A Subway Connection Channel Freezing Simulation Test System

Abstract

The embodiment of the present invention provides a subway communication channel freezing simulation test system, comprising: a model box, including a water inlet chamber, a filling chamber and a water outlet chamber, for simulating the environment of the subway communication channel; a refrigeration cycle module, including a cold bath machine and a freezing pipe group arranged on the simulation box, for providing a low-temperature environment to the simulation box to simulate the low-temperature environment during freezing construction; a seepage module, including a water tank, a heater and a circulation pipeline, for injecting water into the model box to simulate the seepage return of the subway communication channel; and a monitoring module, including a sensor group and a collector, for real-time monitoring of the environmental data of the simulated subway communication channel.

Description

Technical Field

[0001] The present invention relates to the technical field of urban rail transit construction, and in particular to a freezing simulation test system for a subway communication channel. Background Art

[0002] In recent years, the construction and operation mileage of my country's subway has exploded. For example, by the end of 2020, the total operating mileage of Beijing Metro has reached 727km. According to the plan, by 2050, the Beijing subway operating line will exceed 1,000km. In the past, municipal rail excavation projects in Beijing were mainly based on precipitation construction, with daily precipitation of 250,000-600,000 cubic meters and annual precipitation of hundreds of millions of cubic meters, resulting in a huge waste of groundwater resources. Therefore, since 2017, it has been prohibited to extract groundwater for construction. As a typical method of non-precipitation construction, artificial freezing method has been widely promoted in underground engineering fields such as mines, tunnels, and foundation pits. Artificial freezing method refers to the construction of temporary freezing walls around various underground projects under complex hydrogeological conditions to isolate the connection between groundwater inside and outside the freezing wall and resist water and soil pressure to ensure the stability of water-bearing soil during excavation construction. Its essence is to use artificial refrigeration technology to temporarily change the properties of rock and soil to achieve the purpose of strengthening the stratum.

[0003] The strength of artificial frozen soil is an important theoretical basis for evaluating the stability of frozen walls, and it is significantly affected by the temperature and thickness of the frozen wall. Compared with the soft soil in Tianjin, clay and sandy silt in East China, and red soil in South China, Beijing is located at the junction of Taihang Mountains, Yanshan Mountains and North China Plain, mainly on the Yongding River alluvial fan, and the groundwater storage state is complex. Sandy and gravel strata are widely distributed along the subway line, with extremely strong permeability. The freezing temperature field is significantly affected by the seepage of groundwater. It has certain particularities in the freezing process and cannot directly refer to the research results of freezing construction in other cities. Groundwater seepage is the core factor affecting the freezing temperature field. The flow of groundwater in the stratum will continuously replenish the heat in the freezing area, resulting in a large difference between the distribution and development of the freezing temperature field and the static water conditions. The average temperature and thickness of the frozen wall are lower than expected, which seriously restricts the safe advancement of the freezing project.

[0004] During the process of artificial freezing to reinforce the stratum, with the continuous heat exchange, the stratum temperature continues to decrease. When the temperature reaches the freezing point, the volume of the soil increases significantly due to the freezing of pore water in situ and the segregation freezing caused by the migration of water in the unfrozen area, resulting in uneven deformation of the surface. After the freezing construction is completed, as the stratum temperature rises, the frozen soil gradually melts, and the compaction and rearrangement of soil particles under the overlying load are superimposed, and the stratum shows obvious thawing and settling. Considering the complex environment around the urban subway connecting channel, if the frost heave and thaw settlement cannot be effectively controlled, it will have an adverse effect on the foundation of the upper structure or building and the adjacent municipal pipe network facilities, causing huge economic losses and social impacts.

[0005] In view of this, the formation law of frozen wall in the communication channel of sandy and gravel strata under seepage conditions and the effect on the surrounding environment need to be further studied. At present, the research methods of such problems mainly include numerical simulation, field test and model test. The model simplification, parameter selection and boundary conditions of numerical simulation have an important influence on the calculation results. Considering the complexity of the freezing project of the communication channel, the guiding role of its calculation results on the actual project needs to be discussed; the field test has high credibility and can reflect the actual situation on site, but the cost and energy consumption during the test are extremely large, and there is no possibility of repeated tests; the model test has controllable funds and high credibility, which is an important means to study complex engineering problems. However, the existing model test research related to freezing method mainly considers the freezing of strata under static water or low-speed seepage conditions, and most of the simulation objects are fine-grained soils such as clay and sand, simulating the artificial freezing of clay and sand combined strata, while the sandy and gravel strata have extremely strong permeability, and the freezing temperature field and deformation field are significantly affected by the seepage effect. It has certain particularity in the freezing process, and it is impossible to directly refer to the research results of fine-grained soil freezing. In addition, the freezing pipes in most model tests are arranged in a single-tube, single-row or multi-row layout. This type of pipe layout mainly simulates actual projects such as freezing of subway station floors or foundation pits. The connecting channel is a straight-wall arch structure, and its freezing pipe layout scheme is quite different from the above-mentioned pipe layout scheme. There is no definite conclusion on whether the test results of the experimental scheme can reflect the development laws of the freezing temperature field and deformation field of the connecting channel. Summary of the invention

[0006] The embodiment of the present invention provides a subway communication channel freezing simulation test system to overcome the defects of the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme.

[0008] In one aspect, the present invention provides a subway communication channel freezing simulation test system, comprising:

[0009] The model box, including a water inlet chamber, a soil filling chamber and a water outlet chamber, is used to simulate the environment of a subway communication passage;

[0010] The refrigeration cycle module includes a cold bath machine and a freezing pipe group arranged on the simulation box, which is used to provide a low temperature environment for the simulation box to simulate the low temperature environment during freezing construction;

[0011] A seepage module, including a water tank, a heater and a circulation pipeline, for injecting water into the model box to simulate the seepage return of the subway communication channel; and

[0012] The monitoring module includes a sensor group and a collector, and is used for real-time monitoring of environmental data of a simulated subway communication channel.

[0013] Optionally, a seepage liquid inlet pipe communicating with the water inlet chamber is provided on one side wall of the model box, and a seepage liquid outlet pipe communicating with the water outlet chamber is provided on the other side wall of the model box.

[0014] Optionally, the freezing tube group includes a plurality of freezing tubes arranged in the simulation box and a liquid inlet main pipe and a liquid outlet main pipe respectively arranged at both ends of the plurality of freezing tubes, so as to form a refrigerant circulation loop; the refrigeration module also includes an antifreeze pipe, which is used to respectively connect the cold bath machine and the liquid inlet main pipe, and the cold bath machine and the liquid outlet main pipe, so as to form an antifreeze circulation loop.

[0015] Optionally, the seepage module further includes: a power pump, which is arranged on the circulation pipeline; a pressure gauge, which is arranged on the circulation pipeline and is used to monitor the pressure; and a flow meter, which is arranged on the circulation pipeline and is used to monitor the flow.

[0016] Optionally, the sensor includes a temperature sensor, a stress sensor, and a deformation sensor, and the collector includes a Campbell CR6 series and a plurality of channel expansion boards.

[0017] Optionally, the design method of the system includes the following steps:

[0018] Through dimensional analysis, similarity criteria for influencing factors of model tests are obtained;

[0019] According to the environment of the subway connecting channel, the similarity ratio of the freezing simulation test system of the subway connecting channel is determined, and the similarity ratio includes geometric similarity ratio, material similarity ratio, time similarity ratio, salt water flow similarity ratio, groundwater flow velocity similarity ratio, and load similarity ratio;

[0020] Designing a model box according to first predetermined data, wherein the first predetermined data includes geometric similarity ratio, material strength and stiffness conditions, and controlling initial water head difference;

[0021] Designing a refrigeration cycle module according to second predetermined data, wherein the second predetermined data includes a brine flow similarity ratio, a predetermined communication channel pipe layout structure, and a predetermined energy consumption requirement;

[0022] Designing a seepage module according to third predetermined data, wherein the third predetermined data includes a groundwater velocity similarity ratio, a water temperature similarity ratio, and a predetermined test velocity;

[0023] A monitoring module is designed according to the predetermined test rules, intended test objects and test accuracy requirements of the subway connection channel freezing simulation test system.

[0024] Optionally, the model test influencing factors include temperature field, seepage field and stress field.

[0025] Optionally, the design method of the simulation box also includes:

[0026] Water inlet chamber and water outlet chamber are respectively set on both sides of the simulation box to reduce the direct scouring effect of groundwater on the test soil;

[0027] Two layers of 250-mesh steel wire screens are installed inside the water inlet and outlet chambers to prevent the loss of fine particles of soil and the entry into the system pipelines;

[0028] The outlet chamber is divided into four independent cavities, each of which is connected to a seepage outlet pipe to reduce the different initial flow velocities in different formations caused by the water head difference in the water storage chamber;

[0029] Four layers of customized copper partitions are set up during filling to minimize the infiltration of groundwater due to gravity, and waterproof glue is used to stop water between the partitions and the freezing pipes.

[0030] Optionally, the design method of the refrigeration cycle module further includes:

[0031] Select a cold bath machine with specified power according to energy consumption requirements;

[0032] The freezing pipe group is designed according to the reasonable similarity ratio of the pipe layout scheme of the actual freezing project, and the freezing pipe group is made of the same material as the on-site freezing pipe;

[0033] Solenoid valves are set on both sides of each freezing pipe to control the opening and closing of each freezing pipe.

[0034] Optionally, the design method of the seepage module further includes:

[0035] The groundwater flow rate of 20m / d was simulated by a dynamic pump;

[0036] Each cavity is connected to three water inlet and outlet pipes, which are connected in parallel using a main pipe and then connected to the seepage circulation pipeline;

[0037] The heater and temperature control device installed in the water tank are used for automatic heating to ensure that the water in the water tank is always at a constant temperature;

[0038] Flow rate is controlled by pressure and flow rate.

[0039] The beneficial effects of the present invention are as follows: the temperature field, stress field and deformation field are monitored in real time during the artificial freezing of subway communication channels in gravel and sand formations under seepage conditions, the development and evolution laws of various physical quantities are analyzed, and a basis is provided for the design and construction of freezing projects for subway communication channels. This simulation test system realizes the simulation of high-speed seepage in gravel and sand formations, and solves the problem that the existing model test only considers fine-grained soils such as clay and sand under static water or low-speed seepage conditions; by setting up multi-layer water storage chambers and seepage channels, the problem of the large difference in seepage velocity between the upper and lower layers of the existing model test soil body affecting the test results is solved; at the same time, the freezing pipes of the simulation test are designed according to the pipe layout characteristics of the freezing pipes of the on-site communication channels, and electromagnetic valves are configured to realize flexible simulation of the layout of freezing pipes of different communication channels. This simulation test system is of great significance to the design and construction of freezing projects for subway communication channels in water-rich gravel and sand formations.

[0040] Additional aspects and advantages of the present invention will be given in part in the following description, which will become obvious from the following description, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0042] Figure 1 A schematic diagram of the structure of a subway communication channel freezing simulation test system provided by an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the structure of a model box provided by an embodiment of the present invention;

[0044] Figure 3 A schematic diagram of a refrigeration cycle module provided by an embodiment of the present invention; and

[0045] Figure 4 A schematic diagram of a seepage circulation module provided in an embodiment of the present invention.

[0046] Figure numerals: 1. model box; 2. cold bath machine; 3. water tank; 4. flow meter; 5. pressure gauge; 6. power pump; 7. seepage control gate valve; 8. seepage outlet pipe; 9. seepage inlet pipe; 10. water outlet chamber; 11. water inlet chamber; 12. copper partition; 13. stainless steel punching plate; 14. stainless steel filter; 15. steel partition; 16. refrigerant outlet pipe; 17. refrigerant gate valve; 18. refrigerant inlet pipe; 19. liquid inlet main pipe; 20. liquid outlet main pipe; 21. freezing pipe; 22. solenoid valve; 23. seepage inlet pipe; 24. constant temperature heater; 25. seepage outlet pipe. DETAILED DESCRIPTION

[0047] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0048] Those skilled in the art will appreciate that, unless expressly stated otherwise, the singular forms "a", "an", "" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other elements, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or couplings. The term "and / or" as used herein includes any unit and all combinations of one or more of the associated listed items.

[0049] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0050] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0051] Example

[0052] This embodiment provides a subway communication channel freezing simulation test system, including:

[0053] The model box 1 includes a water inlet chamber 11, a filling chamber and a water outlet chamber 10, which can be used to simulate the environment of a subway connecting channel; a refrigeration cycle module, including a cold bath machine 2 and a freezing pipe group arranged on the simulation box, which can be used to provide a low-temperature environment for the simulation box to simulate the low-temperature environment during freezing construction; a seepage module, including a water tank 18, a heater 24 and a circulation pipeline, which is used to inject water into the model box to simulate the seepage return of the subway connecting channel; and a monitoring module, including a sensor group and a collector, which is used to monitor the environmental data of the simulated subway connecting channel in real time.

[0054] In this embodiment, a seepage liquid inlet pipe 9 communicating with the water inlet chamber 11 is provided on one side wall of the model box body 1 , and a seepage liquid outlet pipe 8 communicating with the water outlet chamber 10 is provided on the other side wall of the model box body 1 .

[0055] In this embodiment, the model box 1 is composed of an inlet chamber 11, a fill chamber and an outlet chamber 10 from left to right. The fill chamber is separated from the outlet chamber 10 and the inlet chamber 11 by a stainless steel perforated plate 13, and a 250-mesh stainless steel filter screen 14 is pasted to prevent fine-grained soil in the fill chamber from invading the seepage system. The inlet chamber 11 and the outlet chamber 10 are divided into four independent cavities, which are respectively connected to the inlet and outlet pipes, and 1-2 cm uniform gravel is filled in layers in the inlet chamber 11 and the outlet chamber 10. The fill chamber is filled with a clay waterproof insulation layer, a test sand and gravel soil, and a clay waterproof insulation layer from bottom to top. Four layers of customized copper partitions are arranged at designated points, and a communication channel freezing pipe group and a sensor group are buried in the corresponding positions of the test soil.

[0056] In this embodiment, the freezing pipe group includes a plurality of freezing pipes 21 arranged in the simulation box 1 and a liquid inlet pipe 19 and a liquid outlet pipe 20 respectively arranged at both ends of the plurality of freezing pipes 21, for forming a freezing liquid circulation loop. The refrigeration module also includes a freezing liquid outlet pipe 16 and a freezing liquid inlet pipe 18, for respectively connecting the cold bath machine 2 and the liquid inlet pipe 19, the cold bath machine 2 and the liquid outlet pipe 20, for forming an antifreeze circulation loop.

[0057] In this embodiment, the cold bath machine adopts a 7.5kw air-cooled high-power chiller, and the antifreeze adopts Shell glycol antifreeze with a freezing point of -45°C. Solenoid valves 22 are set at both ends of the communication channel freezing pipe 21 to control the circulation of brine in the freezing pipe 21. The cold bath machine 2 and the freezing pipe 21 are connected to the antifreeze pipe 18 in turn to form a refrigeration cycle.

[0058] In this embodiment, the seepage module further includes: a power pump 6, which is arranged on the circulation pipeline; a pressure gauge, which is arranged on the circulation pipeline and is used to monitor the pressure; and a flow meter, which is arranged on the circulation pipeline and is used to monitor the flow.

[0059] In this embodiment, the water tank 3 of the seepage module adopts a 0.5m 3 The water tank is made of aluminum and has holes opened at designated locations to connect to the circulation pipeline. The water tank 3 has a built-in high-power heater and a temperature control system. A 30m-lift power pump 6, a flow meter and a pressure gauge are sequentially arranged on the circulation pipeline to control the seepage rate.

[0060] In this embodiment, the sensors include a temperature sensor, a stress sensor, and a deformation sensor, and the collector includes a Campbell CR6 series and multiple channel expansion boards.

[0061] In this embodiment, the monitoring module is composed of sensors and collectors. The sensors include various sensors such as temperature, stress, and deformation, and are buried in the specified position of the test soil. The wires are arranged in sequence, so that the wires are led out from the reserved holes of the box and connected to the collector. The collector is composed of Campbell CR6 series and multiple channel expansion boards, which can realize real-time monitoring of multi-object data.

[0062] In this embodiment, the design method of the system includes the following steps:

[0063] Step 1: Through dimensional analysis, obtain the similarity criteria of the factors affecting the model test.

[0064] Step 2: According to the environment of the subway connecting channel, determine the similarity ratio of the subway connecting channel freezing simulation test system, which includes geometric similarity ratio, material similarity ratio, time similarity ratio, brine flow similarity ratio, groundwater flow velocity similarity ratio, and load similarity ratio.

[0065] Step 3: Design the model box according to the first predetermined data, wherein the first predetermined data includes geometric similarity ratio, material strength and stiffness conditions, and control of initial water head difference.

[0066] Step 3.1: Set up water inlet chamber and water outlet chamber on both sides of the simulation box to reduce the direct scouring effect of groundwater on the test soil;

[0067] Step 3.2: Two layers of 250-mesh steel wire filters are installed inside the water inlet chamber and the water outlet chamber to prevent the loss of fine particles of soil and the entry into the system pipeline;

[0068] Step 3.3: Divide the outlet chamber into four independent cavities, each of which is connected to a seepage outlet pipe to reduce the different initial flow velocities in different formations caused by the water head difference in the water storage chamber;

[0069] Step 3.4: Set up four layers of customized copper partitions during filling to minimize the infiltration of groundwater due to gravity, and use waterproof glue to stop water between the partitions and the freezing pipes.

[0070] Step 4: Design a refrigeration cycle module according to the second predetermined data, wherein the second predetermined data includes a brine flow similarity ratio, a predetermined communication channel piping structure, and a predetermined energy consumption requirement.

[0071] Step 4.1: Select a cold bath machine with specified power according to energy consumption requirements;

[0072] Step 4.2: Design the freezing pipe group according to the reasonable similarity ratio of the pipe layout scheme of the actual freezing project, and use the same material as the on-site freezing pipe to make the freezing pipe group;

[0073] Step 4.3: Set solenoid valves on both sides of each freezing pipe to control the opening and closing of each freezing pipe.

[0074] Step 5: designing a seepage module according to the third predetermined data, wherein the third predetermined data includes a groundwater velocity similarity ratio, a water temperature similarity ratio and a predetermined test velocity;

[0075] Step 5.1: Simulate a groundwater flow rate of 20 m / d by a dynamic pump;

[0076] Step 5.2: Each layer of cavity is connected to three water inlet and outlet pipes, which are connected in parallel using a main pipe and then connected to the seepage circulation pipeline;

[0077] Step 5.3: The heater and temperature control device provided in the water tank are used for automatic heating to ensure that the water in the water tank is always at a constant temperature;

[0078] Step 5.4: Control flow rate by pressure and flow rate.

[0079] Step 6: Design a monitoring module based on the predetermined test rules, intended test objects, and test accuracy requirements of the subway connection channel freezing simulation test system.

[0080] In the embodiment of the present invention, the freezing construction simulation of the communication channel in the typical sand and gravel stratum in Beijing is taken as an example to illustrate the test process.

[0081] Step S1: According to the actual engineering freezing temperature field influence range, groundwater seepage conditions, load distribution, test device and component processing technology level, resource input and budget and expected goals, determine the similarity ratio (1:16) of the test device; according to the similarity ratio, determine the important parameters such as the model box size (1m*1m*0.5m), cold bath machine power (1 7.5kw air-cooled chiller), and power pump head (30m).

[0082] Step S2: Figure 2As shown, the model box 1 is made of 8 mm thick steel plates according to the proposed size of the model box 1, and the model box 1 is assembled by welding; holes are opened on the left and right side steel plates of the model box 1, the seepage outflow pipe 8 and the seepage inlet pipe 9 are welded, and a 200-mesh stainless steel filter 14 is pasted in the left and right side steel plates; stainless steel punching plates 13 are welded on both sides of the inside of the model box to form an inlet chamber 11 and an outlet chamber 10, and a 200-mesh stainless steel filter 14 is pasted on the side of the punching plate close to the test soil.

[0083] Step S3: Figure 3 As shown, the refrigeration cycle module is equipped with a 7.5kw air-cooled chiller 2, and a refrigerant gate valve 17 is configured to control the refrigerant flow. The size and layout spacing of the communication channel freezing pipe model are determined according to the on-site freezing pipe layout plan and similarity ratio, and are composed of stainless steel pipes of designed dimensions connected by joints; the freezing pipe group consists of a freezing pipe 21, a liquid inlet dry pipe 19, and a liquid outlet dry pipe 20. Solenoid valves 22 are set at both ends of each freezing pipe, and any freezing pipe can be flexibly opened and closed through a matching control device, so that the freezing pipe layout plan can be adjusted without disassembling the soil sample. The antifreeze pipe 18 is used to connect the cold bath machine and the liquid inlet and outlet dry pipes to form a circulation loop of the antifreeze liquid.

[0084] Step S4: Figure 4 As shown, the seepage circulation module is customized with a stainless steel water tank 3, a hole is opened on the side of the tank and a joint is used to connect the seepage return pipe 23; a 2.5kw constant temperature heater 24 is arranged in the water tank, which can automatically monitor and control the water temperature in the water tank to a specified temperature; the seepage return pipe 23 is connected with a seepage control gate valve 7, a power pump 6, a pressure gauge 5 and a flow meter 4 in sequence to realize precise control of the seepage velocity.

[0085] Step S5: During the test, gravel with a diameter of 1-2 cm is first used to stack the water inlet chamber and the water outlet chamber in 4 layers, and a 5 mm thick steel plate is pasted when each layer reaches the specified height to form 4 independent water storage chambers; then the lower clay layer, the sand and gravel layer and the upper clay layer are filled in sequence; during the filling process, copper partitions are laid at designated positions to form independent seepage channels, and freezing pipe groups and temperature sensors, earth pressure boxes, displacement sensors and other types of sensors are buried at designated positions to realize real-time monitoring of multi-physical field data such as temperature, stress and deformation during the freezing construction of the sand and gravel stratum communication channel under seepage conditions.

[0086] In summary, the embodiments of the present invention realize the real-time monitoring of the temperature field, stress field and deformation field during the artificial freezing of the subway communication channel in the gravel formation under the seepage condition, analyze the development and evolution law of each physical quantity, and provide a basis for the design and construction of the freezing project of the subway communication channel. This simulation test system realizes the simulation of high-speed seepage in the gravel formation, and solves the problem that the existing model test only considers the static water or low-speed seepage conditions of fine-grained soils such as clay and sand; by setting up multi-layer water storage chambers and seepage channels, the problem of the large difference in seepage velocity between the upper and lower layers of the existing model test soil body affecting the test results is solved; at the same time, the freezing pipes of the simulation test are designed according to the pipe layout characteristics of the on-site communication channel freezing pipes, and electromagnetic valves are configured to realize flexible simulation of different communication channel freezing pipe layout schemes. This simulation test system is of great significance to the design and construction of the freezing project of the subway communication channel in the water-rich gravel formation.

[0087] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0088] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The method and system embodiments described above are merely schematic, in which the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0089] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A subway communication channel freezing simulation test system, characterized in that: include: The model box, including a water inlet chamber, a soil filling chamber and a water outlet chamber, is used to simulate the environment of a subway communication passage; A refrigeration cycle module, including a cold bath and a freezing pipe group arranged on the model box, for providing a low temperature environment to the model box to simulate the low temperature environment during freezing construction; A seepage module, including a water tank, a heater and a circulation pipeline, is used to inject water into the model box to simulate the seepage return of the subway communication channel; as well as A monitoring module, including a sensor group and a collector, for real-time monitoring of environmental data of the simulated subway communication channel; The design method of the system comprises the following steps: Through dimensional analysis, similarity criteria for influencing factors of model tests are obtained; Determine the similarity ratio of the freezing simulation test system of the subway communication channel according to the environment of the subway communication channel, wherein the similarity ratio includes geometric similarity ratio, material similarity ratio, time similarity ratio, salt water flow similarity ratio, groundwater flow velocity similarity ratio, and load similarity ratio; Designing a model box according to first predetermined data, wherein the first predetermined data includes the geometric similarity ratio, material strength and stiffness conditions, and controlling the initial water head difference; Designing a refrigeration cycle module according to second predetermined data, wherein the second predetermined data includes the brine flow similarity ratio, a predetermined communication channel pipe layout structure, and a predetermined energy consumption requirement; Designing the seepage module according to third predetermined data, wherein the third predetermined data includes the groundwater velocity similarity ratio, the water temperature similarity ratio and a predetermined test velocity; Design a monitoring module according to the predetermined test rules, intended test objects and test accuracy requirements of the subway communication channel freezing simulation test system; The water inlet chamber and the water outlet chamber are respectively arranged on both sides of the model box body to reduce the direct scouring effect of groundwater on the test soil; Two layers of 250-mesh steel wire filters are provided inside the water inlet chamber and the water outlet chamber to prevent the loss of fine particles of soil and the pipes entering the system; The outlet chamber is divided into four independent cavities, each of which is connected to a seepage outlet pipe to reduce the different initial flow velocities in different formations caused by the water head difference in the water storage chamber; Four layers of customized copper partitions are set during filling to minimize the infiltration of groundwater due to gravity, and waterproof glue is used to stop water between the copper partitions and the freezing pipes.

2. The system according to claim 1, characterized in that A seepage liquid inlet pipe communicating with the water inlet chamber is arranged on one side wall of the model box, and a seepage liquid outlet pipe communicating with the water outlet chamber is arranged on the other side wall of the model box.

3. The system according to claim 2, characterized in that: The freezing pipe group includes a plurality of freezing pipes arranged in the model box and a liquid inlet dry pipe and a liquid outlet dry pipe respectively arranged at both ends of the plurality of freezing pipes, for forming a freezing liquid circulation loop; The refrigeration cycle module also includes an antifreeze pipe, which is used to respectively connect the cold bath machine and the liquid inlet main pipe, and the cold bath machine and the liquid outlet main pipe to form an antifreeze liquid circulation loop.

4. The system according to claim 3, characterized in that The seepage module also includes: A power pump, arranged on the circulation pipeline; A pressure gauge, disposed on the circulation pipeline, for monitoring pressure; and The flow meter is arranged on the circulation pipeline and is used for monitoring the flow rate.

5. The system according to claim 1, characterized in that The sensors include temperature sensors, stress sensors and deformation sensors. The collector includes Campbell CR6 series and multiple channel expansion boards.

6. The system according to claim 1, characterized in that The influencing factors of the model test include temperature field, seepage field and stress field.

7. The system according to claim 1, characterized in that The design method of the refrigeration cycle module also includes: Connect multiple Thermo Fisher high-power cold baths in series; The freezing pipe group is designed according to the pipe layout scheme of the actual freezing project in accordance with a reasonable similarity ratio, and the freezing pipe group is made of the same material as the on-site freezing pipe; Solenoid valves are set on both sides of each freezing pipe to control the opening and closing of each freezing pipe.

8. The system according to claim 1, characterized in that The design method of the seepage module also includes: The groundwater flow rate of 20m / d was simulated by a dynamic pump; Each cavity is connected to three water inlet and outlet pipes, which are connected in parallel using a main pipe and then connected to the seepage circulation pipeline; The heater and temperature control device provided in the water tank are used for automatic heating to ensure that the water in the water tank is always at a constant temperature; Flow rate is controlled by pressure and flow rate.

Images