Simulation device for ice plug test of underwater concrete pipeline and test method thereof

Abstract

The application relates to a simulation underwater concrete pipeline ice plug test device and a test method thereof, and belongs to the technical field of underwater pipeline plugging tests. The test pipeline is composed of a concrete layer, two water isolation bodies are arranged in the test pipeline to separate the test pipeline into a water ice cavity section filled with water in the middle and upstream and downstream liquid cavity sections on the two sides; when the ice plug is formed, the two sides of the water ice cavity section are controlled to be subjected to equal pressure, and a refrigerant pipe is directly inserted into the water ice section to gradually change the water in the water ice section into an ice plug; after the ice plug is formed, a pressure difference is formed on the two sides of the ice plug, so that the formation of the ice plug under the underwater pressure and the situation of the ice plug subjected to the water head pressure after the ice plug is formed are completely simulated; the ice plug formation process and the process of the ice plug subjected to the one-way pressure after the ice plug is formed can be observed through an observation window, and powerful reference data for the actual underwater pipeline ice plug formation can be provided.

Description

Technical Field

[0001] This invention relates to a test device for simulating the formation of ice plugs in concrete pipes under water pressure underwater and their pressure-resistant sealing, belonging to the field of underwater pipe sealing test technology. Background Technology

[0002] During underwater pipeline maintenance, it is necessary to seal and isolate the pipeline; one method of this is to form a sealing body within the pipeline. For a sealing body formed in an underwater pipeline, it must both block water flow and withstand water head pressure. In recent years, an ice plug sealing technology has emerged, utilizing water's natural adaptability to pipelines and the natural physical properties of ice. However, there is currently a lack of reports on its practical application in large-diameter pipelines, as well as a lack of scientific methods for evaluating the sealing capability of ice plugs. Especially for large-diameter underwater pipelines, how to stably form ice plugs under a certain water head pressure, and the pressure-resistant sealing capability of the formed ice plug within the pipeline, are still lacking in practical reports.

[0003] Existing pipe ice-blocking testing devices are all designed for pipes visible on land, and all employ a kraft-type ice-block sleeve installed on the outer wall of the test pipe to form an ice block inside. Examples include a pipe ice-blocking testing device disclosed in Chinese Patent Publication No. CN110763272A and another ice-blocking testing device disclosed in Chinese Patent Publication No. CN211318272U, etc. However, these existing testing devices cannot test the sealing of pipes underwater under water pressure, where ice blockage occurs. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to simulate the formation of ice plugs in a pipeline under a certain water head pressure and obtain data on the pressure resistance and sealing capacity of the ice plugs after they are formed.

[0005] The technical solution proposed by this invention to solve the above-mentioned technical problems is as follows: A device for simulating underwater concrete pipe ice blockage test includes a test pipe consisting of a steel sleeve and a concrete layer attached to the inner wall of the steel sleeve, two pressure storage tanks for storing antifreeze and a refrigeration unit. Two water-isolated bodies, separated from each other and covering the cross-section of the test pipe, are arranged inside the test pipe. The test pipe between the inner sides of the two water-isolated bodies is filled with water, forming a water-ice-forming cavity section. An observation window is provided on the test pipe above the water-ice-forming cavity section. The test pipes outside the two water-isolated bodies are filled with antifreeze, forming an upstream liquid cavity section and a downstream liquid cavity section, respectively. Sealed end caps are provided at both ends of the test pipe. The pressure storage tanks are connected by pressure pipes. After passing through the end cap, the seal connects the upstream liquid chamber section and the downstream liquid chamber section. A refrigerant pipe is installed in the water-to-ice chamber section. Both ends of the refrigerant pipe are sealed and pass through the test pipe, connecting to the refrigerant inlet and outlet of the refrigeration unit. When an ice plug forms, the two pressure tanks apply the same pressure to the upstream and downstream liquid chamber sections to ensure equal pressure on both sides of the water-to-ice chamber section. Simultaneously, the refrigeration unit circulates refrigerant through the refrigerant pipe, causing the water in the water-to-ice section to gradually turn into an ice plug. After the ice plug forms, the two pressure tanks apply different pressures to the upstream and downstream liquid chamber sections to ensure unequal pressure on both sides of the ice plug. During the test, the condition of the ice plug is observed and recorded through the observation window.

[0006] Furthermore, the water barrier is a flexible water barrier plate, and a rubber sealing gasket is provided around the perimeter of the flexible water barrier plate that contacts the inner wall of the test pipe.

[0007] Furthermore, the water-blocking body is a rubber bladder with a variable volume, and the antifreeze fills the rubber bladder, causing the rubber bladder to form the upstream liquid cavity section and the downstream liquid cavity section respectively within the test pipe.

[0008] Furthermore, the flexible waterproofing sheet is made of rubber or plastic.

[0009] Furthermore, a connecting pipe is connected between the pressure pipes of the two pressure storage tanks, and a shut-off valve is installed on the connecting pipe.

[0010] Furthermore, sealing rings are provided at both ends of the refrigerant pipe where it passes through the test pipe, a water injection valve is provided on the test pipe above the water-ice-forming cavity section, the sealing end cap is a sealing flange, and the pressure storage tank is provided with a scale indicating volume change.

[0011] Furthermore, the refrigerant pipe is a stainless steel corrugated pipe.

[0012] The second technical solution proposed by this invention to solve the above-mentioned technical problem is: a method for simulating underwater concrete pipe ice blockage test using the device of the first technical solution, comprising the following steps:

[0013] 1) First, control the two pressure storage tanks to deliver antifreeze to the upstream and downstream liquid chamber sections respectively, so that the water-proof body fills the cross-section of the test pipe;

[0014] 2) Fill the test pipe between the two water-blocking bodies with water to form a water-ice cavity section;

[0015] 3) Continue to control the pressure storage tank to deliver antifreeze ice to the upstream and downstream liquid chamber sections respectively, with equal pressure applied. This pressure is the water head pressure specified in the test.

[0016] 4) Turn on the refrigeration unit and circulate refrigerant at the specified temperature into the refrigerant pipe to gradually turn the water in the water freezing section into an ice block. According to practice, adding a layer of insulation cotton to the outside of the steel cylinder can save energy.

[0017] 5) After the ice block forms, first open the observation window and mark the scale lines on the visible surface of the ice block;

[0018] 6) Control the two pressure storage tanks to apply different pressures to the upstream and downstream liquid chamber sections respectively, and make the pressure difference on both sides of the ice plug equal to the water head pressure specified in the test. During this process, observe and record the slippage or damage of the ice plug through the observation window.

[0019] Furthermore, in step 4), the volume change of antifreeze in the upstream graduated water tank 19 and the downstream graduated water tank 15 is calculated every 3 hours, and the water in the water-freezing section is determined to have all turned into ice blockage based on the volume change.

[0020] Furthermore, in step 6), the minimum ice plug length under a specified ice plug diameter and water head pressure is determined based on whether the ice plug has slipped or cracked.

[0021] Further, step 6) involves first draining the antifreeze from the upstream or downstream liquid chamber section, removing the sealed end cap at one end of the test pipe, and installing a displacement gauge in the upstream or downstream liquid chamber section; then applying pressure to the upstream or downstream liquid chamber section using only a pressure reservoir, and measuring the overall slippage and deformation of the ice plug using the displacement gauge.

[0022] The beneficial effects of this invention are as follows: Because a test pipe constructed of concrete layers is designed, and two water-blocking bodies are installed inside the test pipe to divide it into a water-ice-forming cavity section filled with water in the middle and upstream and downstream liquid cavity sections on either side; therefore, during ice plug formation, the two pressure storage tanks are controlled to pressurize the upstream and downstream liquid cavity sections respectively, ensuring equal pressure on both sides of the water-ice-forming cavity section. Simultaneously, refrigerant is circulated through a refrigerant pipe directly inserted into the water-ice-forming cavity section, causing the water in the water-ice-forming cavity section to gradually turn into an ice plug. The ice plug formation process can then be observed through an observation window on the test pipe. This invention fully simulates the formation of ice plugs under underwater pressure. After the ice plug forms, two pressure reservoirs are used to pressurize the upstream and downstream liquid chambers, creating a pressure difference on both sides of the ice plug. This simulates the underwater head pressure on an already formed ice plug (since in typical underwater pipes, only one side experiences head pressure after ice plugging). The observation window on the test pipe allows observation of the changes in the ice plug under unequal pressure (head pressure), such as sliding to one side or even rupturing. This experimental device accurately simulates the process of ice plug formation and subsequent sealing in underwater pipes under head pressure, providing valuable reference data for the safety and economic efficiency of ice plug formation in actual underwater pipes. Attached Figure Description

[0023] The following description, in conjunction with the accompanying drawings, illustrates the simulated underwater concrete pipe ice blockage test apparatus and its test method of the present invention.

[0024] Figure 1 This is a schematic diagram of the simulated underwater concrete pipe ice blockage test device in Example 1.

[0025] Figure 2 This is a schematic diagram of the simulated underwater concrete pipe ice blockage test device in Example 2.

[0026] Figure 3 This is a schematic diagram of the simulated underwater concrete pipe ice block test device in Example 3. Implementation Example 1

[0027] The simulated underwater concrete pipe ice blockage test device in this embodiment, such as Figure 1 As shown, the test pipeline includes a steel sleeve 1 and a concrete layer 2 attached to the inner wall of the steel sleeve 1, with shear reinforcement bars between the steel sleeve and the concrete. It also includes two pressure tanks 15 and 18 for storing antifreeze and a refrigeration unit 22. Two separate water-stop bodies covering the cross-section of the test pipeline are installed inside the pipeline. In this embodiment, the water-stop bodies are flexible water-stop plates 4, such as rubber or plastic plates. A rubber sealing gasket 5 is provided around the perimeter where the flexible water-stop plate 4 contacts the inner wall of the test pipeline.

[0028] like Figure 1 As shown, the test pipe between the inner sides of the two flexible baffles 4 is filled with water, forming a water-ice-forming cavity section 16. An observation window 9 is provided on the test pipe above the water-ice-forming cavity section 16. The observation window 9 is sealed with bolts before opening. The test pipe outside the two flexible baffles 4 is filled with antifreeze, forming an upstream liquid cavity section 10 and a downstream liquid cavity section 3, respectively. Sealing end caps 11 are provided at both ends of the test pipe. In this embodiment, the sealing end caps are sealing flanges. The sealing end cap 11 can be a flat plate or an arc-shaped plate.

[0029] Two pressure storage tanks 18 and 15 are respectively connected to the upstream liquid chamber section 3 and the downstream liquid chamber section 10 after passing through the end cap 11 with sealed pressure pipes. The water-to-ice chamber section 16 is equipped with a refrigerant pipe 8. In this embodiment, the refrigerant pipe 8 is a stainless steel corrugated pipe, but other types of pipes can also be used. The two ends of the refrigerant pipe 8 are sealed and pass through the test pipeline to connect to the refrigerant inlet and outlet of the refrigeration unit.

[0030] In this embodiment, sealing rings 6 are provided at both ends of the refrigerant pipe 8 where it passes through the test pipe; a water injection valve 7 is provided on the test pipe above the water-ice-forming cavity section 16; scales indicating volume changes are provided on the two pressure storage tanks 18 and 15; a drain valve 17 is provided on the test pipe below the water-ice-forming cavity section 16; and pressure pumps 13 and 14 are provided on the pressure pipes of the two pressure storage tanks 18 and 15 that respectively supply liquid to the upstream liquid cavity section 10 and the downstream liquid cavity section 3.

[0031] The simulated underwater concrete pipe ice blockage test method in this embodiment is as follows:

[0032] 1) First, control the two pressure storage tanks 18 and 15 to deliver antifreeze to the upstream liquid chamber section 3 and the downstream liquid chamber section 10 respectively, so that the two flexible baffles are evenly distributed across the cross-section of the test pipe.

[0033] 2) Water is injected into the test pipe between the two flexible baffles 4 on opposite inner sides through the water injection valve 7 to form a water-ice cavity section;

[0034] 3) Continue to control the two pressure storage tanks 18 and 15 to deliver antifreeze ice to the upstream liquid chamber section 3 and the downstream liquid chamber section 10 respectively to load equal pressure. This pressure is the water head pressure specified in the test.

[0035] 4) Turn on the freezer 22 and circulate refrigerant at a specified temperature into the refrigerant pipe 8 to cause the water in the water-ice-forming section 16 to gradually turn into an ice plug;

[0036] During this process, the volume change of antifreeze in the upstream pressure storage tank 18 and the downstream pressure storage tank 15 is calculated every 3 hours, and the water in the water-freezing section is determined to have all turned into ice based on the volume change.

[0037] 5) After the ice block forms, first open the observation window 9 and mark the scale lines on the visible surface of the ice block;

[0038] 6) Control the two pressure reservoirs 18 and 15 to load antifreeze at different pressures onto the upstream liquid chamber section 3 and the downstream liquid chamber section 10 respectively, ensuring that the pressure difference across the formed ice plug equals the test-specified head pressure (one method is to completely depressurize the downstream liquid chamber section 10 or the upstream liquid chamber section 3 until the pressure is zero, thus the pressure on the upstream liquid chamber section 3 or the downstream liquid chamber section 10 is the test-specified head pressure). During this process, observe and record the slippage and damage of the ice plug through the observation window 9. Based on the observed slippage or cracks, the minimum ice plug length under the test-specified ice plug diameter and head pressure can be determined.

[0039] The following are three sets of test results using the test apparatus of this embodiment and according to the test method:

[0040] The first set of tests: Keeping the diameter of the concrete pipe constant at 500mm, ice plugs of different lengths (50mm, 100mm, 150mm, 200mm, 250mm) were formed under a water pressure of 1.0MPa (ice formation temperature -30℃). The failure and slippage of ice plugs of different lengths under a horizontal thrust of 1.0MPa were then tested. During the loading process, if the ice plug broke or completely slipped from the inner wall of the concrete, it indicated that the ice plug of that size could not perform its sealing function. When the ice plug length increased to a certain size, the ice plug did not break and the overall slippage remained stable, indicating that this length was the minimum ice plug length that could meet the sealing requirements.

[0041] The second set of tests: keeping the concrete pipe diameter at 500mm and the ice-forming cavity length at 200mm constant, ice plugs of a specified size (ice-forming temperature -30℃) were formed under a water pressure of 1.0MPa. The ultimate sealing capacity of the ice plugs of this size under progressively increasing horizontal thrust was then tested. As the water head pressure gradually increased, the ultimate sealing capacity of the ice plugs of this size could be determined when they broke or completely slipped.

[0042] The third set of experiments: Keeping the concrete pipe diameter at 500mm and the ice-forming cavity section at 200mm constant, ice plugs of different temperatures were formed by varying the refrigerant temperature under a water pressure of 1.0MPa. The failure and slippage of ice plugs of the same size at different temperatures under a horizontal thrust of 1.0MPa were then tested. As the ice-forming temperature increases, the maximum temperature of the ice plug of this size can be determined when it breaks or completely slips. Example 2

[0043] The simulated underwater concrete pipe ice blockage test device in this embodiment, such as Figure 2The diagram shows a variation based on Example 1. The difference is that the two flexible water-blocking plates 4 and the rubber sealing gasket 5 are removed and replaced with a variable-volume rubber bladder 12. The rubber bladder 12 is filled with antifreeze and forms an upstream liquid cavity section 3 and a downstream liquid cavity section 10 in the test pipeline.

[0044] Obviously, the antifreeze inside the rubber bladder 12 in this embodiment can also be replaced with gas.

[0045] The method for conducting the test using the simulated underwater concrete pipe ice blockage test device in this embodiment is the same as in Embodiment 1, and will not be repeated here. Example 3

[0046] The simulated underwater concrete pipe ice blockage test device in this embodiment, such as Figure 3 As shown, this is a variation based on Embodiment 1, except that a connecting pipe 19 is connected between the pressure pipes of the two pressure storage tanks 18 and 15, and a shut-off valve 20 is installed on the connecting pipe. Thus, when using the simulated underwater concrete pipe ice blockage test device of this embodiment, in step 3), only one pressure storage tank 18 or 15 can be opened, and one pressure storage tank 18 or 15 can simultaneously supply antifreeze ice to the upstream liquid chamber section 3 and the downstream liquid chamber section 10, applying equal pressure; while in step 6), the shut-off valve 20 is closed, cutting off the connecting pipe 19.

[0047] The method for conducting the test using the simulated underwater concrete pipe ice blockage test device in this embodiment is the same as in Embodiment 1, and will not be repeated here. Example 4

[0048] The simulated underwater concrete pipe ice block test device in this embodiment is the same as that in Embodiment 1, Embodiment 2, or Embodiment 3. The difference is that the method of conducting the test using the simulated underwater concrete pipe ice block test device in this embodiment is slightly different from that in Embodiment 1, 2, and 3. The difference is that step 6) is replaced by: first emptying the antifreeze in the upstream liquid chamber section 3 or the downstream liquid chamber section 10, removing the closed end cap 11 at one end of the test pipe, and setting up a displacement gauge in the upstream liquid chamber section 3 or the downstream liquid chamber section 10; then supplying antifreeze to the upstream liquid chamber section 3 or the upstream liquid chamber section 10 with pressure through only one pressure storage tank (18 or 15), and measuring the overall slippage and deformation of the ice block through the displacement gauge.

[0049] The above description is only a preferred embodiment of the present invention, but the present invention is not limited thereto. All equivalent substitutions or modifications made to the concepts and technical solutions of the present invention should be covered within the protection scope of the present invention.

Claims

1. A device for simulating underwater concrete pipe ice blockage test, characterized in that: An underwater concrete pipe ice blockage test device includes a test pipe consisting of a steel sleeve and a concrete layer attached to the inner wall of the steel sleeve, two pressure tanks for storing antifreeze, and a chiller. Two separate water-blocking bodies are arranged inside the test pipe, filling its cross-section. The test pipe between the inner sides of the two water-blocking bodies is filled with water, forming a water-ice-forming cavity. An observation window is provided on the test pipe above the water-ice-forming cavity. The test pipes outside the two water-blocking bodies are filled with antifreeze, forming an upstream and downstream liquid cavity section, respectively. Sealed end caps are provided at both ends of the test pipe. The pressure tanks are connected to the end caps via sealed pressure pipes. The upstream and downstream liquid chamber sections, and the water-to-ice chamber section, are equipped with refrigerant pipes. The refrigerant pipes are sealed at both ends, pass through the test pipeline, and connect to the refrigerant inlet and outlet of the refrigeration unit. When an ice plug forms, two pressure tanks are controlled to apply the same pressure to the upstream and downstream liquid chamber sections to ensure equal pressure on both sides of the water-to-ice chamber section. Simultaneously, the refrigeration unit circulates refrigerant through the refrigerant pipes, causing the water in the water-to-ice chamber section to gradually turn into an ice plug. After the ice plug forms, the two pressure tanks are controlled to apply different pressures to the upstream and downstream liquid chamber sections to ensure unequal pressure on both sides of the ice plug. During the test, the condition of the ice plug is observed and recorded through the observation window.

2. The simulated underwater concrete pipe ice blockage test device according to claim 1, characterized in that: The water barrier is a flexible water barrier plate, and a rubber sealing gasket is provided around the perimeter of the flexible water barrier plate that contacts the inner wall of the test pipe.

3. The simulated underwater concrete pipe ice blockage test device according to claim 1, characterized in that: The water-blocking body is a variable-volume rubber bladder, and the antifreeze fills the rubber bladder, causing the rubber bladder to form the upstream liquid cavity section and the downstream liquid cavity section respectively within the test pipe.

4. The simulated underwater concrete pipe ice blockage test device according to claim 2, characterized in that: Flexible waterproofing sheets are made of rubber or plastic.

5. The simulated underwater concrete pipe ice blockage test device according to claim 1, 2 or 3, characterized in that: A connecting pipe is connected between the pressure pipes of the two pressure storage tanks, and a shut-off valve is installed on the connecting pipe.

6. The simulated underwater concrete pipe ice blockage test device according to claim 1, 2 or 3, characterized in that: The refrigerant pipe is equipped with sealing rings at both ends where it passes through the test pipe. A water injection valve is installed on the test pipe above the water-to-ice cavity section. The closed end cap is a sealing flange. The pressure storage tank is equipped with a scale indicating volume change. The refrigerant pipe is a stainless steel corrugated pipe.

7. A test method for the simulated underwater concrete pipe ice blockage test device as described in claim 1, characterized in that: Includes the following steps: 1) First, control the two pressure storage tanks to deliver antifreeze to the upstream and downstream liquid chamber sections respectively, so that the water-proof body fills the cross-section of the test pipe; 2) Fill the test pipe between the two water-blocking bodies with water to form a water-ice cavity section; 3) Continue to control the two pressure storage tanks to supply antifreeze ice to the upstream and downstream liquid chamber sections respectively, with equal pressure. This pressure is the water head pressure specified in the test. 4) Turn on the refrigeration unit and circulate refrigerant at a specified temperature into the refrigerant pipe to gradually turn the water in the water-freezing section into ice plugs; calculate the volume change of antifreeze in the upstream and downstream pressure storage tanks every 3 hours, and determine whether all the water in the water-freezing section has turned into ice plugs based on the volume change. 5) After the ice block forms, first open the observation window and mark the scale lines on the visible surface of the ice block; 6) Two pressure storage tanks apply different pressures to the upstream and downstream liquid chamber sections respectively, making the pressure difference on both sides of the ice plug equal to the water head pressure specified in the test. During this process, the ice slippage and damage are observed and recorded through the observation window.

8. The test method according to claim 7, characterized in that: In step 6), the minimum ice plug length and ice plug diameter under the water head pressure are determined based on the observed overall ice plug sliding distance.

9. The test method according to claim 7, characterized in that: Step 6) involves first draining the antifreeze from the upstream or downstream liquid chamber section, removing the sealed end cap at one end of the test pipe, and installing a displacement gauge in the upstream or downstream liquid chamber section; then applying pressure to the upstream or downstream liquid chamber section using only a pressure reservoir, and measuring the overall slippage and deformation of the ice plug using the displacement gauge.

Images