Simulation platform for roadbed water migration under complex conditions and its application in hydraulic model construction

Abstract

The present invention discloses a simulation platform for subgrade moisture migration under complex conditions, including a base, wherein a plurality of test areas are arranged on the upper surface of the base, and each test area is separated by a thermal insulation plate; the thermal insulation plates are fixedly connected by a central axis; a top plate is connected to the top of the thermal insulation plate and the central axis, the outer side of the thermal insulation plate is in contact with an arc-shaped cover plate, and the upper and lower ends of the arc-shaped cover plate are respectively fixedly connected to the top plate and the base; the test areas include test area A, test area B, test area C and test area D. The present invention also provides an application of a simulation platform for subgrade moisture migration under complex conditions, which is used to construct a hydraulic characteristic model of subgrade soil under full environmental conditions. The present invention can comprehensively simulate the environmental state that drives subgrade moisture migration, realizes the simulation of subgrade moisture migration under the influence of a single factor and multiple factors coupling, and at the same time provides a method for constructing a corresponding hydraulic model to solve the problems existing in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of indoor tests for road engineering, and relates to a roadbed moisture migration simulation platform under complex conditions and its application in hydraulic model construction. Background Art

[0002] The moisture distribution inside the roadbed is a key factor affecting the overall structural performance of the roadbed. The roadbed is filled with reference to the optimal moisture content during the construction phase. During the operation period, driven by complex environmental factors such as deadweight, vehicle load, rainfall, slope vegetation, evaporation, and groundwater, the moisture inside the roadbed will migrate and redistribute, causing the structural performance of the roadbed to change. Therefore, it is crucial to accurately reveal the evolution of moisture migration inside the roadbed and propose a hydraulic characteristic model to describe its migration.

[0003] The main methods for studying the migration of subgrade moisture include indoor tests, field tests and theoretical simulations. Among them, indoor simulation tests are widely used because of their advantages such as simple implementation and strong representativeness. At present, when using indoor tests to study the migration of subgrade moisture, the focus is on considering a single factor (such as: a test device and method for the evolution of the water holding state of subgrade soil under traffic load disclosed in the invention patent with publication number CN114577642A), which cannot accurately and systematically characterize the complex environment in which the subgrade is located in actual engineering. Therefore, there is an urgent need for a subgrade moisture migration test platform that can simulate multiple environmental factors, and at the same time match the corresponding hydraulic characteristic model construction method to lay the foundation for accurate evaluation of the evolution of subgrade moisture. Summary of the invention

[0004] In order to achieve the above-mentioned purpose, the present invention provides a roadbed moisture migration simulation platform under complex conditions and its application in hydraulic model construction, which can comprehensively simulate the environmental conditions that drive roadbed moisture migration, realize the simulation of roadbed moisture migration under the influence of single factors and multiple factors coupling, and at the same time construct a corresponding hydraulic model to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is a roadbed moisture migration simulation platform under complex conditions, comprising a base, a plurality of test areas are arranged on the upper surface of the base, and each test area is separated by a thermal insulation board; the thermal insulation boards are fixedly connected by a central axis; a top plate is connected to the top of the thermal insulation board and the central axis, the outer side of the thermal insulation board is in contact with an arc cover plate, and the upper and lower ends of the arc cover plate are respectively fixedly connected to the top plate and the base; the test areas include test area A, test area B, test area C and test area D, wherein:

[0006] The A test area is used to simulate the water migration of the roadbed under the action of groundwater;

[0007] The B test area is used to simulate the situation when the roadbed slope is facing rainfall;

[0008] The C test area is used to simulate the water migration of the roadbed under the combination of the roadbed and pavement deadweight and vehicle load;

[0009] The D test area is used to simulate the influence of the water migration on the roadbed under the combination of the roadbed and pavement deadweight and vehicle load, and the external environment temperature change and the internal temperature difference;

[0010] The top plate and the C test area are connected with a first loading head, the top plate and the D test area are connected with a second loading head, the first loading head and the second loading head are respectively connected with a servo control system, and the servo control system is connected with a microcomputer.

[0011] Furthermore, the A test area includes a first soil column, a water supply and drainage system, and a data acquisition system, wherein:

[0012] The first soil column includes a cylinder and a soil body, the cylinder is provided with an opening on the side wall according to the buried position of the first sensor, and the soil body is located inside the cylinder;

[0013] The water supply and drainage system comprises a first water inlet pipe, one end of which is connected to the first Mach flask, and the other end is connected to the first water storage chamber; the two ends of the first drainage pipe are respectively connected to the first water storage chamber and the first water collector; the first water storage chamber is located below the first soil column, and a first filter paper is arranged between the first soil column and the first water storage chamber; the first water storage chamber comprises a first bottom plate and a first top plate, and the first bottom plate and the first top plate are fixed by a first support column; an opening is arranged on the first top plate; a first water inlet valve is arranged on the first water inlet pipe, and a first drainage valve is arranged on the first drainage pipe;

[0014] The data acquisition system comprises a first sensor, which is arranged inside the first soil column; the first sensor comprises sensors for testing matrix suction, water content and stress; the first sensor is connected to the data acquisition circuit, and the data acquisition circuit is connected to the microcomputer circuit.

[0015] Furthermore, the B test area includes a second soil column, a data acquisition system, a drainage system, and a rainfall system, wherein:

[0016] The second soil column includes a cylinder and a soil body, wherein the cylinder is provided with an opening on the side wall according to the buried position of the second sensor, and the soil body is located inside the cylinder; and plants are planted in the soil body;

[0017] The drainage system comprises a second drainage pipe, the two ends of which are respectively connected to the second water storage chamber and the second water collector; a third drainage valve is arranged on the second drainage pipe, and a second drainage valve is arranged on the top of the second soil column; the second water storage chamber is located below the second soil column, and a second filter paper is arranged between the second water storage chamber and the second soil column; the second water storage chamber comprises a second bottom plate and a second top plate, and the second bottom plate and the second top plate are fixed by a second support column; an opening is arranged on the second top plate;

[0018] The data acquisition system includes a second sensor, which is arranged inside the second soil column; the second sensor includes a sensor for testing matrix suction, moisture content and stress; the second sensor is connected to the data acquisition circuit, and the data acquisition circuit is connected to the microcomputer circuit;

[0019] The rainfall system comprises a water supply tank, a flow control valve and a sprinkler head, wherein the flow control valve is arranged on a pipeline between the water supply tank and the sprinkler head.

[0020] Furthermore, the C test area includes a third soil column, a water supply and drainage system, a data acquisition system and a loading system, wherein:

[0021] The third soil column includes a cylinder and soil, the cylinder is provided with an opening on the side wall according to the buried position of the third sensor, and the soil is located inside the cylinder;

[0022] The water supply and drainage system comprises a second water inlet pipe, one end of which is connected to a second Mach flask, and the other end is connected to a third water storage chamber; two ends of a third drainage pipe are respectively connected to a third water storage chamber and a third water collector; the third water storage chamber is located below a third soil column, and a third filter paper is arranged between the third water storage chamber and the third soil column; the third water storage chamber comprises a third bottom plate and a third top plate, and the third bottom plate and the third top plate are fixed by a third support column; an opening is arranged on the third top plate; a second water inlet valve is arranged on the second water inlet pipe, and a fourth drainage valve is arranged on the third drainage pipe;

[0023] The loading system includes a first loading head, a first loading rod, a servo control system and a first loading plate, wherein the top of the first loading plate is connected to the first loading rod, and the top of the first loading rod is fixedly connected to the first loading head; the first loading plate is located directly above the third soil column; the servo control system is electrically connected to the first loading head;

[0024] The data acquisition system comprises sensors inside the third soil column (37) and external sensors. The sensors inside the third soil column (37) comprise third sensors (50), which are buried in layers in the third soil column (37) and comprise sensors for testing matrix suction, water content and stress. The external sensors comprise a first pen-type displacement meter (48) installed on the top of a first loading plate (51) and a first load sensor (78) installed on a first loading head (7). The third sensor (50), the first pen-type displacement meter (48) and the first load sensor (78) are respectively connected to the circuit of a data acquisition instrument (18), and the data acquisition instrument (18) is connected to the circuit of a microcomputer (9).

[0025] Furthermore, the D test area includes a fourth soil column, a water supply and drainage system, a data acquisition system, a loading system and a temperature control system, wherein:

[0026] The fourth soil column includes a cylinder and a soil body, wherein the cylinder is provided with an opening on the side wall according to the buried position of the third sensor, and the soil body is located inside the cylinder; and an insulation layer is provided outside the soil body;

[0027] The water supply and drainage system comprises a third water inlet pipe, one end of which is connected to a third Mach flask, and the other end is connected to a fourth water storage chamber; two ends of a fourth drainage pipe are respectively connected to a fourth water storage chamber and a fourth water collector; the fourth water storage chamber is located below a fourth soil column, and a fourth filter paper is arranged between the fourth water storage chamber and the fourth soil column; the fourth water storage chamber comprises a fourth bottom plate and a fourth top plate, and the fourth bottom plate and the fourth top plate are fixed by a fourth support column; an opening is arranged on the fourth top plate; a third water inlet valve is arranged on the third water inlet pipe, and a fifth drainage valve is arranged on the fourth drainage pipe;

[0028] The loading system includes a second loading head, a second loading rod, a servo control system and a second loading plate, the top of the second loading plate is connected to the second loading rod, and the top of the second loading rod is fixedly connected to the second loading head; the second loading plate is located directly above the fourth soil column; the servo control system is electrically connected to the second loading head;

[0029] The data acquisition system comprises sensors inside the fourth soil column (53) and external sensors. The sensors inside the fourth soil column (53) comprise fourth sensors (65), which are buried in layers in the fourth soil column (53) and comprise sensors for testing matrix suction, water content and stress; the external sensors comprise a second pen-type displacement meter (80) installed on the top of the second loading plate (66) and a second load sensor (79) installed on the second loading head (77); the fourth sensor (65), the second pen-type displacement meter (80) and the second load sensor (79) are respectively connected to the circuit of the data acquisition instrument (18), and the data acquisition instrument (18) is connected to the circuit of the microcomputer (9);

[0030] The temperature control system includes a second temperature plate and a first temperature plate, the second temperature plate is located inside the fourth water storage chamber, and the two ends of the second temperature plate are respectively connected to the second heating pipe and the second return pipe; the second heating pipe and the second return pipe are both connected to the temperature control device; the second temperature plate is provided with a support column reserved hole according to the position of the fourth support column; the first temperature plate is located under the second loading plate, and the two ends of the first temperature plate are respectively fixedly connected to the first heating pipe and the first return pipe; the side wall of the fourth soil column is respectively provided with through hole grooves at the contact positions with the first heating pipe and the first return pipe, and deformation coordination devices are provided on both sides of the fourth soil column, and the first heating pipe and the first return pipe respectively pass through the deformation coordination device and are connected to the temperature control device.

[0031] Furthermore, the deformation coordination device includes a support frame and a spring, the spring is located in the support frame, and the spring is respectively located on the upper and lower sides of the first heating supply pipe and the upper and lower sides of the first return pipe.

[0032] The present invention also provides an application of a roadbed moisture migration simulation platform under complex conditions, which is used to construct a roadbed soil hydraulic characteristic model under full environmental conditions.

[0033] Furthermore, the hydraulic characteristic model of the subgrade soil under the full environmental conditions includes a soil-water characteristic curve model and a permeability coefficient function. The soil-water characteristic curve model includes a soil-water characteristic curve model considering the influence of groundwater, a soil-water characteristic curve model considering a combination of dynamic and static loads, a soil-water characteristic curve model considering the influence of temperature effect and a combination of dynamic and static loads, and a soil-water characteristic curve model considering the influence of plant roots. The construction method of the soil-water characteristic curve model considering the influence of groundwater is as follows:

[0034] Step 1: Take the test data of the middle section test of the first soil column as a representative to describe the soil-water characteristics of the roadbed soil;

[0035] Step 2: construct a time history curve of the evolution of matrix suction and water content during the soil column test;

[0036] Step 3, starting from the matrix suction of 0 kPa, take values ​​at intervals of 50 kPa to 100 kPa. The greater the content of fine particles in the soil, the greater the interval value. Take several groups of data points within the matrix suction interval range, and take the corresponding moisture content values ​​at the same time. Repeat the above steps to obtain a soil-water characteristic curve describing the soil-water characteristics of the soil.

[0037] Step 4: After obtaining the soil-water characteristic curve, the following model is used to fit the soil-water characteristic curve:

[0038]

[0039] Where: effective saturation S = (θ-θ r ) / (θ s -θ r ), θ is the moisture content, θ r is the residual moisture content, θ s is the saturated moisture content; h m is the matrix suction; e is the porosity ratio; m1, m2, m3 and m4 are fitting parameters;

[0040] Step 5: After fitting, the soil-water characteristic curve model considering the influence of groundwater is obtained.

[0041] Furthermore, the method for establishing the soil-water characteristic curve model considering the dynamic and static load combination is: converting the porosity e by the soil deformation recorded by the third sensor, establishing the functional relationship between the porosity e and the dynamic and static load values, and obtaining it by fitting the following formula:

[0042]

[0043] In the formula, e(e0,σ 静 ,σ 动 ) is related to e0, σ 静 , σ 动 Related functions; e0 is the initial porosity, σ 静 is the static load, σ 动 is the dynamic load amplitude;

[0044] The method for constructing the soil-water characteristic curve model considering the temperature effect and the combined influence of dynamic and static loads is as follows: the porosity ratio e is converted by the soil deformation recorded by the fourth sensor, a functional relationship is established between the porosity ratio e and the dynamic and static load values ​​and the temperature difference, and the following fitting is obtained:

[0045]

[0046] Where: e(e0,σ 静 ,σ 动 ,T) is related to e0, σ静 , σ 动 , T-related functions; T is temperature;

[0047] The method for constructing the soil-water characteristic curve model considering the influence of plant roots is as follows: using CT scanning technology, the volume ratio R of the root system in the second soil column is calculated. v , and the relationship between the initial porosity ratio e0 is established to construct the porosity ratio e, and the following equation is used to fit it:

[0048]

[0049] Where: e(e0,R v ) is related to e0 and R v Related functions.

[0050] Furthermore, the permeability coefficient function is constructed according to the soil moisture content and matrix suction data measured at each sensor point, and the steps are as follows:

[0051] Step 1: Take the positions of two sensors in any soil column as the calculation section, record the heights as h1 and h2, and measure the time intervals as t1 and t2 respectively. The flow velocity v of the calculation section is equal to the rate of change of water volume in the time interval t1-t2:

[0052]

[0053] Where: V w is the amount of water passing through the calculated cross section during the time t1-t2, △V w is the change in the amount of water passing through the calculated cross section during the time t1-t2; A is the cross-sectional area of ​​the seepage soil column, and the seepage soil column refers to the soil column infiltrated by water in any of the soil columns;

[0054]

[0055] θ(z) is the equation of the volumetric water content of the seepage profile changing with depth, which can be obtained by using the piecewise linear fitting method on the volumetric water content profile. N is the total number of reference sections, n∈N; h n Indicates the height of the nth section;

[0056] Step 2: Calculate the hydraulic gradient i h,ave :

[0057]

[0058] In the formula, It represents the water head value of point h1 at time t1. It represents the water head value of point h1 at time t2. Indicates the water head value at point h2 at time t1, It represents the water head value of point h2 at time t2;

[0059] Step 3: Calculate the unsaturated permeability coefficient k:

[0060]

[0061] Step 4: Calculate the unsaturated permeability coefficient and take the average value of the matrix suction at position h1 at time t1 and t2 to obtain the matrix suction h m The relationship between the unsaturated permeability coefficient and the permeability coefficient function is obtained by fitting the following formula:

[0062]

[0063] In the formula, k s is the saturated permeability coefficient, and m5, m6, m7 and m8 are fitting parameters.

[0064] The beneficial effects of the present invention are:

[0065] (1) The constructed test platform integrates the main environmental conditions of the roadbed and can meet the test of the evolution of moisture migration under the single or coupled influence of all environmental conditions.

[0066] (2) The use of a water storage chamber device in the water supply and drainage system solves the problem of the influence of turbulent water flow on the migration of water inside the soil during water supply, and realizes the stable infiltration of water into the soil column.

[0067] (3) A temperature control system and a loading system were used to realize indoor simulation tests on subgrade moisture migration under the influence of temperature difference and the coupling of dynamic and static loads.

[0068] (4) The construction methods of the hydraulic characteristic curves and models of the roadbed under various environments are given. The construction method of the soil-water model considering the influence of different factors is given. In the construction of the permeability coefficient function, the segmented fitting method and the CAD software are given to quickly process the calculation method of the water content change; at the same time, this method can customize the water supply head for permeability coefficient calculation, which can speed up the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0070] Figure 1 It is an overall schematic diagram of the test platform of an embodiment of the present invention.

[0071] Figure 2It is a structural diagram of a water migration simulation test area of ​​a roadbed under the action of groundwater according to an embodiment of the present invention.

[0072] Figure 3 It is a structural diagram of a water migration simulation test area under the combined action of "rainfall + vegetation" in an embodiment of the present invention.

[0073] Figure 4 It is a structural diagram of a water migration simulation test area under the combined action of dynamic and static forces according to an embodiment of the present invention.

[0074] Figure 5 It is a structural diagram of a water migration simulation test area under the combined action of "load combination + temperature effect" in an embodiment of the present invention.

[0075] Figure 6 It is a structural diagram of the annular reflux of the temperature plate; wherein, (a) is the structural diagram of the first temperature plate, and (b) is the lower structural diagram of the second temperature plate.

[0076] Figure 7 It is a time course graph of the evolution of matrix suction and water content.

[0077] Figure 8 It is a reference diagram for calculating the permeability coefficient; among them, (a) is a schematic diagram of the distribution of each monitoring point, and (b) is a schematic diagram of the polygon formed by the water content and height of each monitoring point.

[0078] In the figure, 1. base, 2. arc cover plate, 3. central axis, 4. insulation plate, 5. top plate, 6. spray head, 7. first loading head, 8. servo control system, 9. microcomputer, 10. first soil column, 11. first sensor, 12. first drainage pipe, 13. first water inlet pipe, 14. first water storage chamber, 15. first water collector, 16. first filter paper, 17. first Martens flask, 18. data acquisition instrument, 19. first bottom plate, 20. first top plate, 21. first support column, 22. water supply tank, 23. flow 1. The second sensor, 2. The second drain pipe, 2. The second water storage chamber, 2. The second water collector, 2. The second filter paper, 2. The second bottom plate, 3. The second top plate, 3. The second support column, 3. The first water inlet valve, 3. The first drain valve, 3. The second drain valve, 3. The third drain valve, 3. The second soil column, 3. The third soil column, 3. The second Martens flask, 3. The second water inlet pipe, 4. The third drain pipe, 4. The third water storage chamber, 4. The third water collector, 4. The second water inlet valve, 4. The third drain valve, 4. The third soil column, 4. The third water collector, 4. The second water inlet valve, 4. The third drain pipe, 4. The third water storage chamber, 4. The third water collector, 4. The second water inlet valve, 4. The third drain valve ... second water inlet valve, 4. The third water collector, 4. The second water inlet valve, 4. The second water inlet valve, 4. The third water collector, 4. The second water inlet valve, 4. The second water inlet valve, 4. The third water collector, 4 3rd filter paper, 44. 3rd bottom plate, 45. 3rd top plate, 46. 3rd support column, 47. 2nd water inlet valve, 48. 1st pen displacement meter, 49. 4th drain valve, 50. 3rd sensor, 51. 1st loading plate, 52. 1st loading rod, 53. 4th soil column, 54. 3rd Martens flask, 55. 3rd water inlet pipe, 56. 4th drain pipe, 57. 4th water storage chamber, 58. 4th water collector, 59. 4th filter paper, 60. 4th bottom plate, 61. 4th top plate, 62. 4th support column, 63. 3rd Inlet valve, 64. Fifth drain valve, 65. Fourth sensor, 66. Second loading plate, 67. Second loading rod, 68. First heating pipe, 69. First return pipe, 70. First temperature plate, 71. Second heating pipe, 72. Second return pipe, 73. Second temperature plate, 74. Temperature control device, 75. Deformation coordination device, 76. Insulation layer, 77. Second loading head, 78. First load sensor, 79. Second load sensor, 80. Second pen displacement meter, 81. Reserved hole for support column. DETAILED DESCRIPTION

[0079] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] like Figure 1 to Figure 6As shown, the present invention provides a roadbed moisture migration simulation platform under complex conditions, including a base 1, various test areas, a central axis 3, an insulation board 4, a top plate 5, a spray head 6, a first loading head 7, a second loading head 77, a servo control system 8, a microcomputer 9, and an arc cover plate 2.

[0081] Among them, the base 1 is a circular structure, located at the bottom of the platform for supporting the entire platform; four test areas A, B, C, and D are arranged on the upper surface of the base 1, each test area is isolated by an insulation board 4, and each insulation board 4 is fixedly connected to the central axis 3; the insulation board 4 and the top of the central axis 3 are connected to the top plate 5, and the outer side of the insulation board 4 is in contact with the arc cover plate 2, and a closed structure is formed between the top plate 5, the base 1, and the arc cover plate 2; the top plate 5 is connected to the sprinkler head 6 of the B test area for rainfall simulation in the B test area; the top plate 5 is connected to the C with a first loading head 7, and the top plate 5 is connected to the D test area with a second loading head 77, the first loading head 7 and the second loading head 77 are respectively connected to the servo control system 8, and the servo control system 8 is connected to the microcomputer 9.

[0082] A test area is used to simulate the water migration law of the roadbed under the action of groundwater, such as Figure 2 As shown. A test area is provided with an overall soil column structure, which includes: a first soil column body 10, a water supply and drainage system, and a data acquisition system, wherein:

[0083] The first soil column 10 is composed of a cylinder and soil, wherein the cylinder is made of acrylic or plexiglass, and a hole is opened on the side wall according to the buried position of the first sensor 11 to facilitate the circuit output of the first sensor 11. The size of the cylinder complies with the following requirements: the inner diameter of the cylinder must be greater than 10 times the maximum particle size of the soil and the diameter of the sensor, and the ratio of the height of the cylinder to the inner diameter is greater than 2, which can eliminate the size effect caused by the excessive size of the sensor and soil particles; on this basis, the height is increased by 10cm to 20cm for easy filling; the first filter paper 16 is spread flat on the bottom, and the soil is pressed into the cylinder in layers to form the first soil column 10.

[0084] The water supply and drainage system consists of a first drainage pipe 12 at the bottom, a first water inlet pipe 13, a first water storage chamber 14 and a first water collector 15. The first drainage pipe 12 at the bottom is connected to the first water collector 15 to discharge and collect the water in the first soil column 10 after the test; one end of the first water inlet pipe 13 is connected to the first Mach flask 17, and the other end is connected to the first water storage chamber 14, which is used to supply water to the first soil column 10; the first water storage chamber 14 is located below the first soil column 10, and a first filter paper 16 is arranged between the first soil column 10. The first water storage chamber 14 adopts the design of the first bottom plate 19 + the first top plate 20 + the first support column 21. The first top plate 20 has a hole, and the diameter D of the hole ranges from 0 to 2 cm. The distance between the center points of the holes is D+0.5 to 2 cm, which can ensure that the water passes through the uniform small holes on the top plate of the first water storage chamber 14 and smoothly passes through the first filter paper 16 to enter the first soil column 10. The first water inlet pipe 13 is provided with a first water inlet valve 32 , and the first drain pipe 12 is provided with a first drain valve 33 , which are used to control water inlet and drain, respectively.

[0085] The data acquisition system is composed of the first sensors 11, the data acquisition instrument 18 and the microcomputer 9. The first sensors 11 inside the first soil column 10 are distributed at equal intervals. The distance between the top layer of the first sensors 11 and the top surface is half of the distance between the two layers of the first sensors 11. The distance between the bottom layer of the first sensor 11 and the bottom of the soil layer also complies with this rule, so that the sensor of this layer can represent the test results of the nearby soil. The first sensor 11 at each position is composed of sensors for testing matrix suction, moisture content and stress, and is used to test the water migration and stress distribution inside the soil. The data acquisition instrument 18 connects all the first sensors 11 and inputs the collected signals into the microcomputer 9 to obtain the final test data.

[0086] A test area is used as follows:

[0087] 1. Filling of the first soil column 10. The first water storage chamber 14 is placed at the bottom of the cylinder, and the first filter paper 16 is placed, and the soil is statically pressed into shape according to a layer of 5 cm.

[0088] 2. Burying and connecting the first sensor 11. After filling the soil to the data collection point, bury the first sensor 11, and then fill the next layer. After all the first sensors 11 are buried, connect them to the data acquisition device 18 and the microcomputer 9.

[0089] 3. Water supply system access: Connect the first Malchnitz flask 17 to the first water storage chamber 14 .

[0090] 4. Start and end of the test. Turn on the data acquisition instrument 18 and the microcomputer 9 to collect data in real time, open the first water inlet valve 32 of the first Malchow flask 17 to supply water to the first soil column 10, and start the test; when the moisture meter reading at the top tends to balance, terminate the test.

[0091] In the water supply and drainage system of the present invention, a water storage chamber is used for water supply and drainage, so that the water flow can penetrate into the soil body stably, and the problem that the turbulent water flow generated by the traditional test device directly supplying water through the water pipe will affect the migration of water in the soil body is solved. At the same time, filter paper is arranged under the soil body to prevent soil loss.

[0092] Test area B is a combination of "rainfall + vegetation", which is used to simulate the situation when the roadbed slope is facing rainfall, such as Figure 3 It is composed of a second soil column 36, a data acquisition system, a drainage system, and a rainfall system.

[0093] The structure of the second soil column 36 is consistent with that of the first soil column 10 in the test area A.

[0094] The data acquisition system is consistent with that of the A test area: it includes a second sensor 24, which is arranged inside the second soil column 36; the second sensor 24 includes sensors for testing matrix suction, moisture content and stress; the second sensor 24 is connected to the data acquisition instrument 18 circuit, and the data acquisition instrument 18 is connected to the microcomputer 9 circuit.

[0095] The rainfall system consists of a water supply tank 22, a flow control valve 23 and a sprinkler head 6. The water supply tank 22 provides the moisture required for rainfall. The flow control valve 23 is connected between the water supply tank 22 and the sprinkler head 6 to control the water flow in the pipeline to simulate different rainfall intensities. The sprinkler head 6 is in a cone shape with the top connected to the pipeline and the bottom disc dispersing the water onto the surface of the second soil column 36 through a large number of small holes.

[0096] The drainage system includes a second drainage pipe 25, the two ends of which are connected to the second water storage chamber 26 and the second water collector 27 respectively; a third drainage valve 35 is provided on the second drainage pipe 25, and a second drainage valve 34 is provided on the top of the second soil column 36; the second water storage chamber 26 is located below the second soil column 36, and a second filter paper 28 is provided between the second water storage chamber 26 and the second soil column 36; the second water storage chamber 26 includes a second bottom plate 29 and a second top plate 30, and the second bottom plate 29 and the second top plate 30 are fixed by a second support column 31; and an opening is provided on the second top plate 30. The drainage system connects the second drainage pipe 25 through the second water storage chamber 26 at the bottom for drainage, and collects the water with the second water collector 27.

[0097] The method of using the B test area is as follows:

[0098] 1. The second soil column 36 is filled. The filling process is the same as that of the A test area. After the filling is completed, seeds are evenly sown on the upper surface of the soil, and vegetation is cultivated by regular watering. The test is carried out when the vegetation grows to about 3 to 6 months.

[0099] 2. The second sensor 24 is buried and connected. It is consistent with the A test area.

[0100] 3. Water supply and drainage system access. Set the rainfall intensity according to the test plan, place the sprinkler head 6 above the second soil column 36; open the third drainage valve 35 at the bottom, collect excess water with the second water collector 27, and then open the second drainage valve 34 at the top to drain the water that has not penetrated into the second soil column 36.

[0101] 4. Start and end of the test. Turn on the data acquisition instrument 18 and the microcomputer 9 to collect data in real time, open the flow control valve 23 to spray, and start the test; when the moisture meter reading tends to balance, the test is terminated.

[0102] The C test area is used to simulate the water migration law of the roadbed under the combination of roadbed and pavement deadweight (static) and vehicle load (dynamic), such as Figure 4 It is composed of a third soil column 37, a water supply and drainage system, a data acquisition system, and a loading system.

[0103] The third soil column 37 is consistent with the test area A.

[0104] The structure of the water supply and drainage system is consistent with that of the test area A: it includes a second water inlet pipe 39, one end of which is connected to the second Mach flask 38 and the other end is connected to the third water storage chamber 41; the two ends of the third drainage pipe 40 are respectively connected to the third water storage chamber 41 and the third water collector 42; the third water storage chamber 41 is located below the third soil column 37, and a third filter paper 43 is arranged between the third soil column 37; the third water storage chamber 41 includes a third bottom plate 44 and a third top plate 45, and the third bottom plate 44 and the third top plate 45 are fixed by a third support column 46; the third top plate 45 is provided with an opening; the second water inlet pipe 39 is provided with a second water inlet valve 47, and the third drainage pipe 40 is provided with a fourth drainage valve 49. The water supply and drainage system supplies water through the second Mach flask 38 and discharges excess water into the third water collector 42 through the third drainage pipe 40.

[0105] The data acquisition system includes sensors located inside the third soil column 37 and external sensors, wherein the sensors inside the third soil column 37 include a third sensor 50, the buried position and type of the third sensor 50 are consistent with the buried position and type of the first sensor 11 in the test area A, and the sensors outside the third soil column 37 are mainly the first pen-type displacement meter 48 placed on the top of the first loading plate 51 and the first load sensor 78 installed on the first loading head 7, which reflect the overall deformation of the third soil column 37 and the size of the applied load; the data acquisition instrument 18 is respectively connected to all the third sensors 50, the first pen-type displacement meter 48, and the first loading head 7, and the collected signals are input into the microcomputer 9 to obtain the final test data.

[0106] Loading system: It consists of a first loading head 7, a first loading rod 52, a servo control system 8, and a first loading plate 51, wherein the first loading head 7 is fixed on the top plate 5, the top plate 5 of the test platform provides a reaction force, and the servo control system 8 provides control over the output load size, frequency, and waveform of the first loading head 7; the first loading plate 51 is a cone, and the first loading rod 52 on the top is fixedly connected.

[0107] The C test area is used as follows:

[0108] 1. The third soil column 37 is filled. The filling process is the same as that of the A test area.

[0109] 2. The embedding and connection of the sensors inside and outside the third soil column 37. The embedding of the internal sensors is consistent with that of the A test area. The first pen displacement meter 48 of the external sensor is installed on the top of the first loading plate 51, and the first load sensor 78 is installed on the first loading head 7. The first pen displacement meter 48 and the first load sensor 78 are connected to the data acquisition instrument 18 respectively.

[0110] 3. Water supply and drainage system access. Same as test area A.

[0111] 4. Loading system access: After the first loading head 7 , the first loading plate 51 , and the first loading plate 51 are installed, they are connected to the servo control system 8 and the microcomputer 9 , and the first loading plate 51 is placed on the top of the third soil column 37 .

[0112] 5. Start and end of the test. Turn on the data acquisition instrument 18 and the microcomputer 9 to collect data in real time, set the loading scheme in the microcomputer 9 and start loading; at the same time, open the second water inlet valve 47 of the second Martens flask 38 to supply water to the third soil column 37, and open the fourth drain valve 49 to release excess water. When the moisture meter reading tends to balance, terminate the test.

[0113] The D test area is a combination of "load combination + temperature effect" to simulate the impact of the roadbed on the external environment temperature changes and the internal temperature differences on the water migration, such as Figure 5 As shown. It includes a fourth soil column 53, a water supply and drainage system, a data acquisition system, and a loading system. Among them,

[0114] The fourth soil column 53 includes a cylinder and soil. The cylinder is provided with an opening on the side wall according to the buried position of the third sensor 50. The soil is located inside the cylinder. A heat preservation layer 76 is provided outside the soil.

[0115] The water supply and drainage system includes a third water inlet pipe 55, one end of which is connected to the third Mach flask 54, and the other end is connected to the fourth water storage chamber 57; the fourth drainage pipe 56 is connected to the fourth water storage chamber 57 and the fourth water collector 58 at both ends; the fourth water storage chamber 57 is located below the fourth soil column 53, and a fourth filter paper 59 is arranged between the fourth soil column 53; the fourth water storage chamber 57 includes a fourth bottom plate 60 and a fourth top plate 61, and the fourth bottom plate 60 and the fourth top plate 61 are fixed by a fourth support column 62; the fourth top plate 61 is provided with an opening; the third water inlet pipe 55 is provided with a third water inlet valve 63, and the fourth drainage pipe 56 is provided with a fifth drainage valve 64. The water supply and drainage system is used to supply water to the fourth soil column 53 and discharge excess water.

[0116] The loading system includes a second loading head 77, a second loading rod 67, a servo control system 8, and a second loading plate 66. The top of the second loading plate 66 is connected to the second loading rod 67, and the top of the second loading rod 67 is fixedly connected to the second loading head 77. The second loading plate 66 is located directly above the fourth soil column 53. The servo control system 8 is electrically connected to the second loading head 77. The loading system is used to apply a load force to the fourth soil column 53.

[0117] The data acquisition system includes sensors inside the fourth soil column 53 and external sensors, wherein the sensors inside the fourth soil column 53 include a fourth sensor 65, which is buried in the fourth soil column 53 and includes sensors for testing matrix suction, moisture content and stress; the external sensors include a second pen-type displacement meter 80 installed on the top of the second loading plate 66 and a second load sensor 79 installed on the second loading head 77; the fourth sensor 65, the second pen-type displacement meter 80, and the second load sensor 79 are respectively connected to the data acquisition instrument 18 circuit, and the data acquisition instrument 18 is connected to the microcomputer 9 circuit.

[0118] In order to meet the requirements of the combination of temperature and load effects, a temperature control system is also provided, wherein a second temperature plate 73 is provided in the fourth water storage chamber 57 at the bottom of the fourth soil column 53, and the second temperature plate 73 adopts an annular reflux structure (such as Figure 6 (b) in the figure), and the two ends are connected to the second heating pipe 71 and the second return pipe 72 respectively; the second temperature plate 73 is provided with a support column reserved hole 81 according to the position of the fourth support column 62 of the fourth water storage chamber 57, so as to facilitate the establishment of the fourth support column 62; the first temperature plate 70 (structure as shown in FIG. 5 ) is installed on the upper end of the fourth soil column 53 Figure 6As shown in (a) in the figure, the first temperature plate 70 and the second loading plate 66 are connected and fixed with bolts to form a whole. A deformation coordination device 75 with a double spring structure is set at the contact position between the first temperature plate 70 and the side wall of the fourth soil column 53 to coordinate the deformation during load application and the deformation of the pipeline to avoid the reciprocating motion of the second loading plate 66 + the first temperature plate 70 during the cyclic dynamic load loading process, which causes the first heating pipeline 68 and the first return pipeline 69 to be damaged by the torsion between the outer wall of the cylinder; the first temperature plate 70 and the second temperature plate 73 are both connected to a temperature control device 74, through which different temperatures are applied in the fourth soil column 53 to form a temperature difference and produce a temperature effect; the outside of the fourth soil column 53 is made of high-performance thermal insulation material to make an insulation layer 76 to isolate the internal temperature of the fourth soil column 53 from the exchange of the external temperature.

[0119] Through-hole grooves are respectively provided at the contact positions between the side walls of the fourth soil column 53 and the first heating pipe 68 and the first return pipe 69 to facilitate the up and down movement of the first heating pipe 68 and the first return pipe 69; the deformation coordination device 75 includes a support frame and a spring, the spring is located in the bracket, and the spring is respectively located on the upper and lower sides of the first heating pipe 68 and the upper and lower sides of the first return pipe 69.

[0120] The method of using the D test area is as follows:

[0121] 1. Fill the fourth soil column 53. Place the second temperature plate 73 on the fourth bottom plate 60 of the fourth water storage chamber 57, then pass the fourth support column 62 of the fourth water storage chamber 57 through the support column reserved hole of the second temperature plate 73 and fix it. The subsequent steps are the same as those of the A test area.

[0122] 2. The installation and connection of sensors inside and outside the fourth soil column 53 are consistent with the C test area.

[0123] 3. Water supply and drainage system access. Same as test area A.

[0124] 4. Loading system connection: Place the first temperature plate 70 on the top of the soil, place the second loading plate 66 on the top of the first temperature plate 70, and then connect the second loading rod 67, the second loading head 77, the servo control system 8 and the microcomputer 9 accordingly.

[0125] 5. Temperature control system connection. Connect the heating supply pipe and return pipe to the corresponding temperature plate respectively.

[0126] 6. Start and end of the test. Turn on the data acquisition instrument 18 and the microcomputer 9 to collect data in real time, turn on the temperature control device 74 to make the fourth soil column 53 form a set temperature difference, and then set the loading plan in the microcomputer 9 to start loading; at the same time, open the third water inlet valve 63 of the fourth Malchow flask 54 to supply water to the fourth soil column 53, and terminate the test when the moisture meter reading tends to balance.

[0127] The D test area uses the temperature control device 74 to adjust the temperatures of the first temperature plate 70 and the second temperature plate 73 respectively, so that a temperature difference is generated between the upper and lower ends of the fourth soil column 53. At the same time, the second loading head 77 is cooperated to realize the indoor simulation of roadbed moisture migration under the influence of temperature difference and dynamic and static load coupling.

[0128] The experimental platform constructed by the embodiment of the present invention sets four test areas A, B, C, and D to respectively simulate four situations: moisture migration of the roadbed under the action of groundwater, moisture migration of the roadbed slope when facing rainfall, moisture migration of the roadbed under the combination of the self-weight of the roadbed and pavement and the driving load, and the influence of the external environmental temperature change and the internal temperature difference on the moisture migration. It integrates the main environmental conditions of the roadbed and can meet the test of the evolution law of moisture migration under the single or coupled influence of all environmental conditions.

[0129] It should be noted that the circuit connections not mentioned in the present invention are all conventional connections that can be implemented by those skilled in the art based on their professional knowledge.

[0130] The present invention also provides a method for constructing a hydraulic model of subgrade soil under complex conditions. The hydraulic characteristics are divided into soil-water characteristics and permeability characteristics of subgrade soil. Based on the above-mentioned water migration simulation test data, the evolution data of matrix suction and water content over time can be obtained, and then the soil-water characteristic curve model and permeability coefficient function can be constructed, as follows:

[0131] (1) Construction of soil-water characteristic curve model.

[0132] 1) The test data of the middle section of the soil column is used as a representative to describe the soil-water characteristics of the roadbed soil.

[0133] 2) Construct the time course curve of the evolution of matrix suction and water content during the above soil column test, such as Figure 7 As shown; at the same time, the corresponding matrix suction and water content values ​​are taken, such as the matrix suction p1 and water content value θ1 at time t1.

[0134] 3) Starting from the matrix suction of 0 kPa, take values ​​at intervals between 50 kPa and 100 kPa. The greater the content of fine particles in the soil, the larger the interval value, and take 5 sets of data points within the matrix suction interval range (matrix suction and water content corresponding to the same time). Figure 7 Between P1 and P2 in , it is divided into 6 equal parts with an interval of 50kPa to 100kPa, corresponding to 5 equally spaced matrix suction values ​​(excluding the endpoints), and the starting point and these 5 values ​​are counted in the same group; and the moisture content value corresponding to the same moment is taken, and the soil-water characteristic curve describing the soil-water characteristics of the soil is obtained by repeating the above steps.

[0135] 4) After obtaining the soil-water characteristic curve, the following model can be used to fit it:

[0136]

[0137] Where: effective saturation S = (θ-θ r ) / (θ s -θ r ), θ is the moisture content, θ r is the residual moisture content, θ s is the saturated moisture content; h m is the matrix suction; e is the porosity ratio; m1, m2, m3 and m4 are fitting parameters.

[0138] 5) The method of constructing the soil-water characteristic curve model considering the influence of different factors is as follows:

[0139] ① When considering the influence of groundwater, the above model fitting is used to construct a soil-water characteristic curve model considering the influence of groundwater.

[0140] ② When considering the combined effects of dynamic and static loads, the deformation recorded by the displacement meter is converted into the void ratio e, and a functional relationship between the void ratio e and the dynamic and static load values ​​is established, thereby obtaining a soil-water characteristic curve model considering the dynamic and static load combination.

[0141]

[0142] Where: e(e0,σ 静 ,σ 动 ) is related to e0, σ 静 , σ 动 The relevant function can be obtained by using the data fitting method; e0 is the initial porosity, σ 静 is the static load, σ 动 is the dynamic load amplitude.

[0143] ③ When considering the combination of dynamic and static loads and temperature effects, as in ②, a functional relationship is established between the porosity e and the dynamic and static load values ​​and temperature difference, and a soil-water characteristic curve model that considers the influence of temperature effects and the combination of dynamic and static loads can be constructed.

[0144]

[0145] Where: e(e0,σ 静 ,σ 动 ,T) is related to e0, σ 静 , σ 动 , T-related functions can be obtained by using the data fitting method; e0 is the initial porosity, σ 静 is the static load, σ 动 is the dynamic load amplitude, and T is the temperature.

[0146] ④Use CT scanning technology to calculate the volume ratio R of the root system in the soil column v , using this as an indicator to establish a relationship with the initial porosity ratio e0 to construct a new porosity ratio e, and then construct a soil-water characteristic curve model that takes into account the influence of plant roots.

[0147]

[0148] (2) Construction of permeability coefficient function. Based on the soil moisture content and matrix suction data tested at each point, the unsaturated permeability coefficient of the soil under different matrix suctions can be calculated. The steps are as follows:

[0149] 1) Water volume change rate v. The position of the sensor at the bottom of any soil column is taken as the calculation section, denoted as h1, see Figure 8 In (a), the measurement time intervals are t1 and t2. The flow velocity v in the calculated cross section of the sample is equal to the rate of change of the water volume in the time interval t1-t2.

[0150]

[0151] Where: V w is the amount of water passing through the calculated cross section during the time t1-t2, see formula 1-2; △V w It is the change in the amount of water passing through the calculated cross section during the time t1-t2; A is the cross-sectional area of ​​the seepage soil column. The seepage soil column refers to any soil column that is infiltrated by water.

[0152] The change in the amount of water above the cross section during the interval t1-t2 is the amount of water passing through the cross section. The amount of water above V w As shown below:

[0153]

[0154] Where: θ(z) is the equation of the volumetric water content of the seepage profile changing with depth, which can be obtained by using the piecewise linear fitting method on the volumetric water content profile, N is the total number of reference sections, h is n Represents the height of the nth section. Here is a simple method to calculate the above V w Value: Figure 8 As shown in (b), the moisture content values ​​of each position tested by the sensor and the height values ​​in the vertical direction form the horizontal and vertical coordinates. The CAD software is used to use its polyline function to input the coordinate values, and then a closed polygon is formed with the vertical coordinates. The "block" function is used to form a block of the polygon. By querying the area of ​​the block, V can be obtained. w This method can avoid fitting and reintegrating the moisture content function of each segment and can quickly obtain the result.

[0155] Interval time t1-t2 water volume change V w , see the following formula:

[0156]

[0157] 2) Hydraulic gradient i h,ave . Hydraulic gradient i h,ave The forward difference method is used in the calculation process, and its expression is:

[0158]

[0159] In the formula, It represents the water head value of point h1 at time t1. It represents the water head value of point h1 at time t2. Indicates the water head value at point h2 at time t1, Represents the head value of point h2 at time t2.

[0160] The total water head borne by the calculation section is composed of position head, pressure head and velocity head. Compared with the position head and pressure head, the velocity head can be ignored, so the total water head can be expressed as:

[0161]

[0162] Where: h is the total water head value; s is the matrix suction; h g is the position head, with the 0 head position as the reference plane. For the water content in the soil above this base plane, the gravity inhibits the water content, so a negative value is taken to reduce the total head value. Below the base plane, a positive value is taken to increase the total head value to drive the water migration; ρ w is the density of water at the test temperature; g is the acceleration due to gravity, and g=9.8N / kg.

[0163] 3) Unsaturated permeability coefficient k. The water volume change rate v obtained above is combined with the hydraulic gradient i ave The unsaturated permeability coefficient can be calculated by making a comparison:

[0164]

[0165] 4) Permeability coefficient function. When the unsaturated permeability coefficient is calculated, the average value of the matrix suction at position h1 at time t1 and t2 is taken to obtain the matrix suction h m The relationship between the permeability coefficient and the unsaturated permeability coefficient can be obtained by fitting the following formula.

[0166]

[0167] In the formula, k s is the saturated permeability coefficient and is tested using an indoor variable water head test device. m5, m6, m7, and m8 are fitting parameters. The values ​​of e under each factor are consistent with the values ​​of e in the soil-water characteristic curve.

[0168] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0169] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A platform for simulating water migration in roadbed under complex conditions, comprising a base (1), characterized in that: The upper surface of the base (1) is provided with a plurality of test areas, each of which is separated by a thermal insulation plate (4); the thermal insulation plates (4) are fixedly connected to each other by a central axis (3); a top plate (5) is connected to the top of the thermal insulation plate (4) and the central axis (3); the outer side of the thermal insulation plate (4) is in contact with the arc-shaped cover plate (2), and the upper and lower ends of the arc-shaped cover plate (2) are respectively fixedly connected to the top plate (5) and the base (1); the test areas include an A test area, a B test area, a C test area and a D test area, wherein: The A test area is used to simulate the water migration of the roadbed under the action of groundwater; The B test area is used to simulate the situation when the roadbed slope is facing rainfall; The C test area is used to simulate the water migration of the roadbed under the combination of the roadbed and pavement deadweight and vehicle load; The D test area is used to simulate the influence of the water migration on the roadbed under the combination of the roadbed and pavement deadweight and vehicle load, and the external environment temperature change and the internal temperature difference; The top plate (5) and the C test area are connected with a first loading head (7), the top plate (5) and the D test area are connected with a second loading head (77), the first loading head (7) and the second loading head (77) are respectively connected with a servo control system (8), and the servo control system (8) is connected with a microcomputer (9); The A test area includes a first soil column (10), a water supply and drainage system, and a data acquisition system, wherein: The first soil column (10) comprises a cylinder and soil, the cylinder being provided with an opening on the side wall according to the buried position of the first sensor (11), and the soil being located inside the cylinder; The water supply and drainage system comprises a first water inlet pipe (13), one end of the first water inlet pipe (13) is connected to a first Malchow flask (17), and the other end is connected to a first water storage chamber (14); two ends of a first drainage pipe (12) are respectively connected to the first water storage chamber (14) and a first water collector (15); the first water storage chamber (14) is located below the first soil column (10), and a first filter paper (16) is arranged between the first water storage chamber (14) and the first soil column (10); the first water storage chamber (14) comprises a first bottom plate (19) and a first top plate (20), and the first bottom plate (19) and the first top plate (20) are fixed by a first support column (21); an opening is arranged on the first top plate (20); a first water inlet valve (32) is arranged on the first water inlet pipe (13), and a first drainage valve (33) is arranged on the first drainage pipe (12); The data acquisition system comprises a first sensor (11), which is layered inside a first soil column (10); the first sensor (11) comprises a sensor for testing matrix suction, water content and stress; the first sensor (11) is connected to a data acquisition device (18) in circuit, and the data acquisition device (18) is connected to a microcomputer (9) in circuit.

2. The roadbed water migration simulation platform under complex conditions according to claim 1 is characterized in that: The B test area includes a second soil column (36), a data acquisition system, a drainage system, and a rainfall system, wherein: The second soil column (36) comprises a cylinder and soil, the cylinder is provided with an opening on the side wall according to the buried position of the second sensor (24), the soil is located inside the cylinder; and plants are planted in the soil; The drainage system comprises a second drainage pipe (25), the two ends of which are respectively connected to a second water storage chamber (26) and a second water collector (27); a third drainage valve (35) is arranged on the second drainage pipe (25), and a second drainage valve (34) is arranged on the top of the second soil column (36); the second water storage chamber (26) is located below the second soil column (36), and a second filter paper (28) is arranged between the second water storage chamber (26) and the second soil column (36); the second water storage chamber (26) comprises a second bottom plate (29) and a second top plate (30), and the second bottom plate (29) and the second top plate (30) are fixed by a second support column (31); and an opening is arranged on the second top plate (30); The data acquisition system comprises a second sensor (24), the second sensor (24) being arranged in layers inside the second soil column (36); the second sensor (24) comprising a sensor for testing matrix suction, water content and stress; the second sensor (24) being connected to a data acquisition instrument (18) in circuit, and the data acquisition instrument (18) being connected to a microcomputer (9) in circuit; The rainfall system comprises a water supply tank (22), a flow control valve (23) and a sprinkler head (6); the flow control valve (23) is arranged on a pipeline between the water supply tank (22) and the sprinkler head (6).

3. The roadbed water migration simulation platform under complex conditions according to claim 1 is characterized in that: The C test area includes a third soil column (37), a water supply and drainage system, a data acquisition system and a loading system, wherein: The third soil column (37) comprises a cylindrical body and a soil body, wherein the cylindrical body is provided with an opening on the side wall according to the buried position of the third sensor (50), and the soil body is located inside the cylindrical body; The water supply and drainage system comprises a second water inlet pipe (39), one end of which is connected to the second Malchnitz flask (38), and the other end of which is connected to the third water storage chamber (41); two ends of the third drainage pipe (40) are respectively connected to the third water storage chamber (41) and the third water collector (42); the third water storage chamber (41) is located below the third soil column (37), and a third filter paper (43) is arranged between the third water storage chamber (41) and the third soil column (37); the third water storage chamber (41) comprises a third bottom plate (44) and a third top plate (45), and the third bottom plate (44) and the third top plate (45) are fixed by a third support column (46); the third top plate (45) is provided with an opening; the second water inlet pipe (39) is provided with a second water inlet valve (47), and the third drainage pipe (40) is provided with a fourth drainage valve (49); The loading system comprises a first loading head (7), a first loading rod (52), a servo control system (8) and a first loading plate (51); the top of the first loading plate (51) is connected to the first loading rod (52), and the top of the first loading rod (52) is fixedly connected to the first loading head (7); the first loading plate (51) is located directly above the third soil column (37); the servo control system (8) is electrically connected to the first loading head (7); The data acquisition system comprises sensors inside the third soil column (37) and external sensors. The sensors inside the third soil column (37) comprise third sensors (50), which are buried in layers in the third soil column (37) and comprise sensors for testing matrix suction, water content and stress. The external sensors comprise a first pen-type displacement meter (48) installed on the top of a first loading plate (51) and a first load sensor (78) installed on a first loading head (7). The third sensor (50), the first pen-type displacement meter (48) and the first load sensor (78) are respectively connected to the circuit of a data acquisition instrument (18), and the data acquisition instrument (18) is connected to the circuit of a microcomputer (9).

4. The roadbed water migration simulation platform under complex conditions according to claim 1 is characterized in that: The D test area includes a fourth soil column (53), a water supply and drainage system, a data acquisition system, a loading system and a temperature control system, wherein: The fourth soil column (53) comprises a cylindrical body and a soil body, wherein the cylindrical body is provided with an opening on the side wall according to the buried position of the third sensor (50), and the soil body is located inside the cylindrical body; and a heat-insulating layer (76) is provided outside the soil body; The water supply and drainage system comprises a third water inlet pipe (55), one end of the third water inlet pipe (55) is connected to the third Malchnitz flask (54), and the other end is connected to the fourth water storage chamber (57); the two ends of the fourth drainage pipe (56) are respectively connected to the fourth water storage chamber (57) and the fourth water collector (58); the fourth water storage chamber (57) is located below the fourth soil column (53), and a fourth filter paper (59) is arranged between the fourth water storage chamber (57) and the fourth soil column (53); the fourth water storage chamber (57) comprises a fourth bottom plate (60) and a fourth top plate (61), and the fourth bottom plate (60) and the fourth top plate (61) are fixed by a fourth support column (62); the fourth top plate (61) is provided with an opening; the third water inlet pipe (55) is provided with a third water inlet valve (63), and the fourth drainage pipe (56) is provided with a fifth drainage valve (64); The loading system comprises a second loading head (77), a second loading rod (67), a servo control system (8) and a second loading plate (66); the top of the second loading plate (66) is connected to the second loading rod (67); the top of the second loading rod (67) is fixedly connected to the second loading head (77); the second loading plate (66) is located directly above the fourth soil column (53); the servo control system (8) is electrically connected to the second loading head (77); The data acquisition system comprises sensors inside the fourth soil column (53) and external sensors. The sensors inside the fourth soil column (53) comprise fourth sensors (65), which are buried in layers in the fourth soil column (53) and comprise sensors for testing matrix suction, water content and stress; the external sensors comprise a second pen-type displacement meter (80) installed on the top of the second loading plate (66) and a second load sensor (79) installed on the second loading head (77); the fourth sensor (65), the second pen-type displacement meter (80) and the second load sensor (79) are respectively connected to the circuit of the data acquisition instrument (18), and the data acquisition instrument (18) is connected to the circuit of the microcomputer (9); The temperature control system comprises a second temperature plate (73) and a first temperature plate (70); the second temperature plate (73) is located inside the fourth water storage chamber (57); two ends of the second temperature plate (73) are respectively connected to a second heating pipe (71) and a second return pipe (72); the second heating pipe (71) and the second return pipe (72) are both connected to a temperature control device (74); the second temperature plate (73) is provided with a support column reserved hole (81) according to the position of the fourth support column (62); the first temperature plate (70) is located Below the second loading plate (66), the two ends of the first temperature plate (70) are respectively fixedly connected to the first heating pipe (68) and the first return pipe (69); through-hole grooves are respectively provided at the contact positions between the side wall of the fourth soil column (53) and the first heating pipe (68) and the first return pipe (69); deformation coordination devices (75) are provided on both sides of the fourth soil column (53); the first heating pipe (68) and the first return pipe (69) respectively pass through the deformation coordination devices (75) and are connected to the temperature control device (74).

5. The platform for simulating roadbed water migration under complex conditions according to claim 4 is characterized in that: The deformation coordination device (75) comprises a support frame and a spring, wherein the spring is located in the support frame, and the spring is respectively located on the upper and lower sides of the first heating pipe (68) and the upper and lower sides of the first return pipe (69).

6. Application of a roadbed water migration simulation platform under complex conditions as claimed in any one of claims 1 to 5, characterized in that: Used to construct a hydraulic characteristics model of roadbed soil under full environmental conditions.

7. The application of a roadbed water migration simulation platform under complex conditions according to claim 6 is characterized in that: The hydraulic characteristic model of subgrade soil under full environmental conditions includes a soil-water characteristic curve model and a permeability coefficient function. The soil-water characteristic curve model includes a soil-water characteristic curve model considering the influence of groundwater, a soil-water characteristic curve model considering a combination of dynamic and static loads, a soil-water characteristic curve model considering the influence of temperature effect and a combination of dynamic and static loads, and a soil-water characteristic curve model considering the influence of plant roots. The soil-water characteristic curve model considering the influence of groundwater is constructed as follows: Step 1, taking the test data of the middle section of the first soil column (10) as a representative to describe the soil-water characteristics of the roadbed soil; Step 2: construct the time history curve of the evolution of matrix suction and water content during the soil column test; Step 3, starting from the matrix suction of 0 kPa, take values ​​at intervals of 50 kPa to 100 kPa. The greater the content of fine particles in the soil, the greater the interval value. Take several groups of data points within the matrix suction interval range, and take the corresponding moisture content values ​​at the same time. Repeat the above steps to obtain a soil-water characteristic curve describing the soil-water characteristics of the soil. Step 4: After obtaining the soil-water characteristic curve, the following model is used to fit the soil-water characteristic curve: Where: effective saturation S = (θ-θ r ) / (θ s -θ r ), θ is the moisture content, θ r is the residual moisture content, θ s is the saturated moisture content; h m is the matrix suction; e is the porosity ratio; m1, m2, m3 and m4 are fitting parameters; Step 5: After fitting, the soil-water characteristic curve model considering the influence of groundwater is obtained.

8. The application of the roadbed water migration simulation platform under complex conditions according to claim 7 is characterized in that: The method for establishing the soil-water characteristic curve model considering the dynamic and static load combination is as follows: converting the soil deformation recorded by the third sensor (50) into the void ratio e, establishing a functional relationship between the void ratio e and the dynamic and static load values, and obtaining the relationship through fitting the following formula: In the formula, e(e0,σ 静 ,σ 动 ) is related to e0, σ 静 , σ 动 Related functions; e0 is the initial porosity, σ 静 is the static load, σ 动 is the dynamic load amplitude; The method for constructing the soil-water characteristic curve model considering the temperature effect and the combined influence of dynamic and static loads is as follows: the soil deformation recorded by the fourth sensor (65) is used to convert the void ratio e, a functional relationship is established between the void ratio e and the dynamic and static load values ​​and the temperature difference, and the following fitting is performed to obtain: Where: e(e0,σ 静 ,σ 动 ,T) is related to e0, σ 静 , σ 动 , T-related functions; T is temperature; The method for constructing the soil-water characteristic curve model considering the influence of plant roots is as follows: using CT scanning technology to calculate the volume ratio R of the root system in the second soil column (36) v , and the relationship between the initial porosity ratio e0 is established to construct the porosity ratio e, and the following equation is used to fit it: Where: e(e0,R v ) is related to e0 and R v Related functions.

9. The application of a roadbed water migration simulation platform under complex conditions according to claim 7, characterized in that: The permeability coefficient function is constructed according to the soil moisture content and matrix suction data measured at each sensor point, and the steps are as follows: Step 1: Take the positions of two sensors in any soil column as the calculation section, record the heights as h1 and h2, and measure the time intervals as t1 and t2 respectively. The flow velocity v of the calculation section is equal to the rate of change of water volume in the time interval t1-t2: Where: V w is the amount of water passing through the calculated cross section during the time t1-t2, △V w is the change in the amount of water passing through the calculated cross section during the time t1-t2; A is the cross-sectional area of ​​the seepage soil column, and the seepage soil column refers to the soil column infiltrated by water in any of the soil columns; θ(z) is the equation of the volumetric water content of the seepage profile changing with depth, which is obtained by piecewise linear fitting method in the volumetric water content profile. N is the total number of reference sections, n∈N; h n Indicates the height of the nth section; Step 2: Calculate the hydraulic gradient i h,ave : In the formula, It represents the water head value of point h1 at time t1. It represents the water head value of point h1 at time t2. Indicates the water head value at point h2 at time t1, It represents the water head value of point h2 at time t2; Step 3: Calculate the unsaturated permeability coefficient k: Step 4: Calculate the unsaturated permeability coefficient and take the average value of the matrix suction at position h1 at time t1 and t2 to obtain the matrix suction h m The relationship between the unsaturated permeability coefficient and the permeability coefficient function is obtained by fitting the following formula: In the formula, k s is the saturated permeability coefficient, and m5, m6, m7 and m8 are fitting parameters.

Images