A method for evaluating ice layer bearing capacity during the ice growth and decay period

Abstract

A method for evaluating the ice layer bearing capacity during the ice layer growth and decay period, which relates to the technical field of ice layer bearing capacity monitoring. Aiming at the problem that the existing bearing capacity evaluation method only evaluates through the ice layer thickness at the current moment and does not consider the ice layer growth and decay period, resulting in inaccurate bearing capacity. This application determines whether there is temperature change in the ice layer at the same point through continuous temperature monitoring, and then judges which stage of the ice layer growth and decay period the ice layer belongs to, and calculates the influence of the ice layer growth and decay period on the ice layer thickness during the monitoring period, corrects the ice layer thickness, and thus obtains the bearing capacity. Moreover, this application also classifies the ice surface cracks to obtain the corresponding safety factor, and then makes a secondary correction to the calculated bearing capacity. By making two corrections to the ice layer thickness and the bearing capacity respectively, this application greatly improves the accuracy of the obtained bearing capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of ice layer bearing capacity monitoring, and specifically to a method for evaluating the bearing capacity of ice layers during the ice formation and ablation period. Background Art

[0002] Ice is a special material formed physically in nature. Its properties are relatively complex. In particular, its strength is affected by various factors, among which the external environmental temperature and the temperature of the ice layer itself have a great influence. When ice with a certain strength reaches a certain thickness to form an ice layer, it can provide services such as ice entertainment and transportation for people. Therefore, monitoring the internal temperature change of the ice layer is crucial for studying the ice formation and ablation process, predicting the melting trend, and estimating the impact of its bearing capacity on the surrounding environment.

[0003] Existing bearing capacity evaluation methods only evaluate through the ice layer thickness at the current moment and do not consider the ice formation and ablation period of the ice layer. Therefore, the obtained bearing capacity is inaccurate. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for evaluating the bearing capacity of ice layers during the ice formation and ablation period for the problem that existing bearing capacity evaluation methods only evaluate through the ice layer thickness at the current moment and do not consider the ice formation and ablation period of the ice layer, resulting in inaccurate bearing capacity.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] A method for evaluating the bearing capacity of ice layers during the ice formation and ablation period, the method is implemented based on an internal temperature monitoring device for the ice formation and ablation period. A plurality of temperature sensors 6 are evenly arranged on the internal temperature monitoring device for the ice formation and ablation period, and a flow velocity sensor 9 is arranged at the bottom of the internal temperature monitoring device for the ice formation and ablation period;

[0007] The method includes the following steps:

[0008] Step 1: Place the internal temperature monitoring device for the ice formation and ablation period in the ice layer, use the temperature sensor 6 to monitor the ice layer temperature, and use the flow velocity sensor 9 to monitor the water flow under the ice layer;

[0009] Step 2: Set the monitoring time, and take 5% of the monitoring time as the change time Δt;

[0010] Step 3: Obtain the water flow velocity η monitored by the flow velocity sensor 9 w , and through η w obtain the thickness Δx of the ice layer in the ice-water mixing zone. Δx is expressed as:

[0011]

[0012] where ρi is the density of water, L i is the latent heat of phase change, T a is the average temperature of the ice-water mixing zone;

[0013] Step Four: Statistically detect the temperature sensors 6 with negative values, select the temperature sensor 6 that is farthest from the ice surface among them, and obtain the distance between this temperature sensor 6 and the ice surface, which is the ice layer thickness d;

[0014] Step Five: During the monitoring time, continuously monitor the temperature sensors 6 with detected negative values. If a non-negative value appears in the monitored temperature sensor 6, subtract Δx from the ice layer thickness d, and the resulting value is the corrected ice layer thickness D. Otherwise, add the ice layer thickness d and Δx, and the obtained value is the corrected ice layer thickness D;

[0015] Step Six: Calculate the ice layer bearing capacity P using the corrected ice layer thickness D y , the ice layer bearing capacity P y is expressed as:

[0016]

[0017] Step Seven: Obtain the safety factor μ according to the grade of the ice surface cracks;

[0018] Step Eight: Use the safety factor μ to correct the ice layer bearing capacity P y to obtain the corrected ice layer bearing capacity P r , P r is expressed as:

[0019] P r = μ·η·P y

[0020] where η is the ice layer modulus correction factor.

[0021] Furthermore, the specific steps for determining the grade of the ice surface cracks and obtaining the safety factor μ in Step Eight are as follows:

[0022] If the crack width is less than 1 mm, the depth is less than 10 cm, and the ice surface is transparent, it is a first-level crack, and the safety factor μ is 0.81;

[0023] If the crack width is between 1 mm and 3 mm, the depth is between 10 and 20 cm, and the ice surface is locally whitened, it is a second-level crack, and the safety factor μ is 0.68;

[0024] If the crack width is greater than 3 mm, the depth is greater than 20 cm, and the ice surface is severely whitened, it is a third-level crack, and the safety factor μ is 0.43;

[0025] Otherwise, there are no cracks, and the safety factor μ is 0.87.

[0026] Furthermore, the internal temperature monitoring device during the ice layer growth and decay period is cylindrical, and a limiting hole 7 is provided on the internal temperature monitoring device during the ice layer growth and decay period, and the temperature sensor 6 is arranged on the limiting hole 7.

[0027] Furthermore, a heating tape 8 is also provided on the internal temperature monitoring device during the ice layer growth and decay period, and the heating tape 8 is spirally wound around the internal temperature monitoring device during the ice layer growth and decay period.

[0028] Furthermore, a solar panel 4 is also provided on the internal temperature monitoring device during the ice layer growth and decay period.

[0029] Furthermore, the internal temperature monitoring device during the ice layer growth and decay period is of a hollow structure, and the cavity is filled with foam rubber 11.

[0030] Furthermore, the internal temperature monitoring device during the ice layer growth and decay period is made of PPR material.

[0031] Furthermore, the multiple temperature sensors 6 are uniformly arranged with left-right crossing.

[0032] Furthermore, the multiple temperature sensors 6 are uniformly arranged with spiral crossing.

[0033] Furthermore, the monitoring time is 60 - 100 min.

[0034] The beneficial effects of the present invention are as follows:

[0035] This application determines whether there is a temperature change in the ice layer at the same point through continuous temperature monitoring, and then judges which stage of the ice layer growth and decay period the ice layer belongs to, and calculates the influence of the ice layer growth and decay period on the ice layer thickness during the monitoring period, corrects the ice layer thickness, and thus obtains the bearing capacity. Moreover, this application also classifies the ice surface cracks to obtain the corresponding safety factor, and then makes a secondary correction to the calculated bearing capacity. By making two corrections to the ice layer thickness and the bearing capacity respectively, this application greatly improves the accuracy of the obtained bearing capacity. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of a specific implementation of this application;

[0037] Figure 2 It is a schematic diagram of the specific structure of the internal temperature monitoring device during the ice layer growth and decay period in this application;

[0038] Figure 3 It is an enlarged view of part A;

[0039] Figure 4 It is a schematic diagram of the layout of the limiting holes in the implementation manner of this application;

[0040] Figure 5Schematic diagram of the correlation between the actual ice layer thickness and the calculated ice layer thickness result;

[0041] Figure 6 Schematic diagram of the ice layer modulus varying with the internal temperature;

[0042] Figure 7 Schematic diagram of the bearing capacity under different ice layer thicknesses;

[0043] Figure 8 Temperature change trend diagram at 0 m;

[0044] Figure 9 Temperature change trend diagram at 0.3 m;

[0045] Figure 10 Temperature change trend diagram at 0.5 m. Detailed implementation manner

[0046] It should be specifically noted that, without conflict, the various implementation manners disclosed in this application can be combined with each other.

[0047] Detailed implementation manner one: A method for evaluating the bearing capacity of an ice layer during the ice formation and ablation period, the method is implemented based on an internal temperature monitoring device for the ice formation and ablation period, and a plurality of temperature sensors 6 are uniformly arranged on the internal temperature monitoring device for the ice formation and ablation period, and a flow velocity sensor 9 is arranged at the bottom of the internal temperature monitoring device for the ice formation and ablation period;

[0048] The method includes the following steps:

[0049] Step one: Place the internal temperature monitoring device for the ice formation and ablation period in the ice layer, use the temperature sensor 6 to monitor the ice layer temperature, and use the flow velocity sensor 9 to monitor the water flow under the ice layer;

[0050] Step two: Set the monitoring time, and take 5% of the monitoring time as the change time Δt;

[0051] Step three: Obtain the water flow velocity η monitored by the flow velocity sensor 9 w , and obtain the thickness Δx of the ice layer in the ice-water mixing zone through η w , and Δx is expressed as:

[0052]

[0053] Wherein, ρ i is the density of water, L i is the latent heat of phase change, and T a is the average temperature of the ice-water mixing zone;

[0054] Step 4: Count the temperature sensors 6 that detect negative values, select the temperature sensor 6 that is farthest from the ice surface among them, and obtain the distance between this temperature sensor 6 and the ice surface, which is the ice layer thickness d;

[0055] Step 5: During the monitoring time, continuously monitor the temperature sensors 6 that detect negative values. If the monitored temperature sensor 6 shows a non - negative value, subtract Δx from the ice layer thickness d, and the resulting value is the corrected ice layer thickness D. Otherwise, add the ice layer thickness d and Δx, and the obtained value is the corrected ice layer thickness D;

[0056] Step 6: Calculate the ice layer bearing capacity P using the corrected ice layer thickness D y , the ice layer bearing capacity P y is expressed as:

[0057]

[0058] Step 7: Obtain the safety factor μ according to the grade of the ice surface crack;

[0059] Step 8: Use the safety factor μ to correct the ice layer bearing capacity P y to obtain the corrected ice layer bearing capacity P r , P r is expressed as:

[0060] P r = μ·η·P y

[0061] where η is the ice layer modulus correction coefficient.

[0062] If the temperature sensor shows a non - negative value, it is considered that the ice layer is melting at this time. Therefore, select the temperature sensor 6 closest to the ice surface as the demarcation point between the ice layer and the ice - water mixing area, and based on 5% of the monitoring time as the change time, then calculate Δx, and use Δx as the compensation for the ice layer growth and disappearance period.

[0063] When the monitoring device of this application is specifically implemented, it is divided into three parts: 1. Temperature monitoring device 2. Cloud data platform 3. Data receiving device (such as Figure 1 ), where the temperature detection device is built - in with high - precision temperature sensors, which can perform accurate measurements in the range of 40°C - 30°C. And high - precision vibration flow velocity sensors, which can perform accurate measurements in the range of 40°C - 0°C. The sensors are equipped with resistance induction devices and are connected to the data acquisition module using a wired connection output method to ensure the stability and accuracy of data transmission.

[0064] The external part of the ice - detection section of the temperature monitoring device is made of high and low temperature resistant materials (PPR material), with good high - temperature resistance, cold resistance performance and mechanical strength. The outer layer is wrapped with a heating tape 8 from top to bottom. After the later use is completed, the device can be heated and retrieved for repeated use. The internal temperature sensor connecting wire is sealed and reinforced by foam glue 11, and the end of the temperature sensor is sealed and reinforced with glass glue and the external PPR pipe to ensure long - term use in extreme environments.

[0065] Inside the upper circular device of the temperature monitoring device, there is a highly efficient data acquisition module and corresponding system modules, which can collect temperature data in real - time and transmit the data to the cloud platform terminal through a wireless communication module. This system supports multiple communication protocols to ensure the stability of data transmission in different environments; externally, there are corresponding power - on indicators 5, device main switch 1, heating switch 2, Type - C conversion interface 3 and solar panels 4. To ensure the persistent use of the data acquisition module, the device adopts a power - supply scheme combining highly efficient solar cells and rechargeable batteries, which can self - charge under sufficient sunlight conditions and ensure normal operation on cloudy days or at night. The temperature sensor 6 is connected through the temperature sensor connecting wire 10.

[0066] This application also includes a set of supporting software systems. Users can view temperature data, generate data reports and set alarm thresholds in real - time through mobile or computer - side applications, which is convenient for timely discovery of abnormal temperature changes. At the same time, this monitoring device is simply designed and easy to install and maintain. Users can choose different installation depths and device densities according to their needs (refer to Figure 4 ) to meet the monitoring requirements of different ice layer thicknesses.

[0067] The ice layer bearing capacity evaluation method corresponding to the device of this application is as follows:

[0068] Since the temperature change of the ice layer is affected by heat conduction, especially when the ice layer is in a temperature gradient. Therefore, by using the temperature monitoring device of this application, temperature data at different times and different points (depths) are collected in real - time. Based on the existing temperature data at different points, it is judged whether the ice - water interface is frozen, and then the size of the bearing capacity is determined.

[0069] If the temperature at a certain point at this interface appears negative and lasts for 60 - 100 minutes, the water at this point has turned into ice. If the temperature at this point lasts for about 6 hours and shows a downward trend, the ice at this point has a certain bearing capacity;

[0070] If the temperature at a certain point on the interface is 0°C, then calculate the temperature gradient of the ice layer between the two adjacent upper and lower points. Then, combined with the heat flux density and the relationship between energy balance and heat flux density, use the least squares method to fit the historical observation data to obtain the relationship formula between its relevant indicators and the water flow velocity. According to the formulas (1)(2)(3)(4), thus determine whether the ice-water interface freezes. Among them, the energy balance equation at the bottom of the ice layer is:

[0071]

[0072] The calculation formula for the ice-water heat flux density is as follows:

[0073] q iw =C iw (T a -T0) (2)

[0074] The ice-water heat exchange coefficient formula:

[0075]

[0076] The thickness of the ice layer in the ice-water mixing zone:

[0077]

[0078] Among them: q iw is the ice-water heat flux density (unit: W / m 2 ); ρ i is the density of water (unit: kg / m 3 ); L i is the latent heat of phase change (unit: W / m 2 ); is the rate of change of the ice layer thickness; C iw is the ice-water heat exchange coefficient; T a is the average temperature of the ice-water mixing zone (unit: °C); T0 is the freezing point (unit: °C); η w is the water flow velocity (unit: m / s); Δx is the ice layer thickness in the ice-water mixing zone (unit: m);

[0079] Through the calculation of the above empirical formulas, combined with the real-time ice layer temperature and the ice layer thickness obtained from the actual ice extraction survey, it can be seen that the calculated ice layer thickness has a good correlation with the actual ice layer thickness (as Figure 5 shown), and perform a fitting analysis on its modulus. The lower the ice layer temperature, the higher the corresponding modulus. Furthermore, estimate the bearing capacity of the ice layer. The thicker the ice layer, the greater its bearing capacity (as Figure 7 shown). However, when calculating the bearing capacity of ice layers with different positions and integrity, their reduction should be considered, as shown in Table 1.

[0080] Table 1 Reduction coefficient

[0081]

[0082] Note: No cracks: The ice surface has no cracks and is transparent.

[0083] Level 1 cracks: The crack width is less than 1 mm, the depth is less than 10 cm, and the ice surface is transparent.

[0084] Level 2 cracks: The crack width is between 1 mm and 3 mm, the depth is between 10 and 20 cm, and the ice surface is locally whitened.

[0085] Level 3 cracks: The crack width is greater than 3 mm, the depth is greater than 20 cm, and the ice surface is severely whitened.

[0086] That is, the revised ice layer bearing capacity calculation formula is:

[0087]

[0088] P r = μ·η·P y (6)

[0089] Where: P y is the ice layer bearing capacity before revision (unit: t / m 2 ); D is the ice layer thickness (unit: m); P r is the ice layer bearing capacity after revision (unit: t / m 2 ); μ is the safety factor; η is the ice layer modulus correction factor (0.812 at -5°C; 1 at -10°C; 1.14 at -15°C; intermediate values can be interpolated).

[0090] Therefore, this application proposes a device dedicated to the internal temperature monitoring during the ice growth and decay period, which can provide high-precision, real-time, and reliable temperature data, and has important theoretical value and application prospects. This device can not only deeply detect the temperature inside the ice layer, but also has good cold resistance and anti-interference capabilities, and can operate stably for a long time in extreme environments. Figures 5 - 7 "x" in it is the revised ice layer thickness "D".

[0091] Example:

[0092] A temperature monitoring device is deployed in a certain section of the Songhua River in Heilongjiang Province. Taking the ice layer changes at different points in the same time period from December to February of a certain year as an example. As can be seen from Table 1, around December 23, the ice layer thickness is about 35 cm; around January 10, the ice layer thickness is about 55 cm; around January 30, the ice layer thickness is about 86 cm.

[0093] Table 1 Temperature record table at different points at different times

[0094]

[0095] Table 2 Ice layer bearing capacity under different thickness conditions

[0096]

[0097] It should be noted that the specific implementation manners are only explanations and descriptions of the technical solutions of the present invention, and the scope of the right protection cannot be limited thereby. Those that are only partially changed according to the claims and the description of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An ice layer bearing capacity evaluation method for the ice growth and decay period, characterized in that The method is implemented based on the internal temperature monitoring device during the ice formation and ablation period. A plurality of temperature sensors (6) are uniformly arranged on the internal temperature monitoring device during the ice formation and ablation period, and a flow velocity sensor (9) is arranged at the bottom of the internal temperature monitoring device during the ice formation and ablation period; The method includes the following steps: Step 1: Place the internal temperature monitoring device during the ice formation and ablation period in the ice layer, use the temperature sensor (6) to monitor the ice layer temperature, and use the flow velocity sensor (9) to monitor the water flow under the ice layer; Step 2: Set the monitoring time, and take 5% of the monitoring time as the change time Δt; Step 3: Obtain the water flow velocity η monitored by the flow velocity sensor (9) w , and based on η w , obtain the thickness Δx of the ice layer in the ice-water mixing zone. Δx is expressed as: where ρ i is the density of water, L i is the latent heat of phase change, and T a is the average temperature of the ice-water mixing zone; Step 4: Count the temperature sensors (6) that detect negative values, select the temperature sensor (6) that is farthest from the ice surface among them, and obtain the distance between this temperature sensor (6) and the ice surface, that is, the ice layer thickness d; Step 5: During the monitoring time, continuously monitor the temperature sensors (6) that detect negative values. If the monitored temperature sensor (6) shows a non-negative value, subtract Δx from the ice layer thickness d, and the resulting value is the corrected ice layer thickness D. Otherwise, add the ice layer thickness d and Δx, and the obtained value is the corrected ice layer thickness D; Step 6: Calculate the ice layer bearing capacity P using the corrected ice layer thickness D y , the ice layer bearing capacity P y is expressed as: Step 7: Obtain the safety factor μ according to the grade of the ice surface crack; Step Eight: Use the safety factor μ to correct the ice layer bearing capacity P y to obtain the corrected ice layer bearing capacity P r , P r is expressed as: P r = μ·η·P y Among them, η is the ice layer modulus correction coefficient.

2. The ice layer bearing capacity evaluation method for the ice growth and decay period according to claim 1, characterized in that The specific steps for obtaining the safety factor μ according to the grade of the ice surface crack in Step 8 are as follows: If the crack width is less than 1 mm, the depth is less than 10 cm, and the ice surface is transparent, it is a first-level crack, and the safety factor μ is 0.81; If the crack width is between 1 mm and 3 mm, the depth is between 10 and 20 cm, and the ice surface is locally whitened, it is a second-level crack, and the safety factor μ is 0.68; If the crack width is greater than 3 mm, the depth is greater than 20 cm, and the ice surface is severely whitened, it is a third-level crack, and the safety factor μ is 0.43; Otherwise, there is no crack, and the safety factor μ is 0.

87.

3. A method for evaluating ice layer bearing capacity during the ice formation and ablation period according to claim 1, characterized in that The internal temperature monitoring device during the ice formation and ablation period is a cylinder. A limiting hole (7) is provided on the internal temperature monitoring device during the ice formation and ablation period, and the temperature sensor (6) is arranged on the limiting hole (7).

4. A method for evaluating ice layer bearing capacity during the ice formation and ablation period according to claim 1, characterized in that A heating belt (8) is also provided on the internal temperature monitoring device during the ice formation and ablation period, and the heating belt (8) is spirally wound around the internal temperature monitoring device during the ice formation and ablation period.

5. A method for evaluating ice layer bearing capacity during the ice formation and ablation period according to claim 1, characterized in that A solar panel (4) is also provided on the internal temperature monitoring device during the ice formation and ablation period.

6. The ice layer bearing capacity evaluation method for the ice formation and ablation period according to claim 1, characterized in that The internal temperature monitoring device during the ice formation and ablation period is a hollow structure, and the cavity is filled with foam rubber (11).

7. A method for evaluating the ice layer bearing capacity during the ice growth and decay period according to claim 1, characterized in that The internal temperature monitoring device during the ice formation and ablation period is made of PPR material.

8. A method for evaluating ice layer bearing capacity during the ice growth and decay period according to claim 1, characterized in that The plurality of temperature sensors (6) are uniformly arranged in a left-right cross pattern.

9. The ice layer bearing capacity evaluation method for the ice growth and decay period according to claim 1, characterized in that The plurality of temperature sensors (6) are uniformly arranged in a spiral cross pattern.

10. The ice layer bearing capacity evaluation method for the ice growth and decay period according to claim 1, characterized in that The monitoring time is 60 - 100 min.

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