In-situ continuous monitoring method and system for ice lens thickness in artificial freezing construction

Abstract

The application discloses a kind of artificial freezing construction ice lens thickness in-situ continuous monitoring method and system, belong to artificial freezing construction technical field, in the freezing construction area, determine the freezing range, then set multiple to be detected routes in freezing range, measure temperature on each to be detected route, record temperature change data with time, the movement rate of 0 ℃ freezing front along to be detected line can be calculated from to be detected route, the ice lens predicted thickness of each position on to be detected route is calculated by substituting the movement rate of freezing front into empirical model formula;Through the continuous, in-situ monitoring of temperature on to be detected route, the thickness of ice lens in freezing construction area can be predicted in real time, and then provide reference for the adjustment of freezing temperature, freezing mode and the like in artificial freezing construction process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial freezing construction, and in particular to a method and system for in-situ continuous monitoring of ice lens thickness in artificial freezing construction. BACKGROUND

[0002] In the actual process of tunnel artificial freezing construction, by accurately controlling the freezing rate of the frozen side, various freezing modes can be formed, which have a significant influence on the formation process of open frost-heave ice lens, and can effectively reduce the occurrence of frost heave and thaw settlement. Therefore, real-time monitoring of the evolution process of ice lens in engineering has a crucial role in controlling frost heave and thaw settlement caused by artificial freezing and improving tunnel artificial freezing construction technology.

[0003] However, in the traditional artificial freezing research, the observation of ice lens mainly relies on microscopic observation methods such as scanning electron microscope, computer tomography and nuclear magnetic resonance. Although these methods play an important role in providing high-precision observation results and revealing the formation mechanism of ice lens, they have significant limitations in monitoring the distribution and evolution process of ice lens in actual engineering applications. Frost heave and thaw settlement are the gradual accumulation process of ice lens structure evolution, and in-situ continuous observation of the whole process of ice lens in artificial freezing construction is crucial for tunnel deformation control. However, the above-mentioned traditional observation methods are all observed after sampling in the laboratory, which has a lag and cannot provide real-time in-situ monitoring, making it difficult to guide the construction process of artificial freezing. SUMMARY

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application provides a method for in-situ continuous monitoring of ice lens thickness in artificial freezing construction, which can realize in-situ and real-time monitoring in the freezing construction area, predict the thickness of the ice lens, and guide the progress of artificial freezing construction.

[0005] The method for in-situ continuous monitoring of ice lens thickness in artificial freezing construction according to the first aspect of the present application comprises:

[0006] determining the freezing range of the freezing construction area;

[0007] setting a plurality of to-be-detected routes in the freezing range, and obtaining temperature change data over time on each to-be-detected route;

[0008] calculating the 0℃ freezing front measured moving rate of the to-be-detected route according to the temperature change data over time;

[0009] calculating the predicted thickness of the ice lens at any position on the to-be-detected route according to the 0℃ freezing front measured moving rate and an empirical model formula.

[0010] The artificial freezing construction ice lens thickness in-situ continuous monitoring method according to the embodiment of the present application has at least the following beneficial effects: the freezing range is determined in the freezing construction area, then a plurality of to-be-detected routes are set in the freezing range, the temperature is measured on each to-be-detected route, and the temperature change data with time are recorded, the moving rate of the 0℃ freezing front can be calculated from the to-be-detected routes, that is, the measured moving rate of the 0℃ freezing front at any position on the to-be-detected route is calculated, and finally the ice lens predicted thickness at the corresponding position is calculated according to the measured moving rate of the 0℃ freezing front at the position and the empirical model formula; the in-situ and real-time monitoring can be realized in the freezing construction area, the thickness of the ice lens can be predicted, and then the progress of the artificial freezing construction is guided.

[0011] According to some embodiments of the present application, the empirical model formula is as follows:

[0012] W1=W0+b÷V1 a ;

[0013] wherein W1 is the ice lens predicted thickness, W0 is the initial crack thickness of the in-situ soil body, a is a first parameter, b is a second parameter, and V1 is the measured moving rate of the 0℃ freezing front;

[0014] The first parameter a and the second parameter b are obtained by performing an open freezing laboratory experiment on the soil sample in the freezing range.

[0015] According to some embodiments of the present application, the open freezing laboratory experiment on the soil sample in the freezing range to obtain the first parameter a and the second parameter b comprises:

[0016] The unfrozen soil sample in the freezing range is obtained by using a thin-walled soil sampler;

[0017] A plurality of laboratory experiment monitoring points are arranged on the soil sample, and the plurality of laboratory experiment monitoring points are distributed at equal intervals along the side of the cylindrical soil sample, and the distance between every two adjacent laboratory experiment monitoring points is a preset distance;

[0018] The sample is subjected to open freezing, and the sample is vertically placed during freezing, the top plane of the cylindrical sample is the freezing surface, and the bottom plane is the water replenishment surface; during the freezing process, the 0℃ freezing front moves from the top plane to the bottom plane;

[0019] The experimental temperatures of all the laboratory experiment monitoring points are obtained during the freezing experiment, and the time when the temperature of each monitoring point is 0℃ is recorded;

[0020] According to the distance L between the two adjacent laboratory experiment monitoring points and the time difference t when the temperatures of the two adjacent laboratory experiment monitoring points reach 0℃, the average speed V of the 0℃ freezing front between the two adjacent monitoring points is calculated according to the formula V=L / t.

[0021] obtaining the laboratory experiment 0℃ freezing front moving rate of each position along the vertical direction of the sample;

[0022] obtaining the laboratory experiment ice lens thickness of each position along the vertical direction of the sample according to the image of the sample;

[0023] substituting the laboratory experiment 0℃ freezing front moving rate of each position and the laboratory experiment ice lens thickness into the empirical model formula, and obtaining the first parameter a and the second parameter b by regression analysis.

[0024] According to some embodiments of the present application, the monitoring method further comprises:

[0025] drawing a scatter plot according to the laboratory experiment 0℃ freezing front moving rate and the laboratory experiment ice lens thickness, and obtaining a relationship curve of the laboratory experiment 0℃ freezing front moving rate and the laboratory experiment ice lens thickness according to the scatter plot;

[0026] obtaining the initial crack thickness of the soil sample, and constructing an empirical model formula according to the relationship curve and the initial crack thickness.

[0027] According to some embodiments of the present application, the obtaining the first parameter a and the second parameter b by transferring the soil sample in the freezing range to an open freezing laboratory for laboratory experiment further comprises:

[0028] preparing a laboratory ice lens in-situ observation device, the observation device comprising a sample chamber and a monitoring computer, the sample chamber being made of high-density polystyrene, a first semiconductor refrigerating sheet being installed at the upper end of the sample chamber, and the first semiconductor refrigerating sheet being used to regulate the temperature gradient and the upper end cooling rate of the sample chamber according to experimental requirements;

[0029] m temperature sensors are uniformly distributed on the inner wall of the sample chamber, the distance between every two adjacent temperature sensors being k, the temperature sensors being electrically connected to the monitoring computer, and the monitoring computer being used to monitor the temperature change of the soil sample in the sample chamber in real time.

[0030] According to some embodiments of the present application, the obtaining the image of the soil sample comprises:

[0031] The observation device further comprises an electron microscope, a photographing chamber, a rotating lifting platform and a dehumidifier, a side wall of the photographing chamber is provided with a transparent material, a second semiconductor refrigerating fin is arranged at an upper end of the photographing chamber, the second semiconductor refrigerating fin is used for regulating the temperature and the cooling rate at the upper and lower ends of the photographing chamber according to the experimental requirements, so that the temperature environment of the photographing chamber is the same as that of the sample, the lower end of the photographing chamber is communicated with the dehumidifier, the lower end of the photographing chamber is connected with the rotating lifting platform, the rotating angle and the height of the photographing chamber are adjusted by the rotating lifting platform to change the photographing surface of the soil sample, and the lens of the electron microscope is directed to the photographing chamber.

[0032] The rotating lifting platform adjusts the height of the photographing chamber to zero, the inner and outer walls of the photographing chamber are uniformly sprayed with an anti-fog agent, the dehumidifier is started, the second semiconductor refrigerating fin is turned on when the humidity of the photographing chamber is lower than 30%, and the dehumidifier is turned off when the temperature of the photographing chamber is equal to that of the sample room.

[0033] According to some embodiments of the present application, the obtaining of the temperature change data with time of each of the to-be-detected routes is realized by a chain temperature sensor, the chain temperature sensor comprises a plurality of polyethylene rods and a plurality of temperature sensitive elements, the plurality of temperature sensitive elements are respectively installed on the plurality of polyethylene rods, the distance between every two adjacent temperature sensitive elements is A, the length of the chain temperature sensor is h, and the number n of the temperature sensitive elements satisfies A*n=h.

[0034] According to some embodiments of the present application, the setting of a plurality of to-be-detected routes in the freezing range comprises:

[0035] The plurality of to-be-detected routes are distributed in the freezing construction area in a circumferential array with the freezing center as the center;

[0036] Each of the to-be-detected routes does not exceed the freezing range;

[0037] The chain temperature sensor is placed on the to-be-detected route.

[0038] According to some embodiments of the present application, the placing of the chain temperature sensor on the to-be-detected route comprises:

[0039] A mounting hole is drilled on each of the to-be-detected routes, the mounting hole does not exceed the freezing range, and the diameter of the mounting hole is not less than the outer diameter of the chain sensor;

[0040] The mounting hole is cleaned, the chain temperature sensor is placed in the mounting hole, and the temperature sensitive element is tightly attached to the hole wall of the mounting hole.

[0041] checking the working state of the chain temperature sensor and calibrating the temperature of the chain temperature sensor.

[0042] The artificial frozen construction ice lens thickness in-situ continuous monitoring system according to the second aspect of the present application comprises a memory and a processor, the memory stores a computer program, and the processor implements the artificial frozen construction ice lens thickness in-situ continuous monitoring method according to the above-mentioned embodiments when executing the computer program.

[0043] The artificial frozen construction ice lens thickness in-situ continuous monitoring system according to the second aspect of the present application has at least the following beneficial effects: the freezing center in the frozen construction area is determined, the freezing range is calculated based on the freezing center, a plurality of to-be-detected routes are set in the freezing range, the temperature is measured on each to-be-detected route, the temperature change data with time are recorded, the moving speed of the 0℃ freezing front can be calculated from the to-be-detected route, that is, the measured moving speed of the 0℃ freezing front at any position on the to-be-detected route is calculated, and finally the predicted ice lens thickness at the corresponding position is calculated according to the measured moving speed of the 0℃ freezing front at the position and the empirical model formula; the in-situ and real-time monitoring can be realized in the frozen construction area, the thickness of the ice lens can be predicted, and the progress of the artificial frozen construction is guided. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a flowchart of the artificial frozen construction ice lens thickness in-situ continuous monitoring method according to an embodiment of the present application;

[0045] Figure 2 is a structural schematic diagram of the chain temperature sensor according to an embodiment of the present application;

[0046] Figure 3 is a distribution schematic diagram of the chain temperature sensor in the freezing range according to an embodiment of the present application;

[0047] Figure 4 is a structural schematic diagram of the observation device according to an embodiment of the present application;

[0048] Figure 5 is a structural schematic diagram of the photographing room according to an embodiment of the present application.

[0049] BRIEF DESCRIPTION OF DRAWINGS: frozen construction area 10, observation device 20, chain temperature sensor 100, temperature sensitive element 110, photographing room 300, second semiconductor refrigeration sheet 310, monitoring computer 400, refrigeration device 500, electron microscope 600, rotating lifting platform 700, dehumidifier 800. DETAILED DESCRIPTION

[0050] Embodiments of the present application will be described below in detail with examples thereof shown in the accompanying drawings, wherein the same or similar components or components having the same or similar functions are designated by the same or similar reference numerals throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are for the purpose of explanation only, and are not to be understood as limiting the present application.

[0051] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms front, back, up, down, axial, circumferential, etc. is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and does not indicate or imply that the device or component referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0052] In the description of the present application, the meaning of multiple is more than two, greater than, less than, more than, etc. is not included in the number, and above, below, etc. is included in the number. If it is described as first, second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of technical features indicated.

[0053] In the description of the present application, it should be noted that the words such as setting, mounting, connecting, etc. should be understood broadly, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0054] The technical solutions of the present application will be described below in detail with reference to the accompanying drawings. Obviously, the following described embodiments are part of the embodiments of the present application, not all embodiments.

[0055] Specifically, in the actual tunnel artificial freezing construction process, by accurately controlling the freezing rate of the freezing side, various freezing modes can be formed, which have a significant influence on the formation process of open ice lens, and can effectively reduce the occurrence of frost heaving and thawing settlement. Therefore, real-time monitoring of the ice lens evolution process in the project plays a crucial role in controlling frost heaving and thawing settlement caused by artificial freezing and improving tunnel artificial freezing construction technology.

[0056] However, in traditional artificial freezing research, the observation of ice lens mainly relies on microscopic observation methods such as scanning electron microscopy (SEM), computer tomography (CT) and nuclear magnetic resonance (NMR). Although these methods play an important role in providing high-precision observation results and revealing the formation mechanism of ice lens, there are significant limitations in monitoring the distribution and evolution process of ice lens in actual engineering applications. Specifically, the traditional ice lens observation methods are based on laboratory soil samples, and require the entire test process to maintain a constant and undulating low temperature environment. However, when these methods are applied to the monitoring of ice lens in actual tunnel surrounding rock, core sampling is required, and the test observation is carried out after sampling. In this process, since ice lens is extremely sensitive to temperature, the temperature fluctuation in the sampling and transportation link has a great influence on the test observation results, thereby seriously affecting the accuracy of the monitoring results. In addition, frost heaving and thawing settlement are the accumulation process of ice lens structure evolution. Therefore, continuous observation of ice lens throughout the process is crucial for tunnel deformation control in artificial freezing construction. However, the above traditional observation methods are intermittent observations of laboratory tests after field sampling, and cannot achieve continuous observation.

[0057] The present application provides a kind of artificial freezing construction ice lens thickness in-situ continuous monitoring method, mainly based on the empirical model formula of experimental ice lens thickness in laboratory and the actual moving speed of actual freezing front in the freezing process of actual engineering soil body, and the monitoring method includes the following steps.

[0058] First, laboratory experiments are carried out to obtain the undetermined parameters of the prediction model.

[0059] The laboratory special ice lens in-situ observation device 20 is prepared, which comprises a sample chamber 200, a refrigeration device 500, a monitoring computer 400, an electron microscope 600 and a photographing chamber 300. The sample chamber 200 is made of high-density polystyrene, and a first semiconductor refrigerating sheet 210 is installed at the upper and lower ends of the sample chamber 200, respectively. The first semiconductor refrigerating sheet 210 is connected with the external refrigeration device 500 through a wire, so that the temperature and the cooling rate of the upper and lower ends of the sample chamber 200 can be accurately controlled according to the experimental requirements. The inner wall of the sample chamber 200 is uniformly distributed with m temperature sensors, the positions of the temperature sensors correspond to the positions of the experimental monitoring points, the distance between two adjacent sensors is k meters, that is, the preset distance is k meters, and the temperature sensors are connected with the monitoring computer 400 through a data line, so that the soil temperature change in the sample chamber 200 can be monitored in real time and accurately on the computer. The refrigeration device 500 provides a stable cold source for the sample chamber 200, and the working state of the first semiconductor refrigerating sheet 210 can be accurately controlled, so that the temperature of the sample chamber 200 can be quickly and accurately adjusted. The monitoring computer 400 is a data monitoring and processing center, which is connected with the temperature sensors and the electron microscope 600, receives real-time data of the two, and provides a direct monitoring interface for the experimental personnel. The photographing chamber 300 is a cuboid, the front and side surfaces of the shell are made of transparent acrylic material, and the back surface is made of white acrylic material. The upper and lower surfaces are square, the second semiconductor refrigerating sheet 310 is arranged at the upper end of the photographing chamber 300, the second semiconductor refrigerating sheet 310 is connected with the refrigeration device 500 through a wire, so that the temperature and the cooling rate of the upper and lower ends of the sample chamber 200 can be accurately controlled according to the experimental requirements, and the error caused by the temperature influence of the soil sample in the photographing process is reduced. A dehumidifying port is arranged at the lower end of the photographing chamber 300, and the dehumidifying port is connected with a dehumidifier 800 through a silica gel pipeline. The lower end of the photographing chamber 300 is connected with a rotary lifting platform 700, the center of the rotary lifting platform 700 coincides with the geometric center of the bottom surface of the photographing chamber 300, the rotation angle and the height of the rotary lifting platform 700 can be set and adjusted outside the photographing chamber 300 through an electronic servo machine, and the photographing surface of the soil sample is adjusted. The upper surface of the rotary platform is made of high-density polystyrene, so as to further reduce the interference of temperature on the soil sample. The rotary platform is provided with four adjustable rotation angles, which are 0°, 90°, 180° and 270°, respectively. The initial height of the rotary platform is 0 mm, and the height value increases as the rotary platform descends. The lens of the electron microscope 600 faces the front surface of the acrylic shell of the photographing chamber 300, and the height of the lens, the distance from the lens to the acrylic shell and the magnification of the electron microscope 600 can be adjusted.

[0060] Soil samples were collected from the frozen construction area 10 using a thin-walled soil sampler. The soil samples were then removed from the laboratory, cut, and carefully placed vertically into the sample chamber 200. The soil samples should have a flat and tight contact surface with the observation equipment 20. The sample chamber 200 was closed, and the target cooling rate and freezing temperature were set in the refrigeration system. The refrigeration equipment was then turned on. The monitoring computer 400 monitored and recorded the time ti when each sensor in the sample chamber 200 displayed 0°C during the freezing process. The average freezing front movement speed V was calculated using the spacing between adjacent sensors and the recorded time. When the temperature of the temperature sensor stopped changing, the soil sample was completely frozen. The data was recorded, and the refrigeration equipment 500 was turned off. Where V = k ÷ (t) i+1 -t i Zero the height of the rotating stage inside the photography chamber 300. Evenly spray anti-fogging agent onto the inner and outer walls of the photography chamber 300. Turn on the dehumidifier 800. When the humidity in the photography chamber 300 drops below 30%, turn on the cooling equipment 500 to lower the temperature to the specified temperature, and then turn off the dehumidifier 800. Adjust the magnification of the electron microscope 600 to the specified value. Adjust the height of the electron microscope 600 and the distance between the lens and the photography chamber 300. Observe the image on the monitoring computer 400. The upper surface of the rotating stage should be aligned with the reference horizontal line, and the central axis of the rotating stage should be aligned with the reference vertical line. Open the sample chamber 200 and quickly and carefully transfer the soil sample from the sample chamber 200 to the rotating lifting platform 700 in the photography chamber 300. Fine-tune the distance between the electron microscope 600 lens and the photography chamber 300 until the image seen on the monitoring computer 400 is clear. Take pictures using the photography software on the monitoring computer 400. Take pictures of each layer from four different angles by adjusting the rotating stage.

[0061] The second step is to set up on-site testing routes and obtain real-time on-site monitoring data.

[0062] The artificial freezing construction area 10 was determined, and the inspection route and its depth relative to the freezing center were set to h meters according to the actual project requirements. (Refer to...) Figure 2 As shown, a specially designed chain-type temperature sensor 100 with a length of h meters is prepared. This sensor includes uniformly distributed polyethylene rods, temperature-sensitive elements 110, and a circuit board. The polyethylene rods are slightly thicker than the temperature-sensitive elements 110. The spacing between the temperature-sensitive elements 110 is A meters. The positions of the temperature-sensitive elements 110 correspond to the positions of the real-time monitoring points. Therefore, multiple real-time monitoring points are set up along the route to be monitored. The distance between every two real-time monitoring points is a preset distance of A meters. The number n of temperature-sensitive elements 110 satisfies A × n = h. The circuit board is powered by a battery and transmits data to a computer. (Refer to...) Figure 3As shown, a selected route to be detected is selected, a drilling rig is used to drill an installation hole to the maximum depth required for the artificial freezing construction, and the diameter of the installation hole is not less than the outer diameter of the special chain temperature sensor. The installation hole is cleaned, the special chain temperature sensor 100 is placed in the installation hole, and the temperature sensitive element 110 thereof is ensured to be in close contact with the hole wall. The working state of the special chain temperature sensor 100 is checked by a computer, and the temperature of the sensor is calibrated. The artificial freezing construction is started. The time when each temperature sensitive element 110 of the sensor monitors a preset temperature is recorded, and the preset temperature in this embodiment is 0℃.

[0063] The empirical model formula of the ice lens thickness is W1=W0+b÷V1 a , wherein W1 represents the predicted thickness of the ice lens of a section of the frozen area, V1 is the measured moving rate of the 0℃ freezing front of the section, W0 is the initial crack thickness of the soil sample, the first parameter a and the second parameter b are related to the soil type, and the first parameter a and the second parameter b are determined through a laboratory test. V1=A÷△t,△t is the time difference when the second temperature of two selected real-time monitoring points drops to the preset temperature, when the moving rate of the actual freezing front is zero, W1 tends to infinity, when the position of the actual freezing front tends to be stable, the moving rate of the actual freezing front is equal to zero, and theoretically, under this condition, the thickness of the ice lens will continue to accumulate, leading to a tendency to infinity. When the moving rate of the actual freezing front tends to infinity, the thickness of the ice lens will be equal to the initial crack thickness of the soil sample.

[0064] In the third step, the real-time monitoring data on site is substituted into the prediction model to predict the thickness of the ice lens on site in real time.

[0065] The photo is subjected to gray scale processing, and the average thickness W0 of the ice lens crack in the photo is counted by using a MATLAB program. According to the empirical model formula W=W0+b÷V a , the experimental data W, V and W0 are fitted to obtain the first parameter a and the second parameter b corresponding to the soil sample. Thereafter, when the ice lens thickness empirical model formula is used for the same position, the parameters a and b can be directly used.

[0066] The monitoring method of this embodiment provides a simple and safe means for predicting the thickness of the ice lens in the construction of the engineering freezing method. The measurement cost is low, and the measurement equipment can be recycled. Not only is it energy-saving and environment-friendly, but also it realizes green and pollution-free operation.

[0067] The device used by the monitoring method of the embodiment is simple, the process is simplified, and a thought and method for indirectly observing the microscopic changes by monitoring the macroscopic data are provided, that is, the growth of the soil microscopic ice lens and the frost heaving effect are predicted by the moving rate of the macroscopic soil freezing front. In actual engineering, the method is used as an in-situ measurement method, which avoids the errors caused by harsh conditions such as sampling difficulty, temperature change and the like, and the problems of complex measurement process and the like.

[0068] The ice lens thickness prediction empirical model relied on by the monitoring method of the embodiment has high reliability based on a large amount of laboratory experimental data, and is widely applicable to various working conditions and environments.

[0069] The monitoring method of the embodiment can stably record the temperature change of the soil in the measured area during the whole freezing process of the freezing method construction, and realize continuous observation of the ice lens growth of each soil body.

[0070] Referring to Figure 1 The present application provides an in-situ continuous monitoring method for the thickness of an ice lens in artificial freezing construction.

[0071] The in-situ continuous monitoring method for the thickness of an ice lens in artificial freezing construction comprises the following steps.

[0072] Step S100, determine the freezing center of the freezing construction area 10, and determine the freezing range according to the freezing center.

[0073] After determining the freezing center of the freezing construction area 10, the actual freezing front spreads radially outward from the freezing center, the freezing range is determined according to the requirements of the freezing construction, and the ice lens will appear in the freezing range.

[0074] Step S200, set a plurality of to-be-detected routes in the freezing range, and obtain the temperature change data with time on each to-be-detected route.

[0075] Setting a plurality of to-be-detected routes for real-time monitoring helps to improve the accuracy of monitoring and ensure that the actual ice lens predicted thickness is not affected by the abnormality of a to-be-detected route.

[0076] Avoiding the to-be-detected route from exceeding the freezing range and causing the ice lens predicted thickness to deviate.

[0077] The to-be-detected route is selected on the spot in the frozen construction area 10, and the 0℃ freezing front measured moving speed of the to-be-detected route is obtained in real time. For example, the speed of the experimental freezing front can be obtained by measuring the position change rate of the position where the temperature near the to-be-detected route drops to 0℃. A plurality of temperature sensors can be arranged on the to-be-detected route, and the temperature change near the to-be-detected route is measured by the temperature sensors. Alternatively, the 0℃ freezing front measured moving speed can be obtained by acquiring the position change rate of the actual freezing front position through image processing technology. The image processing technology can place a camera on the to-be-detected route.

[0078] A plurality of real-time monitoring points are arranged on the to-be-detected route, and the plurality of real-time monitoring points are distributed at equal intervals along the moving direction of the actual freezing front. The distance between every two adjacent real-time monitoring points is a preset distance.

[0079] When the frozen construction area 10 is subjected to frozen construction, a plurality of real-time monitoring points are arranged on each to-be-detected route. The moving condition of the actual freezing front is determined by measuring the temperature of all real-time monitoring points during the frozen construction.

[0080] The plurality of real-time monitoring points are distributed at equal intervals along the moving direction of the actual freezing front, and the distance between every two adjacent real-time monitoring points is a preset distance.

[0081] The temperatures of all real-time monitoring points are obtained, and the time when each temperature drops to a preset temperature is obtained.

[0082] When the actual freezing front moves through the real-time monitoring point, the temperature measured by the real-time monitoring point drops to the preset temperature. Therefore, it can be determined that the actual freezing front has reached the real-time monitoring point. Therefore, the time when the temperature of each real-time monitoring point drops to the preset temperature is recorded. The time corresponding to the time when the actual freezing front moves through the plurality of real-time monitoring points in sequence can be determined. Therefore, the temperature change data with time can be obtained.

[0083] In step S300, the 0℃ freezing front measured moving speed of the to-be-detected route is calculated according to the temperature change data with time.

[0084] The 0℃ freezing front measured moving speed is calculated according to the preset distance and the time.

[0085] The time consumed by the actual freezing front to move can be obtained by the time difference between the time of any two real-time monitoring points. Then, the distance between the above two real-time monitoring points is calculated according to the preset distance. The average speed of the actual freezing front to move between the above two real-time monitoring points, that is, the 0℃ freezing front measured moving speed, can be obtained by dividing the distance by the time.

[0086] Step S400, according to the measured moving rate of the 0℃ freezing front and the empirical model formula, the predicted thickness of the ice lens at any position on the to-be-detected route is calculated.

[0087] The measured moving rate of the 0℃ freezing front is substituted into a more accurate empirical model formula, and a more accurate actual ice lens predicted thickness can be obtained.

[0088] In some embodiments, the empirical model formula is as follows:

[0089] W1 = W0 + b ÷ V1 a ;

[0090] Wherein, W1 is the predicted thickness of the ice lens, W0 is the initial crack thickness, a is the first parameter, b is the second parameter, and V1 is the measured moving rate of the 0℃ freezing front.

[0091] The soil sample in the freezing range is transferred to an open freezing laboratory for experiments to obtain the first parameter a and the second parameter b.

[0092] The soil sample in the freezing range is transferred to an open freezing laboratory for experiments to obtain the first parameter a and the second parameter b, including:

[0093] Obtaining the soil sample in the freezing range;

[0094] A plurality of experimental monitoring points are set for the soil sample, and the plurality of experimental monitoring points are distributed at equal intervals along the moving direction of the experimental freezing front, and the distance between every two adjacent experimental monitoring points is a preset distance;

[0095] Obtaining the experimental temperature of all the experimental monitoring points, and recording the time when each experimental temperature drops to a preset temperature;

[0096] According to the preset distance and the plurality of time, the laboratory experimental 0℃ freezing front moving rate of the soil sample is calculated;

[0097] Obtaining the image of the soil sample, and obtaining the laboratory experimental ice lens thickness of the soil sample according to the image;

[0098] The laboratory experimental 0℃ freezing front moving rate and the laboratory experimental ice lens thickness are substituted into the empirical model formula, and the first parameter a and the second parameter b are calculated.

[0099] When the soil sample is subjected to the freezing experiment, the freezing side of the soil sample is taken as the starting side, and the position of the experimental freezing front is obtained by measuring the temperature change or by image processing technology, for example, the rate of the experimental freezing front can be obtained by measuring the position change rate of the soil sample temperature dropping to 0℃, or the laboratory experimental 0℃ freezing front moving rate can be obtained by image processing technology.

[0100] And through image processing technology, the image of the experimental ice lens generated by the movement of the freezing front in the soil sample is obtained first, and then the thickness of the laboratory experimental ice lens is calculated and analyzed by computer.

[0101] After obtaining the laboratory experimental 0℃ freezing front movement rate and the laboratory experimental ice lens thickness from the above steps, since the experimental ice lens is generated after the movement of the experimental freezing front, that is, there is a correlation between the laboratory experimental 0℃ freezing front movement rate and the laboratory experimental ice lens thickness. In theory, when the laboratory experimental 0℃ freezing front movement rate is zero, the experimental freezing front stays at this position for a long time, causing the experimental ice lens at this position to continuously increase. When the position of the experimental freezing front tends to be stable, corresponding to the laboratory experimental 0℃ freezing front movement rate equal to zero, in theory, under this condition, the laboratory experimental ice lens thickness will continuously accumulate, leading to tend to infinity. When the laboratory experimental 0℃ freezing front movement rate tends to infinity, the laboratory experimental ice lens thickness will be equal to the thickness of the soil sample.

[0102] Therefore, according to the correlation between the laboratory experimental 0℃ freezing front movement rate and the laboratory experimental ice lens thickness, a scatter plot is drawn with the laboratory experimental 0℃ freezing front movement rate as the abscissa and the laboratory experimental ice lens thickness as the ordinate, and then the relationship curve between the laboratory experimental 0℃ freezing front movement rate and the laboratory experimental ice lens thickness can be obtained according to the scatter plot.

[0103] Before the soil sample has not been subjected to freezing experiment, the soil sample is in a loose multi-crack structure, and the soil sample is subjected to image analysis, and the initial crack thickness of the cracks in the soil sample is obtained by analysis and calculation.

[0104] Since the ice lens forms cracks in the soil and expands the cracks as the ice lens increases, the initial crack thickness of the cracks in the soil sample and the thickness of the ice lens also have a correlation, so according to the relationship curve between the laboratory experimental 0℃ freezing front movement rate and the laboratory experimental ice lens thickness, the relevant empirical model formula can be fitted, and the initial crack thickness can be used as a constant in the empirical model formula to modify the empirical model formula, which helps to improve the prediction accuracy of the ice lens prediction thickness.

[0105] Substituting the measured 0℃ freezing front movement rate into the more accurate empirical model formula can obtain a more accurate actual ice lens prediction thickness.

[0106] According to the relationship curve, since the experimental ice lens is generated after the movement of the experimental freezing front, there is a correlation between the movement rate of the 0°C freezing front in the laboratory experiment and the thickness of the ice lens in the laboratory experiment. In theory, when the movement rate of the 0°C freezing front in the laboratory experiment is zero, the experimental freezing front stays at the position for a long time, causing the experimental ice lens at the position to continuously increase. When the position of the experimental freezing front tends to be stable, corresponding to the movement rate of the 0°C freezing front in the laboratory experiment being equal to zero, in theory, under this condition, the thickness of the ice lens in the laboratory experiment will continuously accumulate, leading to a tendency to infinity. When the movement rate of the 0°C freezing front in the laboratory experiment tends to infinity, the thickness of the ice lens in the laboratory experiment will be equal to the initial crack thickness of the original crack of the soil sample.

[0107] Therefore, according to the above relationship, the image of the relationship curve is relatively close to the image of the inverse power function, and the first parameter a is greater than 0; the more the movement rate of the 0°C freezing front in the laboratory experiment tends to 0, the more the thickness of the ice lens in the laboratory experiment tends to infinity; the more the movement rate of the 0°C freezing front in the laboratory experiment tends to infinity, the more the thickness of the ice lens in the laboratory experiment tends to the initial crack thickness.

[0108] According to the empirical model formula fitted according to the relationship curve, the first parameter a and the second parameter b also need to be corrected, so the related parameters in the scatter plot and the initial crack thickness W0 are substituted into the above empirical model formula to obtain the first parameter a and the second parameter b, and then an accurate empirical model formula is obtained.

[0109] The measured movement rate V1 of the 0°C freezing front in the real-time monitoring of the to-be-detected route of the freezing construction area 10 is substituted into the empirical model formula, and the actual ice lens prediction thickness of the to-be-detected route is calculated by the empirical model formula, thereby guiding the progress of artificial freezing construction.

[0110] When the freezing experiment is performed on the soil sample, a plurality of experimental monitoring points need to be arranged on the soil sample, and the movement of the experimental freezing front is determined by measuring the temperature of all the experimental monitoring points during the freezing experiment.

[0111] Therefore, in order to simulate the actual situation of the freezing construction area 10, the plurality of experimental monitoring points are distributed at equal intervals along the movement direction of the experimental freezing front, and the distance between every two adjacent experimental monitoring points is ensured to be a first preset distance.

[0112] When the experimental freezing front moves through the experimental monitoring point, the experimental temperature measured by the experimental monitoring point will drop to a preset temperature, so it can be determined that the experimental freezing front has reached the experimental monitoring point. Therefore, by recording the experimental time when the experimental temperature of each experimental monitoring point drops to the preset temperature, the experimental time corresponding to the movement of the experimental freezing front through the plurality of experimental monitoring points in sequence can be determined.

[0113] The time difference between the experimental time of any two experimental monitoring points can obtain the time consumed by the experimental freezing front moving, and then the distance between the above two experimental monitoring points can be calculated by the first preset distance, and the average speed of the experimental freezing front moving between the above two experimental monitoring points can be obtained by dividing the distance by the time, that is, the moving speed of the 0 DEG C freezing front in the laboratory experiment.

[0114] The average speed of the experimental freezing front moving between the above two experimental monitoring points is the moving speed of the 0 DEG C freezing front in the laboratory experiment, so the thickness of all experimental ice lenses between the above two experimental monitoring points needs to be counted to calculate the average thickness, and the images of all experimental ice lenses between the above two experimental monitoring points need to be obtained.

[0115] The first thickness of all experimental ice lenses between the above two experimental monitoring points is counted by using the image processing technology, and since the moving speed of the 0 DEG C freezing front in the laboratory experiment is the average speed of the experimental freezing front moving between the above two experimental monitoring points, the average value of the first thickness of all experimental ice lenses between the above two experimental monitoring points needs to be calculated to obtain the thickness of the laboratory experimental ice lens, and the thickness of the laboratory experimental ice lens and the moving speed of the 0 DEG C freezing front in the laboratory experiment form a corresponding relationship.

[0116] The moving speed of the 0 DEG C freezing front in the laboratory experiment is taken as the abscissa, and the thickness of the laboratory experimental ice lens is taken as the ordinate to establish a coordinate system, and then a plurality of coordinate points are formed by corresponding all moving speeds of the 0 DEG C freezing front in the laboratory experiment and all thicknesses of the laboratory experimental ice lens, and the scatter diagram is formed by drawing all coordinate points into the coordinate system.

[0117] In the scatter diagram, there are some abnormal data or abnormal coordinate points that do not meet the requirements, and the abnormal data and abnormal coordinate points are removed, and then the relationship curve is fitted by the plurality of coordinate points, so that the relationship curve can accurately show the correlation between the moving speed of the 0 DEG C freezing front in the laboratory experiment and the thickness of the laboratory experimental ice lens.

[0118] The application also provides an artificial freezing construction ice lens thickness in-situ continuous monitoring system, which comprises a memory and a processor, the memory stores a computer program, and the processor realizes the artificial freezing construction ice lens thickness in-situ continuous monitoring method of the above embodiment when executing the computer program.

[0119] The processor and the memory in the in-situ continuous monitoring system for the thickness of the ice lens in the artificial freezing construction can be connected through a bus. The memory, as a non-transitory computer readable storage medium, can be used to store non-transitory software programs and non-transitory computer executable programs. In addition, the memory can include a high-speed random access memory and can also include a non-transitory memory, such as at least one disk memory, a flash memory device, or other non-transitory solid-state memory device. In some embodiments, the memory can optionally include a memory remotely arranged relative to the control processor, and these remote memories can be connected to the controller through a network.

[0120] The non-transitory software programs and instructions required to implement the monitoring method of the above embodiments are stored in the memory, and when executed by the processor, the monitoring method in the above embodiments is executed, for example, the method steps S100 to S400 in the above description are executed. Figure 1

[0121] Those skilled in the art can understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the present application, and can include more or fewer steps than the figures shown, or combine certain steps, or different steps.

[0122] The device embodiments described above are only schematic, and the units illustrated as separate components can or can not be physically separated, i.e., can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment.

[0123] Those skilled in the art can understand that all or some of the steps in the above disclosed method, the functional modules / units in the system and the device can be implemented as software, firmware, hardware and their appropriate combinations.

[0124] The terms "first", "second", "third", "fourth" and the like used in the specification of the present application and the above-described drawings, if any, are used to distinguish similar objects, and do not necessarily have to describe a particular order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0125] ​It should be understood that, in the present application, "at least one" means one or more, "multiple" means two or more. "And / or" is used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after are in an "or" relationship. "At least one of the following" or the like means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, and c can be single or multiple.

[0126] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the above units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0127] The units described above as separate components can or can not be physically separated, and the components displayed as units can or can not be physical units, that is, they can be located in one place, or they can be distributed on multiple network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the present embodiment scheme.

[0128] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0129] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the present application, essentially or in other words, the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes multiple instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various program storage media.

[0130] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application.

Claims

1. A method for in-situ continuous monitoring of artificial freezing construction ice lens thickness, characterized in that, The method comprises the following steps: determining a freezing range of a frozen construction area; setting a plurality of to-be-detected routes in the freezing range, and obtaining temperature change data over time on each to-be-detected route; calculating a 0℃ freezing front measured moving speed of the to-be-detected route according to the temperature change data over time; calculating a predicted ice lens thickness of any position on the to-be-detected route according to the 0℃ freezing front measured moving speed and an empirical model formula; the empirical model formula is as follows: W1 = W0 + b ÷ V1 a ; wherein, W1 is the predicted ice lens thickness, W0 is an initial crack thickness of the in-situ soil, a is a first parameter, b is a second parameter, and V1 is the 0℃ freezing front measured moving speed; obtaining the first parameter a and the second parameter b through open freezing laboratory experiments on soil samples in the freezing range; the step of obtaining the first parameter a and the second parameter b through open freezing laboratory experiments on soil samples in the freezing range comprises the following steps: obtaining non-frozen soil samples in the freezing range by using a thin-walled soil sampler; setting a plurality of laboratory experiment monitoring points on the soil samples, and the plurality of laboratory experiment monitoring points are distributed at equal intervals along the side of the cylindrical soil sample, and the distance between every two adjacent laboratory experiment monitoring points is a preset distance; performing open freezing on the sample, and vertically placing the sample during freezing, and the top plane of the cylindrical sample is a freezing surface, and the bottom plane is a water replenishment surface; during the freezing process, the 0℃ freezing front moves from the top plane to the bottom plane; obtaining the experimental temperature of all the laboratory experiment monitoring points during the freezing experiment, and recording the time when the temperature of each monitoring point is 0℃; calculating the average speed V of the 0℃ freezing front between two adjacent monitoring points according to the distance L between the two adjacent monitoring points and the time difference t of the temperature of the two adjacent monitoring points reaching 0℃, according to the formula V=L / t; obtaining the laboratory experiment 0℃ freezing front moving speed at each position along the vertical direction of the sample; obtaining the laboratory experiment ice lens thickness at each position along the vertical direction of the sample by using a microscopic camera to obtain an image of the soil sample; substituting the laboratory experiment 0℃ freezing front moving speed at each position and the laboratory experiment ice lens thickness at each position into the empirical model formula, and obtaining the first parameter a and the second parameter b by using regression analysis.

2. The method for in-situ continuous monitoring of artificial freezing construction ice lens thickness according to claim 1, characterized in that, The monitoring method further comprises the following steps: drawing a scatter plot according to the laboratory experiment 0℃ freezing front moving speed and the laboratory experiment ice lens thickness, and obtaining a relationship curve of the laboratory experiment 0℃ freezing front moving speed and the laboratory experiment ice lens thickness according to the scatter plot; obtaining the initial crack thickness of the soil sample, and constructing an empirical model formula according to the relationship curve and the initial crack thickness.

3. The method for in-situ continuous monitoring of ice lens thickness in artificial ground freezing construction according to claim 1, characterized in that, The step of obtaining the first parameter a and the second parameter b by transferring the soil samples in the freezing range to an open freezing laboratory for laboratory experiments further comprises the following steps: The application discloses a laboratory ice lens in-situ observation device, which comprises a sample chamber and a monitoring computer, wherein the sample chamber is made of high-density polystyrene, and a first semiconductor refrigerating sheet is arranged at the upper end of the sample chamber and used for regulating the temperature gradient and the cooling rate of the upper end of the sample chamber according to experimental requirements. The inner wall of the sample chamber is uniformly distributed with m temperature sensors, the distance between every two adjacent temperature sensors is k, the temperature sensors are electrically connected with the monitoring computer, and the monitoring computer is used for monitoring the temperature change of the soil sample in the sample chamber in real time.

4. The method according to claim 3, characterized in that, The image of the soil sample is obtained. The observation device further comprises an electron microscope, a photographing chamber, a rotating lifting platform and a dehumidifier, the side wall of the photographing chamber is made of transparent material, a second semiconductor refrigerating sheet is arranged at the upper end of the photographing chamber and used for regulating the temperature and the cooling rate of the upper end of the photographing chamber according to experimental requirements, the temperature environment of the photographing chamber is the same as that of the sample chamber, the lower end of the photographing chamber is communicated with the dehumidifier, the lower end of the photographing chamber is connected with the rotating lifting platform, the rotating angle and the height of the photographing chamber are adjusted by the rotating lifting platform, and the lens of the electron microscope is directed to the photographing chamber. The height of the photographing chamber is adjusted to zero, the inner and outer walls of the photographing chamber are uniformly sprayed with anti-fog agent, the dehumidifier is started, the second semiconductor refrigerating sheet is turned on when the humidity of the photographing chamber is lower than 30%, and the dehumidifier is turned off when the temperature of the photographing chamber is equal to that of the sample chamber.

5. The method for in-situ continuous monitoring of artificial freezing construction ice lens thickness according to claim 1, characterized in that, The temperature change data of each detection route over time is obtained by a chain temperature sensor, the chain temperature sensor comprises a plurality of polyethylene rods and a plurality of temperature sensitive elements, the plurality of temperature sensitive elements are respectively arranged on the plurality of polyethylene rods, the distance between every two adjacent temperature sensitive elements is A, the length of the chain temperature sensor is h, and the number n of the temperature sensitive elements satisfies A*n=h.

6. The method according to claim 5, characterized in that, The plurality of detection routes are arranged in the freezing construction area. The plurality of detection routes are arranged in the freezing construction area. The length of each detection route does not exceed the freezing range. The chain temperature sensor is arranged on the detection route.

7. The method according to claim 6, characterized in that, The chain temperature sensor is arranged on the detection route. An installation hole is drilled on each detection route, the installation hole does not exceed the freezing range, and the diameter of the installation hole is not less than the outer diameter of the chain temperature sensor. The installation hole is cleaned, the chain temperature sensor is arranged in the installation hole, and the temperature sensitive element is tightly attached to the hole wall of the installation hole. The working state of the chain temperature sensor is checked, and the temperature of the chain temperature sensor is calibrated.

8. An in-situ continuous monitoring system of artificial freezing construction ice lens thickness, characterized in that, The application discloses a laboratory ice lens in-situ observation device, which comprises a sample chamber and a monitoring computer, wherein the sample chamber is made of high-density polystyrene, and a first semiconductor refrigerating sheet is arranged at the upper end of the sample chamber and used for regulating the temperature gradient and the cooling rate of the upper end of the sample chamber according to experimental requirements.

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