Device and method for testing biaxial mechanical properties of two-phase medium cementation surface after freeze-thaw cycle

Abstract

The invention belongs to the technical field of biaxial mechanical property testing, and particularly relates to a biaxial mechanical property testing device and method for a two-phase medium cementation surface after freezing and thawing circulation.The testing device comprises a sealing chamber, a sample is arranged in the sealing chamber, and biaxial loading systems are arranged on the top and the side wall of the sealing chamber; the biaxial loading system penetrates through the sealing chamber to be in contact with the sample, and a freeze-thaw cycle simulation system communicated with the sealing chamber is further arranged on the side wall of the sealing chamber. A freezing and thawing cycle environment is provided for the sample, a stable biaxial or uniaxial complex stress state can be provided, and a rock / concrete mechanical property test under freezing and thawing cycle and a concrete mechanical property test under biaxial or uniaxial compressive stress can be carried out; the defect that a traditional concrete mechanical property test cannot simulate the mechanical property of a cement-based-rock two-phase medium cementation surface in a complex biaxial compressive stress state after freezing and thawing cycle is overcome, and the device has the advantages of being convenient to carry and install, easy and convenient to operate, good in coordination, short in test period, remarkable in effect and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of biaxial mechanical properties testing, and in particular relates to a device and method for testing the biaxial mechanical properties of a two-phase medium cementing surface after freeze-thaw cycles. Background Art

[0002] Many large-scale hydraulic concrete structures constructed in severely cold northern regions, such as sluice gates, gravity dams, and arch dams, are often subject to freeze-thaw cycles during their long-term service life. This leads to significant degradation of the concrete matrix over time, including spalling and cracking, caused by freeze-thaw damage. This severely impacts the durability of these structures. These large-scale hydraulic concrete structures not only experience freeze-thaw cycles but also complex multiaxial stress states. Furthermore, the interfacial transition zone (ITZ), the weakest region of hydraulic concrete, exhibits low strength and heterogeneous physical properties. These unfavorable factors can easily lead to the initiation and propagation of cracks at the interface between the cementitious material and the aggregate in the hydraulic concrete, thus compromising the overall performance of the hydraulic concrete. Therefore, it is crucial to analyze the mechanical properties of the cementitious-rock bond under complex stress states after freeze-thaw cycles.

[0003] By conducting experimental research on the mechanical properties of cement-based-rock bonding surfaces under complex stresses after freeze-thaw cycles, and analyzing their mechanical characteristics and failure mechanisms, this study provides important guidance for the construction, operation, and maintenance of water conservancy projects. Existing experimental research on the mechanical properties of concrete / rock materials after freeze-thaw cycles requires the use of large-scale electro-hydraulic servo test systems and rapid freeze-thaw testing machines, among other instruments. These instruments are complex, bulky, and difficult to move, and the testing process is cumbersome and lacks coordination. Furthermore, due to the lack of experimental equipment and the difficulty of operating the tests, there is currently little research on the mechanical properties of concrete materials under biaxial compressive stress after freeze-thaw cycles. In particular, there are no reports on the mechanical properties of concrete under biaxial compressive stress after freeze-thaw cycles. Therefore, it is necessary to develop a device and method for testing the mechanical properties of cement-based-rock two-phase bonding surfaces under biaxial compressive stress after freeze-thaw cycles. Summary of the Invention

[0004] The purpose of the present invention is to provide a biaxial mechanical properties test device and method for a two-phase medium cemented surface after freeze-thaw cycles, so as to solve the technical problems of the prior art in that the device structure is complex, the operation is cumbersome and the test operation is difficult. In order to achieve the above object, the present invention adopts the following technical solutions: A biaxial mechanical properties testing device for a two-phase medium cementing surface after freeze-thaw cycles comprises a sealed chamber, a sample is arranged in the sealed chamber, a biaxial loading system is arranged on the top and side walls of the sealed chamber, the biaxial loading system passes through the sealed chamber and contacts the sample, and a freeze-thaw cycle simulation system connected to the sealed chamber is also arranged on the side wall of the sealed chamber.

[0005] Preferably, the sealed chamber includes a base, which is connected to a sealed top cover via a connecting rod; a sealed side wall is sealed between the base and the sealed top cover, the base, the sealed top cover and the sealed side wall constitute a sealed chamber, and the sample is arranged on the base inside the sealed chamber; the biaxial loading system contacts the sample through the sealed top cover and the sealed side wall, and the freeze-thaw cycle simulation system is connected to the sealed chamber through the sealed side wall.

[0006] Preferably, the bottom end of the connecting rod is fixed on the base, the top end is fixed to the sealing top cover by a fastening nut, the sealing top cover and the sealing side wall are fixed by high-pressure bolts, and a high-elasticity silicone pad is provided between the sealing top cover and the sealing side wall.

[0007] Preferably, a temperature sensor is further provided on the sealing top cover for measuring the temperature in the sealing chamber.

[0008] Preferably, the biaxial loading system includes an axial pressure loading rod and a load control system. The axial pressure loading rod is arranged at the top of the sealed chamber. The lower end of the axial pressure loading rod is connected to an upper loading plate with a built-in axial pressure sensor. The upper loading plate is in contact with the top of the specimen. The load control system is arranged outside the test device. The load control system is electrically connected to two portable presses. The portable presses are arranged on opposite sides of the sealed chamber. The portable presses are connected to a lateral axial loading device. The lateral axial loading device passes through the side wall of the sealed chamber and is in contact with the side wall of the specimen.

[0009] Preferably, a freeze-thaw cycle resistant sealing sleeve is provided at the place where the lateral shaft loading device passes through the side wall of the sealing chamber, and a freeze-thaw cycle resistant sealing sleeve is provided at the contact point between the axial pressure loading rod and the sealing top cover, and the freeze-thaw cycle resistant sealing sleeve is fixed to the side wall of the sealing chamber by screws.

[0010] Preferably, the freeze-thaw cycle resistant sealing sleeve is in an I-shape, made of FEP material, and fixed to the inner and outer surfaces of the side wall of the sealing chamber.

[0011] Preferably, the freeze-thaw cycle simulation system includes a cooler, a refrigeration system, a heating control system, a high-temperature pipeline and a high-temperature pipeline control valve; the refrigeration system is fixed above the outer side of the side wall of the sealed chamber, the cooler is fixed above the inner side of the side wall of the sealed chamber, the refrigeration system is electrically connected to the cooler, the heating control system is connected to the sealed chamber through the high-temperature pipeline, and the high-temperature pipeline control valve is arranged on the high-temperature pipeline.

[0012] In a second aspect, the present application discloses a method for testing the biaxial mechanical properties of a two-phase medium cemented surface after freeze-thaw cycles, which is implemented using any of the test devices described above, and includes the following steps: Install the specimens and assemble the experimental apparatus; According to the test purpose, the vertical and horizontal axial pressure, freezing and melting temperature control values of the freeze-thaw cycle simulation system, action time, number of freeze-thaw cycles, and cycle time interval are preset; Perform freeze-thaw cycle simulation according to the freezing and melting temperature control values, action time, number of freeze-thaw cycles, and cycle time interval of the preset freeze-thaw cycle simulation system; After the freeze-thaw cycle simulation is completed, vertical and horizontal loads are applied according to the preset vertical and horizontal axial pressures; after the sample is destroyed, the loading is stopped and the sample is taken out for test data analysis.

[0013] Preferably, the sample is obtained by: The processed half core sample was placed in the test mold, and cement-based vibrating agent was poured on the surface of the core sample. After standing for 48 hours, the demoulded sample was placed in a standard curing room for 28 days to obtain the sample.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention can provide a freeze-thaw cycle environment for the sample and a stable biaxial or uniaxial complex stress state, and can carry out mechanical property tests of rock / cement-based materials under freeze-thaw cycles and mechanical property tests of cement-based materials under biaxial or uniaxial compressive stress.

[0015] 2) The present invention overcomes the defect of traditional concrete mechanical property tests that cannot simulate the mechanical properties of the cement-rock two-phase medium bonding surface under complex biaxial compressive stress state after freeze-thaw cycles. The provided test device and method have the advantages of easy transportation and installation, simple operation, good coordination, short test cycle, and significant results.

[0016] 3) The test specimens in the present invention are formed by placing processed rocks in a test mold and then pouring cement mortar, which can well simulate the mechanical behavior of the bonding interface between the coarse aggregate of the concrete material and the cement mortar at the macro level.

[0017] 4) The test device of the present invention can carry out mechanical property tests of cement-based-rock bonding surfaces and concrete materials under different freeze-thaw cycles and different combinations of biaxial compression conditions according to test requirements, and study the failure morphology of cement-based-rock bonding surfaces and concrete materials, the relationship between strength and freeze-thaw cycles, and damage and failure mechanisms.

[0018] 5) The present invention can set specific biaxial compressive load parameters based on actual engineering conditions. By varying the number of freeze-thaw cycles, it can more scientifically simulate the effects of freeze-thaw cycles in cold regions on the mechanical properties and crack resistance of the concrete material interface transition zone of large-volume hydraulic concrete structures (such as concrete anti-seepage panels, sluices, gravity dams, etc.).

[0019] 6) During the test of the present invention, the collection of axial pressure data in different directions and temperature data in the sample sealing chamber does not interfere with each other, and real-time data collection and storage can be achieved throughout the test process.

[0020] 7) The device of the present invention provides temperature-insulating sealing sleeves on the horizontal and vertical loading columns and the loading hole of the sample sealing chamber, respectively, to avoid temperature fluctuations during the freeze-thaw cycle caused by temperature loss during the load loading process, thereby ensuring the reliability of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a schematic structural diagram of a test device according to an embodiment of the present invention; Figure 2 This is a schematic structural diagram of a temperature insulating sealing sleeve according to an embodiment of the present invention; Figure 3 This is a side view of a temperature insulating sealing sleeve according to an embodiment of the present invention.

[0023] Among them: 1-axial pressure loading rod; 2-connecting rod; 3-fastening nut; 4-sealing top cover; 5-high-pressure bolt; 6-high-elastic silicone pad; 7-temperature sensor; 8-axial pressure loading sensor; 9-upper loading plate; 10-sample; 11-sealing chamber side wall; 12-lateral axial loading device; 13-cement-based-rock bonding interface; 14-freeze-thaw cycle resistant sealing sleeve; 15-screw; 16-portable press; 17-load control system; 18-heating control system; 19-high-temperature pipeline control valve; 20-high-temperature pipeline; 21-base; 22-cooling device; 23-refrigeration system. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of 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. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0027] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0030] The present invention is described in further detail below with reference to the accompanying drawings: See also Figure 1The present application discloses a biaxial mechanical properties test device for a two-phase medium bonding surface after freeze-thaw cycles, comprising a sealed chamber, a sample 10 arranged in the sealed chamber, a biaxial loading system arranged on the top and side walls of the sealed chamber, the biaxial loading system passing through the sealed chamber and in contact with the sample 10, and a freeze-thaw cycle simulation system connected to the sealed chamber is also arranged on the side walls of the sealed chamber. Wherein: the sample 10 is a cubic sample having a cement-based-rock bonding interface 13 formed by pouring cement-based materials on the surface of a prefabricated cubic rock sample; the present invention can provide a freeze-thaw cycle environment for the sample and can also provide a stable biaxial or uniaxial complex stress state, and can carry out rock / concrete mechanical properties tests under freeze-thaw cycles, and concrete mechanical properties tests under biaxial or uniaxial compressive stress; it changes the defect of traditional concrete mechanical properties tests that cannot simulate the mechanical properties of the cement-based-rock two-phase medium bonding surface under complex biaxial compressive stress states after freeze-thaw cycles, and the provided test device and method have the advantages of easy transportation and installation, simple operation, good coordination, short test cycle, and significant effect.

[0031] In some embodiments, the sealed chamber includes a base 21, which is connected to the sealed top cover 4 through a connecting rod 2; a sealed side wall 11 is sealed between the base 21 and the sealed top cover 4, and the base 21, the sealed top cover 4 and the sealed side wall 11 constitute a sealed chamber, and the sample 10 is set on the base 21 and located inside the sealed chamber; and the sample 10 is placed at the center of the base 21; the biaxial loading system contacts the sample 10 through the sealed top cover 4 and the sealed side wall 11, and the freeze-thaw cycle simulation system is connected to the sealed chamber through the sealed side wall 11.

[0032] In some embodiments, the bottom end of the connecting rod 2 is fixed on the base 21, and the top end is fixed to the sealing top cover 4 through a fastening nut 3. The sealing top cover 4 and the sealing side wall 11 are fixed through high-pressure bolts 5, and a high-elasticity silicone pad 6 is arranged between the sealing top cover 4 and the sealing side wall 11.

[0033] In some embodiments, the sealing sidewall 11 is connected to the base and sealed to the sealing top cover 4 via high-pressure bolts 5. A highly elastic silicone pad 6 is provided between the sealing top cover 4 and the top of the sealing sidewall 11. After the sealing top cover 4 is secured, the connecting rods 2 are respectively connected and secured to the sealing top cover 4 via tightening nuts 3, forming a lateral pressure support system.

[0034] In some embodiments, a temperature sensor 7 is further provided on the sealing top cover 4 for measuring the temperature inside the sealing chamber.

[0035] In some embodiments, the biaxial loading system includes an axial pressure loading rod 1 and a load control system 17. The axial pressure loading rod 1 is arranged at the top of the sealed chamber. The lower end of the axial pressure loading rod 1 is connected to an upper loading plate 9 with a built-in axial pressure sensor 8. The upper loading plate 9 is in contact with the top of the specimen 10. The load control system 17 is arranged outside the test device. The load control system 17 is electrically connected to two portable presses 16. The portable presses 16 are arranged on opposite sides of the sealed chamber. The portable presses 16 are connected to a lateral axial loading device 12. The lateral axial loading device 12 passes through the side wall of the sealed chamber and contacts the side wall of the specimen 10.

[0036] Furthermore, the axial pressure loading rod 1 is connected to the external loading system to provide axial pressure, and the bottom extends into the upper loading plate 9. An axial pressure sensor 8 is set between the axial pressure loading rod 1 and the upper loading plate 9 for real-time monitoring and recording of the axial pressure applied in a direction perpendicular to the sample.

[0037] In some embodiments, the lateral shaft loading device 12 is provided with a freeze-thaw cycle resistant sealing sleeve 14 at the point where it passes through the side wall of the sealing chamber, and the freeze-thaw cycle resistant sealing sleeve 14 is provided at the contact point between the axial pressure loading rod 1 and the sealing top cover 4. The freeze-thaw cycle resistant sealing sleeve 14 is fixed to the side wall of the sealing chamber by screws 15.

[0038] In some embodiments, the lateral shaft loading device 12 has an H-shaped topology configuration and is formed as an integral frame by fusion welding of alloy steel and steel plates. The lateral shaft loading device 12 passes through a freeze-thaw cycle resistant sealing sleeve 14 and contacts the side of the specimen 10 and the portable press 16 respectively to create a lateral shaft pressure environment.

[0039] In some embodiments, the freeze-thaw cycle resistant sealing sleeve 14 is in an I-shape, made of FEP material, and fixed to the inner and outer surfaces of the side wall of the sealing chamber.

[0040] In some embodiments, see Figure 2 、 Figure 3 The freeze-thaw cycle resistant sealing sleeve 14 is in an I-shaped shape, preferably made of FEP material, passes through the prefabricated hole of the sealing side wall 11, and is fixed to the inner and outer surfaces of the sealing side wall 11 by screws 15 respectively.

[0041] In some embodiments, the freeze-thaw cycle simulation system includes a cooler 22, a refrigeration system 23, a heating control system 18, a high-temperature pipeline 20 and a high-temperature pipeline control valve 19; the refrigeration system 23 is fixed above the outer side of the sealed chamber side wall, the cooler 22 is fixed above the inner side of the sealed chamber side wall, the refrigeration system 23 is electrically connected to the cooler 22, the heating control system 18 is connected to the sealed chamber through the high-temperature pipeline 20, and the high-temperature pipeline control valve 19 is set on the high-temperature pipeline 20.

[0042] The present application also discloses a method for testing the biaxial mechanical properties of a two-phase medium cemented surface after freeze-thaw cycles, which is implemented using any of the test devices described above and includes the following steps: S1: Install specimen 10 and assemble the experimental apparatus; S2: According to the test purpose, the vertical and horizontal axial pressure, the freezing and melting temperature control values of the freeze-thaw cycle simulation system, the action time, the number of freeze-thaw cycles, and the cycle time interval are preset; S3: performing freeze-thaw cycle simulation according to the freezing and melting temperature control values, action time, number of freeze-thaw cycles, and cycle time interval of the preset freeze-thaw cycle simulation system; S4: After the freeze-thaw cycle simulation is completed, vertical and horizontal loads are applied according to the preset vertical and horizontal axial compressive forces. After the specimen 10 is destroyed, the loading is stopped and the specimen 10 is removed for test data analysis.

[0043] Further preferably, the sample 10 is obtained by: The processed half core sample was placed in a test mold, and cement-based vibrating agent was poured on the surface of the core sample. After standing for 48 hours, the demolded sample was placed in a standard curing room for curing for 28 days to obtain sample 10.

[0044] In some embodiments, a method for testing biaxial mechanical properties of a two-phase medium cemented surface after freeze-thaw cycles includes: The first step is to make the sample: first place the processed half core sample in the test mold, pour the prepared cement-based vibrator on the surface of the core sample, let it stand for 48 hours, and then place the demolded sample in a standard curing room for 28 days for experimental research.

[0045] The second step is to assemble the sealing chamber and install the sample: place a high-elasticity silicone pad 6 at the top of the sealing side wall 11, place the cement-based-rock sample 10 at the center of the sealing chamber base 21, and make the upper loading plate 9 contact the top of the sample; then, place the axial pressure sensor 8 in the upper loading plate 9 and make contact with the axial pressure loading rod 1 for real-time monitoring of the vertical pressure applied to the sample; use high-pressure bolts 5 to fix the sealing top cover 4 to the top of the sealing chamber.

[0046] The third step is to install the biaxial loading system: use nut 3 to fix the connecting rod 2 to the sealing sleeve, adjust the position of the portable press 16, and use structural adhesive to stick it to the connecting rod and the sealing chamber side wall lateral axis loading device 12; then connect the portable press 16 to the load control system 17 for real-time control and recording of lateral pressure load data.

[0047] The fourth step is to install the freeze-thaw cycle simulation system: connect the cold transfer device 22 located at the top of the sealed side wall 11 to the refrigeration system 23; then, connect the high-temperature pipeline 20 with the high-temperature pipeline control valve 19 to the heating control system 18.

[0048] Step 5. Design test parameters: According to the purpose of the test, set the vertical and horizontal axial pressure, freezing and melting temperature control values of the freeze-thaw cycle simulation system, action time, number of freeze-thaw cycles, cycle time interval and other parameters.

[0049] Step 6: Apply freeze-thaw cycle: According to the established freeze-thaw cycle parameters, start the heating control system 18 and the high-temperature pipeline control valve 19 to preheat the sample through the high-temperature pipeline 20. After the temperature sensor 7 detects that the temperature has risen to the set value and maintained for a certain period of time, the high-temperature pipeline control valve 19 is closed and the refrigeration system 23 is turned on to cool the sealed chamber through the cold transfer device 22. After the temperature sensor 7 detects that the temperature has dropped to the set value and maintained for a certain period of time, the refrigeration system 23 is turned off and the high-temperature pipeline control valve 19 is reopened. This process is a complete freeze-thaw cycle. Repeat the freeze-thaw cycle a certain number of times according to the test plan; The seventh step is to apply biaxial load: start the load control system 17 and the load loading system connected to the axial compression loading rod 1, apply vertical and horizontal loads to the sample, and conduct a mechanical property test under biaxial compressive stress after freeze-thaw cycles of the cement-based-rock two-phase medium bonding surface by controlling the magnitude of the vertical and horizontal loads according to the actual engineering situation.

[0050] Step 8, end of test: After the sample is destroyed, the biaxial loading system is stopped, the sealing top cover 4 of the sealing chamber is disassembled, the sample is taken out and the next step of test data analysis is carried out.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles, characterized in that: The invention comprises a sealed chamber, wherein a sample (10) is arranged in the sealed chamber, a biaxial loading system is arranged on the top and side walls of the sealed chamber, the biaxial loading system passes through the sealed chamber and contacts the sample (10), and a freeze-thaw cycle simulation system is also arranged on the side walls of the sealed chamber and communicates with the sealed chamber.

2. The biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles according to claim 1 is characterized in that: The sealed chamber comprises a base (21), which is connected to a sealed top cover (4) via a connecting rod (2); a sealed side wall (11) is sealed between the base (21) and the sealed top cover (4); the base (21), the sealed top cover (4) and the sealed side wall (11) constitute a sealed chamber, and the sample (10) is arranged on the base (21) and located inside the sealed chamber; the biaxial loading system contacts the sample (10) through the sealed top cover (4) and the sealed side wall (11), and the freeze-thaw cycle simulation system communicates with the sealed chamber through the sealed side wall (11).

3. The biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles according to claim 2, characterized in that: The bottom end of the connecting rod (2) is fixed on the base (21), and the top end is fixed to the sealing top cover (4) via a fastening nut (3). The sealing top cover (4) and the sealing side wall (11) are fixed via high-pressure bolts (5), and a high-elasticity silicone pad (6) is provided between the sealing top cover (4) and the sealing side wall (11).

4. The biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles according to claim 2, characterized in that: The sealing top cover (4) is also provided with a temperature sensor (7) for measuring the temperature inside the sealing chamber.

5. The biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles according to claim 1, characterized in that: The biaxial loading system includes an axial pressure loading rod (1) and a load control system (17), wherein the axial pressure loading rod (1) is arranged at the top of the sealed chamber, and the lower end of the axial pressure loading rod (1) is connected to an upper loading plate (9) with a built-in axial pressure sensor (8), and the upper loading plate (9) contacts the top of the specimen (10), and the load control system (17) is arranged outside the test device. The load control system (17) is electrically connected to two portable presses (16), and the portable presses (16) are arranged on opposite sides of the sealed chamber. The portable presses (16) are connected to a lateral axial loading device (12), and the lateral axial loading device (12) passes through the side wall of the sealed chamber and contacts the side wall of the specimen (10).

6. The biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles according to claim 5, characterized in that: A freeze-thaw cycle resistant sealing sleeve (14) is provided at the place where the lateral shaft loading device (12) passes through the side wall of the sealing chamber, and a freeze-thaw cycle resistant sealing sleeve (14) is provided at the contact place between the axial pressure loading rod (1) and the sealing top cover (4). The freeze-thaw cycle resistant sealing sleeve (14) is fixed to the side wall of the sealing chamber by screws (15).

7. A biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles according to claim 6, characterized in that: The freeze-thaw cycle resistant sealing sleeve (14) is in an I-shaped shape, made of FEP material, and fixed to the inner and outer surfaces of the side wall of the sealing chamber.

8. The biaxial mechanical properties testing device for a two-phase medium cemented surface after freeze-thaw cycles according to claim 1, characterized in that: The freeze-thaw cycle simulation system includes a cold transfer device (22), a refrigeration system (23), a heating control system (18), a high-temperature pipeline (20) and a high-temperature pipeline control valve (19); the refrigeration system (23) is fixed above the outer side of the sealed chamber side wall, the cold transfer device (22) is fixed above the inner side of the sealed chamber side wall, the refrigeration system (23) is electrically connected to the cold transfer device (22), the heating control system (18) is connected to the sealed chamber through the high-temperature pipeline (20), and the high-temperature pipeline control valve (19) is provided on the high-temperature pipeline (20).

9. A method for testing the biaxial mechanical properties of a two-phase medium cemented surface after freeze-thaw cycles, characterized in that: The test device according to any one of claims 1 to 8 is used, comprising the following steps: Install the specimen (10) and assemble the experimental apparatus; According to the test purpose, the vertical and horizontal axial pressure, freezing and melting temperature control values of the freeze-thaw cycle simulation system, action time, number of freeze-thaw cycles, and cycle time interval are preset; Perform freeze-thaw cycle simulation according to the freezing and melting temperature control values, action time, number of freeze-thaw cycles, and cycle time interval of the preset freeze-thaw cycle simulation system; After the freeze-thaw cycle simulation is completed, vertical and horizontal loads are applied according to the preset vertical and horizontal axial pressures; after the specimen (10) is destroyed, the loading is stopped and the specimen (10) is taken out for test data analysis.

10. A biaxial mechanical properties test method for a two-phase medium cemented surface after freeze-thaw cycles according to claim 9, characterized in that: The sample (10) is obtained by the following method: The processed half core sample was placed in a test mold, and cement-based vibrating agent was poured on the surface of the core sample. After standing for 48 hours, the demoulded sample was placed in a standard curing room for 28 days to obtain a sample (10).

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