A partition temperature control and water supplement monitoring device and method for layered soil differential frost heaving test

Abstract

The application discloses a partition temperature control water supplement monitoring device and method for layered soil differential frost heaving test, and belongs to the technical field of frozen soil test. The device comprises a test cylinder (1), a bottom temperature control assembly (2), a top partition temperature control water supplement assembly (3), a water supplement metering assembly (4), a multi-field monitoring assembly (5) and a deformation monitoring assembly (6). The two groups of semicircular temperature control plates, the water permeable parts and the partition membranes form water storage cavities corresponding to the left and right soil sample regions respectively, realize partition temperature control, constant water head water supplement and separate water supplement metering, and meanwhile, the hydraulic connection at the soil sample interface is maintained. During the test process, a temperature boundary of cold at the bottom and warm at the top is applied, and the temperature, moisture, matric suction, conductivity, frost heaving displacement and inclination on both sides of the interface are synchronously monitored. The application can represent the water and heat changes near the layered soil interface and the differential frost heaving process, and provides a test means for studying the differential frost heaving mechanism of layered soil.

Description

Technical Field

[0001] This invention belongs to the field of indoor testing technology for frozen soil engineering and geotechnical engineering. Specifically, it relates to a zoned temperature control and water replenishment monitoring device and method for differential frost heave testing of layered soils. In particular, it relates to a test device and method suitable for zoned temperature control, constant water head replenishment, multi-field monitoring, and frost heave deformation monitoring of the top semicircle of a cylindrical soil sample with left and right layers. Background Technology

[0002] Stratified soils are widely found in cold-region foundations, roadbeds, artificial freezing projects, engineering sites in seasonally frozen soil areas, and artificially filled strata. Due to differences in particle composition, pore structure, permeability, water-holding capacity, thermal conductivity, and frost heave sensitivity among different soil layers, complex temperature transfer, water migration, ice crystal precipitation, and deformation coordination issues often arise near the interlayer interfaces during freezing. Especially when two heterogeneous soils are cooled together in the same freezing system, different freezing front advancement characteristics, unfrozen water migration paths, and frost heave deformation responses may form on both sides of the interface, inducing differential frost heave, interfacial shear deformation, and local stress concentration. Therefore, accurately simulating the freezing boundary conditions of stratified soils and simultaneously acquiring the hydrothermal state and deformation response on both sides of the interface is a crucial foundation for studying the differential frost heave mechanism of stratified soils.

[0003] Existing freezing test apparatuses are mostly used for homogeneous soil samples or stratified soil samples, typically employing a monolithic cold end, a monolithic warm end, and a single water replenishment boundary. While these apparatuses can meet the requirements of general one-dimensional freezing tests, they have limitations when studying stratified soil samples with distinct layers on either side. For cylindrical stratified soil samples with heterogeneous soil masses on both sides, if the top temperature boundary and water replenishment boundary are monolithic, it is difficult to establish clear temperature and moisture boundaries for the soil sample regions on both sides, and it is also difficult to separately calculate the water replenishment volume for different soil regions. Especially under water-replenished freezing conditions, the water-holding capacity, permeability, and suction of different soil masses vary, making it difficult to distinguish the water replenishment contribution and water migration response on both sides of the interface using a monolithic water replenishment method.

[0004] Furthermore, in existing freezing tests, temperature measuring points are often arranged along the height of the sample, mainly to obtain the vertical temperature gradient and the location of the freezing front. For stratified soil samples, the key differences near the interface often manifest as lateral temperature, moisture, and matrix suction differences within the same horizontal section. Without a multi-point monitoring system arranged perpendicular to the interlayer interface, it is difficult to obtain the lateral hydrothermal field changes on both sides of the interface. On the other hand, if sensors are arranged laterally throughout the entire sample, they may penetrate the interlayer interface and disturb the interface contact state, affecting the accuracy of the interlayer response of the stratified soil sample.

[0005] Meanwhile, differential frost heave is not only manifested in changes in overall frost heave volume, but may also manifest in different displacements of the tops of the soil on the left and right sides, tilting of the top structure, and inconsistent deformation near the interface. Existing devices typically use single-point displacement or overall displacement as frost heave indicators, which are insufficient to reflect the differential frost heave and tilt changes of heterogeneous soils on the left and right sides during the freezing process. Therefore, it is necessary to propose a device and method suitable for zonal temperature control, zonal water replenishment, zonal multi-field monitoring, and deformation monitoring of stratified soil samples on the left and right sides of a cylinder, in order to achieve accurate simulation and comprehensive observation of the differential frost heave process of stratified soils. Summary of the Invention

[0006] The purpose of this invention is to provide a zoned temperature control and water replenishment monitoring device and method for differential frost heave tests of stratified soils, in order to solve the problems of existing freezing test devices that make it difficult to apply top temperature boundaries and water replenishment boundaries to the left and right stratified soil samples respectively, difficult to measure the water replenishment on both sides of the interface respectively, difficult to obtain the cross-interface hydrothermal state changes in the same horizontal section, and difficult to monitor the differential frost heave deformation on the left and right sides.

[0007] To achieve the above objectives, this invention provides a zoned temperature control and water replenishment monitoring device for differential frost heave tests of stratified soils, comprising a test cylinder, a bottom temperature control component, a top zoned temperature control and water replenishment component, a water replenishment metering component, a multi-field monitoring component, and a deformation monitoring component. The test cylinder is used to contain left and right stratified soil samples of a cylinder, which includes a first semi-cylindrical soil sample area, a second semi-cylindrical soil sample area, and an interlayer interface located between them. The bottom temperature control component is disposed at the bottom of the left and right stratified soil samples of the cylinder and is used to apply a low-temperature boundary to the left and right stratified soil samples of the cylinder.

[0008] The top-zoned temperature and water supply assembly is located at the top of the left and right layered soil samples of the cylinder. It includes a first semi-circular temperature control plate, a second semi-circular temperature control plate, a first semi-circular permeable element, a second semi-circular permeable element, a first diaphragm, and a second diaphragm. The first semi-circular temperature control plate and the first semi-circular permeable element are positioned corresponding to the first semi-circular soil sample area, and the second semi-circular temperature control plate and the second semi-circular permeable element are positioned corresponding to the second semi-circular soil sample area. The first and second diaphragms are respectively positioned around the outside of the first and second semi-circular permeable elements to form a first water storage chamber and a second water storage chamber.

[0009] The water replenishment metering assembly includes a first water replenishment unit and a second water replenishment unit. The first water replenishment unit is connected to the first water storage chamber, and the second water replenishment unit is connected to the second water storage chamber. These units provide constant head water replenishment conditions to the first and second water storage chambers and measure the replenishment volume respectively. A multi-field monitoring assembly is arranged within the left and right layers of soil samples in the cylinder to acquire changes in temperature, moisture, matrix suction, and electrical conductivity on both sides of the interlayer interface during freezing. A deformation monitoring assembly is used to monitor the frost heave displacement and tilt angle changes of the first and second semi-cylindrical soil sample areas during freezing.

[0010] This invention also provides a method for testing differential frost heave in stratified soil based on the above-mentioned device, comprising: placing left and right layered soil samples of a cylinder into a test tube; sequentially placing a semi-circular filter paper, a semi-circular permeable element, and a top zoned temperature-controlled water replenishment component on the top of the soil sample, and forming a first water storage cavity and a second water storage cavity through a PET diaphragm; connecting the first water replenishment unit and the second water replenishment unit to the first water storage cavity and the second water storage cavity respectively; arranging multiple monitoring components in the left and right layered soil samples of the cylinder; performing initial constant temperature equilibrium; activating the bottom temperature control component and the top zoned temperature-controlled water replenishment component to form a freezing boundary with a cold bottom and a warm top; collecting temperature, moisture, matrix suction, electrical conductivity, water replenishment amount, frost heave displacement, and tilt angle data; and analyzing the differential frost heave behavior of the left and right soil sample areas and the hydrothermal response near the interlayer interface based on the collected data.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] First, the present invention uses a first semi-circular temperature control plate and a second semi-circular temperature control plate to correspond to the left and right semi-cylindrical soil sample areas respectively. This allows for the application of zoned temperature boundaries to the top of the left and right layered soil samples of the cylinder. This enables both sides to be controlled at the same temperature or to be controlled independently on both sides, thereby improving the controllability of the boundary conditions in the freezing test of stratified soil.

[0013] Secondly, the present invention forms a first water storage chamber and a second water storage chamber by surrounding a semi-circular permeable element with a PET diaphragm, and performs constant water head replenishment and water replenishment statistics through the first water replenishment unit and the second water replenishment unit respectively. This can form a zoned water replenishment boundary at the top, while preserving the hydraulic connection at the interlayer interface inside the soil sample, which is beneficial for studying the differences in water migration and water replenishment response on both sides of the interface.

[0014] Third, the present invention sets up multiple monitoring components in the left and right layered soil samples of the cylinder, which can obtain changes in temperature, moisture, matrix suction and electrical conductivity in the same horizontal monitoring section along the direction perpendicular to the interlayer interface, thereby more accurately characterizing the differences in lateral hydrothermal state near the interlayer interface.

[0015] Fourth, the multi-point temperature sensor of the present invention can be horizontally inserted from both sides of the test cylinder, so that the temperature measuring points are distributed across the interface in the same horizontal section, but the sensor rod does not cross the interlayer interface, thereby reducing the disturbance of the interface contact state caused by the sensor layout.

[0016] Fifth, the present invention is equipped with a deformation monitoring component, which can simultaneously acquire the frost heave displacement and dip angle changes of soil sample areas on the left and right sides, which is beneficial to reveal the development process of differential frost heave and its interface response mechanism during the freezing process of heterogeneous stratified soil. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments are briefly described below. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the zoned temperature control and water replenishment monitoring device of the present invention;

[0019] Figure 2 This is a top view of the partitioned temperature control and water replenishment monitoring device of the present invention;

[0020] Figure 3 This is a schematic diagram of the top-zone temperature control and water replenishment component of the present invention;

[0021] Figure 4 This is a schematic diagram of the temperature boundary, water replenishment boundary, and multi-field monitoring layout of the differential frost heave test device for stratified soil of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1. Test cylinder; 2. Bottom temperature control component; 3. Top zoned temperature control and water replenishment component; 4. Water replenishment metering component; 5. Multi-field monitoring component; 6. Deformation monitoring component; 11. Left and right layered soil samples of the cylinder; 111. First semi-cylindrical soil sample area; 112. Second semi-cylindrical soil sample area; 113. Interlayer interface; 31. Copper temperature control plate; 311. First semi-circular temperature control plate; 312. Second semi-circular temperature control plate; 32. Semi-circular permeable component; 321. First semi-circular permeable component; 322. Second semi-circular permeable component; 33. PET diaphragm; 331. First diaphragm; 332. Second diaphragm; 34. Water storage chamber; 341. First water storage chamber; 342. Second water storage chamber; 35. Water replenishment hole; 41. First water replenishment unit; 42. Second water replenishment unit; 51. Multi-point temperature sensor. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0025] like Figure 1 and Figure 2As shown, this embodiment provides a zoned temperature control and water replenishment monitoring device for differential frost heave tests of stratified soils, including a test cylinder (1), a bottom temperature control component (2), a top zoned temperature control and water replenishment component (3), a water replenishment metering component (4), a multi-field monitoring component (5), and a deformation monitoring component (6). The test cylinder 1 is used to contain cylindrical soil samples (11) in left and right layers. The cylindrical soil samples (11) in left and right layers include a first semi-cylindrical soil sample area (111), a second semi-cylindrical soil sample area (112), and an interlayer interface (113) located between the two. The interlayer interface (113) extends along the axial direction of the cylindrical soil samples (11), so that the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) are within the same height range during the test.

[0026] The bottom temperature control component (2) is located at the bottom of the cylindrical left and right layered soil samples (11) and is used to apply a low-temperature boundary to the cylindrical left and right layered soil samples (11). In this embodiment, the bottom temperature control component (2) is an integral circular cold-end temperature control plate, preferably a copper temperature control plate, and is connected to a low-temperature circulating bath. During the test, the bottom temperature control component (2) can be set to -10℃ to form the lower cold-end boundary. The test cylinder (1) is preferably an acrylic cylinder, and the outside of the test cylinder (1) is covered with an insulation layer to reduce lateral heat exchange and to form a unidirectional freezing condition with the bottom cold and the top warm for the cylindrical left and right layered soil samples (11).

[0027] The top-zoned temperature control and water replenishment assembly (3) is installed on the top of the cylindrical left and right layered soil samples (11), including a first semi-circular temperature control plate (311), a second semi-circular temperature control plate (312), a first semi-circular permeable component (321), a second semi-circular permeable component (322), a first diaphragm (331), and a second diaphragm (332). The first semi-circular temperature control plate (311) and the first semi-circular permeable component (321) are set corresponding to the first semi-circular soil sample area (111), and the second semi-circular temperature control plate (312) and the second semi-circular permeable component (322) are set corresponding to the second semi-circular soil sample area (112). The first semi-circular temperature control plate (311) and the second semi-circular temperature control plate (312) can be connected to temperature control circulation pipelines respectively. They can be connected in parallel to apply the same temperature boundary to the soil sample areas on both sides, or they can be connected independently to apply different temperature boundaries to the soil sample areas on both sides. In this embodiment, the first semicircular temperature control plate (311) and the second semicircular temperature control plate (312) are subjected to the same warm end temperature conditions during the test.

[0028] like Figure 3As shown, the first semi-circular temperature control plate (311) and the second semi-circular temperature control plate (312) are preferably copper temperature control plates (31), and more preferably red copper temperature control plates. The copper temperature control plate (31) is 2 cm thick and has a temperature control medium flow channel with a diameter of 4 mm inside. The temperature control medium flow channel is used to supply the circulating temperature control medium to improve the uniformity and stability of the top temperature boundary. The copper temperature control plate (31) is provided with a water inlet hole (35) with a diameter of 8 mm. The water inlet pipe can extend into the corresponding semi-circular permeable part (32) through the water inlet hole (35).

[0029] The first semi-circular permeable element (321) and the second semi-circular permeable element (322) are preferably semi-circular permeable stones. During the test, semi-circular filter paper can be laid on the top of the layered soil samples (11) on the left and right sides of the cylinder before the semi-circular permeable element (32) is set to improve the uniformity of water supply. The first diaphragm (331) and the second diaphragm (332) are preferably PET diaphragms (33). The PET diaphragm (33) is respectively wrapped around the outside of the corresponding semi-circular permeable element (32) and glued and sealed to the side of the corresponding semi-circular permeable element (32) to form a semi-circular water storage cavity (34) above the corresponding semi-circular permeable element (32). Thus, a first water storage cavity (341) is formed above the first semi-circular permeable element (321), and a second water storage cavity (342) is formed above the second semi-circular permeable element (322).

[0030] The water replenishment metering component (4) includes a first water replenishment unit (41) and a second water replenishment unit (42). The first water replenishment unit (41) is connected to the first water storage chamber (341), and the second water replenishment unit (42) is connected to the second water storage chamber (342). In this embodiment, the first water replenishment unit (41) and the second water replenishment unit (42) respectively include a Marshall bottle, a water replenishment pipeline, and a valve. The Marshall bottle is used to provide constant head water replenishment conditions to the corresponding water storage chamber (34) and to record the water replenishment volume corresponding to the first water storage chamber (341) and the second water storage chamber (342). Preferably, the water replenishment head under constant head water replenishment conditions is 1.5 cm.

[0031] The first water storage chamber (341) and the second water storage chamber (342) are separated from each other at the top of the left and right layered soil samples (11) of the cylinder, so that the top water replenishment boundary can correspond to the first semi-cylindrical soil sample region (111) and the second semi-cylindrical soil sample region (112) respectively. However, the first semi-cylindrical soil sample region (111) and the second semi-cylindrical soil sample region (112) remain in contact at the interlayer interface (113), so water can still migrate inside the left and right layered soil samples (11) of the cylinder through the interlayer interface (113). This structure can not only separately count the water replenishment on both sides, but also be used to study the water exchange and hydrothermal coupling response on both sides of the interface during freezing.

[0032] A multi-field monitoring component (5) is arranged within the left and right layers of soil samples (11) of the cylinder to acquire changes in temperature, moisture, matrix suction, and electrical conductivity on both sides of the interlayer interface (113) during freezing. The multi-field monitoring component (5) includes a multi-point temperature sensor (51). The multi-point temperature sensor (51) includes multiple horizontal temperature measurement sections spaced apart along the height direction of the left and right layers of soil samples (11) of the cylinder. Preferably, there are five horizontal temperature measurement sections, and nine temperature measurement points are set in each horizontal temperature measurement section. The nine temperature measurement points are distributed in a direction perpendicular to the interlayer interface (113). Among them, four temperature measurement points are located in the first semi-cylindrical soil sample area (111), four temperature measurement points are located in the second semi-cylindrical soil sample area (112), and one temperature measurement point is located at the interlayer interface (113).

[0033] When the diameter of the cylindrical soil samples (11) is 200 mm, the spacing between two adjacent temperature measuring points in the same horizontal temperature measurement section is preferably 2 cm. The temperature measuring point located in the first semi-cylindrical soil sample area (111) is inserted horizontally from one side of the test cylinder (1), and the temperature measuring point located in the second semi-cylindrical soil sample area (112) is inserted horizontally from the other side of the test cylinder (1), and the sensor rod does not cross the interlayer interface (113). Thus, while obtaining the cross-interface temperature distribution in the same horizontal section, the disturbance of the interlayer interface (113) caused by the sensor layout can be reduced.

[0034] The multi-field monitoring component (5) may further include a moisture sensor, a matrix suction sensor, and a conductivity sensor. The moisture sensor, matrix suction sensor, and conductivity sensor are inserted into the left and right layers of soil samples (11) along the circumference of the test cylinder at preset angular intervals, using the diameter of the interlayer interface (113) as the angular reference, and arranged within the same or multiple horizontal monitoring sections. In a preferred embodiment, the preset angular interval is an integer multiple of 30°. The moisture sensor may be a time-domain reflectometry moisture sensor, the matrix suction sensor may be a matrix potential sensor, and the conductivity sensor may be a soil apparent conductivity sensor or a pore water conductivity sensor.

[0035] The deformation monitoring component (6) is used to monitor the frost heave displacement and tilt angle changes of the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) during the freezing process. The deformation monitoring component (6) may include a displacement sensor and / or a tilt angle sensor. The displacement sensor may be set corresponding to the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) respectively, and is used to obtain the difference in frost heave displacement between the two soil sample areas. The tilt angle sensor may be set on the top pressure plate, the semi-circular temperature control plate, or a monitoring plate that moves synchronously with the top of the soil sample, and is used to obtain the tilt angle change of the top structure during the freezing process.

[0036] This embodiment also provides a method for testing differential frost heave in stratified soils, including the following steps.

[0037] S1. Place the cylindrical soil sample (11) in the test tube (1) and make the bottom of the cylindrical soil sample (11) contact the bottom temperature control component (2).

[0038] S2. A semi-circular filter paper, a semi-circular permeable component (32) and a top zone temperature control and water replenishment component (3) are sequentially set on the top of the left and right layered soil samples (11) of the cylinder, and the corresponding semi-circular permeable components (32) are surrounded by PET diaphragms (33) to form the first water storage chamber (341) and the second water storage chamber (342).

[0039] S3. Connect the first water replenishment unit (41) and the second water replenishment unit (42) to the first water storage chamber (341) and the second water storage chamber (342) respectively, form a partition constant head water replenishment boundary through the Marshall bottle, and record the water replenishment amount respectively.

[0040] S4. Multiple monitoring components (5) are arranged in the left and right layered soil samples (11) of the cylinder, and the sensor insertion positions are sealed and waterproofed.

[0041] S5. Initial isothermal equilibrium is performed on the left and right layered soil samples (11) of the cylinder to stabilize the internal temperature field and moisture state of the soil sample.

[0042] S6. Start the bottom temperature control component (2) to apply a low temperature boundary to the bottom of the left and right layered soil samples (11) of the cylinder, start the top zone temperature control and water replenishment component (3) to apply a warm end constant temperature boundary to the top of the left and right layered soil samples (11) of the cylinder, and replenish water with constant head through the first water replenishment unit (41) and the second water replenishment unit (42).

[0043] S7. Collect data on temperature, moisture, matrix suction, electrical conductivity, water replenishment, frost heave displacement, and tilt angle during the freezing process.

[0044] S8. Based on the temperature, moisture, matrix suction, electrical conductivity, water replenishment, frost heave displacement and tilt angle data, analyze the differential frost heave behavior of the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) as well as the hydrothermal response near the interlayer interface (113).

[0045] The above embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All equivalent substitutions, modifications, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A zoned temperature control and water replenishment monitoring device for differential frost heave tests of stratified soils, characterized in that, It includes a test cylinder (1), a bottom temperature control component (2), a top zone temperature control and water replenishment component (3), a water replenishment and metering component (4), a multi-field monitoring component (5), and a deformation monitoring component (6); The test cylinder (1) is used to contain the cylindrical soil samples (11) in left and right layers. The cylindrical soil samples (11) in left and right layers include a first semi-cylindrical soil sample area (111), a second semi-cylindrical soil sample area (112), and an interlayer interface (113) located between the two. The bottom temperature control component (2) is set at the bottom of the left and right layered soil samples (11) of the cylinder, and is used to apply a low temperature boundary to the left and right layered soil samples (11) of the cylinder. The top-zoned temperature control and water replenishment component (3) is installed on the top of the cylindrical left and right layered soil samples (11), including a first semi-circular temperature control plate (311), a second semi-circular temperature control plate (312), a first semi-circular permeable component (321), a second semi-circular permeable component (322), a first diaphragm (331), and a second diaphragm (332); the first semi-circular temperature control plate (311) and the first semi-circular permeable component (321) are installed corresponding to the first semi-circular soil sample area (111). The second semi-circular temperature control plate (312) and the second semi-circular permeable element (322) are set corresponding to the second semi-cylindrical soil sample area (112); the first diaphragm (331) and the second diaphragm (332) are respectively surrounded on the outside of the first semi-circular permeable element (321) and the second semi-circular permeable element (322) to form the first water storage cavity (341) and the second water storage cavity (342) respectively corresponding to the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112); The water replenishment metering component (4) includes a first water replenishment unit (41) and a second water replenishment unit (42). The first water replenishment unit (41) is connected to the first water storage chamber (341), and the second water replenishment unit (42) is connected to the second water storage chamber (342). They are respectively used to provide constant water head replenishment conditions to the first water storage chamber (341) and the second water storage chamber (342), and respectively measure the replenishment amount. The multi-field monitoring component (5) is arranged in the left and right layered soil samples (11) of the cylinder to obtain the changes in temperature, moisture, matrix suction and electrical conductivity on both sides of the interlayer interface (113) during the freezing process; The deformation monitoring component (6) is used to monitor the frost heave displacement and tilt angle changes of the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) during the freezing process.

2. The zoned temperature control and water replenishment monitoring device according to claim 1, characterized in that, The first semi-circular temperature control plate (311) and the second semi-circular temperature control plate (312) are both heat-conducting metal plates. They are respectively connected to the temperature control circulation pipeline and can apply the same temperature boundary to the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) in parallel.

3. The zoned temperature control and water replenishment monitoring device according to claim 2, characterized in that, The first semi-circular temperature control plate (311) and the second semi-circular temperature control plate (312) are both copper temperature control plates (31). The copper temperature control plate (31) is 2cm thick and has a temperature control medium flow channel with a diameter of 4mm inside. The copper temperature control plate (31) is provided with a water inlet hole (35) with a diameter of 8mm. The water inlet pipe extends into the corresponding semi-circular water-permeable part (32) through the water inlet hole (35).

4. The zoned temperature control and water replenishment monitoring device according to claim 1, characterized in that, The first diaphragm (331) and the second diaphragm (332) are both PET diaphragms (33). The PET diaphragms (33) respectively cover the outside of the corresponding semi-circular permeable part (32) and are glued and sealed to the side of the corresponding semi-circular permeable part (32) to form a semi-circular water storage cavity (34) above the corresponding semi-circular permeable part (32).

5. The zoned temperature control and water replenishment monitoring device according to claim 1, characterized in that, The first water replenishment unit (41) and the second water replenishment unit (42) respectively include a Marshall bottle, a water replenishment pipeline and a valve. The Marshall bottle is used to provide constant head water replenishment conditions to the corresponding water storage chamber (34) and to record the water replenishment volume corresponding to the first water storage chamber (341) and the second water storage chamber (342) respectively.

6. The zoned temperature control and water replenishment monitoring device according to claim 1, characterized in that, The first water storage chamber (341) and the second water storage chamber (342) are separated from each other at the top of the left and right layered soil samples (11) of the cylinder. The first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) are in contact at the interlayer interface (113), so that water can migrate through the interlayer interface (113) inside the left and right layered soil samples (11).

7. The zoned temperature control and water replenishment monitoring device according to claim 1, characterized in that, The multi-field monitoring component (5) includes a multi-point temperature sensor (51). The multi-point temperature sensor (51) includes multiple horizontal temperature measurement sections spaced apart along the height direction of the left and right layers of soil samples in the cylinder. Multiple temperature measurement points are set in each horizontal temperature measurement section. The multiple temperature measurement points are distributed in a direction perpendicular to the interlayer interface (113) and are respectively located in the first semi-cylindrical soil sample area (111), the interlayer interface (113) or near the interlayer interface, and the second semi-cylindrical soil sample area (112).

8. The zoned temperature control and water replenishment monitoring device according to claim 7, characterized in that, Temperature measuring points located in the first semi-cylindrical soil sample area (111) are inserted horizontally from one side of the test tube (1), and temperature measuring points located in the second semi-cylindrical soil sample area (112) are inserted horizontally from the other side of the test tube (1), and the sensor rod does not cross the interlayer interface (113).

9. The zoned temperature control and water replenishment monitoring device according to claim 1, characterized in that, The multi-field monitoring component (5) also includes a moisture sensor, a matrix suction sensor and an electrical conductivity sensor. The moisture sensor, matrix suction sensor and electrical conductivity sensor are arranged with the diameter of the interlayer interface (113) as the reference. They are inserted into the left and right layered soil samples (11) of the cylinder along the circumference of the test cylinder (1) at a preset angle and arranged in the same horizontal monitoring section or multiple horizontal monitoring sections.

10. A method for testing differential frost heave in stratified soils based on the apparatus described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Place the cylindrical soil samples (11) into the test tube (1) and make the bottom of the cylindrical soil samples (11) contact the bottom temperature control component (2); S2. A semi-circular filter paper, a semi-circular permeable component (32) and a top zone temperature control and water replenishment component (3) are sequentially set on the top of the layered soil sample (11) on the left and right sides of the cylinder, and the corresponding semi-circular permeable components (32) are surrounded by PET diaphragms (33) to form the first water storage chamber (341) and the second water storage chamber (342); S3. Connect the first water replenishment unit (41) and the second water replenishment unit (42) to the first water storage chamber (341) and the second water storage chamber (342) respectively, form a partition constant head water replenishment boundary through the Marsh bottle, and record the water replenishment amount respectively; S4. Multiple monitoring components were arranged in the left and right layered soil samples (11) of the cylinder, and the sensor insertion positions were sealed and waterproofed. S5. Initial isothermal equilibrium was achieved for the soil samples (11) in the left and right layers of the cylinder; S6. Start the bottom temperature control component (2) to apply a low temperature boundary to the bottom of the left and right layered soil samples (11) of the cylinder, start the top zone temperature control and water replenishment component (3) to apply a warm end constant temperature boundary to the top of the left and right layered soil samples (11) of the cylinder, and replenish water with constant head through the first water replenishment unit (41) and the second water replenishment unit (42); S7. Collect data on temperature, moisture, matrix suction, electrical conductivity, water replenishment, frost heave displacement, and tilt angle during the freezing process; S8. Based on the temperature, moisture, matrix suction, electrical conductivity, water replenishment, frost heave displacement and tilt angle data, analyze the differential frost heave behavior of the first semi-cylindrical soil sample area (111) and the second semi-cylindrical soil sample area (112) as well as the hydrothermal response near the interlayer interface (113).

Images