A frost damage experimental device for frozen soil subgrade structure under freeze-thaw cycles

Abstract

The present invention relates to the technical field of subgrade testing, and specifically discloses a frost damage experimental device for a frozen soil subgrade structure under freeze-thaw cycles, including a bottom plate. A test area and a subgrade simulation area are arranged on the bottom plate. A slide plate is arranged in the subgrade simulation area. A freezing box is arranged on one side of the slide plate, and a melting box is arranged on the other side. A compaction device is arranged on one side of the slide plate. Subgrade materials are placed on the slide plate, and the subgrade materials are layered and compacted into a simulated subgrade through the compaction device. A cross beam is arranged on the compaction device, and a water tank is slidably connected to the cross beam. A water spray pipe is arranged at the bottom of the water tank, and a pressure device can perform pressure tests on the specimens. When manufacturing the subgrade sample in the subgrade simulation area of the present invention, different amounts of water are directly added to different positions of the subgrade materials, so that the moisture contents of different positions of the subgrade are different. In this way, samples of the subgrade with different moisture contents can be sequentially taken during the test, so as to test the stability of the subgrade under different moisture content states.

Description

Technical Field

[0001] The present invention relates to the technical field of subgrade testing, and particularly to a frost damage experimental device for a frozen soil subgrade structure under freeze-thaw cycles. Background Art

[0002] A frozen soil subgrade refers to a subgrade built on a foundation containing frozen soil. Frozen soil is soil or rock with a temperature below 0°C and containing ice. Under temperature changes, the frozen soil subgrade will experience frost heave and thaw settlement phenomena, posing challenges to the stability of the subgrade. Seasonal frozen soil will produce frost heave under the action of freeze-thaw cycles. As one of the adverse geological conditions, it is the main engineering geological feature in cold regions of our country. The soil in seasonal frozen soil areas undergoes at least one freeze-thaw cycle every year. This freeze-thaw will affect the engineering properties of the soil, such as physical properties like permeability, water content, and mechanical properties. These performance changes will cause subgrade settlement and road surface frost in the road surface system, seriously affecting the safe operation of the road. The change in subgrade water migration is the main cause of frost damage. Its essence is that the lower moisture migrates into the subgrade interior under the action of driving forces, and ice crystal penetration is formed under the influence of external negative temperature, resulting in frost heave of the upper soil and damaging the subgrade structure and infrastructure. Therefore, in order to control the frost heave and thaw settlement of the subgrade, reduce the frost damage of the subgrade, and timely reduce the water content of the subgrade, it is particularly important to hinder the migration of groundwater into the subgrade interior. Therefore, when building a subgrade on a foundation containing frozen soil, it is necessary to conduct experiments on the stability of the subgrade structure under freeze-thaw cycles. The existing frost damage experimental devices for frozen soil subgrade structures can only realize the stability of the subgrade under freeze-thaw cycles, but they cannot realize the stability of subgrades with different water contents under freeze-thaw cycles. Therefore, they cannot meet various numerical calculations before subgrade construction. Summary of the Invention

[0003] The purpose of the present invention is to solve the deficiencies existing in the prior art and propose a frost damage experimental device for a frozen soil subgrade structure under freeze-thaw cycles.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A frost damage experimental device based on the frozen soil subgrade structure under freeze-thaw cycles, including a bottom plate. A test area and a subgrade simulation area are arranged on the bottom plate. A test plate is arranged in the test area. A test hole is arranged on the upper side of the test plate. A sensor is arranged at the bottom of the test hole. A sliding plate is arranged in the subgrade simulation area. A freezing box is arranged on one side of the sliding plate, and a melting box is arranged on the other side. The sliding plate can slide to both sides and enter the freezing box and the melting box respectively. A compaction device is arranged on one side of the sliding plate. Subgrade materials are placed on the sliding plate, and the subgrade materials are compacted into a simulated subgrade layer by layer through the compaction device. A cross beam is arranged on the compaction device. A water tank is slidably connected to the cross beam. A water spraying pipe is arranged at the bottom of the water tank. A cantilever is installed on the upper side of the bottom plate. A sampling device is installed on the cantilever. The sampling device can dig out a frustum-shaped sample downward on the subgrade, and then put the frustum-shaped sample into the test hole. A pressure device is installed on the bottom plate, and the pressure device can perform pressure tests on the sample.

[0006] Preferably, the compaction device includes a track fixed on the upper side of the bottom plate. A moving block is slidably connected to the track. A guiding column is installed on the upper side of the moving block. A guiding block is slidably connected to the guiding column. A compaction roller is rotatably connected to one side of the guiding block. The cross beam is fixed to the guiding column.

[0007] Preferably, the pressure device includes a vertical plate. A horizontal plate is fixedly connected to one side of the vertical plate. A hydraulic cylinder is installed on the horizontal plate. A pressing plate is installed at the lower end of the hydraulic cylinder.

[0008] Preferably, the cantilever includes a column. A swing arm is rotatably connected to the upper side of the column. A sliding sleeve is slidably connected to the swing arm. A first electric push rod is installed on the lower side of the sliding sleeve. The sampling device is installed at the lower end of the first electric push rod. A second electric push rod is installed on the swing arm, and the second electric push rod is used to push the sliding sleeve to move back and forth.

[0009] Preferably, the sampling device includes a motor. A plurality of mutually cooperating sampling components are fixedly connected to the main shaft of the motor. The number of the sampling components is greater than or equal to three. Each sampling component includes an adjustable telescopic rod. One end of the adjustable telescopic rod is fixedly connected to an installation block. A rechargeable electric telescopic rod is fixedly connected to the upper side of the installation block. The telescopic end of the rechargeable electric telescopic rod is fixedly connected to an insertion knife.

[0010] Preferably, a base plate is fixedly connected to the lower side of the installation block. A dovetail groove is arranged on one side of the base plate. A dovetail slider is slidably connected in the dovetail groove. The dovetail slider is fixed to the upper end of the insertion knife.

[0011] Preferably, a cavity is arranged in the base plate. A communication hole is arranged in the dovetail groove. An electric spray head is installed at the communication hole. A helping mucus is installed in the cavity.

[0012] Preferably, electric doors are arranged on both the freezing box and the melting box.

[0013] Advantages of the present invention: When making the subgrade sample in the subgrade simulation area of the present invention, different amounts of water are directly added to different positions of the subgrade material, so that the moisture content of different positions of the subgrade is different. In this way, samples of the subgrade with different moisture contents can be taken in sequence during the test, so as to test the stability of the subgrade under different moisture content states. Description of the Drawings

[0014] Figure 1 is the basic structure diagram of a frost damage experimental device for a frozen soil subgrade structure based on freeze-thaw cycles provided by the present invention;

[0015] Figure 2 is Figure 1 the basic structure diagram without the freezing box and the melting box;

[0016] Figure 3 is the basic structure diagram of the compaction device;

[0017] Figure 4 is the basic structure diagram of the sampling device;

[0018] Figure 5 is the basic structure schematic diagram of the sampling component;

[0019] Figure 6 is the usage diagram of the present invention.

[0020] In the figure: bottom plate - 1, freezing box - 11, melting box - 12, simulated subgrade - 2, sliding plate - 21, test plate - 3, test hole - 31, cantilever - 4, column - 41, swing arm - 42, second electric push rod - 43, sliding sleeve - 44, first electric push rod - 45, sampling device - 5, motor - 50, adjustable telescopic rod - 51, mounting block - 52, base plate - 53, rechargeable electric telescopic rod - 54, insertion knife - 55, electric spray head - 56, compaction device - 6, track - 61, moving block - 62, guide post - 63, guide block - 64, compaction roller - 65, cross beam - 66, water tank - 67, pressure device - 7, vertical plate - 71, horizontal plate - 72, hydraulic cylinder - 73, pressing plate - 74. Detailed Embodiments

[0021] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Embodiment 1

[0022] As Figures 1-6As shown in the figure, a frost damage experimental device for a frozen soil subgrade structure based on freeze-thaw cycles in this embodiment includes a bottom plate 1, on which a test area and a subgrade simulation area are provided. A test plate 3 is arranged in the test area. On the upper side of the test plate 3, there is a test hole 31, and the test hole 31 is a frustum-shaped hole. A sensor is arranged at the bottom of the test hole 31. The sensor is a prior art and will not be elaborated here, and it is used to measure the settlement value. The subgrade is simulated in the subgrade simulation area through freeze-thaw cycles, and then moved to the test area to test the simulated subgrade specimen. In this way, the sensor can be installed at a fixed position in the test area. After the subgrade specimen is moved to the test area, the position of the sensor and the subgrade specimen is the same each time, so that the test results will be more accurate.

[0023] A sliding plate 21 is arranged in the subgrade simulation area. The sliding plate 21 can reciprocally move along the sliding groove 13 on the bottom plate 1 through the sliding seat below it. The way to drive the sliding seat to move is a prior art and will not be elaborated here. On one side of the sliding plate 21, there is a freezing box 11, and on the other side, there is a melting box 12. The sliding plate 21 can slide into the freezing box 11 and the melting box 12 respectively when it slides to both sides. Electric doors are arranged on both the freezing box 11 and the melting box 12, and the electric doors are closed when the sliding plate 21 enters the freezing box 11 and the melting box 12, so that freeze-thaw cycles can be carried out in the freezing box 11 and the melting box 12.

[0024] A compaction device 6 is arranged on one side of the sliding plate 21. Subgrade materials are placed on the sliding plate 21, and the subgrade materials are compacted into a simulated subgrade 2 layer by layer through the compaction device 6. The compaction device 6 includes a track 61 fixed on the upper side of the bottom plate 1. A moving block 62 is slidably connected to the track 61. A guiding column 63 is installed on the upper side of the moving block 62. A guiding block 64 is slidably connected to the guiding column 63. One side of the guiding block 64 is rotatably connected to a compaction roller 65. A cross beam 66 is fixed to the guiding column 63. The structures for driving the moving block 62 and the guiding block 64 are prior arts and are not shown in the figure. A cross beam 66 is arranged on the guiding column 63. A water tank 67 is slidably connected to the cross beam 66. A water spraying pipe is arranged at the bottom of the water tank 67. The water tank 67 moves along the cross beam 66 through corresponding guiding sleeves. The way to drive the guiding sleeve to reciprocally move along the cross beam 66 is a prior art and will not be elaborated here, and it is not shown in the figure. The purpose of arranging the water tank 67 is to spray water in a specified area when compacting the subgrade materials, so that the moisture content of different positions of the simulated subgrade 2 is different, so that subgrade specimens with different water contents can be tested during the later test process.

[0025] On the upper side of the bottom plate 1, there is a cantilever device 4. The cantilever device 4 includes a column 41. The upper side of the column 41 is rotatably connected to a swing arm 42. A sliding sleeve 44 is slidably connected to the swing arm 42. A first electric push rod 45 is installed on the lower side of the sliding sleeve 44. A second electric push rod 43 is installed on the swing arm 42. The second electric push rod 43 is used to push the sliding sleeve 44 to reciprocate. A first electric push rod 45 is installed on the sliding sleeve 44. A sampling device 5 is installed at the lower end of the first electric push rod 45. The sampling device 5 can dig out a frustum-shaped sample downward on the simulated roadbed 2 and then put the frustum-shaped sample into the test hole 31. A pressure device 7 is installed on the bottom plate 1. The pressure device 7 can perform a pressure test on the sample. The pressure device 7 includes a vertical plate 71. One side of the vertical plate 71 is fixedly connected to a horizontal plate 72. A hydraulic cylinder 73 is installed on the horizontal plate 72. The lower end of the hydraulic cylinder 73 is equipped with a pressing plate 74. The frustum-shaped sample is subjected to a pressure test through the pressing plate 74, so as to test the stability of the roadbed sample. After the test is completed, the sample is taken out and discarded through the sampling device.

[0026] During use, when the roadbed simulation area enters the freezer 11 and then enters the thawing box 12, it is one freeze-thaw cycle. The roadbed simulation area can repeatedly enter the freezer 11 and the thawing box 12 to achieve multiple freeze-thaw cycles, so as to test the stability of the roadbed under multiple freeze-thaw cycles. The sampling device can extract samples at different positions in the roadbed simulation area. Therefore, when making the roadbed sample in the roadbed simulation area of the present invention, different amounts of water are directly added to different positions of the roadbed material, so that the moisture content of different positions of the roadbed is different. In this way, samples of the roadbed with different moisture contents can be taken in turn during the test, so as to test the stability of the roadbed under different moisture content states. Embodiment 2

[0027] On the basis of Embodiment 1, the sampling device 5 includes a motor 50. A plurality of mutually cooperating sampling components are fixedly connected to the main shaft of the motor 50. The number of sampling components is greater than or equal to three. The sampling component includes an adjustable telescopic rod 51. One end of the adjustable telescopic rod 51 is fixedly connected to a mounting block 52. A rechargeable electric telescopic rod 54 is fixedly connected to the upper side of the mounting block 52. The telescopic end of the rechargeable electric telescopic rod 54 is fixedly connected to an inserting knife 55. During sampling, the inserting knife 55 is driven by the rechargeable electric telescopic rod 54 to insert into the simulated roadbed. At the same time, the motor 50 drives the sampling component to rotate, so as to cut out a roadbed specimen. The sampling device 5 is moved upward. Since the inserting knife 55 is inclined, when moving upward, the roadbed specimen is just lifted by the inserting knife 55. A substrate 53 is fixedly connected to the lower side of the mounting block 52. A dovetail groove is provided on one side of the substrate 53. A dovetail slider is slidably connected in the dovetail groove. The dovetail slider is fixed to the upper end of the inserting knife 55. In this way, through the guiding of the dovetail slider and the dovetail groove, the stability of the inserting knife 55 can be improved, and the inserting knife 55 can be prevented from deforming. A cavity is provided in the substrate 53. A communication hole is provided in the dovetail groove. An electric spray head 56 is installed at the communication hole. Auxiliary mucus is contained in the cavity. When the roadbed specimen is placed into the test hole 31, the electric spray head 56 sprays the auxiliary mucus onto the inserting knife 55. The auxiliary mucus flows along the inserting knife 55 into the space between the test hole 31 and the roadbed specimen. The two are adhered together through the auxiliary mucus, preventing the roadbed specimen from shaking during the test. In this way, the accuracy of the test can be guaranteed to a certain extent.

Claims

1. A frost damage experimental device for frozen soil subgrade structure under freeze-thaw cycles, characterized in that: It includes a bottom plate (1), on which a test area and a subgrade simulation area are provided. A test plate (3) is arranged in the test area. A test hole (31) is provided on the upper side of the test plate (3), and a sensor is arranged at the bottom of the test hole (31). A sliding plate (21) is arranged in the subgrade simulation area. A freezing box (11) is provided on one side of the sliding plate (21), and a melting box (12) is provided on the other side. The sliding plate (21) can slide to both sides and enter the freezing box (11) and the melting box (12) respectively. A compaction device (6) is provided on one side of the sliding plate (21). Subgrade materials are placed on the sliding plate (21), and the subgrade materials are compacted into a simulated subgrade (2) layer by layer through the compaction device (6). A cross beam (66) is arranged on the compaction device (6), and a water tank (67) is slidably connected to the cross beam (66). A water spraying pipe is provided at the bottom of the water tank (67). A cantilever (4) is installed on the upper side of the bottom plate (1), and a sampling device (5) is installed on the cantilever (4). The sampling device (5) can dig out a frustum-shaped sample downward on the subgrade (2), and then put the frustum-shaped sample into the test hole (31). A pressure device (7) is installed on the bottom plate (1), and the pressure device (7) can perform pressure tests on the sample; The cantilever (4) includes a column (41), the upper side of the column (41) is rotatably connected to a swing arm (42), a sliding sleeve (44) is slidably connected to the swing arm (42), a first electric push rod (45) is installed on the lower side of the sliding sleeve (44), the sampling device (5) is installed at the lower end of the first electric push rod (45), a second electric push rod (43) is installed on the swing arm (42), and the second electric push rod (43) is used to push the sliding sleeve (44) to move back and forth; The sampling device (5) includes a motor (50), and a plurality of mutually cooperating sampling components are fixedly connected to the main shaft of the motor (50). The number of the sampling components is greater than or equal to three. The sampling component includes an adjustable telescopic rod (51), one end of the adjustable telescopic rod (51) is fixedly connected to a mounting block (52), a rechargeable electric telescopic rod (54) is fixedly connected to the upper side of the mounting block (52), and the telescopic end of the rechargeable electric telescopic rod (54) is fixedly connected to an inserting knife (55); A substrate (53) is fixedly connected to the lower side of the mounting block (52). A dovetail groove is provided on one side of the substrate (53), and a dovetail slider is slidably connected in the dovetail groove. The dovetail slider is fixed to the upper end of the inserting knife (55); A cavity is provided in the substrate (53), a communication hole is provided in the dovetail groove, an electric spray head (56) is installed at the communication hole, and a helping mucus is installed in the cavity.

2. The frost damage experimental device for a frozen soil subgrade structure under freeze-thaw cycles according to claim 1, characterized in that: The compaction device (6) includes a track (61) fixed on the upper side of the bottom plate (1), a moving block (62) is slidably connected to the track (61), a guiding column (63) is installed on the upper side of the moving block (62), a guiding block (64) is slidably connected to the guiding column (63), a compaction roller (65) is rotatably connected to one side of the guiding block (64), and the cross beam (66) is fixed to the guiding column (63).

3. The frost damage experimental device for a frozen soil subgrade structure under freeze-thaw cycles according to claim 1, characterized in that: The pressure device (7) includes a vertical plate (71), one side of the vertical plate (71) is fixedly connected to a horizontal plate (72), a hydraulic cylinder (73) is installed on the horizontal plate (72), and a pressing plate (74) is installed at the lower end of the hydraulic cylinder (73).

4. An experimental device for frost damage of a frozen soil subgrade structure based on freeze-thaw cycles according to claim 1, characterized in that: Electric doors are provided on both the freezer (11) and the melting box (12).

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