Freezing wall online monitoring method and system for tunnel freezing project

Abstract

The invention relates to the technical field of tunnel freezing engineering monitoring, in particular to a frozen wall online monitoring method and system for tunnel freezing engineering. Temperature time sequence data of all freezing pipe monitoring points are obtained, the soil layer loosening degree and freezing interference indexes are quantified through the temperature difference, amplitude trend and fluctuation characteristics of the monitoring points, the two indexes are further combined with position distribution of the freezing pipe monitoring points, and the freezing liquid demand index of all freezing pipes is determined; dynamically adjusting the refrigerating fluid correction value according to the refrigerating fluid demand index to match the actual cooling capacity demand; analyzing a disordered index of the correction value of the freezing liquid of each freezing pipe through a time sequence (calculating a conveying pause evaluation index; if the evaluation index exceeds the limit, circulation of the low-demand freezing pipe is suspended, the high-demand freezing pipe runs according to the correction value, and otherwise, dynamic adjustment of the whole pipe is maintained. According to the method, soil layer characteristics and interference factors are quantified through multi-parameter coupling, precise adaptation of cooling capacity supply is achieved, and the uniformity of the frozen wall is effectively controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel freezing engineering monitoring, in particular to a freezing wall online monitoring method and system for tunnel freezing engineering. BACKGROUND

[0002] In tunnel engineering, freezing method is an important construction auxiliary technology, which is especially suitable for complex geological conditions such as water-rich soft stratum. The method arranges freezing pipes around the tunnel, circulates low-temperature frozen liquid, freezes the surrounding soil layer to form a closed freezing wall, and thus plays a role of temporary support and water isolation. In the tunnel freezing engineering, it is crucial to adjust the temperature at different positions of the freezing wall consistently. Uneven temperature distribution will lead to differences in the strength and thickness of the freezing wall, forming structural weak links and significantly increasing the risk of water inrush and sand gushing.

[0003] In the prior art, the temperature threshold is fixed and compared with the actual temperature value of each position to control the frozen liquid flow of the freezing pipe, thereby realizing the monitoring process of the freezing wall. However, due to the complex and variable geological conditions of tunnel engineering in the tunnel environment, the temperature is easily affected by underground water flow, soil layer, thermal bridge effect, etc. These factors will cause different disturbances to the temperature at different positions. Therefore, if the differences in the disturbance of the temperature at different positions are ignored and the temperature threshold is uniformly set for frozen liquid flow control, the monitoring and control of the freezing wall will have great blindness. SUMMARY

[0004] In order to solve the technical problem that the geological conditions of tunnel engineering are complex and variable, the temperature is easily affected by underground water flow, soil layer, thermal bridge effect, etc. These factors will cause different disturbances to the temperature at different positions. Therefore, if the differences in the disturbance of the temperature at different positions are ignored and the temperature threshold is uniformly set for frozen liquid flow control, the monitoring and control of the freezing wall will have great blindness. The purpose of the present application is to provide a freezing wall online monitoring method and system for tunnel freezing engineering, and the technical solution is as follows: A freezing wall online monitoring method for tunnel freezing engineering, comprising: obtaining temperature time series data at each monitoring point on each freezing pipe; At each time, based on the difference characteristics between the temperature values at all monitoring points, and analyzing the amplitude change trend of the temperature values of each monitoring point in the preset time window, the looseness index at each monitoring point is determined. At each time, the fluctuation change characteristics of the temperature values of all monitoring points in the preset time window are analyzed to determine the freezing disturbance index at each monitoring point. At each time, based on the positional relationship between the monitoring point on the freeze pipe and the liquid supply main, and in combination with the loose index corresponding to each monitoring point and the freeze interference index, a freeze liquid demand index of each freeze pipe is determined; at each time, the preset freeze liquid flow value is adjusted according to the freeze liquid demand index of each freeze pipe, to obtain a freeze liquid correction value of each freeze pipe; At all times, the freeze liquid correction values of the freeze pipes are compared based on the degree of disorder of the freeze liquid correction values of all the freeze pipes for freeze wall monitoring at the current time.

[0005] Further, the loose index acquisition method comprises: At each time, the temperature value at each monitoring point is compared with the temperature value at other monitoring points for difference characteristics, to determine a first loose factor at each monitoring point; A preset time window corresponding to each time is determined, and at each time, the amplitude variation trend of the temperature value of each monitoring point within the preset time window is analyzed to determine a second loose factor at each monitoring point; At each time, the normalized value of the sum of the first loose factor and the second loose factor of each monitoring point is taken as the loose index at each monitoring point.

[0006] Further, the first loose factor acquisition method comprises: Optionally, one monitoring point is taken as a to-be-tested point, and the remaining monitoring points are taken as reference points; At each time, the temperature value difference between the to-be-tested point and each reference point is calculated as a temperature difference factor; The normalized value of the sum of all temperature value difference factors corresponding to the to-be-tested point at each time is taken as the first loose factor at the to-be-tested point.

[0007] Further, the second loose factor acquisition method comprises: At each time, a first-order difference sequence of the temperature value sequence is calculated within the preset time window of each monitoring point; In the first-order difference sequence, the number of positive values is counted as a number of rises, and the ratio of the number of rises to the total number of values in the first-order difference sequence is taken as a rise proportion factor; The product of the normalized value of the mean of all values in the first-order difference sequence and the rise proportion factor is normalized to obtain the second loose factor at each monitoring point.

[0008] Further, the freeze interference index acquisition method comprises: At each time, curve data corresponding to the temperature value is obtained within the preset time window of each monitoring point; In each of the curve data, the difference between the maximum value and the minimum value is taken as a fluctuation range; The number of extreme points in each of the curve data is taken as an extreme number parameter, and the ratio of the extreme number parameter of each curve data to the maximum value among the extreme number parameters of all the curve data is taken as a fluctuation frequency factor; According to the fluctuation range and the fluctuation frequency factor corresponding to each monitoring point, a freezing interference index at each monitoring point is determined, and both the fluctuation range and the fluctuation frequency factor are positively correlated with the freezing interference index.

[0009] Further, the method for obtaining the freezing liquid demand index comprises: For any monitoring point, the length of the monitoring point to the liquid supply main along the freezing pipe to which the monitoring point belongs is determined as a distance factor; The value obtained by negatively correlating the freezing interference index at the monitoring point is taken as a cooling demand factor of the monitoring point; The value obtained by normalizing the product of the cooling demand factor of the monitoring point, the corresponding loose index, and the distance factor is taken as a cooling demand index of the monitoring point; On each freezing pipe, the number of monitoring points with a cooling demand index greater than a preset cooling demand threshold is counted as a demand quantity factor; The product of the mean value of the cooling demand indices of all the monitoring points on each freezing pipe and the demand quantity factor of each freezing pipe is normalized to obtain a freezing liquid demand index of each freezing pipe.

[0010] Further, the method for obtaining the freezing liquid correction value comprises: The sum of the freezing liquid demand index of each freezing pipe and a preset parameter is taken as a flow adjustment factor; The product of the flow adjustment factor of each freezing pipe and a preset freezing liquid flow value is taken as a freezing liquid correction value of each freezing pipe.

[0011] Further, the comparison of the freezing liquid correction values of the freezing pipes on the basis of the degree of disorder of the freezing liquid correction values of all the freezing pipes at all times for monitoring the freezing wall at the current time comprises: At each time, the degree of disorder of the freezing liquid correction values of all the freezing pipes is analyzed to determine a freezing liquid flow disorder index of the freezing wall; In time sequence, the times are sequentially traversed from the current time, and when the freezing liquid distribution disorder index of the freezing wall at the traversed time is less than a preset disorder threshold, the traversal is stopped, the time corresponding to the stopping is taken as an endpoint time, the time interval between the current time and the endpoint time is taken as a disorder duration, and the sum of the freezing liquid distribution disorder indices of the freezing wall at all the traversed times is taken as a disorder parameter. The product of the normalized value of the duration of the chaos, the chaos parameter and the frozen liquid flow chaos index of the frozen wall at the current time is taken as a frozen liquid delivery suspension evaluation index; When the frozen liquid delivery suspension evaluation index is greater than a preset suspension threshold, the delivery of frozen liquid is suspended for the frozen pipes with a frozen liquid demand index less than a preset frozen liquid demand threshold, and the delivery of frozen liquid is carried out according to the frozen liquid correction value for the frozen pipes with a frozen liquid demand index greater than or equal to the preset frozen liquid demand threshold. When the frozen liquid delivery suspension evaluation index is less than or equal to the preset suspension threshold, the delivery of frozen liquid is carried out according to the frozen liquid correction value for all the frozen pipes.

[0012] Further, the method for obtaining the frozen liquid flow chaos index comprises: At each time, the standard deviation of the frozen liquid correction values of all the frozen pipes is calculated as a first chaos factor; At each time, the difference between the maximum value and the minimum value of the frozen liquid correction values of all the frozen pipes is taken as a second chaos factor; At each time, the product of the first chaos factor and the second chaos factor is normalized to obtain the frozen liquid flow chaos index of the frozen wall at the current time.

[0013] A frozen wall online monitoring system for a tunnel freezing project, comprising a processor and a memory, the memory storing at least one instruction, at least one program, a code set or an instruction set, the at least one instruction, the at least one program, the code set or the instruction set being loaded and executed by the processor to implement the steps of the frozen wall online monitoring method for the tunnel freezing project.

[0014] The present application has the following advantages: First, temperature time series data is obtained at each monitoring point on each freezing pipe to understand the temperature dynamics of the water layer at the freezing location. Due to the influence of groundwater flow, soil layers, and thermal bridge effects, some freezing pipes lose cooling capacity, resulting in lower temperatures at some monitoring points compared to other locations. This cumulative effect over time can lead to distortion of the frozen wall shape. Therefore, by comparing the temperature differences between monitoring points at each moment and the amplitude trends of the temperature values ​​at each monitoring point, the looseness of the soil layer is quantified, and a looseness index is obtained at each monitoring point. This allows for a more accurate assessment of the thermal conductivity of different areas and avoids uneven freezing caused by varying soil conditions. Furthermore, by analyzing the temperature fluctuations at the monitoring points, the effects of external interferences such as groundwater seepage and construction disturbances on the freezing process are effectively identified, and a freezing interference index is calculated. Furthermore, since the cooling capacity of the refrigerant varies at different locations within the freezing pipe, the refrigerant demand index for each freezing pipe is determined by considering the distribution of monitoring points on the freezing pipe and combining the looseness index and freezing interference index. This index is then used to precisely control the refrigerant flow rate and obtain a refrigerant correction value. Dynamic adjustment of the refrigerant flow rate ensures that the refrigerant supply between each freezing pipe matches actual demand. However, when the refrigerant correction values ​​required by different freezing pipes vary significantly, simply adjusting the flow rates of the different freezing pipes is no longer sufficient to quickly achieve uniform freezing wall temperatures around the different freezing pipes. Refrigerant circulation in some freezing pipes should be stopped. Therefore, the degree of disparity in the refrigerant correction values ​​of all freezing pipes is analyzed at all times, allowing comparison of these values ​​for monitoring the uniformity of the freezing wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A method flow chart of an online monitoring method for frozen walls in tunnel freezing projects provided by one embodiment of the present invention; Figure 2 A flowchart of a method for obtaining a loose indicator provided by an embodiment of the present invention; Figure 3 A schematic diagram of a pipeline arrangement provided by an embodiment of the present invention; Figure 4 A system block diagram of an online monitoring system for frozen walls in tunnel freezing projects provided by one embodiment of the present invention; Figure 5 Fig. 1 is a schematic diagram of a system structure of a freezing wall online monitoring system for a tunnel freezing project according to an embodiment of the present application; Reference signs: 1 - monitoring point, 2 - liquid supply main, 3 - freezing pipe, d - length from monitoring point to liquid supply main. DETAILED DESCRIPTION

[0017] In order to further clarify the technical means and effects taken by the present application to achieve the predetermined object, the specific embodiments, structure, features and effects of the freezing wall online monitoring method and system for a tunnel freezing project according to the present application are described in detail below in combination with the drawings and preferred embodiments. Different "one embodiment" or "another embodiment" in the following description do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0019] The specific scheme of the freezing wall online monitoring method and system for a tunnel freezing project according to the present application is described in detail below in combination with the drawings.

[0020] Please refer to Figure 1 which shows a method flowchart of a freezing wall online monitoring method for a tunnel freezing project according to an embodiment of the present application. The method comprises the following steps: Step S1: Obtain temperature time series data at each monitoring point on each freezing pipe.

[0021] The freezing wall is a cylindrical frozen soil structure formed in loose water-bearing strata through artificial refrigeration technology. The formation of the freezing wall depends on the circulation of refrigerants in the freezing pipe, which absorbs the heat of the strata, so that the temperature of the surrounding soil layer is lowered below the freezing point, thereby forming frozen soil. In the freezing wall construction, the liquid supply main is responsible for transporting refrigerants from the refrigeration unit to each freezing pipe, which is the starting point of refrigerant transportation. The freezing pipe is a pipeline for transporting refrigerants (such as low-temperature brine) to the strata, which branches from the liquid supply main. The freezing pipes are usually arranged according to a certain layout and spacing to ensure that the refrigerants can be uniformly distributed to the area that needs to be frozen.

[0022] In the tunnel freezing project, it is crucial to adjust the temperature of different positions of the freezing wall uniformly. Uneven temperature distribution will cause differences in the strength and thickness of the freezing wall, forming structural weak links and significantly increasing the risk of water and sand gushing. Therefore, actively adjusting the delivery of the freezing liquid can ensure the uniform development of the freezing wall, forming a continuous, complete and design strength closed barrier, which is a key control measure to ensure construction safety and ground stability.

[0023] Firstly, the temperature time series data of each monitoring point on each freezing pipe can be obtained. Specifically, a monitoring point is set every 5 meters on each freezing pipe, 5 temperature sensors are installed at the monitoring point on the circular cross section along the freezing pipe at equal intervals, and the average of the temperature values monitored by the 5 temperature sensors is taken as the temperature value at the monitoring point, thereby obtaining the temperature time series data of each monitoring point on each freezing pipe. The collection frequency of the temperature time series data is one minute, and the length can be set to half an hour from the current time.

[0024] It should be noted that the installation interval and number of temperature sensors, the collection frequency and length of temperature time series data can be adjusted according to the implementation scenario, which is not limited here.

[0025] Step S2: At each time, based on the difference characteristics between the temperature values of all monitoring points, and analyzing the amplitude change trend of the temperature values of each monitoring point in the preset time window, the looseness index of each monitoring point is determined; at each time, the fluctuation change characteristics of the temperature values of all monitoring points in the preset time window are analyzed, and the freezing interference index of each monitoring point is determined.

[0026] The geological conditions of the tunnel are complex, and the looseness of the soil layer varies significantly (such as the junction of water-rich sand layer and hard rock). The freezing process is essentially a process of heat conduction through the soil layer. The loose soil layer has a small contact area between particles, high porosity, and a thermal conductivity coefficient that is usually lower than that of dense soil. Therefore, in order to achieve the same freezing depth in different soil layers, the cold flow of the soil layer with higher looseness needs to be increased to compensate for the heat resistance loss.

[0027] At the same time, if the temperature of a monitoring point is significantly higher than the surrounding temperature, it indicates that the thermal conductivity of the soil layer in this area is poor (possibly due to high gas content caused by looseness). The loose soil layer has large thermal resistance and slow heat conduction, so the temperature will rise due to heat convection, while the temperature of the dense soil layer will drop steeply. Therefore, by analyzing the difference characteristics between the temperature values of all monitoring points at each time, and the amplitude change trend of the temperature values of each monitoring point in the preset time window, the looseness index of each monitoring point is determined, which reflects the thermal conductivity of the soil layer and provides a correction basis for the subsequent calculation of the freezing liquid demand based on the geological conditions.

[0028] Preferably, in one embodiment of the present application, the loose index acquisition method comprises the following steps: Referring to Figure 2 , a method flow chart of the loose index acquisition method in one embodiment of the present application is shown, which comprises the following steps: Step S201: At each time point, compare the temperature value at each monitoring point with the temperature values at other monitoring points in terms of difference characteristics, so as to determine a first loose factor at each monitoring point.

[0029] For the convenience of explanation and description, one monitoring point is selected as the to-be-tested point, and the remaining monitoring points are selected as reference points.

[0030] At each time point, calculate the temperature value difference between the to-be-tested point and each reference point as a temperature difference factor, and if the temperature difference factor is greater than 0 and greater, it indicates that the temperature value of the to-be-tested point is higher than that of the reference point, and then it indicates that the heat conduction of the to-be-tested point is worse relative to the reference point, and the loose soil layer is likely to have a high gas content.

[0031] At this time, there is a temperature difference factor between the to-be-tested point and each reference point at each time point, and finally, the sum of the normalized values of all temperature value difference factors of the to-be-tested point at each time point is taken as the first loose factor of the to-be-tested point. Based on the foregoing analysis, the greater the first loose factor, the greater the degree of soil layer loosening at the position of the to-be-tested point, and the flow of the refrigerant needs to be increased to overcome the thermal resistance. Since the temperature difference factor may have positive and negative values, the normalization method here can use the function .

[0032] At this time, there is a temperature difference factor between the to-be-tested point and each reference point at each time point, and finally, the sum of the normalized values of all temperature value difference factors of the to-be-tested point at each time point is taken as the first loose factor of the to-be-tested point. Based on the foregoing analysis, the greater the first loose factor, the greater the degree of soil layer loosening at the position of the to-be-tested point, and the flow of the refrigerant needs to be increased to overcome the thermal resistance. Since the temperature difference factor may have positive and negative values, the normalization method here can use the function

[0033] Step S202: Determine a preset time window corresponding to each time point, analyze the amplitude variation trend of the temperature value of each monitoring point in the preset time window at each time point, and determine a second loose factor at each monitoring point.

[0034] Since the loose soil layer has slow heat conduction, and even may have temperature rebound phenomenon due to thermal convection, at each time point, the preset time window of each monitoring point is determined, and the first-order difference sequence of the temperature value sequence is calculated in the preset time window.

[0035] In the first-order difference sequence, the number of positive values is counted as an increase number factor, and the greater the increase number factor, the more the number of rebound phenomena, and the higher the possibility of loose soil layer. The ratio of the increase number factor to the total number of values in the first-order difference sequence is taken as an increase proportion factor.

[0036] Finally, the mean value of all the values in the first-order difference sequence is normalized, and the product of the normalized value of the increase ratio factor is taken as the second loose factor at each monitoring point. The greater the second loose factor, the greater the degree of soil loosening at the location of the monitoring point, and the greater the flow of the refrigerant liquid needs to be increased to overcome the thermal resistance. Since the values in the first-order difference sequence can be positive or negative, when normalizing the mean value of all the values in the first-order difference sequence, the function .

[0037] Step S203: At each time, the first loose factor and the second loose factor of each monitoring point are fused to obtain a loosening index at each monitoring point.

[0038] Based on the analysis in the foregoing steps S201 and S202, the first loose factor and the second loose factor of each monitoring point are positively correlated with the degree of loosening at the monitoring point. Therefore, at each time, the sum of the first loose factor and the second loose factor of each monitoring point is normalized to obtain a loosening index at each monitoring point. The greater the loosening index, the higher the degree of soil loosening, and the greater the refrigerant liquid flow needs to be compensated in the subsequent process. The normalization is a technique well known to those skilled in the art, and the normalization function can be linear normalization or standard normalization, and the specific normalization method is not limited herein.

[0039] It should be noted that the size of the preset time window in this embodiment of the application is 5 times, which is composed of each time and the nearest 4 times from each time. In other embodiments, the size of the preset time window can be adjusted according to the implementation scenario, which is not limited herein.

[0040] In a tunnel freezing project, different freezing disturbances have different effects on the freezing wall of the refrigerant liquid delivery pipeline. For example, when the influence of groundwater flow on the freezing wall is significantly greater than the thermal bridge effect, the temperature change of the position affected by the groundwater flow will be more frequent than the position affected by the thermal bridge effect in the same period, and thus the degree of disturbance is greater, and the temperature is more variable. To avoid frequent and large changes in the refrigerant liquid flow caused by frequent temperature changes, the degree of adjustment should not be too large when adjusting the temperature by controlling the refrigerant liquid flow. At each time, the fluctuation characteristics of the temperature values of all the monitoring points in the preset time window can be analyzed to determine the freezing disturbance index at each monitoring point, which is used to quantify the degree of temperature variability.

[0041] Preferably, in one embodiment of the application, the method for obtaining the freezing disturbance index comprises: At each time, in the preset time window of each monitoring point, curve fitting is performed on all temperature values to obtain curve data corresponding to the temperature values. The curve fitting herein can adopt the least square method, which is a known technology and will not be described herein.

[0042] In each curve data, the difference between the maximum value and the minimum value is taken as a fluctuation range. The greater the fluctuation range, the greater the change amplitude of the temperature value in the curve data, that is, the more obvious the fluctuation and the stronger the interference degree.

[0043] Meanwhile, since the extreme point is the position where the data change trend changes, if the number of extreme points is greater, it means that the temperature change trend has changed more times and the fluctuation is more significant. Therefore, the number of extreme points in each curve data is taken as an extreme number parameter.

[0044] Then, the ratio of the extreme number parameter of each curve data to the maximum value in the extreme number parameters of all curve data is taken as a fluctuation frequency factor. The greater the fluctuation frequency factor, the greater the fluctuation of the temperature value in the curve data.

[0045] Based on the foregoing analysis, the fluctuation range and the fluctuation frequency factor corresponding to each monitoring point are positively correlated with the fluctuation degree of the temperature data thereof, that is, positively correlated with the interference degree. Therefore, in the embodiment of the present application, the product of the fluctuation range and the fluctuation frequency factor corresponding to each monitoring point is taken as a frozen interference index of each monitoring point after normalization, and the greater the frozen interference index, the more obvious the temperature fluctuation at the monitoring point, so that the adjustment degree is less likely to be too large when adjusting the refrigerant flow in the subsequent adjustment. The normalization is a technology known to those skilled in the art, and the selection of the normalization function can be linear normalization or standard normalization, and the specific normalization method is not limited herein.

[0046] Step S3: At each time, based on the positional relationship between the monitoring points on the freezing pipe and the liquid supply main, and in combination with the looseness index and the frozen interference index corresponding to each monitoring point, a refrigerant demand index of each freezing pipe is determined; at each time, the preset refrigerant flow value is adjusted according to the refrigerant demand index of each freezing pipe to obtain a refrigerant correction value of each freezing pipe.

[0047] In addition to the two indexes calculated in step S2, which can be used for subsequent adjustment of the refrigerant flow, since the different positions on the freezing pipe have different distance distributions from the liquid supply main, which will result in different losses of cold energy of the refrigerant when circulating in the pipeline to reach each monitoring point, the influence of the loss of cold energy should also be considered when adjusting the refrigerant flow in the subsequent adjustment.

[0048] Therefore, at each time, the positional relationship between each monitoring point on the freezing pipe and the supply liquid main pipe is analyzed, and is combined with the loose index corresponding to the monitoring point and the freezing interference index, so that the refrigerant demand index of each freezing pipe is calculated.

[0049] Preferably, in an embodiment of the present application, the method for obtaining the refrigerant demand index comprises: For any monitoring point on the freezing pipe, the length of the monitoring point to the supply liquid main pipe along the freezing pipe to which the monitoring point belongs is determined as a distance factor. The greater the distance factor, the farther the distance between the monitoring point and the supply liquid main pipe, and the greater the cold consumption, so that the demand for the refrigerant is greater. Please refer to Figure 3 Fig. 1 shows a schematic diagram of pipeline arrangement in an embodiment of the present application.

[0050] Since the greater the freezing interference index, the more obvious the temperature fluctuation at the monitoring point, and the less suitable the degree of subsequent adjustment of the refrigerant flow is, the freezing interference index at each monitoring point is negatively correlated and mapped to achieve logical relationship correction, so that the cooling demand factor of each monitoring point is obtained. The greater the cooling demand factor, the higher the demand degree of the refrigerant, and the greater the adjustment degree. The negative correlation mapping processing here can adopt the formula wherein, represents an exponential function with the natural constant e as the base, and x represents the independent variable.

[0051] Since the greater the loose index, the higher the loose degree of the soil layer, and the greater the refrigerant flow needs to be compensated in the subsequent process, the product of the cooling demand factor of each monitoring point, the corresponding loose index and the distance factor after normalization is taken as the cooling demand index of the monitoring point. The greater the cooling demand index, the greater the cooling demand at the monitoring point, and the greater the degree of refrigerant flow adjustment. The normalization is a technical means familiar to those skilled in the art, and the selection of the normalization function can be linear normalization or standard normalization, and the specific normalization method is not limited here.

[0052] Then, on each freezing pipe, the number of monitoring points with the cooling demand index greater than the preset cooling demand threshold is counted as a demand quantity factor. The greater the demand quantity factor, the more monitoring points with high demand for the refrigerant on the freezing pipe.

[0053] Finally, the product of the average of the cooling demand indicators of all monitoring points on each freeze pipe and the demand quantity factor of each freeze pipe is normalized as the refrigerant demand indicator of each freeze pipe. The greater the refrigerant demand indicator of a freeze pipe, the greater the flow of refrigerant passing through the freeze pipe should be. The normalization is a technique well known to those skilled in the art, and the normalization function can be linear normalization or standard normalization, etc. The specific normalization method is not limited here.

[0054] It should be noted that the preset cooling demand threshold in the embodiment of the present application is 0.8, and the specific value can be adjusted according to the implementation scenario, which is not limited here.

[0055] Based on the foregoing steps, the demand degree of each freeze pipe for refrigerant can be obtained, so that the preset refrigerant flow value can be adjusted according to the refrigerant demand indicator of each freeze pipe at each time to obtain a refrigerant correction value of each freeze pipe.

[0056] Preferably, in an embodiment of the present application, the method for obtaining the refrigerant correction value comprises: The sum of the refrigerant demand indicator of each freeze pipe and a preset parameter is used as a flow adjustment factor. The greater the flow adjustment factor, the greater the refrigerant flow required by the freeze pipe. In this embodiment of the present application, in order to prevent over-adjustment, the preset parameter is set to 1.

[0057] Finally, the product of the flow adjustment factor of each freeze pipe and the preset refrigerant flow value is used as the refrigerant correction value of each freeze pipe.

[0058] The preset refrigerant flow value in the embodiment of the present application is set to 10 m³ / h, and the specific flow can be set according to the implementation scenario, which is not limited.

[0059] Step S4: At all times, the refrigerant correction values of all freeze pipes are compared based on the degree of disorder of the refrigerant correction values of the freeze pipes for monitoring the freeze wall at the current time.

[0060] The refrigerant correction value reflects the flow of refrigerant required by each freeze pipe, but if the refrigerant correction values required by different freeze pipes differ greatly during the entire freeze wall construction process and have lasted for a long period of time, simply adjusting the refrigerant flow of different freeze pipes cannot quickly achieve the purpose of adjusting the temperature of the freeze wall to be consistent as soon as possible, and the phenomenon of uneven freezing still occurs. Therefore, in the embodiment of the present application, when monitoring the uniformity of the freeze wall, the degree of disorder of the refrigerant correction values of the freeze pipes can be analyzed, and the time sequence is traversed forward to analyze the duration of the degree of disorder, and then it is judged whether the refrigerant circulation of part of the freeze pipes needs to be stopped in order to achieve the purpose of rapid adjustment.

[0061] Preferably, in one embodiment of the present application, at all times, the frozen liquid correction values of all frozen pipes are compared on the basis of the degree of disorder of the frozen liquid correction values of all frozen pipes for frozen wall monitoring at the current time, including: At each time, the degree of disorder of the frozen liquid correction values of all frozen pipes is analyzed to determine the frozen liquid flow disorder index of the frozen wall: at each time, the standard deviation of the frozen liquid correction values of all frozen pipes is calculated as a first disorder factor, which can reflect the distribution dispersion degree of the frozen liquid correction values of all frozen pipes, and the greater the value, the more significant the difference between the frozen liquid correction values; at the same time, at each time, the difference between the maximum and minimum values of the frozen liquid correction values of all frozen pipes is calculated as a second disorder factor, which can reflect the numerical range of the frozen liquid correction values of all frozen pipes, and the greater the value, the wider the numerical fluctuation range, and the greater the degree of disorder; therefore, at each time, the product of the first disorder factor and the second disorder factor after normalization is taken as the frozen liquid flow disorder index of the frozen wall at each time, and based on the foregoing analysis, the greater the frozen liquid flow disorder index, the greater the difference between the frozen liquid correction values required by different frozen pipes at the same time. The normalization is a technical means well known to those skilled in the art, and the selection of the normalization function can be linear normalization or standard normalization, and the specific normalization method is not limited herein.

[0062] Then the time sequence of the disorder state and the cumulative fluctuation intensity are evaluated: from the current time, the historical time is sequentially traversed in time sequence, and when the frozen wall frozen liquid distribution disorder index at the traversed time is less than the preset disorder threshold, the traversal is stopped, the time corresponding to the stop is taken as the end time, which is regarded as the starting point of the fluctuation state, the time interval between the current time and the end time is taken as the disorder duration, and the sum of the frozen wall frozen liquid distribution disorder indexes at all traversed times is taken as the disorder parameter. The greater the disorder duration, the longer the disorder of the frozen liquid correction value lasts, and the greater the disorder parameter, the greater the cumulative fluctuation, so it is necessary to pause the frozen liquid delivery to some frozen pipes for balancing the freezing conditions of the frozen walls at all positions.

[0063] The current state of the frozen wall, the duration of the frozen wall disorder state, and the cumulative fluctuation are integrated: the product of the disorder duration, the disorder parameter, and the frozen liquid flow disorder index of the frozen wall at the current time after normalization is taken as the frozen liquid delivery pause evaluation index, and the greater the frozen liquid delivery pause evaluation index, the more necessary it is to pause some frozen pipes at the current time. The normalization is a technical means well known to those skilled in the art, and the selection of the normalization function can be linear normalization or standard normalization, and the specific normalization method is not limited herein.

[0064] Therefore, when the freezing liquid delivery suspension evaluation index is greater than the preset suspension threshold, in order to make the freezing degree of each position of the frozen wall consistent faster, the delivery of the freezing liquid is suspended in the freezing pipes corresponding to the frozen wall, and the freezing pipes with the freezing liquid demand index less than the preset freezing liquid demand threshold are suspended from the delivery of the freezing liquid, and the freezing pipes with the freezing liquid demand index greater than or equal to the preset freezing liquid demand threshold are delivered with the freezing liquid according to the freezing liquid correction value. Conversely, when the freezing liquid delivery suspension evaluation index is less than or equal to the preset suspension threshold, the delivery of the freezing liquid in all the freezing pipes can be directly performed according to the freezing liquid correction value.

[0065] It should be noted that the preset disorder threshold is 0.6, the preset suspension threshold is 0.8, and the preset freezing liquid demand threshold is 0.4. The specific values can be adjusted according to the implementation scene, and are not limited herein.

[0066] In summary, first, the temperature time series data of each monitoring point on each freezing pipe is obtained, which is used to master the temperature dynamics of the water stratum to be frozen. Due to the influence of underground water flow, soil layer, thermal bridge effect and the like, the delivery of cold energy of part of the freezing pipes is lost, and the temperature at part of the monitoring points is lower than that at other positions. Long-term cumulative effect will cause distortion of the shape of the frozen wall. Therefore, by comparing the difference characteristics of the temperature values of the monitoring points and the amplitude change trend of the temperature values of the monitoring points at each time, the looseness index of each monitoring point is obtained, the heat conduction performance of different regions can be more accurately evaluated, and uneven freezing caused by differences in soil conditions is avoided. Meanwhile, the fluctuation change characteristics of the temperature values of the monitoring points are analyzed, the influence of external interference such as underground water seepage and construction disturbance on the freezing process is effectively identified, and the freezing interference index is calculated. Further, the cold energy loss of the freezing liquid is different when the freezing liquid reaches different positions in the freezing pipe. Therefore, the position distribution of the monitoring points on the freezing pipe is considered, and the looseness index and the freezing interference index are combined to determine the freezing liquid demand index of each freezing pipe, which is used to realize accurate regulation and control of the freezing liquid flow, and the freezing liquid correction value is obtained. By dynamically adjusting the freezing liquid flow, the freezing liquid supply between the freezing pipes is matched with the actual demand. However, when the freezing liquid correction values required by different freezing pipes are greatly different, the flow adjustment of different freezing pipes cannot achieve the purpose of quickly adjusting the temperature of the frozen wall around different freezing pipes to be consistent, and the freezing liquid circulation process of part of the freezing pipes should be stopped. Therefore, at all times, the disorder degree of the freezing liquid correction value of all the freezing pipes is analyzed, and the freezing liquid correction values of the freezing pipes are compared to monitor the uniformity of the frozen wall.

[0067] The embodiment of the present application also provides a frozen wall online monitoring system for a tunnel freezing project, please refer to Figure 4The system block diagram is shown, and the system includes a data acquisition module 401 configured to implement step S1 in the above method embodiments; a frozen condition analysis module 402 configured to implement step S2 in the above method embodiments; a frozen liquid flow determination module 403 configured to implement step S3 in the above method embodiments; and a frozen wall monitoring module 404 configured to implement step S4 in the above method embodiments.

[0068] It should be noted that the system provided in the above embodiments is only exemplified by the division of the above functional modules, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the computer device is divided into different functional modules to complete all or part of the above-described functions. In addition, the frozen wall online monitoring system for tunnel freezing engineering and the frozen wall online monitoring method for tunnel freezing engineering provided in the above embodiments belong to the same concept, and the specific implementation process is described in the method embodiments, which will not be repeated here.

[0069] Please refer to Figure 5 The system structure schematic diagram of the frozen wall online monitoring system for tunnel freezing engineering provided in the embodiment of the present application is shown, and the system includes a processor 500, a memory 501, a bus 502 and a communication interface 503, the processor 500, the communication interface 503 and the memory 501 are connected through the bus 502; wherein the memory 501 can include a high-speed random access memory, the bus 502 can be an ISA bus, a PCI bus or an EISA bus, etc., the processor 500 can be an integrated circuit chip with signal processing capability; the memory 501 stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are loaded and executed by the processor to implement the steps in the frozen wall online monitoring method for tunnel freezing engineering.

[0070] It should be noted that the above embodiment sequence of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are also possible or can be advantageous.

[0071] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment mainly describes the differences from other embodiments.

Claims

1. A frozen wall online monitoring method for tunnel freezing engineering, characterized in that: The method comprises: Obtaining the temperature time series data at each monitoring point on each freezing pipe; At each moment, based on the difference characteristics between the temperature values ​​at all monitoring points and analyzing the amplitude change trend of the temperature value of each monitoring point within the preset time window, the looseness index at each monitoring point is determined; at each moment, the fluctuation change characteristics of the temperature values ​​of all monitoring points within the preset time window are analyzed to determine the freezing interference index at each monitoring point; At each moment, the refrigerant demand index of each freezing pipe is determined based on the positional relationship between the monitoring point on the freezing pipe and the liquid supply main, combined with the looseness index and freezing interference index corresponding to each monitoring point. At each moment, the preset refrigerant flow value is adjusted according to the refrigerant demand index of each freezing pipe to obtain the refrigerant correction value of each freezing pipe. At all times, based on the disorder of the refrigerant correction values ​​of all the freezing pipes, the refrigerant correction values ​​of the freezing pipes are compared for performing frozen wall monitoring at the current time.

2. The method for online monitoring of frozen walls in tunnel freezing projects according to claim 1, characterized in that: The method for obtaining the loose indicator includes: At each moment, the temperature value at each monitoring point is compared with the temperature values ​​at other monitoring points for difference characteristics, thereby determining the first looseness factor at each monitoring point; Determine a preset time window corresponding to each moment, analyze the amplitude change trend of the temperature value of each monitoring point within the preset time window at each moment, and determine the second looseness factor at each monitoring point; At each moment, the normalized sum of the first looseness factor and the second looseness factor of each monitoring point is used as the looseness index at each monitoring point.

3. The method for online monitoring of frozen walls in tunnel freezing projects according to claim 2, characterized in that: The method for obtaining the first loose factor includes: Select any one monitoring point as the point to be measured and use the remaining monitoring points as reference points; At each moment, the temperature difference between the measured point and each reference point is calculated as the temperature difference factor; The normalized sum of all temperature difference factors corresponding to the test point at each moment is used as the first looseness factor at the test point.

4. The method for online monitoring of frozen walls in tunnel freezing projects according to claim 2, characterized in that: The method for obtaining the second loose factor includes: At each moment, within the preset time window of each monitoring point, calculate the first-order difference sequence of the temperature value sequence; In the first-order difference sequence, the number of positive values ​​is counted as an increase factor, and the ratio of the increase factor to the total number of values ​​in the first-order difference sequence is used as an increase proportional factor; The product of the normalized mean of all values ​​in the first-order difference sequence and the rising proportional factor is normalized to obtain the second looseness factor at each monitoring point.

5. The online monitoring method for frozen walls in tunnel freezing projects according to claim 1, characterized in that: The method for obtaining the frozen interference index includes: At each moment, within the preset time window of each monitoring point, obtain the curve data corresponding to the temperature value; In each of the curve data, the difference between the maximum value and the minimum value is taken as the fluctuation range; Obtaining the number of extreme value points in each of the curve data as an extreme value number parameter, and taking the ratio of the extreme value number parameter of each curve data to the maximum value of the extreme value number parameters of all curve data as a fluctuation frequency factor; According to the fluctuation range and the fluctuation frequency factor corresponding to each monitoring point, the freezing interference index at each monitoring point is determined, and the fluctuation range and the fluctuation frequency factor are both positively correlated with the freezing interference index.

6. The method for online monitoring of frozen walls in tunnel freezing projects according to claim 1, characterized in that: The method for obtaining the refrigerant demand index includes: For any monitoring point, determine the length from the monitoring point to the liquid supply main along the freezing pipe to which the monitoring point belongs as the distance factor; The value after negative correlation mapping of the freezing interference index at the monitoring point is used as the cooling demand factor of the monitoring point; The product of the cooling demand factor, the corresponding loose index and the distance factor of the monitoring point is normalized and used as the cooling demand index of the monitoring point; On each freezing pipe, the number of monitoring points whose cooling demand index is greater than the preset cooling demand threshold is counted as the demand quantity factor; The product of the average of the cooling demand indexes of all monitoring points on each freezing pipe and the demand quantity factor of each freezing pipe is normalized to obtain the refrigerant demand index of each freezing pipe.

7. The method for online monitoring of frozen walls in tunnel freezing projects according to claim 1, characterized in that: The method for obtaining the refrigerant correction value includes: The sum of the freezing liquid demand index of each freezing pipe and the preset parameters is used as the flow adjustment factor; The product of the flow adjustment factor of each freezing pipe and the preset freezing liquid flow value is used as the freezing liquid correction value of each freezing pipe.

8. The method for online monitoring of frozen walls in tunnel freezing projects according to claim 1, characterized in that: The method of comparing the frozen liquid correction values ​​of all frozen pipes at all times based on the disorder of the frozen liquid correction values ​​for monitoring the frozen wall at the current time includes: At each moment, the chaos of the refrigerant correction values ​​of all freezing pipes is analyzed to determine the chaos index of the refrigerant flow of the freezing wall; In terms of time sequence, the system starts from the current moment and sequentially traverses forward. When the chaos index of the frozen wall's refrigerant distribution at the traversed moment is less than the preset chaos threshold, the system stops. The corresponding moment of the stop is taken as the endpoint moment, the time interval between the current moment and the endpoint moment is taken as the chaos duration, and the sum of the chaos indexes of the frozen wall's refrigerant distribution at all traversed moments is taken as the chaos parameter. The product of the chaos duration, the chaos parameter, and the chaos index of the freezing liquid flow of the freezing wall at the current moment is normalized to obtain a value as the evaluation index of the freezing liquid delivery suspension; When the refrigerant delivery suspension evaluation index is greater than a preset suspension threshold, among all the freezing pipes corresponding to the freezing wall, the delivery of refrigerant to the freezing pipes whose refrigerant demand index is less than the preset refrigerant demand threshold is suspended; and the delivery of refrigerant to the freezing pipes whose refrigerant demand index is greater than or equal to the preset refrigerant demand threshold is performed according to the refrigerant correction value; When the refrigerant delivery suspension evaluation index is less than or equal to a preset suspension threshold, refrigerant is delivered to all freezing pipes according to the refrigerant correction value.

9. The method for online monitoring of frozen walls in tunnel freezing projects according to claim 8, characterized in that: The method for obtaining the refrigerant flow disorder index includes: At each moment, the standard deviation of the refrigerant correction values ​​of all freezing pipes is calculated as the first disorder factor; At each moment, the difference between the maximum and minimum values ​​of the refrigerant correction values ​​of all freezing pipes is used as the second confusion factor; At each moment, a normalized value of the product of the first and second chaos factors is used as a chaos index of the refrigerant flow of the freezing wall at each moment.

10. An online monitoring system for frozen walls in tunnel freezing projects, characterized in that: The invention comprises a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and when the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor, the steps of the online monitoring method of frozen wall for tunnel freezing engineering as described in any one of claims 1 to 9 are implemented.

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