the roadbed slope surface, the wick geotextile layer 12 inside the roadbed is laid horizontally, the drying module 5 is arranged in the slope section corresponding to the connection of the wick geotextile layer 3 and the wick geotextile layer 12 inside the roadbed. After the wick geotextile layer 3 extends horizontally from the connection to the outside of the capillary barrier covering layer, it is laid in the drying chamber of the drying module 5 along the roadbed slope surface direction.

[0085] The working modes of the drying module 5 include a normal operation mode and a protection mode. In the normal operation mode, when the soil temperature and humidity sensor 8 detects that the humidity inside the roadbed exceeds the set threshold, the control module activates the drying module 5. After the air pump 9 starts, air is introduced into the module, and the heater 10 raises the temperature to increase the air temperature on the surface of the wicking geotextile layer 3, thereby accelerating the evaporation and release of moisture and promoting the continuous migration and discharge of moisture inside the roadbed. In the protection mode, when the air temperature and humidity sensor 11 detects high humidity in the outside world (such as rainfall), the control module automatically shuts down the drying module 5 to prevent moisture from flowing back into the roadbed interior.

[0086] For the soil temperature and humidity sensor 8, as Figure 2 shown, multiple soil temperature and humidity sensors 8 are arranged at intervals above the wicking geotextile layer 12 inside the roadbed for real-time monitoring of the temperature and humidity inside the roadbed and on the surface of the wicking geotextile layer 12 inside the roadbed.

[0087] For the solar panel 6, it is arranged in a sunny place and is used to convert solar energy into electrical energy by the photovoltaic effect and supply power to the drying module 5 and the soil temperature and humidity sensor 8.

[0088] Furthermore, the solar panel 6 can store excess electrical energy for use at night or on rainy and cloudy days to ensure the all-weather operation of the adaptive control system.

[0089] As Figure 2 and Figure 3 shown, as an optional implementation scheme of the present invention, the solar panel 6 is installed on the top of the drying module 5.

[0090] Furthermore, the adaptive control system further includes a control module. The control module is communicatively connected to the air pump 9, the heater 10, the air temperature and humidity sensor 11 of the drying module 5 and each soil temperature and humidity sensor 8 respectively. It can receive the real-time temperature and humidity data of the drying part from the air temperature and humidity sensor 11, receive the real-time temperature and humidity data of their respective corresponding acquisition points from each soil temperature and humidity sensor 8, send a target wind speed command to the air pump 9, and send a target temperature command to the heater 10. The control module can also judge whether the humidity inside the roadbed exceeds the limit according to the real-time temperature and humidity data of all acquisition points. When the humidity inside the roadbed exceeds the limit, after calculating the target temperature and target wind speed based on the received data (the real-time temperature and humidity data of the drying part and the real-time temperature and humidity data of all acquisition points), the control module sends the target temperature command and the target wind speed command to the heater 10 and the air pump 9 of the drying module 5 respectively. The heater 10 and the air pump 9 send hot air with the target temperature and target wind speed to the drying chamber to promote the evaporation and discharge of moisture in the drying part. When the humidity inside the roadbed does not exceed the limit, the process of calculating the target temperature and target wind speed and sending commands to the drying module 5 does not need to be executed.

[0091] The way for the control module to judge whether the humidity inside the roadbed exceeds the limit is specifically as follows: The control module obtains the real-time moisture content distribution inside the roadbed based on the real-time temperature and humidity data of all the acquisition points, extracts the moisture content characteristic data from the real-time moisture content distribution, obtains the deviation of the moisture content characteristic data from the preset moisture content characteristic data threshold, compares the deviation with the preset deviation threshold. If the deviation is greater than the preset deviation threshold, the humidity inside the roadbed exceeds the limit; otherwise, the humidity inside the roadbed does not exceed the limit.

[0092] Furthermore, the adaptive control system further includes a drainage ditch 7 arranged at the bottom of the roadbed slope.

[0093] Furthermore, the adaptive control system further includes an angle adjustment mechanism. The solar panel 6 is connected to the angle adjustment mechanism, and the angle adjustment mechanism can adjust the angle of the solar panel, and the angle adjustment mechanism is controlled by the control module. This design with adjustable angle enables the solar panel 6 to adapt to the solar illumination angles in different regions and seasonal changes.

[0094] Such as Figure 2 and Figure 3 shown, as an optional implementation scheme of the present invention, the solar panel 6 is installed on the top of the drying module 5 through the angle adjustment mechanism.

[0095] The adaptive control system provided by the present invention is applicable to various types of road engineering, that is, the roadbed mentioned in the present invention includes but is not limited to highways, urban roads, rural roads, etc.

[0096] The second aspect of the present invention provides an intelligent roadbed soil moisture content adaptive control method based on the above intelligent roadbed soil moisture content adaptive control system.

[0097] The soil moisture content adaptive control method includes the following steps:

[0098] Step S1: Based on the power supply of the solar energy system, use each soil temperature and humidity sensor 8 inside the roadbed to respectively obtain the real-time temperature and humidity data of the corresponding acquisition points.

[0099] Step S2: In the control module, use the control equation based on hydrothermal coupling, and according to the real-time temperature and humidity data collected in step S1, inversely deduce the real-time moisture content distribution inside the roadbed, and extract the moisture content characteristic data from the real-time moisture content distribution.

[0100] Specifically, the moisture content characteristic data is mainly composed of at least one moisture content characteristic such as the average moisture content, the moisture content in the key control area, and the peak moisture content.

[0101] Specifically, the control equation based on hydrothermal coupling is:

[0102]

[0103] In the formula, C T , K T , are the coefficients of the equation; is the matric suction, with the unit of m; T is the temperature, with the unit of K; K w is the permeability coefficient, with the unit of m / s; ρ l is the density of liquid water, with the unit of kg / m 3 ; t is the time variable, with the unit of s, is the nabla operator, is the partial derivative symbol.

[0104] This governing equation is applicable to the subgrade soil, the capillary absorption geotextile, and the capillary barrier cover layer area. According to the differences in water retention performance between different layers, it can simulate the protective effect of the capillary barrier cover layer on rainfall.

[0105] Among them, the equation coefficients are obtained through the following equations respectively:

[0106]

[0107] In the formula, ρ l is the density of liquid water, ρ v is the density of water vapor, θ is the volumetric water content, is the matric suction of the soil, n is the porosity of the soil, ρ0 is the density of saturated water vapor, h is the relative humidity, g is the acceleration due to gravity, M w is the mass of water vapor molecules, R is the universal gas constant, T is the soil temperature, D atm is the molecular diffusivity of water vapor in air, α is the soil curvature factor, β is the cross-sectional area of the soil in vapor flow, and K is the permeability coefficient of unsaturated soil.

[0108] Among them, the equation coefficients C T , K T , are obtained through the following equations respectively:

[0109]

[0110] In the formula, ρ v is the density of water vapor, θ is the volumetric water content, is the matric suction of the soil, n is the porosity of the soil, ρ0 is the density of saturated water vapor, h is the relative humidity, g is the acceleration due to gravity, M w is the mass of water vapor molecules, R is the universal gas constant, T is the soil temperature, D atmis the molecular diffusivity of water vapor in air, α is the soil curvature factor, β is the cross-sectional area of the soil in steam flow, C is the specific heat capacity of the soil, and L v is the latent heat value of water evaporation, and λ is the thermal conductivity of the soil.

[0111] Step S3: In the control module, obtain the deviation of the moisture content characteristic data obtained in Step S2 from the preset moisture content characteristic data threshold.

[0112] The process of obtaining the deviation is specifically as follows: By subtracting the real-time value of each moisture content characteristic in the moisture content characteristic data from the preset threshold, the deviation corresponding to each moisture content characteristic is obtained, and the deviations corresponding to all moisture content characteristics form the deviation situation.

[0113] Step S4: In the control module, compare the deviation situation with the preset deviation threshold. If the deviation situation is greater than the preset deviation threshold, it means that the humidity inside the roadbed exceeds the limit. According to the real-time moisture content distribution obtained in Step S2 and the real-time temperature and humidity data of the drying section received from the air temperature and humidity sensor 11, after calculating the target temperature and target wind speed, send the target temperature command and target wind speed command to the heater 10 and air pump 9 of the drying module 5 respectively. The heater 10 and air pump 9 send hot air with the target temperature and target wind speed to the drying chamber to promote the evaporation and discharge of moisture in the drying section;

[0114] Otherwise, the humidity inside the roadbed does not exceed the limit, and there is no need to perform the process of calculating the target temperature and target wind speed and sending commands to the drying module 5.

[0115] Optionally, the process of comparing the deviation situation with the preset deviation threshold is specifically as follows: When the deviation corresponding to any moisture content characteristic is greater than the preset deviation threshold, the deviation situation is greater than the preset deviation threshold.

[0116] In Step S4, the process of calculating the target temperature and target wind speed is specifically as follows:

[0117] Step S41: Combine the real-time moisture content distribution obtained in Step S2 and the control equation based on hydrothermal coupling to obtain the real-time maximum flow rate of the core geotextile layer 12 in the roadbed;

[0118] Step S42: Process the real-time maximum flow rate of the core geotextile layer 12 in the roadbed through the following formula to obtain the target evaporation rate:

[0119]

[0120] In the formula, E is the target evaporation rate; v max is the real-time maximum flow rate of the core geotextile layer 12 in the roadbed; D wick is the thickness of the core geotextile layer 12 in the roadbed; L wickis the effective paving length of the drying section for the wick geotextile layer 3 inside the drying module;

[0121] Step S43: Process the target evaporation rate through the following formula to obtain the target temperature and target wind speed:

[0122]

[0123] In the formula, E is the target evaporation rate; Γ is the slope of the saturation vapor pressure - temperature curve, with the unit of kPa / ℃; k is the equivalent forced convection heat transfer coefficient, with the unit of mm / d℃; T a is the target temperature, with the unit of ℃; T wick is the surface temperature of the wick geotextile layer 12 in the roadbed, with the unit of ℃, which can be calculated using the control equation based on hydrothermal coupling according to the real-time temperature and humidity data collected in step S1; ν is the humidity constant, with the unit of hPa / ℃; u is the target wind speed, with the unit of m / s; h a is the relative humidity of the air on the surface of the drying section of the wick geotextile layer 3, with the unit of 1; A is the reciprocal of the relative humidity on the surface of the wick geotextile layer 12 in the roadbed, with the unit of 1, which can be calculated using the control equation based on hydrothermal coupling according to the real-time temperature and humidity data collected in step S1; m, n are fitting constants obtained from the fitting results of the calibration experiment;

[0124] The relative humidity h of the air on the surface of the drying section of the wick geotextile layer 3 a is the real-time humidity data collected by the air temperature and humidity sensor 11;

[0125] The surface temperature T of the wick geotextile layer 12 in the roadbed wick and the reciprocal A of the relative humidity on the surface of the wick geotextile layer 12 in the roadbed are calculated using the control equation based on hydrothermal coupling according to the real-time temperature and humidity data collected in step S1.

[0126] Step S5: Continuously run steps S1 to S4 to achieve the adaptive control of the water content of the roadbed soil.

[0127] In summary, the system and method of the present invention are applicable to various climate and soil conditions, and can prevent external moisture from entering the roadbed in rainy climates. At the same time, the system is driven by solar energy, with significant energy-saving and emission-reduction effects, and has environmental and economic benefits, providing important technical support and application prospects for the moisture management of road engineering and other infrastructure.

[0128] The above specific implementation manners are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. Any equivalent transformation or improvement made to the present invention by using the content of the specification of the present invention falls within the protection scope of the present invention.

Claims

1. An intelligent subgrade soil moisture content adaptive control system based on hydrothermal coupling, characterized in that, Including: A capillary blockage covering layer, covering the slope surface of the subgrade, including a vegetation layer (1), a silt layer (2), a wicking geotextile layer (3), and a gravel layer (4) laid successively from top to bottom; A wicking geotextile layer (12) inside the subgrade, buried in the lower part of the subgrade, and the wicking geotextile layer (12) inside the subgrade is connected to the wicking geotextile layer (3); A drying module (5), including a drying chamber, an air pump (9) with adjustable speed, a heater (10) with adjustable temperature, and an air temperature and humidity sensor (11). The part of the wicking geotextile layer (3) spread in the drying chamber forms a drying section. The drying module (5) dries the drying section through the air pump (9) and the heater (10), and the air temperature and humidity sensor (11) monitors the temperature and humidity of the drying section in real time; A plurality of soil temperature and humidity sensors (8), arranged above the wicking geotextile layer (12) inside the subgrade; A solar panel (6), used to convert solar energy into electrical energy and supply power to the adaptive control system.

2. The intelligent roadbed soil moisture content adaptive control system based on hydrothermal coupling according to claim 1, characterized in that: The capillary blockage covering layer is used to regulate, block, and drain the infiltration of water caused by rainfall by utilizing the difference in hydrophilic and hydrophobic properties between layers; the specific difference in hydrophilic and hydrophobic properties between layers is that the water retention performance relationship of each layer meets the following requirements: the air entry value of the silt layer (2) is greater than or equal to the water entry value of the wicking geotextile layer (3), and the air entry value of the wicking geotextile layer (3) is greater than or equal to the water entry value of the gravel layer (4).

3. The intelligent roadbed soil moisture content adaptive control system based on hydrothermal coupling according to claim 2, characterized in that: The thickness of the silt layer (2) is set according to the following formula: where d slit is the thickness of the silt layer (2); x max is the maximum value of the continuous rainfall in the subgrade area under the preset safety probability; θ wick is the volumetric water content of the silt layer (2) corresponding to the matrix suction water intake value of the capillary absorption geotextile layer (3); α is the slope of the capillary blockage covering layer; Among them, the maximum value x of the continuous rainfall in the area where the roadbed is located max is obtained through the following process: Summarize and organize the rainfall data of previous years in the area where the roadbed is located, count the rainfall of continuous rainfall with a daily minimum scale, calculate the statistical distribution of the rainfall, the statistical distribution includes the mean value and the standard deviation, test the distribution type of the statistical distribution, and calculate the maximum value x of the continuous rainfall in the area where the roadbed is located according to the statistical distribution and the preset safety probability max ; The thickness of the wicking geotextile layer (3) is set according to the following formula: where d wick is the thickness of thewicking geotextile layer (3); k silt is the saturated permeability coefficient of the silt layer (2); B is the covering width; k wick is the permeability coefficient of the wicking geotextile layer (3).

4. The intelligent roadbed soil moisture content adaptive control system based on hydrothermal coupling according to claim 1, characterized in that: Each layer in the capillary blockage covering layer is laid from the top of the subgrade slope surface to the bottom of the subgrade slope surface along the slope direction. The wicking geotextile layer (12) inside the subgrade is laid horizontally, and one end of the outer side is connected to the wicking geotextile layer (3) in the capillary blockage covering layer, forming a continuous water transmission channel to realize the directional migration of water from the part with high moisture content to the part with low moisture content; The drying module (5) is arranged at the slope section corresponding to the connection of the wicking geotextile layer (3) and the wicking geotextile layer (12) inside the subgrade. After the wicking geotextile layer (3) extends outward from the connection point towards the outside of the subgrade, it is spread in the drying chamber of the drying module (5) along the subgrade slope direction; The gravel layer (4) extends 3 - 5 times the thickness of the capillary blockage covering layer along the horizontal direction towards the inside of the subgrade from the connection of the wicking geotextile layer (3) and the wicking geotextile layer (12) inside the subgrade, and the extended part of the gravel layer (4) is arranged on both the upper and lower sides of the wicking geotextile layer (12) inside the subgrade.

5. The intelligent subgrade soil moisture content adaptive control system based on hydrothermal coupling according to claim 1, characterized in that: The adaptive control system further includes a control module. The control module is communicatively connected to the air pump (9), the heater (10), and the air temperature and humidity sensor (11) of the drying module (5) and each soil temperature and humidity sensor (8) respectively. It can receive the real-time temperature and humidity data of the drying section from the air temperature and humidity sensor (11), receive the real-time temperature and humidity data of the corresponding collection points from each soil temperature and humidity sensor (8), send a target wind speed command to the air pump (9), and send a target temperature command to the heater (10). The output wind speed of the air pump (9) and the output temperature of the heater (10) can be adjusted according to the target wind speed command and the target temperature command respectively; The control module can also judge whether the humidity inside the roadbed exceeds the limit according to the real-time temperature and humidity data of all collection points. When the humidity inside the roadbed exceeds the limit, after calculating the target temperature and target wind speed based on the received data, the target temperature command and the target wind speed command are respectively sent to the heater (10) and the air pump (9) of the drying module (5). When the humidity inside the roadbed does not exceed the limit, the processes of calculating the target temperature and target wind speed and sending commands to the drying module (5) do not need to be executed; The specific method for the control module to judge whether the humidity inside the roadbed exceeds the limit is as follows: The control module obtains the real-time moisture content distribution inside the roadbed according to the real-time temperature and humidity data of all collection points, extracts the moisture content characteristic data from the real-time moisture content distribution, obtains the deviation of the moisture content characteristic data from the preset moisture content characteristic data threshold, compares the deviation with the preset deviation threshold. If the deviation is greater than the preset deviation threshold, the humidity inside the roadbed exceeds the limit; otherwise, the humidity inside the roadbed does not exceed the limit.

6. The intelligent roadbed soil moisture content adaptive control system based on hydrothermal coupling according to claim 5, characterized in that: The adaptive control system further includes a drainage ditch (7) and an angle adjustment mechanism; the solar panel (6) is connected to the angle adjustment mechanism, and the angle adjustment mechanism can adjust the angle of the solar panel (6), and the angle adjustment mechanism is controlled by the control module.

7. An intelligent subgrade soil moisture content adaptive control method based on the intelligent subgrade soil moisture content adaptive control system according to any one of claims 1 to 6, characterized in that, It includes the following steps: Step S1: Use each soil temperature and humidity sensor (8) to obtain the real-time temperature and humidity data of the corresponding collection points respectively; Step S2: In the control module, use the control equation based on hydrothermal coupling, and according to the real-time temperature and humidity data collected in Step S1, obtain the real-time moisture content distribution inside the roadbed, and extract the moisture content characteristic data according to the real-time moisture content distribution; The moisture content characteristic data is mainly composed of the real-time values of at least one moisture content characteristic among the average moisture content, the moisture content in the key control area, and the peak moisture content; Step S3: In the control module, obtain the deviation of the moisture content characteristic data obtained in Step S2 from the preset moisture content characteristic data threshold; Step S4: In the control module, compare the offset situation with the preset offset threshold. If the offset situation is greater than the preset offset threshold, it means that the humidity inside the roadbed exceeds the limit. According to the real-time moisture content distribution obtained in Step S2 and the real-time temperature and humidity data of the drying section received from the air temperature and humidity sensor (11), after calculating the target temperature and target wind speed, send the target temperature command and the target wind speed command to the heater (10) and the air pump (9) of the drying module (5) respectively. The heater (10) and the air pump (9) convey hot air with the target temperature and target wind speed to the drying chamber, promoting the evaporation and discharge of the moisture in the drying section; Otherwise, the humidity inside the roadbed does not exceed the limit, and there is no need to perform the process of calculating the target temperature and target wind speed and sending commands to the drying module (5); Step S5: Continuously run Step S1 to Step S4 to achieve the adaptive control of the moisture content of the roadbed soil.

8. The intelligent subgrade soil moisture content adaptive control method according to claim 7, characterized in that: In the said Step S4, the process of calculating the target temperature and target wind speed is specifically as follows: Step S41: Combine the real-time moisture content distribution obtained in Step S2 and the control equation based on hydrothermal coupling to obtain the real-time maximum flow rate of the inner core geotextile layer (12) of the roadbed; Step S42: Process the real-time maximum flow rate of the inner core geotextile layer (12) of the roadbed through the following formula to obtain the target evaporation rate: where E is the target evaporation rate; v max is the real-time maximum flow velocity of the core soil absorption geotextile layer (12) in the subgrade; D wick is the thickness of the core soil absorption geotextile layer (12) in the subgrade; L wick is the effective paving length of the drying part of the core soil absorption geotextile layer (3) in the drying module; Step S43: Process the target evaporation rate through the following formula to obtain the target temperature and target wind speed: where E is the target evaporation rate; Γ is the slope of the saturation vapor pressure - temperature curve; k is the equivalent forced convection heat transfer coefficient; T a is the target temperature; T wick is the surface temperature of the wick geotextile layer (12) inside the subgrade; ν is the humidity constant; u is the target wind speed; h a is the relative humidity of the air on the drying section surface of the wick geotextile layer (3); A is the reciprocal of the relative humidity on the surface of the wick geotextile layer (12) inside the subgrade; m, n are fitting constants; among them, the relative humidity h a of the air on the drying section surface of the wick geotextile layer (3) is the real - time humidity data collected by the air temperature and humidity sensor (11); the surface temperature T wick of the wick geotextile layer (12) inside the subgrade and the reciprocal A of the relative humidity on the surface of the wick geotextile layer (12) inside the subgrade can be calculated from the real - time temperature and humidity data collected in step S1 by using the control equations based on hydro - thermal coupling.

9. The intelligent subgrade soil moisture content adaptive control method according to claim 7 or 8, characterized in that: The control equation based on hydrothermal coupling is specifically as follows: In the formula, C T , is the coefficient of the equation; is the matric suction; T is the temperature; K w is the permeability coefficient; ρ l is the density of liquid water; t is the time variable, is the nabla operator, is the partial derivative symbol.

10. The intelligent roadbed soil moisture content adaptive control method according to claim 7, wherein: The comparison of the offset situation with the preset offset threshold is specifically as follows: When the offset corresponding to any moisture content feature is greater than the preset offset threshold, the offset situation is greater than the preset offset threshold.

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