Ice layer bearing capacity evaluation method for ice layer growth and disappearance period

Abstract

The invention discloses an ice layer bearing capacity evaluation method for an ice layer growth and disappearance period, relates to the technical field of ice layer bearing capacity monitoring, and aims to solve the problem that the obtained bearing capacity is not accurate due to the fact that an existing bearing capacity evaluation method only evaluates the thickness of an ice layer at the current moment and does not consider the growth and disappearance period of the ice layer. According to the method, whether the ice layer at the same point position has temperature change or not is monitored through continuous temperature, so that which stage of the ice layer growth and disappearance period the ice layer belongs to is judged, the influence of the monitoring period and the ice layer growth and disappearance period on the thickness of the ice layer is calculated, the thickness of the ice layer is corrected, and the bearing capacity is obtained. Moreover, according to the method, ice surface cracks are graded to obtain corresponding safety coefficients, and then secondary correction is carried out on the calculated bearing capacity. According to the method, the ice layer thickness and the bearing capacity are corrected twice, so that the accuracy of the obtained bearing capacity is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ice layer bearing capacity monitoring, and in particular to an ice layer bearing capacity evaluation method for ice layer formation and decay periods. Background Art

[0002] Ice is a special material formed physically in nature. Its properties are relatively complex, especially its strength, which is affected by many factors. The external ambient temperature and the temperature of the ice layer itself have a huge impact. Ice with a certain strength and reaching a certain thickness can provide people with ice entertainment, transportation and other services. Therefore, monitoring the temperature changes inside the ice layer is crucial for studying the formation and disappearance of the ice layer, predicting the melting trend and estimating its carrying capacity and its impact on the surrounding environment.

[0003] The existing bearing capacity evaluation method only evaluates the ice thickness at the current moment, without considering the formation and disappearance period of the ice layer, resulting in inaccurate bearing capacity. Summary of the invention

[0004] The purpose of the present invention is to provide an ice layer bearing capacity evaluation method for the ice layer growth and disappearance period in view of the problem that the existing bearing capacity evaluation method only evaluates the ice layer thickness at the current moment, does not take into account the growth and disappearance period of the ice layer, and thus leads to inaccurate bearing capacity.

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

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

[0007] The method comprises the following steps:

[0008] Step 1: Place the internal temperature monitoring device for the ice layer formation and disappearance period in the ice layer, use the temperature sensor 6 to monitor the temperature of the ice layer, and use the flow rate 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 rate η monitored by the flow rate sensor 9 w , and through η w The thickness of the ice layer in the ice-water mixing zone is obtained, Δx, which is expressed as:

[0011]

[0012] Among them, 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 4: Count the temperature sensors 6 that detect negative values, select the temperature sensor 6 farthest from the ice surface, and obtain the distance between the temperature sensor 6 and the ice surface, that is, the ice layer thickness d;

[0014] Step 5: During the monitoring time, the temperature sensor 6 that detects a negative value is continuously monitored. If the monitored temperature sensor 6 shows a non-negative value, the ice layer thickness d and Δx are subtracted, and the result obtained is the corrected ice layer thickness D. Otherwise, the ice layer thickness d and Δx are added, and the value obtained is the corrected ice layer thickness D.

[0015] Step 6: Use the corrected ice thickness D to calculate the ice bearing capacity P y , ice layer bearing capacity P y It is expressed as:

[0016]

[0017] Step 7: Obtain the safety factor μ according to the level of ice cracks;

[0018] Step 8: Use the safety factor μ to calculate the ice layer bearing capacity P y After correction, the corrected ice bearing capacity P is obtained. r , P r It is expressed as:

[0019] P r =μ·η·P y

[0020] Where η is the ice modulus correction factor.

[0021] Furthermore, the specific steps of determining the grade of the ice surface cracks in step eight and obtaining the safety factor μ according to the grade of the ice surface cracks are:

[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 with a safety factor μ of 0.81;

[0023] If the crack width is between 1mm and 3mm, the depth is between 10 and 20cm, and the ice surface is partially white, it is a secondary crack, and the safety factor μ is 0.68;

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

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

[0026] Furthermore, the device for monitoring the internal temperature during the formation and disappearance of the ice layer is a cylinder, a limiting hole 7 is provided on the device for monitoring the internal temperature during the formation and disappearance of the ice layer, and the temperature sensor 6 is arranged on the limiting hole 7.

[0027] Furthermore, the device for monitoring the internal temperature during the formation and disappearance of ice is also provided with a heating belt 8, and the heating belt 8 is spirally wound around the device for monitoring the internal temperature during the formation and disappearance of ice.

[0028] Furthermore, a solar panel 4 is provided on the internal temperature monitoring device during the ice formation and disappearance period.

[0029] Furthermore, the internal temperature monitoring device during the ice formation and disappearance period is a hollow structure, and the cavity is filled with foam glue 11.

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

[0031] Furthermore, the plurality of temperature sensors 6 are evenly arranged in a cross pattern on the left and right sides.

[0032] Furthermore, the plurality of temperature sensors 6 are evenly arranged in a spirally crossed manner.

[0033] Furthermore, the monitoring time is 60 to 100 minutes.

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

[0035] This application continuously monitors the temperature of the ice layer at the same point to see if there is any temperature change, and then determines which stage of the ice layer formation and disappearance period the ice layer belongs to, and calculates the impact of the ice layer formation and disappearance period on the ice layer thickness during the monitoring period, and corrects the ice layer thickness to obtain the bearing capacity. In addition, this application also classifies the cracks on the ice surface, obtains the corresponding safety factor, and then makes a secondary correction to the calculated bearing capacity. This application greatly improves the accuracy of the obtained bearing capacity by making two corrections to the ice layer thickness and bearing capacity respectively. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0037] Figure 2 This is a schematic diagram of the specific structure of the internal temperature monitoring device during the ice formation and disappearance period in this application;

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

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

[0040] Figure 5This is a schematic diagram of the correlation between the actual ice thickness and the calculated ice thickness results;

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

[0042] Figure 7 It is a schematic diagram of its bearing capacity under different ice thickness;

[0043] Figure 8 This is the temperature change trend chart at 0m;

[0044] Fig. 9 This is the temperature change trend chart of 0.3m;

[0045] Fig.10 This is the temperature change trend chart at 0.5m. DETAILED DESCRIPTION

[0046] It should be particularly noted that, in the absence of conflict, the various embodiments disclosed in this application can be combined with each other.

[0047] Specific implementation method 1: The present implementation method is a method for evaluating the bearing capacity of an ice layer during the ice layer growth and disappearance period. The method is implemented based on an internal temperature monitoring device during the ice layer growth and disappearance period. The internal temperature monitoring device during the ice layer growth and disappearance period is evenly provided with a plurality of temperature sensors 6. The bottom of the internal temperature monitoring device during the ice layer growth and disappearance period is provided with a flow rate sensor 9.

[0048] The method comprises the following steps:

[0049] Step 1: Place the internal temperature monitoring device for the ice layer formation and disappearance period in the ice layer, use the temperature sensor 6 to monitor the temperature of the ice layer, and use the flow rate sensor 9 to monitor the water flow under the ice layer;

[0050] Step 2: Set the monitoring time and take 5% of the monitoring time as the change time Δt;

[0051] Step 3: Obtain the water flow rate η monitored by the flow rate sensor 9 w , and through η w The thickness of the ice layer in the ice-water mixing zone is obtained, Δx, which is expressed as:

[0052]

[0053] Among them, ρ i 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;

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

[0055] Step 5: During the monitoring time, the temperature sensor 6 that detects a negative value is continuously monitored. If the monitored temperature sensor 6 shows a non-negative value, the ice layer thickness d and Δx are subtracted, and the result obtained is the corrected ice layer thickness D. Otherwise, the ice layer thickness d and Δx are added, and the value obtained is the corrected ice layer thickness D.

[0056] Step 6: Use the corrected ice thickness D to calculate the ice bearing capacity P y , ice layer bearing capacity P y It is expressed as:

[0057]

[0058] Step 7: Obtain the safety factor μ according to the level of ice cracks;

[0059] Step 8: Use the safety factor μ to calculate the ice layer bearing capacity P y After correction, the corrected ice bearing capacity P is obtained. r , P r It is expressed as:

[0060] P r =μ·η·P y

[0061] Where η is the ice modulus correction factor.

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

[0063] The monitoring device of this application is specifically implemented in three parts: 1. Temperature monitoring device 2. Cloud data platform 3. Data receiving device (such as Figure 1 ), where the temperature detection device has a built-in high-precision temperature sensor that can accurately measure within the range of 40℃-30℃. And a high-precision vibration flow velocity sensor that can accurately measure within the range of 40℃-0℃. The sensor has its own resistance sensing device and adopts a wired connection output method to connect to the data acquisition module to ensure the stability and accuracy of data transmission.

[0064] The exterior of the under-ice detection part of the temperature monitoring device is made of high and low temperature resistant material (PPR material), which has good high temperature resistance, cold resistance and mechanical strength. The outer layer is wrapped with a heating belt 8 from top to bottom. After later use, the device can be heated and retrieved for reuse. The internal temperature sensor connection line is reinforced and sealed with foam glue 11, and the end of the temperature sensor is sealed and reinforced with glass glue and external PPR pipe to ensure long-term use in extreme environments.

[0065] The upper circular device of the temperature monitoring device is equipped with an efficient data acquisition module and a corresponding system module, which can collect temperature data in real time and transmit the data to the cloud platform terminal through the wireless communication module. The system supports multiple communication protocols to ensure the stability of data transmission in different environments; the outside is equipped with corresponding power indicator lights 5, device main switch 1, heating switch 2, Type-C conversion interface 3 and solar panels 4. In order to ensure the long-term use of the data acquisition module, the device adopts a power supply solution combining efficient solar cells and rechargeable batteries, which can self-charge under sunny conditions and ensure normal operation on cloudy days or at night. The temperature sensor 6 is connected via a temperature sensor connection line 10.

[0066] This application also includes a set of supporting software systems, users can view temperature data in real time, generate data reports, and set alarm thresholds through mobile phone or computer applications, so as to detect abnormal temperature changes in time. At the same time, the monitoring device is simple in design and easy to install and maintain. Users can choose different installation depths and device density according to their needs (refer to Figure 4 ) to meet the monitoring requirements of different ice 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, the temperature monitoring device of the present application is used to collect temperature data at different times and different points (depths) in real time, and based on the existing temperature data at different points, it is determined whether the ice-water interface is frozen, and then the bearing capacity is determined.

[0069] If the temperature at a certain point on the interface becomes negative and lasts for 60 to 100 minutes, the water at that point has turned into ice. If the temperature at that point lasts for about 6 hours and shows a cooling trend, the ice at that point has a certain carrying capacity.

[0070] If the temperature at a certain point on the interface is 0°C, the temperature gradient of the ice layer between the upper and lower adjacent points is calculated. Combined with the heat flux density and the relationship between energy balance and heat flux density, the historical observation data is fitted using the least squares method to obtain the relationship between its relevant indicators and the water flow velocity. According to formulas (1)(2)(3)(4), it is possible to determine whether the ice-water interface is frozen. The energy balance equation at the bottom of the ice layer is:

[0071]

[0072] The calculation formula of ice water heat flux is as follows:

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

[0074] Ice-water heat exchange coefficient formula:

[0075]

[0076] Thickness of ice layer in ice-water mixing zone:

[0077]

[0078] Where: q iw is the heat flux density of ice water (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 ice thickness change rate; 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 velocity (unit: m / s); Δx is the ice thickness in the ice-water mixing zone (unit: m);

[0079] Through the calculation of the above empirical formula, combined with the real-time ice temperature and the ice thickness measured by actual ice sampling survey, it can be seen that the calculated ice thickness has a good correlation with the actual ice thickness (such as Figure 5 As shown in the figure, the modulus is fitted and analyzed. The lower the ice layer temperature, the higher the corresponding modulus. The bearing capacity of the ice layer is then estimated. The thicker the ice layer, the greater its bearing capacity (as shown in the figure). Figure 7 However, when calculating the bearing capacity of ice layers at different locations and degrees of integrity, the 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 crack: The crack width is less than 1mm, the depth is less than 10cm, and the ice surface is transparent;

[0084] Secondary cracks: crack width is between 1mm and 3mm, depth is between 10 and 20cm, and the ice surface is partially white;

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

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

[0087]

[0088] P r =μ·η·P y (6)

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

[0090] Therefore, this application proposes a device dedicated to monitoring the internal temperature of ice during its formation and disappearance 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 detect the temperature deep inside the ice layer, but also has good cold resistance and anti-interference ability, and can operate stably for a long time in extreme environments. Figure 5-Figure 7 The "x" here is the corrected ice thickness "D".

[0091] Example:

[0092] Temperature monitoring devices were deployed in a river area of ​​Songhua River in Heilongjiang Province, and the changes in ice layer at different points in the same period from December to February of a certain year were taken as an example. As shown in Table 1, around December 23, the thickness of the ice layer was about 35 cm; around January 10, the thickness of the ice layer was about 55 cm; around January 30, the thickness of the ice layer was about 86 cm.

[0093] Table 1 Temperature records at different points at different times

[0094]

[0095] Table 2 Bearing capacity of ice layer under different thickness conditions

[0096]

[0097] It should be noted that the specific implementation is only an explanation and description of the technical solution of the present invention, and cannot be used to limit the scope of protection of the rights. Any partial changes made according to the claims and description of the present invention should still fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers, characterized in that The method is implemented based on an internal temperature monitoring device during the formation and disappearance of ice layers, wherein a plurality of temperature sensors (6) are evenly arranged on the internal temperature monitoring device during the formation and disappearance of ice layers, and a flow rate sensor (9) is arranged at the bottom of the internal temperature monitoring device during the formation and disappearance of ice layers; The method comprises the following steps: Step 1: placing an internal temperature monitoring device for the ice layer during its formation and disappearance in the ice layer, using a temperature sensor (6) to monitor the temperature of the ice layer, and using a flow rate 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 rate η monitored by the flow rate sensor (9) w , and through η w The thickness of the ice layer in the ice-water mixing zone is obtained, Δx, which is expressed as: Among them, ρ i 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; Step 4: Count the temperature sensors (6) that detect negative values, select the temperature sensor (6) farthest from the ice surface, and obtain the distance between the temperature sensor (6) and the ice surface, that is, the ice layer thickness d; Step 5: During the monitoring time, the temperature sensor (6) that detects a negative value is continuously monitored. If the monitored temperature sensor (6) shows a non-negative value, the ice layer thickness d and Δx are subtracted, and the result obtained is the corrected ice layer thickness D. Otherwise, the ice layer thickness d and Δx are added, and the value obtained is the corrected ice layer thickness D. Step 6: Use the corrected ice thickness D to calculate the ice bearing capacity P y , ice layer bearing capacity P y It is expressed as: Step 7: Obtain the safety factor μ according to the level of ice cracks; Step 8: Use the safety factor μ to calculate the ice layer bearing capacity P y After correction, the corrected ice bearing capacity P is obtained. r , P r It is expressed as: P r =μ·η·P y Where η is the ice modulus correction factor.

2. The method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers according to claim 1, characterized in that The specific steps of obtaining the safety factor μ according to the grade of ice surface cracks in step eight 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 with a safety factor μ of 0.81; If the crack width is between 1mm and 3mm, the depth is between 10 and 20cm, and the ice surface is partially white, it is a secondary crack, and the safety factor μ is 0.68; If the crack width is greater than 3mm, the depth is greater than 20cm and the ice surface is severely whitened, it is a level 3 crack with a safety factor μ of 0.43; Otherwise, there is no crack and the safety factor μ is 0.

87.

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

4. The method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers according to claim 1, characterized in that The device for monitoring the internal temperature during the ice layer formation and disappearance period is also provided with a heating belt (8), and the heating belt (8) is spirally wound around the device for monitoring the internal temperature during the ice layer formation and disappearance period.

5. The method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers according to claim 1, characterized in that The internal temperature monitoring device during the ice formation and disappearance period is also provided with a solar cell panel (4).

6. The method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers according to claim 1, characterized in that The internal temperature monitoring device during the ice formation and disappearance period is a hollow structure, and the cavity is filled with foam glue (11).

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

8. The method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers according to claim 1, characterized in that The multiple temperature sensors (6) are evenly arranged in a cross pattern on the left and right sides.

9. The method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers according to claim 1, characterized in that The multiple temperature sensors (6) are evenly arranged in a spiral cross pattern.

10. The method for evaluating the bearing capacity of ice layers during the formation and decay period of ice layers according to claim 1, characterized in that The monitoring time is 60 to 100 minutes.

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