System and method for testing freezing characteristics of artificial frozen soil

Abstract

The invention provides an artificial frozen soil freezing characteristic test system and method, and relates to the field of artificial freezing, and the system comprises a refrigeration module, a heat dissipation module, a test module and a simulation test box; the simulation test box is filled with a test soil layer, a plurality of pairs of pre-embedded sleeves are arranged in the simulation test box, all the pre-embedded sleeves are in contact with the test soil layer, each pre-embedded sleeve is internally provided with the corresponding refrigeration module, the heat dissipation module penetrates through the interior of the corresponding refrigeration module, and the heat dissipation module is connected with the corresponding refrigeration module. The testing modules are arranged on the sides of each pair of pre-embedded sleeves; the distance between each pair of embedded sleeves is not less than a preset distance; the test module comprises at least one of a temperature test unit, an electrical method test unit and a sound wave test unit. The artificial freezing construction process can be simulated in the indoor environment, so that the actual freezing construction period, the freezing process and the reinforcing effect are accurately estimated, and the freezing construction risk is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of artificial freezing, in particular to a system and method for testing freezing characteristics of artificial frozen soil. BACKGROUND

[0002] Artificial freezing technology is a construction technology widely used in coal mine shaft, shield machine starting, subway connecting channel and other underground engineering scenes, and is an effective reinforcement technology for water-rich and soft soil strata.

[0003] The construction method of artificial freezing technology is to arrange freezing pipes at intervals along the periphery of the area to be frozen and reinforced, and to uniformly arrange temperature measuring holes inside and outside the area to be frozen and reinforced. Through the operation of the refrigeration system, the freezing pipe absorbs the heat of the stratum and changes the natural rock-soil into artificial frozen soil, so as to achieve the purpose of increasing the strength and stability of the stratum and reducing the permeability. One of the core indicators for determining the freezing and reinforcement effect during artificial freezing construction is the frozen soil temperature. The stratum temperature is determined by the temperature measuring hole. If the temperature reaches a preset temperature, such as-10℃ or below, it is considered that the adjacent freezing pipes have frozen and formed a reliable frozen curtain. During the active freezing construction, the freezing front expansion rate of different sites and soil layers is different, and the construction period required for active freezing is different. The above process is generally determined by theoretical derivation or empirical formula, and the development of the freezing front and whether the frozen curtain is closed often exist inaccurate conditions.

[0004] Therefore, how to test the accurate frozen curtain expansion parameters is an important topic to be solved in the industry at present. SUMMARY

[0005] Therefore, the present application provides a system and method for testing the freezing characteristics of artificial frozen soil to solve the problem that the development of the freezing front and whether the frozen curtain is closed during the artificial freezing process often exist inaccurate conditions.

[0006] The technical scheme of the present application is as follows:

[0007] According to a first aspect, the present application provides a system for testing the freezing characteristics of artificial frozen soil, which comprises:

[0008] a refrigeration module, a heat dissipation module, a test module and a simulation test box;

[0009] The simulation test box is filled with a test soil layer, and a plurality of pairs of pre-buried sleeves are arranged in the simulation test box. All the pre-buried sleeves are in contact with the test soil layer. Each pre-buried sleeve is provided with the refrigeration module, the heat dissipation module passes through the inside of the refrigeration module, and each pair of pre-buried sleeves is provided with the test module on the side.

[0010] The distance between each pair of the embedded sleeves is not less than a preset distance; the test module comprises at least one of a temperature test unit, an electrical method test unit and an acoustic wave test unit; the temperature test unit is used for testing the change of the temperature field of the test soil layer; the electrical method test unit is used for taking each pair of the embedded sleeves in contact with the test soil layer as a corresponding pair of electrodes, arranging a vertically arranged potential probe on the center line of the embedded sleeves according to a symmetric four-pole profile electrical method detection method, and testing the change of the electric field and the resistivity of the test soil layer; the acoustic wave test method is used for taking the same depth in each pair of the embedded sleeves in contact with the test soil layer as a test operation surface, and performing frozen soil acoustic wave velocity testing.

[0011] In combination with the first aspect, in a first implementation manner of the first aspect, each pair of the embedded sleeves is arranged along the length direction of the simulation test box, and is symmetrically arranged on both sides of a longitudinal section passing through the center point of the simulation test box, and the cross section of the embedded sleeve is a regular hexagon.

[0012] In combination with the first implementation manner of the first aspect, in a second implementation manner of the first aspect, the refrigeration module comprises a refrigerator, a refrigeration fin, a heat dissipation fin and a direct current power supply.

[0013] The refrigerator is sleeved in the inside of the embedded sleeve, the cross section of the refrigerator is a regular hexagon, the inner wall of each face of the refrigerator is provided with a refrigeration fin, the refrigeration fin comprises a heat absorption face and a heat release face, the heat absorption face and the heat release face form a thermocouple pair, the heat absorption face is connected with the inner wall of the refrigerator, the heat release face is connected with the heat dissipation fin, each refrigeration fin is electrically connected with the direct current power supply, and the heat dissipation module passes through the inside of the refrigerator.

[0014] In combination with the second implementation manner of the first aspect, in a third implementation manner of the first aspect, a gap is arranged between the outer wall of the refrigerator and the inner wall of the embedded sleeve, and anti-freezing lubricating oil is arranged in the gap.

[0015] In combination with the second implementation manner of the first aspect, in a fourth implementation manner of the first aspect, the heat dissipation module comprises a circulating water tank, a first circulating water pump, a second circulating water pump, a first circulating pipeline, a second circulating pipeline and a circulating water controller.

[0016] The first circulating pipeline and the second circulating pipeline are in communication with the circulating water tank arranged outside the simulation test box, the first circulating pipeline and the second circulating pipeline pass through the two refrigerators respectively, the first circulating pipeline is provided with the first circulating water pump, the second circulating pipeline is provided with the second circulating water pump, and the first circulating water pump and the second circulating water pump are electrically connected with the circulating water controller.

[0017] In combination with the second implementation form of the first aspect, in a fifth implementation form of the first aspect, the temperature testing unit comprises a second temperature sensor arranged at the test soil layer at the periphery of the embedded sleeve, and a temperature testing ring in a freezing radius direction of the refrigeration device is arranged in no less than a first preset number, each temperature testing ring is provided with no less than a second preset number of temperature monitoring points, and each temperature monitoring point is provided with no less than a third preset number of the second temperature sensors.

[0018] In combination with the fifth implementation form of the first aspect, in a sixth implementation form of the first aspect, the temperature testing unit further comprises a plurality of temperature measuring rods, and the second temperature sensors are arranged on the temperature measuring rods.

[0019] In combination with the first aspect, in a seventh implementation form of the first aspect, the electrical method testing unit comprises a potential probe and a resistivity tester.

[0020] Two potential probes are symmetrically arranged on both sides of the center point of the simulation test box, and the potential probes are arranged on the longitudinal section passing through the center point of the simulation test box, and the potential probes are electrically connected with the resistivity tester arranged outside the simulation test box.

[0021] In combination with the first aspect, in an eighth implementation form of the first aspect, the acoustic wave testing unit comprises an acoustic wave transmitter and an acoustic wave receiver.

[0022] The acoustic wave transmitter and the acoustic wave receiver are respectively arranged inside the two embedded sleeves, and the working heights of the acoustic wave transmitter and the acoustic wave receiver are always equal.

[0023] According to the second aspect, an embodiment of the present application provides a testing method for freezing characteristics of artificial frozen soil, and the method comprises the following steps:

[0024] A pair of embedded sleeves are installed in the simulation test box, and a test soil layer is put into the simulation test box.

[0025] A testing module is installed for the embedded sleeves.

[0026] A refrigeration module and a heat dissipation module are installed for the embedded sleeves, and anti-freezing lubricating liquid is smeared in the gap between the embedded sleeves and the refrigeration module.

[0027] The refrigeration module and the heat dissipation module are started, and a first working parameter of the refrigeration module and a second working parameter of the heat dissipation module are set according to a preset test period.

[0028] The testing module is started, and testing data are acquired.

[0029] In a case where a first test index in the testing data reaches a first preset critical value range, the expansion range of the freezing front is determined; the first test index comprises a frozen soil sample temperature, a resistivity and an acoustic wave velocity.

[0030] In a case where it is determined that the second test index in the test data reaches a second preset critical value interval, it is determined that the frozen wall of the pair of pre-buried sleeves has been fully jointed, and the curtain thickness reaches the requirement; the second test index includes temperature, resistivity, and acoustic wave velocity

[0031] The artificial frozen soil freezing characteristic testing system and method have the following advantages over the prior art

[0032] Advantages:

[0033] Through the simulation test box, the user can simulate the artificial freezing construction process in an indoor environment, and then determine whether the freezing front development and the freezing curtain jointing in the artificial freezing construction process are accurate. The indoor model test of artificial freezing is carried out by using the refrigeration module, the heat dissipation module, and the test module, and the accurate freezing characteristics and the freezing curtain expansion parameters of the corresponding engineering site stratum are obtained, so as to accurately estimate the actual freezing construction period, the freezing process, and the reinforcement effect, and reduce the freezing construction risk. In addition, one or more of the temperature test method, the electrical test method, and the acoustic wave test method are combined in the test module to comprehensively determine the freezing front expansion rate and the freezing effect. The user can arbitrarily select one or more test units for joint testing according to the test precision requirement. The three test units are independent of each other and closely related. The pre-buried sleeve can be used as an electrode for the electrical test method and as a sound pipe for the acoustic wave test method. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0035] Figure 1 A structural schematic diagram of the artificial frozen soil freezing characteristic testing system is shown.

[0036] Figure 2 A top view of the test module in the artificial frozen soil freezing characteristic testing system is shown.

[0037] Figure 3 A front view of the test module in the artificial frozen soil freezing characteristic testing system is shown.

[0038] Figure 4 A cross-sectional schematic diagram of the pre-buried sleeve in the artificial frozen soil freezing characteristic testing system is shown.

[0039] Figure 5 A perspective view of a pre-embedded sleeve in a test system for testing the freezing characteristics of artificial frozen soil according to an embodiment of the present application is shown;

[0040] Figure 6 A flowchart of a test method for testing the freezing characteristics of artificial frozen soil according to an embodiment of the present application is shown.

[0041] In the figure; 10 - simulation test box; 20 - pre-embedded sleeve; 30 - refrigeration module; 31 - refrigerator; 32 - refrigeration sheet; 321 - heat absorption surface; 322 - heat release surface; 33 - heat dissipation fin; 34 - direct current power supply; 40 - heat dissipation module; 41 - circulating water tank; 42 - first circulating water pump; 43 - second circulating water pump; 46 - circulating water controller; 50 - temperature test unit; 51 - second temperature sensor; 60 - electrical method test unit; 61 - potential probe; 62 - resistivity tester; 70 - acoustic wave test unit; 71 - acoustic wave transmitter; 72 - acoustic wave receiver. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0043] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second", "third" and the like are only used to distinguish description, and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set", "install", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] Artificial frozen soil refers to the freezing of soil or rock strata that are not in a frozen state by artificial refrigeration technology. It is a temporary ground reinforcement and groundwater control engineering technology. Artificial freezing technology is widely used in coal mine shafts, shield machine launching, subway connecting passages and other underground engineering scenes. It is an effective reinforcement technology for water-rich, soft soil sites. For example, before the excavation of underground engineering (such as tunnels, shafts, foundation pits, and subway stations), a continuous frozen soil wall is formed around the excavation area to provide temporary lateral support to prevent the collapse of the excavation face and deformation of the surrounding soil, forming a temporary support structure, which is especially suitable for soft soil, quicksand, high water content strata and other difficult-to-support situations using conventional methods. Artificial frozen soil can form a temporary water stop curtain, and the frozen soil wall is an excellent water-tight barrier that can effectively block groundwater from flowing into the construction area. Artificial frozen soil can be used in projects with abundant groundwater, high water pressure, or where strict control of groundwater is required to minimize the impact on the surrounding environment (such as preventing ground subsidence and protecting adjacent buildings). In soft ground or underwater construction, artificial frozen soil technology can be used to pre-freeze part of the area to form a hard and stable working platform, providing a stable working platform for equipment operation and construction. Artificial frozen soil technology can also be used in special geological conditions, such as repairing underground pipelines, crossing water-bearing fault zones, mine shaft construction, and underground storage construction. In the remediation of contaminated sites, frozen soil walls are sometimes used to enclose contaminants to prevent their spread with groundwater, effectively controlling the migration of harmful substances.

[0046] The specific construction method of artificial freezing technology is to arrange freezing pipes at intervals around the area to be frozen and reinforced, and to distribute temperature measurement holes inside and outside the area to be frozen and reinforced. Through the operation of the refrigeration system, the natural rock and soil is changed into artificial frozen soil by the freezing pipes absorbing the heat of the stratum, thereby achieving the purpose of increasing the strength and stability of the stratum and reducing the permeability. One of the core indicators for determining the freezing and reinforcement effect during artificial freezing construction is the temperature of the frozen soil. By measuring the temperature of the holes, it can be determined that the adjacent freezing pipes have frozen and formed a reliable frozen curtain when the stratum temperature reaches a predetermined temperature, such as -10°C or below. During active freezing construction, the freezing front expansion rate of different sites and soil layers is different, and the construction period required for active freezing is also different. The above process is generally determined by theoretical derivation or empirical formula, and the development of the freezing front and whether the frozen curtain has been closed often have inaccurate determination.

[0047] In summary, how to test the accurate frozen curtain expansion parameters is an important issue that needs to be addressed in the industry.

[0048] The test system and method for the freezing characteristics of artificial frozen soil provided in this manual are intended to simulate the artificial freezing construction process in an indoor environment, and then to carry out indoor model tests of artificial freezing to address the situation where the development of the freezing front and whether the freezing curtain is intersecting during the artificial freezing construction process are often inaccurate. The system also obtains the accurate freezing characteristics of the strata at the corresponding engineering site and the expansion parameters of the freezing curtain, thereby accurately estimating the actual freezing construction period, freezing process and reinforcement effect, and reducing the risk of freezing construction.

[0049] See also Figures 1 to 5 , Figure 1 FIG. 1 is a schematic diagram showing the structure of a system for testing freezing characteristics of artificial frozen soil according to an embodiment of the present invention. Figure 2 FIG2 shows a top view of a test module in a test system for the freezing characteristics of artificial frozen soil according to an embodiment of the present invention. Figure 3 FIG. 1 is a front view of a test module in a test system for the freezing characteristics of artificial frozen soil according to an embodiment of the present invention. Figure 4 A schematic cross-sectional view of a pre-buried sleeve in a test system for freezing characteristics of artificial frozen soil according to an embodiment of the present invention is shown. Figure 5 The diagram shows an elevation view of a pre-buried sleeve in a system for testing freezing characteristics of artificial frozen soil according to an embodiment of the present invention.

[0050] The system includes:

[0051] A refrigeration module 30, a heat dissipation module 40, a test module and a simulation test box 10, wherein the simulation test box 10 is filled with a test soil layer, and several pairs of embedded sleeves 20 are provided in the simulation test box 10, all of the embedded sleeves 20 are in contact with the test soil layer, each embedded sleeve 20 is provided with a refrigeration module 30, the heat dissipation module 40 passes through the interior of the refrigeration module 30, and a test module is provided next to each pair of embedded sleeves.

[0052] Specifically, the distance between each pair of embedded sleeves 20 is not less than a preset distance, and the test module includes at least one of a temperature test unit 50, an electrical method test unit 60, and a sound wave test unit 70. The temperature test unit 50 is used to test the change of the temperature field of the test soil layer, the electrical method test unit 60 is used to take each pair of embedded sleeves 20 in contact with the test soil layer as a corresponding pair of electrodes, and a vertically arranged potential probe 61 is arranged on the center line of the embedded sleeve 20 according to the symmetric four-pole profile electrical method detection method. After being connected with an external power supply, the change of the electric field and the resistivity of the test soil layer is tested by a resistivity tester 62. The sound wave test method 70 is used to take the same depth in each pair of embedded sleeves 20 in contact with the test soil layer as a test operation surface, and a sound wave transmitter 71 and a sound wave receiver 72 are respectively placed at the test operation surface of a pair of embedded sleeves 20, for example, the sound wave transmitter 71 is placed at the test operation surface of one of the embedded sleeves 20, and the sound wave receiver 72 is placed at the test operation surface of the other embedded sleeve 20. The sound wave transmitter 71 and the sound wave receiver 72 are synchronously lifted from the bottom of the hole to the top of the hole, so as to realize the full-profile frozen soil sound wave velocity test.

[0053] It should be noted that if the sound wave test method needs to be tested, the freezing needs to be temporarily interrupted and the refrigeration module 30 in the embedded sleeve 20 needs to be removed during the test. After the test is completed, the refrigeration module 30 is placed in the embedded sleeve 20 and the freezing is continued.

[0054] In the embodiment of the present application, one or more of the temperature test method (temperature measurement method), electrical method test method and sound wave test method are combined in the test module to comprehensively determine the freezing front expansion rate and freezing effect. The user can arbitrarily select one or more test units for combined testing according to the test accuracy requirement, and the three test units are independent of each other and closely related to each other. For example, the embedded sleeve 20 can be used as an electrode for the electrical method test method, and can also be used as a sound pipe (i.e. a sound wave transmitting hole and a sound wave receiving hole) for the sound wave test method.

[0055] Through the simulation test box 10, the user can simulate the artificial freezing construction process in the indoor environment, and then use the refrigeration module 30, the heat dissipation module 40 and the test module to carry out indoor model test of artificial freezing, and obtain accurate freezing characteristics and freezing curtain expansion parameters of the corresponding engineering site stratum, so as to accurately estimate the actual freezing construction period, freezing process and reinforcement effect, and reduce the freezing construction risk.

[0056] In the embodiment of the present application, the clearance size of the simulation test box 10 when it is not filled with test soil layer, pre-buried sleeve, refrigeration module, heat dissipation module, test module and other components is: the length, width and height are not less than 100 cm, 50 cm and 50 cm respectively.

[0057] Considering the frost heaving effect of the test soil layer as artificial frozen soil, the simulation test box 10 is made of a material with sufficient rigidity to prevent large deformation or cracking of the box during freezing, for example, an isosceles angle steel frame with a size of 30*3 mm and a thickness of 10 mm organic glass panel are used to make the simulation test box 10. In order to ensure that the heat preservation requirement is met, the inside of the simulation test box 10 is fully paved with heat preservation foam board with a thickness of not less than 3 cm, and the joints are completely sealed and water-tight.

[0058] It should be noted that the related size of the isosceles angle steel frame and the thickness is determined according to the size of the simulation test box 10.

[0059] In the embodiment of the present application, each pair of pre-buried sleeves 20 is arranged along the length direction of the simulation test box 10, and symmetrically arranged on both sides of the longitudinal section passing through the center point of the simulation test box 10. The distance between each pair of pre-buried sleeves 20 is not less than a preset distance, for example, 50 cm.

[0060] The pre-buried sleeve 20 is arranged as a sleeve with a regular hexagonal cross section. In order to ensure the structural strength of the pre-buried sleeve 20 and facilitate subsequent testing, the pre-buried sleeve 20 is made of aluminum alloy material, the wall thickness of each face of the pre-buried sleeve 20 is 3 mm, the maximum inner clearance width of the sleeve is 108 mm, and the single side net width is 54 mm.

[0061] In the embodiment of the present application, the refrigeration module 30 includes a refrigeration device 31, a refrigeration fin 32, a heat dissipation fin 33 and a direct current power supply 34. The refrigeration device 31 is sleeved in the pre-buried sleeve, the cross section of the refrigeration device 31 is also arranged as a regular hexagon, the refrigeration device 31 is arranged as a tubular shape, the maximum inner clearance width of the refrigeration device 31 is 100 mm, the single side net width is 50 mm, and a gap is provided between the outer wall of the refrigeration device 31 and the inner wall of the pre-buried sleeve 20, for example, the pre-buried sleeve is designed to have a gap of not more than 2 mm with the outer wall of the internal freezing device, and the gap is coated with anti-freezing lubricating oil. The gap is arranged to facilitate the installation or removal of the refrigeration device 31.

[0062] More specifically, the inner wall of each side of the refrigerator 31 is provided with the above-mentioned refrigeration fin 32, the refrigeration fin 32 includes the heat absorption surface 321 and the heat release surface 322, the heat absorption surface 321 of the refrigeration fin 32 is connected with the inner wall of the refrigerator 31, the heat release surface 322 of the refrigeration fin 32 is connected with the above-mentioned heat dissipation fin 33, the refrigeration fin 32 arranged on the six inner walls of each refrigerator 31 constitutes a refrigeration fin group of the refrigerator 31, each refrigeration fin 32 is electrically connected with the above-mentioned direct current power supply 34, the direct current power supply 34 is responsible for providing adjustable voltage for the refrigeration fin 32, the top and bottom ends of the pipe of the refrigerator 31 are connected with the heat dissipation module 40, and the water temperature and flow are monitored and adjusted through the heat dissipation module 40 to effectively dissipate heat for the refrigeration fin group.

[0063] The specification of a single refrigeration fin 32 does not exceed 40*40mm, the refrigeration fin 32 adopts semiconductor refrigeration technology (thermoelectric refrigeration technology), so that the refrigeration module 30 adopts a new refrigeration method by direct current refrigeration, the core principle of which is to use a P-N junction composed of special semiconductor materials, that is, the two surfaces of the refrigeration fin 32 form a thermocouple pair to produce a Peltier effect, so that one side of the refrigeration fin 32, that is, the absorption surface 321, is cooled (the lowest can reach-30℃), and the other side, that is, the heat release surface 322, generates heat. The specification of a single heat dissipation fin 33 does not exceed 45*2mm, the heat dissipation fin 33 is provided with a first temperature sensor installation position and is provided with a first temperature sensor, the temperature of the heat dissipation fin 33 is monitored in real time through the first temperature sensor, when the temperature of the heat dissipation fin 33 is too high, the voltage of the refrigeration fin 32 can be lowered through the direct current power supply 34, or temporary freezing measures can be taken.

[0064] Preferably, the refrigeration fin 32 adopts a refrigeration fin material of TEC1-12706 semiconductor refrigeration technology, and the refrigeration fin 32 is laid on the inner wall of the refrigerator 31 by using heat-conducting silicone.

[0065] In the embodiment of the present application, the heat dissipation module 40 includes a circulating water tank 41, a first circulating water pump 42, a second circulating water pump 43, a first circulating pipeline 44, a second circulating pipeline 45 and a circulating water controller 46. The first circulating pipeline 44 and the second circulating pipeline 45 are in communication with the circulating water tank 41, the first circulating pipeline 44 and the second circulating pipeline 45 pass through two refrigerators 31 respectively, that is, the first circulating pipeline 44 passes through one of the refrigerators 31 of the pair of embedded sleeves 20, the second circulating pipeline 45 passes through the other refrigerator 31 of the pair of embedded sleeves 20, the first circulating pipeline 44 is provided with the first circulating water pump 42, the second circulating pipeline 45 is provided with the second circulating water pump 43, the first circulating water pump 42 and the second circulating water pump 43 are electrically connected with the circulating water controller 46, and the user adjusts various working parameters of the two circulating water pumps through the circulating water controller 46.

[0066] It can be understood that the pipeline through the refrigeration device 31 refers to the pipeline from the top of the refrigeration device 33 to the bottom of the refrigeration device 33, and specifically, the pipeline passes through the internal area formed by the heat dissipation fins 33.

[0067] The heat dissipation module 40 adopts a water circulation refrigeration technology, that is, the circulating cooling water continuously contacts the heat dissipation surface 322 of the refrigeration fin 32 to realize effective heat dissipation of the refrigeration device by controlling the water temperature, flow and other parameters of the circulating water.

[0068] Preferably, the circulating water temperature should not exceed 30℃.

[0069] In the embodiment of the present application, the temperature test unit 50 includes a second temperature sensor 51 arranged at the test soil layer around the embedded sleeve 20, and the normal working range of the second temperature sensor 51 is -50-200℃, wherein a temperature test ring with a first preset number (for example, 2) of temperature test points is arranged in the freezing radius direction of the refrigeration device 31, each temperature test ring is provided with a second preset number (for example, 8) of temperature monitoring points, and each temperature monitoring point is provided with a third preset number (for example, 2) of second temperature sensors 51.

[0070] Preferably, each temperature test point can be arranged in the middle of the test soil layer, and in addition, a second temperature sensor 51 test point can be added at the outer wall of each refrigeration device 31.

[0071] Of course, the temperature test unit 50 can also be provided with a plurality of temperature measuring rods, and a plurality of second temperature sensors 51 are arranged on the temperature measuring rods, and the temperature test unit 50 tests the temperature by using the temperature measuring rods.

[0072] In the embodiment of the present application, the electrical method test unit 60 includes a potential probe 61 and a resistivity tester 62, two potential probes 61 are symmetrically arranged on both sides of the center point of the simulation test box 10, the potential probe 61 is arranged on the longitudinal section passing through the center point of the simulation test box 10, and the potential probe 61 is electrically connected with the resistivity tester 62 arranged outside the simulation test box 10. The electrical method test unit 60 takes a pair of embedded sleeves 20 as the positive and negative electrodes of the electrode, and therefore the electrode connection terminals can be reserved on the embedded sleeves 20, and the test working range of the resistivity tester 62 is 10-10 4 Ω·m, and the direct current power supply 34 of the refrigeration module 30 needs to be temporarily cut off during the test to reduce current interference.

[0073] Preferably, the longitudinal section passing through the center point of the pair of embedded sleeves 20 is divided into three equal parts, and the potential probe 61 is arranged at the remaining two positions beside the center position.

[0074] In the embodiment of the present application, the sound wave test unit 70 comprises a sound wave transmitter 71 and a sound wave receiver 72, wherein the sound wave transmitter 71 and the sound wave receiver 72 are respectively arranged inside the two embedded sleeves 20, that is, the sound wave transmitter 71 is arranged inside one of the embedded sleeves 20 of the pair of embedded sleeves 20, so that the embedded sleeve 20 provided with the sound wave transmitter 71 serves as a sound wave transmitting hole, and the sound wave receiver 72 is arranged inside the other embedded sleeve 20 of the pair of embedded sleeves 20, so that the embedded sleeve 20 provided with the sound wave receiver 72 serves as a sound wave receiving hole, and the working heights of the sound wave transmitter 71 and the sound wave receiver 72 are always equal. In the sound wave test, the refrigeration module 30 needs to be temporarily interrupted and removed, the inner wall of the embedded sleeve 20 is cleaned, and then the freeze-proof liquid is filled as a coupling medium, and the sound wave transmitter 71 and the sound wave receiver 72 are put into the hole of the embedded sleeve 20 to carry out the test.

[0075] It can be understood that the sound wave transmitter 71 and the sound wave receiver 72 are electrically connected with the ultrasonic tester arranged outside the simulation test box 10.

[0076] In the embodiment of the present application, the refrigeration module 30, the heat dissipation module 40 and the test module are connected to the monitoring platform of the computer intelligent monitoring platform, wherein the test data is uploaded to the monitoring platform at a specific frequency, and the intelligent control of the freezer power is realized through the temperature monitoring result.

[0077] The test system for the freezing characteristics of artificial frozen soil provided by the present application can simulate the artificial freezing construction process in the indoor environment through the simulation test box 10, and can carry out indoor model test of artificial freezing through the refrigeration module 30, the heat dissipation module 40 and the test module, and can obtain accurate freezing characteristics and freezing curtain expansion parameters of the corresponding engineering site stratum, so as to accurately estimate the actual freezing construction period, freezing process and reinforcement effect, and reduce the freezing construction risk. At the same time, one or more of the three freezing test methods of temperature test method, electrical method test method and sound wave test method are combined in the test module to comprehensively determine the freezing front expansion rate and freezing effect. The user can arbitrarily select one or more test units for combined test according to the test precision requirement, and the three test units are independent of each other and closely related. The embedded sleeve 20 can be used as an electrode for the electrical method test method and as a sound measuring pipe for the sound wave test method.

[0078] Please refer to Figure 6 , Figure 6 The flowchart of the test method for the freezing characteristics of artificial frozen soil according to the embodiment of the present application is shown, and the method is realized based on the above-mentioned test system. The method specifically comprises the following steps.

[0079] S10, install the pre-buried sleeve 20 in pairs in the simulation test box 10, and put the test soil layer into the simulation test box 10. The above is the basic preparation work of the indoor simulation experiment.

[0080] S20, install the test module for the pre-buried sleeve 20. The installation of the test module includes pre-buried electronic components such as the potential probe 61, the first temperature sensor, the second temperature sensor 51, and the like in the test soil layer, and connects the line of the external test equipment (such as the resistivity tester 62, the ultrasonic tester, etc.) and prepares for the connection with the host computer.

[0081] S30, install the refrigeration module 30 and the heat dissipation module 40 for the pre-buried sleeve 20, and smear the antifreeze lubricating liquid with good heat conductivity in the gap between the pre-buried sleeve 20 and the refrigeration module 30 to ensure the close contact between the layers and connect the refrigeration module 30 and the heat dissipation module 40.

[0082] S40, start the refrigeration module 30 and the heat dissipation module 40, and set the first working parameter of the refrigeration module 30 and the second working parameter of the heat dissipation module 40 according to the preset test period (such as 1 day-1 week).

[0083] S50, start the test module to obtain test data. The user can arbitrarily select one or more test units for joint testing according to the test accuracy requirement. When the temperature of the heat release surface 321 in the refrigeration device 31 is too high, such as exceeding 60℃, the automatic alarm is started, and the power of the refrigeration device 31 is reduced to ensure the normal operation of the refrigeration module 30. It can be understood that the test module works in the working condition that the refrigeration module 30 operates in the first working parameter and the heat dissipation module 40 operates in the second working parameter.

[0084] It should be noted that, unlike other test modules, the acoustic wave test method needs to set the appropriate acoustic test frequency according to the preset test period, temporarily interrupt the freezing process when using the super deep test, and temporarily extract the refrigeration module 30 (and the corresponding pipeline of the heat dissipation module 40 according to the installation condition) in the pre-buried sleeve 20. After pouring the antifreeze into the pre-buried sleeve 20, the acoustic wave transmitter 71 and the acoustic wave receiver 72 are put in, the test is started, and the wave speed data is uploaded to the monitoring platform. After the data collection is completed, the freezing can be restored.

[0085] S60, during the test process, it is determined whether the three first test indexes of the frozen soil sample temperature, the resistivity, and the acoustic wave speed in the test data reach the first preset critical value interval. When it is determined that the first test index reaches the first preset critical value interval, the expansion range of the freezing front is determined by using multiple test methods.

[0086] S70, in the test process, whether the three second test indexes of temperature, resistivity and acoustic wave velocity in the test data reach a certain specific first preset critical value interval set in advance to end the test, in the case of determining that the second test index reaches the second preset critical value interval, such as the outermost soil temperature measuring point reaches-10 DEG C and below, the measured resistivity of frozen soil reaches 400-500 omega*m and the acoustic wave velocity is in the range of 3000-3500 m / s, it is determined that the freezing wall of a pair of pre-buried sleeves 20 has been fully closed, the curtain thickness meets the requirements, the data collection can be terminated, and the subsequent data processing can be started.

[0087] The artificial frozen soil freezing characteristic test method provided by the application can simulate the artificial freezing construction process in an indoor environment through the simulation test box 10, and can accurately estimate the actual freezing construction period, freezing process and reinforcement effect, reduce the freezing construction risk, and accurately determine the freezing front expansion rate and freezing effect by using one or more of the temperature test method, electrical method test method and acoustic wave test method in the test module. The user can arbitrarily select one or more test units for combined testing according to the test precision requirements, and the three test units are independent and closely related. The pre-buried sleeve 20 can be used as an electrode for the electrical method test method and as a sound probe tube for the acoustic wave test method.

[0088] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A system for testing the freezing characteristics of artificial frozen soil, characterized by: The system comprises: Refrigeration module, heat dissipation module, test module and simulation test chamber; The simulation test box is filled with a test soil layer, and is provided with a plurality of pairs of embedded sleeves, all of which are in contact with the test soil layer. The refrigeration module is provided in each of the embedded sleeves, and the heat dissipation module passes through the interior of the refrigeration module. The test module is provided beside each pair of embedded sleeves. The spacing between each pair of embedded sleeves is not less than a preset distance; the test module includes at least one of a temperature testing unit, an electrical testing unit and an acoustic wave testing unit; the temperature testing unit is used to test changes in the temperature field of the test soil layer; the electrical testing unit is used to use each pair of embedded sleeves in contact with the test soil layer as a corresponding pair of electrodes, and arrange vertically set potential probes on the center line of the embedded sleeves according to the symmetrical quadrupole profile electrical detection method to test changes in the electric field and resistivity of the test soil layer; the acoustic wave testing method is used to use the same depth in each pair of embedded sleeves in contact with the test soil layer as a test working surface, and perform a frozen soil acoustic wave velocity test.

2. The system for testing freezing characteristics of artificial frozen soil according to claim 1, wherein: Each pair of embedded sleeves is arranged along the length direction of the simulation test box and is symmetrically arranged on both sides of the longitudinal section passing through the center point of the simulation test box. The cross section of the embedded sleeve is set to be a regular hexagon.

3. The system for testing the freezing characteristics of artificial frozen soil according to claim 2, wherein: The refrigeration module includes a refrigerator, a refrigeration fin, a heat sink and a DC power supply; The refrigerator is installed inside the embedded sleeve. The cross-section of the refrigerator is a regular hexagon. Refrigeration fins are provided on the inner wall of each side of the refrigerator. The refrigeration fins include a heat-absorbing surface and a heat-releasing surface. The absorbing surface and the heat-releasing surface form a thermocouple pair. The heat-absorbing surface is connected to the inner wall of the refrigerator, and the heat-releasing surface is connected to the heat sink. Each refrigeration fin is electrically connected to a DC power supply, and the heat dissipation module passes through the interior of the refrigerator.

4. The system for testing the freezing characteristics of artificial frozen soil according to claim 3, wherein: A gap is provided between the outer wall of the refrigerator and the inner wall of the embedded sleeve, and antifreeze lubricating oil is provided in the gap.

5. The system for testing freezing characteristics of artificial frozen soil according to claim 3, wherein: The heat dissipation module includes a circulating water tank, a first circulating water pump, a second circulating water pump, a first circulating pipeline, a second circulating pipeline and a circulating water controller; The first circulation pipeline and the second circulation pipeline are both connected to the circulating water tank arranged outside the simulation test box. The first circulation pipeline and the second circulation pipeline pass through two refrigerators respectively. A first circulation water pump is provided on the first circulation pipeline, and a second circulation water pump is provided on the second circulation pipeline. The first circulation water pump and the second circulation water pump are both electrically connected to the circulating water controller.

6. The system for testing freezing characteristics of artificial frozen soil according to claim 3, wherein: The temperature testing unit includes a second temperature sensor arranged in the test soil layer around the embedded sleeve, and a temperature testing circle with a number not less than a first preset number is provided in the freezing radius direction of the refrigerator, each temperature testing circle is provided with a number not less than a second preset number of temperature monitoring points, and each temperature monitoring point is provided with a number not less than a third preset number of the second temperature sensors.

7. The system for testing freezing characteristics of artificial frozen soil according to claim 6, characterized in that: The temperature testing unit further includes a plurality of temperature measuring rods, and the second temperature sensor is arranged on the temperature measuring rods.

8. The system for testing freezing characteristics of artificial frozen soil according to claim 1, wherein: The electrical testing unit includes a potential probe and a resistivity tester; Two potential probes are symmetrically arranged on both sides of the center point of the simulation test box. The potential probes are arranged on the longitudinal section passing through the center point of the simulation test box. The potential probes are electrically connected to the resistivity tester arranged outside the simulation test box.

9. The system for testing freezing characteristics of artificial frozen soil according to claim 1, wherein: The acoustic wave testing unit includes an acoustic wave transmitter and an acoustic wave receiver; The sound wave transmitter and the sound wave receiver are respectively arranged inside the two embedded sleeves, and the working heights of the sound wave transmitter and the sound wave receiver are always equal.

10. A testing method implemented based on the testing system for freezing characteristics of artificial frozen soil according to claim 1, characterized in that: The method comprises: Install the embedded sleeves in pairs into the simulation test box, and place the test soil layer into the simulation test box; Install test modules for embedded sleeves; Install the cooling module and the heat dissipation module on the embedded sleeve, and apply antifreeze lubricant in the gap between the embedded sleeve and the cooling module; Turning on the refrigeration module and the heat dissipation module, and setting a first operating parameter of the refrigeration module and a second operating parameter of the heat dissipation module according to a preset test cycle; Open the test module and obtain test data; When it is determined that a first test indicator in the test data reaches a first preset critical value range, determining the extension range of the freezing front; the first test indicator includes the temperature, resistivity and acoustic wave velocity of the frozen soil sample; When it is determined that the second test indicator in the test data reaches a second preset critical value range, it is determined that the freezing walls of a pair of embedded sleeves have been fully intertwined and the curtain thickness meets the requirements; the second test indicator includes temperature, resistivity, and sound wave velocity.

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