A prototype simulation remodeling frozen soil true triaxial test loading device and its operation method

Abstract

The present invention discloses a prototype simulation remodeling frozen soil true triaxial test loading device and an operation method thereof, wherein the loading device comprises an operation box, a box cover, an axial pressure assembly, a monitoring assembly, a longitudinal top support member and an adjusting member, wherein the operation box is cooperated with a box cover arranged on the top of the operation box, the operation box is provided with an axial pressure assembly and a monitoring assembly, and the box cover is provided with a longitudinal top support member; the axial pressure assembly comprises a first axial pressure member, a second axial pressure member, a third axial pressure member and a fourth axial pressure member, the free ends of each axial pressure member cooperate and contact with each other to form an extrusion cavity with a variable volume, and the free end surface of each axial pressure member is provided with an adjusting member; the free end of the longitudinal top support member cooperates and extends into the extrusion cavity.

Description

Technical Field

[0001] The present invention relates to the technical field of triaxial testing of frozen soil, and in particular to a prototype simulation remodeling frozen soil true triaxial testing loading device and an operating method thereof. Background Art

[0002] my country is the third largest country in the world in terms of permafrost distribution area, of which permafrost and seasonal frozen soil areas account for 21.5% and 53.5% of the country's total area, respectively. With the continuous expansion of human activity space and the growing demand for resources, more and more projects are being carried out in cold regions. Therefore, understanding and mastering the strength and deformation characteristics of frozen soil is of great significance to ensure the safe operation of existing buildings and structures. In actual engineering, frozen soil is affected by the ground temperature, atmospheric temperature, refrigerant temperature and environmental conditions at the same time, making the temperature field of the frozen soil medium a typical non-uniform field; secondly, in the formation process of frozen soil, due to water migration and external water replenishment, the internal moisture content of frozen soil is not uniform. Under the action of external loads, its internal structure changes dramatically; at the same time, the temperature and unfrozen water content inside the frozen soil are also in dynamic changes. Due to the frost heave problem of frozen soil, the end surface of the frozen soil is uneven, which easily causes eccentric loading during the loading process, resulting in a large discreteness of the strength data of frozen soil.

[0003] In the existing frozen soil indoor tests, 1) frozen soil is often in a uniform temperature field, and the change of temperature gradient cannot be considered; 2) water replenishment or ventilation is often not possible during the frozen soil test, and the real water migration law of frozen soil cannot be simulated; 3) the wired temperature sensor installed inside the frozen soil will damage the frozen soil sample, resulting in distorted test results; 4) it cannot reflect the changes in frozen soil structure, water content, pressure, temperature and other characteristics. Under the combined effects of ground stress, frost heave force and frozen soil and structures, frozen soil is generally in a three-dimensional unequal stress state, so it is necessary to further develop multifunctional true triaxial test equipment for frozen soil. Summary of the invention

[0004] Purpose of the invention: The first purpose of the present invention is to provide a prototype simulation reshaped frozen soil true triaxial test loading device, which can not only be used to simulate the loading test of frozen soil samples under normal conditions, but also can simulate the loading test under different temperature gradients and humidity. It has a simple structure and significant effect.

[0005] The second object of the present invention is to provide an operating method for conducting a simulation test using the remodeled frozen soil true triaxial test loading device.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a prototype simulation remodeling frozen soil true triaxial test loading device, the loading device includes an operating box, a box cover, an axial pressure assembly, a monitoring assembly, a longitudinal support member and an adjusting member, wherein the operating box is cooperated with the box cover arranged on the top of the operating box, the operating box is provided with an axial pressure assembly and a monitoring assembly, and the box cover is provided with a longitudinal support member; the axial pressure assembly includes a first axial pressure member, a second axial pressure member, a third axial pressure member and a fourth axial pressure member, the free ends of each axial pressure member cooperate and contact with each other to form an extrusion cavity with a variable volume, and the free end surface of each axial pressure member is provided with an adjusting member; the free end of the longitudinal support member cooperates and extends into the extrusion cavity.

[0007] Furthermore, the interior of the operation box is hollow and has an installation cavity, and the bottom of the cavity has a bearing plate; a hinge seat is arranged on the top side wall of the operation box, and a clamping seat is arranged on the side wall opposite to the hinge seat.

[0008] Furthermore, the edge of the box cover has a flange, and a buckle is provided on the side wall opposite to the flange, the flange can be hinged in the hinge seat, and the buckle can be buckled in the seat.

[0009] Furthermore, the first axial pressure member, the second axial pressure member, the third axial pressure member and the fourth axial pressure member have the same structure, and adjacent axial pressure members are spaced apart; the first axial pressure member includes a hydraulic rod, a ball chain and an end plate, the fixed end of the hydraulic rod is fixed to the side wall of the cavity of the installation cavity, and the telescopic end thereof is in sliding contact with the side wall of the end plate through the ball chain.

[0010] Furthermore, the ball chain includes a limit plate and a ball, wherein the ball is enclosed in a cavity of the limit plate and rolls on a side wall of the end plate; and an end of the end plate is in sliding contact with a side surface of an adjacent end plate.

[0011] Furthermore, the longitudinal supporting member includes a supporting hydraulic rod and an extrusion plate arranged at the telescopic end of the supporting hydraulic rod, and an elastic rubber layer is arranged on the circumferential side wall of the extrusion plate, and each side wall of the elastic rubber layer is in contact with the side wall of the plate body of the end plate.

[0012] Furthermore, the regulating member includes a temperature regulating plate and a humidity regulating plate, both of which are arranged on the side wall of the plate body of the end plate away from the ball chain, and the humidity regulating plate is located on the outside of the temperature regulating plate; the inner cavity of the temperature regulating plate is hollow, and is divided into several layers of compartments along the height direction of the end plate, and each layer of the compartment is provided with a guide pipe, and the guide pipe is provided with a port on the side wall of the temperature regulating plate; the cavity of the humidity regulating plate is hollow, and is distributed with main ducts, and the main duct is connected to a secondary pipe, and the pipe mouth of the secondary pipe passes through the side wall of the humidity regulating plate and is connected to the extrusion cavity.

[0013] Furthermore, the monitoring component includes a temperature sensor, a pressure sensor and a resistivity sensor, the temperature sensors are placed in layers in the sample in the extrusion chamber; the pressure sensor is arranged on the supporting plate and in contact with the sample in the extrusion chamber; the resistivity sensor is respectively arranged on the supporting plate, on the side wall of the end plate, and on the free end plate surface of the extrusion plate.

[0014] An operating method of a prototype simulation remodeling frozen soil true triaxial test loading device, using the above-mentioned loading device, also includes the following operating steps:

[0015] S1: Preparation of reshaped frozen soil samples: crush the original frozen soil, dry it again, and sieve it through a sieve; weigh an appropriate amount of dry soil and distilled water, stir and mix them evenly, and soak them for 24 hours; then weigh an appropriate amount of wet soil and prepare the sample by static pressure method; demould the prepared sample, wrap it with plastic wrap, quickly freeze it at a low temperature of -30℃ for 6 hours, and then put it into a low-temperature box at the test temperature to continue freezing for 24 hours for use;

[0016] S2: Installing sensors: During the sample preparation process through the mold, the temperature sensor is buried in the sample in layers, the pressure sensor is placed on the bearing plate and buried at the bottom of the sample, and the resistivity sensor is arranged on the six surfaces of the sample and contacts the bearing plate, the end plate, and the side wall of the extrusion plate respectively;

[0017] S3: Mould installation: After the steps and are completed, the axial compression assembly is assembled by the internal staggered method, so that during the loading process, each group of end plates can maintain synchronous movement, and then the sample to be tested is placed in the extrusion cavity formed at the end of the axial compression assembly.

[0018] S4: Initial test: After steps S1 and S2 are completed, start the device to test whether the monitoring components and the adjustment parts can work normally, and obtain the initial data when the axial pressure component is not loaded.

[0019] S5: Loading test: By starting the axial compression assembly, the sample is squeezed through the end plate at the free end, and the resistivity at different positions in the sample is monitored in real time through the resistivity sensor. The resistivity data is processed with the help of numerical software to analyze the changes in the unfrozen water content inside the frozen soil during the loading process.

[0020] S6: Loading test under different variables:

[0021] S61: by introducing a cold liquid with a temperature gradient into different compartments of the temperature regulating plate (when introducing cold liquids of different temperatures into different compartments, the temperature of the cold liquids in the compartments is linearly distributed in the vertical direction), the sample presents a temperature gradient, and then the sample is compressed by an axial compression assembly, and the resistivity of different positions in the sample is monitored in real time by a resistivity sensor to obtain data;

[0022] S62: by introducing airflow into the humidity regulating plate, the airflow is blown toward the sample through the pipe opening of the secondary pipe, and then the sample is squeezed by the axial pressure component, and the resistivity of different positions in the sample is monitored in real time by the resistivity sensor to obtain data;

[0023] S63: By passing water into the humidity regulating plate, the water flows to the sample through the pipe mouth of the secondary pipe and penetrates into the sample, and then the sample is squeezed by the axial pressure component, and the resistivity at different positions in the sample is monitored in real time by the resistivity sensor to obtain data; the obtained data is processed with the help of numerical software to analyze the changes in the unfrozen water content inside the frozen soil during the loading process.

[0024] The beneficial effects of the present invention are as follows: through the present invention, in the process of true triaxial loading of frozen soil, the influencing factors such as temperature gradient, wind cooling, and infiltration can be considered to restore the real environmental conditions of frozen soil; at the same time, the loading device can also be used for the transformation of true triaxial instruments for rocks and soils, saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0026] Figure 1 This is a schematic diagram of the overall structure of the true triaxial test loading device for the prototype simulation remodeling of frozen soil of the present invention.

[0027] Figure 2 This is a schematic diagram of the operating box structure of the prototype simulation and reshaping of frozen soil true triaxial test loading device of the present invention.

[0028] Figure 3 This is a schematic diagram of the box cover structure of the prototype simulation and reshaping of frozen soil true triaxial test loading device of the present invention.

[0029] Figure 4 This is a schematic diagram of the structure of the first axial compression member of the true triaxial test loading device for simulating the remodeling of frozen soil in the prototype of the present invention.

[0030] Figure 5 This is a schematic diagram of the front view of the first axial compression member of the true triaxial test loading device for simulating the remodeling of frozen soil in the prototype of the present invention.

[0031] Figure 6 This is a schematic diagram of the internal structure of the temperature regulating plate of the true triaxial test loading device for simulating the remodeling of frozen soil in the prototype of the present invention.

[0032] Figure 7 This is a schematic diagram of the internal structure of the humidity adjustment plate of the true triaxial test loading device for simulating the remodeling of frozen soil in the prototype of the present invention.

[0033] Figure 8 It is a schematic diagram of the overall cross-sectional structure of the prototype simulation and remodeling of frozen soil true triaxial test loading device of the present invention.

[0034] Fig. 9 It is a schematic diagram of the planar local F enlarged structure of the prototype simulation remodeling frozen soil true triaxial test loading device of the present invention. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0036] Example 1

[0037] Reference Figures 1 to 9 , which is the first embodiment of the present invention, provides a prototype simulation remodeling frozen soil true triaxial test loading device, the loading device includes an operation box 1, a box cover 2, an axial pressure assembly 3, a monitoring assembly 4, a longitudinal support member 5 and an adjusting member 6, wherein the operation box 1 is matched with the box cover 2 arranged on the top of the operation box 1, the operation box 1 is provided with an axial pressure assembly 3 and a monitoring assembly 4, and the box cover 2 is provided with a longitudinal support member 5; the axial pressure assembly 3 includes a first axial pressure member 31, a second axial pressure member 32, a third axial pressure member 33 and a fourth axial pressure member 34, the free ends of each axial pressure member are matched and contacted with each other to form an extrusion cavity K with a variable volume, and the free end surface of each axial pressure member is provided with an adjusting member 6; the free end of the longitudinal support member 5 is matched and extended into the extrusion cavity K.

[0038] The operating box 1 is hollow inside and has an installation cavity A, and a bearing plate 11 is provided at the bottom of the cavity; a hinge seat 12 is provided on the top side wall of the operating box 1, and a clamping seat 13 is provided on the side wall opposite to the hinge seat 12.

[0039] The edge of the box cover 2 has a flange 21 , and a buckle 22 is provided on the side wall opposite to the flange 21 . The flange 21 can be hinged in the hinge seat 12 , and the buckle 22 can be buckled in the clamping seat 13 .

[0040] The first axial pressure member 31, the second axial pressure member 32, the third axial pressure member 33 and the fourth axial pressure member 34 have the same structure, and adjacent axial pressure members are distributed at 90 degrees; the first axial pressure member 31 includes a hydraulic rod 31a, a ball chain 31b and an end plate 31c, the fixed end of the hydraulic rod 31a is fixed on the side wall of the cavity A, and the telescopic end thereof is in sliding contact with the side wall of the end plate 31c through the ball chain 31b.

[0041] The ball chain 31b includes a limit plate 31b-1 and a ball 31b-2. The ball 31b-2 is enclosed in the cavity of the limit plate 31b-1 and rolls on the side wall of the end plate 31c. The end of the end plate 31c is in sliding contact with the side of the adjacent end plate.

[0042] The longitudinal supporting member 5 includes a supporting hydraulic rod 51 and an extrusion plate 52 arranged at the telescopic end of the supporting hydraulic rod 51. An elastic rubber layer 53 is arranged on the circumferential side wall of the extrusion plate 52. Each side wall of the elastic rubber layer 53 is in contact with the side wall of the plate body of the end plate 31c.

[0043] The regulating member 6 includes a temperature regulating plate 61 and a humidity regulating plate 62, both of which are arranged on the side wall of the plate body on the side of the end plate 31c away from the ball chain 31b, and the humidity regulating plate 62 is located on the outside of the temperature regulating plate 61; the inner cavity of the temperature regulating plate 61 is hollow, and is divided into several layers of compartments G along the height direction of the end plate 31c, and each layer of the compartment G is provided with a guide pipe 61a, and the guide pipe 61a is provided with a port 61b on the side wall of the temperature regulating plate 61; the cavity of the humidity regulating plate 62 is hollow, and is distributed with a main duct 62a, and the main duct 62a is connected to a secondary duct 62b, and the pipe mouth of the secondary duct 62b passes through the side wall of the humidity regulating plate 62 and is connected to the extrusion cavity K.

[0044] The monitoring component 4 includes a temperature sensor 41, a pressure sensor 42 and a resistivity sensor 43. The temperature sensor 41 is placed in layers in the sample in the extrusion chamber K; the pressure sensor 42 is arranged on the supporting plate 11 and contacts the sample in the extrusion chamber K; the resistivity sensor 43 is respectively arranged on the supporting plate 11, on the side wall of the end plate 31c, and on the free end plate surface of the extrusion plate 52.

[0045] Specifically, the operating box 1 is a box with a hollow inner cavity, and a bearing plate 11 is placed at the bottom thereof. Preferably, a circuit module that can be used for charging and communicating with the monitoring component 4 is provided in the bearing plate 11. The frozen soil sample is placed on the bearing plate 11, and the telescopic end of the axial pressure component 3 performs loading operation on the frozen soil sample. On the outside of the operating box 1, there are a hinge seat 12 and a clamping seat 13 for matching the installation of the box cover 2. The box cover 2 is completely matched with the top of the operating box 1, and has a flange 21 on its circumferential side wall, which is connected to the hinge seat 12 through a hinge shaft, and the buckle 22 on its circumferential side wall can be matched and buckled on the clamping seat 13 to achieve the matching and fixing of the operating box 1 and the box cover 2. It should be noted that in order to facilitate the observation of the loading test of the operating box 1 from the outside, the operating box 1 and / or the box cover 2 are made of transparent materials.

[0046] Among them, the main body of this loading device is an operation box 1, and the box cover 2 is hingedly set on the top of the operation box 1. The axial pressure component 3, the monitoring component 4, the longitudinal support member 5, and the adjustment member 6 are all installed in the installation cavity A of the operation box 1. The installation cavity A is the loading space of the frozen soil sample. The axial pressure component 3 and the longitudinal support member 5 are used for extrusion loading of the frozen soil sample. The monitoring component 4 is used to monitor the temperature, humidity and resistivity parameters of the frozen soil sample; and the adjustment member 6 is used to apply additional variable parameters to the frozen soil sample to improve the diversity of the simulation samples of this loading device.

[0047] Furthermore, the first axial pressure member 31, the second axial pressure member 32, the third axial pressure member 33 and the fourth axial pressure member 34 in the axial pressure assembly 3 adopt the same structure, and the four groups of axial pressure members are distributed at 90 degrees intervals, and the axial pressure members on opposite sides are a group, which are used to apply four circumferential lateral pressures to the frozen soil sample. In this embodiment, the structure of the first axial pressure component 31 is used for explanation, and the structures of the other three axial pressure components are not described in detail. Each axial pressure component includes a hydraulic rod 31a, a ball chain 31b and an end plate 31c, wherein the axis of the hydraulic rod 31a is parallel to the bottom of the installation cavity A, its fixed end is fixed to the side wall of the installation cavity A, and its telescopic end is connected to the side wall of the limit plate 31b-1 in the ball chain 31b, and the ball 31b-2 is limitedly installed on the side of the limit plate 31b-1 away from the hydraulic rod 31a, and the ball 31b-2 rolls and abuts against the side wall of the end plate 31c; it should be noted that the limit plate 31b-1 may have no contact with the side wall of the end plate 31c, or may be in sliding contact with the side wall of the end plate 31c.

[0048] The end plates of the four sets of axial compression parts are connected in sequence with staggered positions, as shown in the attached figure. Figure 2 As shown in , one end of any end plate is in sliding contact with the side wall of the adjacent end plate. A cubic cavity is formed in the middle, namely, the installation cavity A. Thus, the length and width of the installation cavity A can be changed to realize the extrusion loading of the frozen soil sample placed therein.

[0049] Furthermore, the longitudinal supporting member 5 is used to apply longitudinal pressure to the frozen soil sample. Its structure is similar to that of the axial pressure member, including a supporting hydraulic rod 51 and an extrusion plate 52. The length and width of the extrusion plate 52 are slightly smaller than the length and width of the installation cavity A. An elastic rubber layer 53 is distributed on the circumferential side wall of the extrusion plate 52. The elastic rubber layer 53 can be deformed, and is used for the extrusion plate 52 to continuously perform limited extrusion on the frozen soil sample during the loading and extrusion process of the axial pressure member.

[0050] Reference Figures 4 to 6The regulating member 6 is installed on the side of the end plate 31c close to the frozen soil sample, and has a two-side plate structure, which is a temperature regulating plate 61 for temperature parameter changes and a humidity regulating plate 62 for humidity parameter changes. Specifically, the temperature regulating plate 61 has several layers of compartments G, and each layer of compartments G is provided with a flow guide 61a. The port 61b of the flow guide 61a on the side wall of the temperature regulating plate 61 is divided into a liquid inlet and a liquid outlet, that is, a circulating cold liquid of a certain temperature is injected into the flow guide 61a from the liquid inlet; the circulating cold liquids of different temperatures injected into different compartments G can form a sample environment with a temperature gradient in the installation cavity A.

[0051] A main pipe 62a is distributed in the humidity regulating plate 62, and a plurality of secondary pipes 62b are distributed on the main pipe 62a, and the two are kept in communication, and the pipe openings of the secondary pipes 62b pass through the side wall of the humidity regulating plate 62 and are connected to the extrusion cavity K. It should be noted that the pipe openings of the secondary pipes 62b are evenly distributed on the side wall of the humidity regulating plate 62, such as Figure 7 as shown in .

[0052] Furthermore, for each sensor in the monitoring component 4, wireless devices are preferably used to reduce the impact of cables on the test simulation. The temperature sensor 41 is layered and doped in the frozen soil sample to monitor the temperature at different positions in the frozen soil sample. The pressure sensor 42 uses a square 6-way pressure sensor to collect the pressure on the 6 sides of the frozen soil sample in 3 directions. When placed, it is necessary to maintain contact with at least 5 sides of the frozen soil sample. The resistivity sensor 43 is used to monitor the resistivity of various parts of the frozen soil sample. In order to monitor the resistivity of the 6 sides of the frozen soil sample, the resistivity sensor 43 is distributed on the corresponding side walls of the end face of the load-bearing plate 11, the end plate 31c and the extrusion plate 52.

[0053] Example 2

[0054] Reference Figure 1 , which is a second embodiment of the present invention, is an operation method of a prototype simulation remodeling frozen soil true triaxial test loading device, using the above-mentioned loading device, and also includes the following operation steps:

[0055] S1: Preparation of reshaped frozen soil samples: crush the original frozen soil, dry it again, and sieve it through a sieve; weigh an appropriate amount of dry soil and distilled water, stir and mix them evenly, and soak them for 24 hours; then weigh an appropriate amount of wet soil and mix them, and prepare the sample through a mold; demould the prepared sample, wrap it with plastic wrap, quickly freeze it at a low temperature of -30℃ for 6 hours, and then put it into a low-temperature box at the test temperature to continue freezing for 24 hours for use;

[0056] S2: Installing sensors: During the sample preparation process through the mold, the temperature sensor 41 is buried in layers inside the sample, the pressure sensor 42 is placed on the carrier plate 11 and buried at the bottom of the sample, and the resistivity sensor 43 is arranged on the six surfaces of the sample and respectively contacts the carrier plate 11, the end plate 31c, and the side wall of the extrusion plate 52;

[0057] S3: Mold installation: After steps S1 and S2 are completed, the axial pressure assembly 3 is assembled using the internal staggered method so that during the loading process, each group of end plates 31c can maintain synchronous movement, and then the sample to be tested is placed in the extrusion cavity K formed at the end of the axial pressure assembly 3.

[0058] S4: Initial test: After steps S1, S2 and S3 are completed, start the device to test whether the monitoring component 4 and the adjustment member 6 can work normally, and obtain the initial data when the axial pressure component 3 is not loaded.

[0059] S5: Loading test: by starting the axial pressure assembly 3, the sample is squeezed through the end plate 31c at the free end, the resistivity sensor 43 is used to monitor the resistivity at different positions in the sample in real time, and the resistivity data is processed with the help of numerical software.

[0060] S6: Loading test under different variables:

[0061] S61: by introducing a cold liquid with a temperature gradient into different compartments G of the temperature regulating plate 61 (introducing cold liquids of different temperatures into different compartments, the temperature of the cold liquid in the compartments is linearly distributed in the vertical direction), the sample presents a temperature gradient, and then the sample is compressed by the axial compression assembly 3, and the resistivity of different positions in the sample is monitored in real time by the resistivity sensor 43 to obtain data;

[0062] S62: by introducing airflow into the humidity regulating plate 62, the airflow blows toward the sample through the pipe opening of the secondary pipe 62b, and then the sample is squeezed by the axial pressure component 3, and the resistivity of different positions in the sample is monitored in real time by the resistivity sensor 43 to obtain data;

[0063] S63: By introducing water into the humidity regulating plate 62, the water flows toward the sample through the pipe mouth of the secondary pipe 62b and penetrates into the sample, and then the sample is squeezed by the axial pressure component 3, and the resistivity of different positions in the sample is monitored in real time through the resistivity sensor 43 to obtain data; the obtained data is processed with the help of numerical software.

[0064] Compared with Example 1, further, before using the loading device, a reshaped frozen soil sample needs to be prepared. First, the original soil sample is crushed, dried, and sieved with a 2 mm sieve; according to the original moisture content, an appropriate amount of dry soil and distilled water are weighed and mixed evenly, and then soaked for 24 hours; according to the density of the original frozen soil, an appropriate amount of wet soil is weighed, and the sample is prepared by static pressure method. During the sample preparation process, multiple temperature sensors 41 are buried inside the frozen soil sample; then the sample is demoulded, wrapped with plastic wrap, placed in a low-temperature box at -30°C for rapid freezing for 6 hours, and then placed in an environment of test temperature for further freezing for 24 hours for standby;

[0065] In the step of installing the sensor, since the rigidity of the conventional end plate 31c does not match the rigidity of the test sample, it will cause the end face friction effect, making the sample strength too large, and cannot truly reflect the strength and deformation characteristics of the sample under a specific stress state. Therefore, when selecting the pressure sensor 42, its material rigidity must be kept close to the elastic modulus of the frozen soil. (The elastic modulus of the frozen soil can be determined by conducting mechanical tests under the same stress state, so as to select a suitable sensor). The resistivity sensor 43 adopts a "cross-shaped" combination method and is attached to (fixed on) the six faces of the frozen soil sample.

[0066] During the mold installation process: after the above steps are completed, the axial pressure assembly 3 is assembled using the internal staggered method, which can achieve synchronous movement of each end plate 31c during the loading process without interfering with each other; at the same time, its ingenious structure can ensure that the frozen soil sample does not experience eccentric loading during the loading process, thereby reducing the discreteness of the test data.

[0067] Data monitoring during the loading process: After the device is assembled, power supply is turned on to ensure that the temperature sensor 41, the pressure sensor 42 and the resistivity sensor 43 work normally during the loading process, so that the data during the loading process can be completely obtained.

[0068] Since the resistivity of soil, ice and water is different, the resistivity inside the frozen soil sample can be monitored in real time, and the resistivity change can be inferred by inversion with the help of numerical software to infer the change process of the unfrozen water content inside the frozen soil during loading. It is worth noting that before the test begins, the resistivity of pure water, dry soil and ice at the test temperature needs to be measured for data calibration to provide basic parameters for numerical inversion analysis.

[0069] When changing the variable parameters to conduct the test, the specific operation process is as follows:

[0070] Changing the temperature: With the help of the temperature regulating plate 61, a circulating cold liquid of a certain temperature is injected into the flow guide tube 61a from the liquid inlet; the circulating cold liquids of different temperatures are injected into different compartments G to form a test environment with a temperature gradient in the extrusion cavity K.

[0071] Air cooling control: Compared with traditional air cooling, the circulation of cold liquid can make the temperature of frozen soil more uniform, but circulating refrigeration cannot reflect the real freezing mode of frozen soil. Therefore, by using the humidity regulating plate 62 and its structural characteristics, the cold air with constant temperature is introduced to simulate the freezing mode of frozen soil in nature.

[0072] Infiltration control: With the help of the humidity regulating plate 62, water flows with different pressures are injected into the main pipe 62a and the secondary pipe 62b to simulate and achieve different infiltration flow rates in the frozen soil sample.

[0073] The experiment was carried out through the above-mentioned variable control, and the extrusion loading sample process was repeated. The real-time data measured by the temperature sensor 41, the pressure sensor 42 and the resistivity sensor 43 during the loading process were used for data inversion to infer the change process of the unfrozen water content inside the frozen soil during the loading process.

[0074] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A prototype simulation remodeling frozen soil true triaxial test loading device, characterized by: include, An operating box (1) is matched with a box cover (2) arranged on the top of the operating box (1), an axial pressure component (3) and a monitoring component (4) are arranged in the operating box (1), and a longitudinal supporting member (5) is arranged on the box cover (2); The axial pressure assembly (3) comprises a first axial pressure piece (31), a second axial pressure piece (32), a third axial pressure piece (33) and a fourth axial pressure piece (34), the free ends of the axial pressure pieces are in contact with each other to form an extrusion cavity (K) with a variable volume, and the free end surface of each axial pressure piece is provided with an adjusting piece (6); The free end of the longitudinal supporting member (5) is adapted to extend into the extrusion cavity (K); The first axial compression member (31), the second axial compression member (32), the third axial compression member (33) and the fourth axial compression member (34) have the same structure, and adjacent axial compression members are spaced 90 degrees apart. The operating box (1) is hollow inside and has an installation cavity (A). The first axial pressure member (31) comprises a hydraulic rod (31a), a ball chain (31b) and an end plate (31c). The fixed end of the hydraulic rod (31a) is fixed to the side wall of the cavity (A), and the telescopic end thereof is in sliding contact with the side wall of the end plate (31c) through the ball chain (31b). The ball chain (31b) comprises a limiting plate (31b-1) and a ball (31b-2), wherein the ball (31b-2) is coated in the cavity of the limiting plate (31b-1) and rolls on the side wall of the plate body of the end plate (31c); The end of the end plate (31c) is in sliding contact with the side surface of the adjacent end plate; The longitudinal supporting member (5) comprises a supporting hydraulic rod (51) and an extrusion plate (52) arranged at the telescopic end of the supporting hydraulic rod (51), an elastic rubber layer (53) is arranged on the circumferential side wall of the extrusion plate (52), and each side wall of the elastic rubber layer (53) is in contact with the side wall of the plate body of the end plate (31c); The regulating member (6) comprises a temperature regulating plate (61) and a humidity regulating plate (62), both of which are arranged on the side wall of the plate body of the end plate (31c) away from the ball chain (31b), and the humidity regulating plate (62) is located outside the temperature regulating plate (61); The inner cavity of the temperature regulating plate (61) is hollow and is divided into a plurality of compartments (G) along the height direction of the end plate (31c), each compartment (G) is provided with a flow guide pipe (61a), and the flow guide pipe (61a) is provided with a port (61b) on the side wall of the temperature regulating plate (61); The cavity of the humidity regulating plate (62) is hollow and is provided with a main conduit (62a). The main conduit (62a) is connected to a secondary conduit (62b). The pipe opening of the secondary conduit (62b) passes through the side wall of the humidity regulating plate (62) and is connected to the extrusion cavity (K).

2. The prototype simulation remodeling frozen soil true triaxial test loading device according to claim 1, characterized in that: The interior of the operating box (1) is hollow and has an installation cavity (A), and the bottom of the cavity has a bearing plate (11); a hinge seat (12) is arranged on the top side wall of the operating box (1), and a clamping seat (13) is arranged on the side wall opposite to the hinge seat (12).

3. The prototype simulation remodeling frozen soil true triaxial test loading device as claimed in claim 2, characterized in that: The edge of the box cover (2) has a flange (21), and a buckle (22) is provided on the side wall opposite to the flange (21); the flange (21) can be hinged in the hinge seat (12), and the buckle (22) can be buckled in the seat (13).

4. The prototype simulation remodeling frozen soil true triaxial test loading device as claimed in claim 3 is characterized by: The monitoring component (4) comprises a temperature sensor (41), a pressure sensor (42) and a resistivity sensor (43); the temperature sensor (41) is placed in layers in the sample in the extrusion chamber (K); the pressure sensor (42) is arranged on the support plate (11) and in contact with the sample in the extrusion chamber (K); the resistivity sensor (43) is respectively arranged on the support plate (11), on the side wall of the end plate (31c), and on the free end plate surface of the extrusion plate (52).

5. An operating method of a prototype simulation remodeling frozen soil true triaxial test loading device, characterized in that: The loading device according to any one of claims 1 to 4 above further comprises the following operating steps: S1: Preparation of reshaped frozen soil samples: crush the original frozen soil, dry it again, and sieve it through a sieve; weigh an appropriate amount of dry soil and distilled water, stir and mix them evenly, and soak them for 24 hours; then weigh an appropriate amount of wet soil and mix them, and prepare the sample through a mold; demould the prepared sample, wrap it with plastic wrap, quickly freeze it at a low temperature of -30℃ for 6 hours, and then put it into a low-temperature box at the test temperature to continue freezing for 24 hours for use; S2: Installing sensors: During the sample preparation process through the mold, the temperature sensor (41) is buried in layers inside the sample, the pressure sensor (42) is placed on the support plate (11) and buried at the bottom of the sample, and the resistivity sensor (43) is arranged on 6 surfaces of the sample and is in contact with the support plate (11), the end plate (31c), and the side wall of the extrusion plate (52) respectively; S3: mold installation: after steps S1 and S2 are completed, the axial pressure assembly (3) is assembled by the inner staggered method, so that during the loading process, each group of end plates (31c) can maintain synchronous movement, and then the sample to be tested is placed in the extrusion cavity (K) formed at the end of the axial pressure assembly (3); S4: Initial test: After steps S1, S2 and S3 are completed, the device is started to test whether the monitoring component (4) and the adjusting component (6) can work normally, and the initial data of the axial pressure component (3) when it is not loaded is obtained; S5: Loading test: by starting the axial compression assembly (3), the sample is squeezed through the end plate (31c) at the free end, the resistivity at different positions in the sample is monitored in real time through the resistivity sensor (43), and the resistivity data is processed with the help of numerical software; S6: Loading test under different variables: S61: introducing a cold liquid with a temperature gradient into different compartments (G) of the temperature regulating plate (61) so that the sample presents a temperature gradient, and then compressing the sample through the axial pressure assembly (3), and monitoring the resistivity at different positions in the sample in real time through the resistivity sensor (43) to obtain data; S62: by introducing airflow into the humidity regulating plate (62), the airflow passes through the pipe opening of the secondary pipe (62b) and blows toward the sample, and then the sample is squeezed by the axial pressure component (3), and the resistivity of different positions in the sample is monitored in real time by the resistivity sensor (43) to obtain data; S63: by introducing water into the humidity regulating plate (62), the water flows through the pipe opening of the secondary pipe (62b) to the sample and penetrates into the sample, and then the sample is squeezed by the axial pressure component (3), and the resistivity of different positions in the sample is monitored in real time by the resistivity sensor (43) to obtain data; The obtained data are processed with the help of numerical software.

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