An experimental apparatus and method for simulating sand bed damage induced by pipeline leakage.

Abstract

This invention relates to the field of geotechnical engineering model testing technology, and discloses a test device and method for simulating sand bed failure induced by pipe leakage. The test device includes a sand box with at least one partition inside. A sand-containing cavity is formed between one partition and the side wall of the sand box, or between two adjacent partitions. A water-containing cavity is formed between at least one partition forming a sand-containing cavity and the side wall of the sand box. Each water-containing cavity has an overflow port and a water supply port on the sand box. A defective pipe horizontally penetrates the sand box and has a break in it. A first water supply component includes a first water tank and a second water tank. The first water tank is connected to one end of the defective pipe through a first water pipe, and the second water tank is connected to the other end of the defective pipe through a second water pipe. A second water supply component includes a third water tank, which is connected to the water supply port through a third water pipe. This invention solves the technical problem that existing technologies cannot reproduce the true evolution mechanism of sand bed fluidization under the alternating effects of external seepage and internal erosion.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering model testing technology, and in particular to a test apparatus and test method for simulating sand bed damage induced by pipeline leakage. Background Technology

[0002] Currently, underground pipelines are a core component of urban infrastructure. Their leakage has led to sand bed fluidization and damage, which has become a major factor in inducing geological disasters such as ground subsidence, seriously threatening the safety of urban operations. As global warming intensifies and extreme weather events such as heavy rainfall and storm surges become more frequent, groundwater levels rise. The pore water pressure in the sand layer exceeds the water pressure inside the pipeline, leading to internal erosion. This occurs when water from the sand layer seeps into the pipeline through cracks in the pipe, carrying fine particles that migrate and are lost with the flow. This results in loosening of the surrounding soil structure, reduced density, and a gradual decrease in bearing capacity. When rainfall ends and runoff recedes, the groundwater level drops, and the water pressure inside the pipeline exceeds the pore water pressure in the sand layer, causing external seepage. This occurs when pressurized fluid inside the pipeline seeps into the surrounding sand layer through cracks in the pipe. The seepage causes instability of sand particles and damage to the sand's structure, ultimately forming fluidization cavities around the pipeline. Internal erosion and external seepage are not isolated phenomena but are interconnected and alternate with water level fluctuations, jointly dominating the entire process of sand bed fluidization. Accurate reconstruction of their evolutionary patterns is a crucial prerequisite for underground pipeline leakage risk assessment and protective design.

[0003] Currently, research on sand bed fluidization induced by pipeline leakage mainly employs model testing. This method can intuitively present the physical process, provide realistic physical responses, and reduce research costs, making it an important means of revealing the core mechanism of sand bed fluidization. However, existing model testing methods can only simulate external seepage conditions and cannot reproduce the true evolution mechanism of sand bed fluidization under the alternating effects of external seepage and internal erosion. The test results deviate significantly from engineering realities and cannot provide reliable data support for underground pipeline safety assessments. Summary of the Invention

[0004] The technical problem to be solved by this invention is that the model test methods in the prior art can only simulate the external seepage condition and cannot restore the real evolution mechanism of sand bed fluidization under the alternating action of external seepage and internal erosion. The test results deviate significantly from the actual engineering situation and cannot provide reliable data support for the safety assessment of underground pipelines.

[0005] To address the aforementioned technical problems, this invention provides a test apparatus for simulating sand bed damage induced by pipeline leakage, comprising: A sand box, which has at least one partition inside, and a sand-containing cavity is formed between the partition and the side wall of the sand box or between two adjacent partitions for filling sand. At least one partition forming a sand-containing cavity forms a water-containing cavity between it and the side wall of the sand box. The partition forming the water-containing cavity is provided with multiple water-permeable holes, and the sand box in each water-containing cavity is provided with an overflow port and a water supply port. The defective pipe is horizontally penetrating the sand box and has a broken opening located inside the sand-containing cavity. The first water supply component includes a first water tank and a second water tank. The first water tank is connected to one end of the defective pipe through a first water pipe, and the second water tank is connected to the other end of the defective pipe through a second water pipe, so that water in the first water tank or water in the second water tank can flow between the first water tank and the second water tank. The second water supply component includes a third water tank, which is connected to the water supply port via a third water pipe for supplying water to the water storage chamber. A third valve is provided on the third water pipe.

[0006] Preferably, the test apparatus for simulating sand bed damage induced by pipeline leakage further includes: The first pressure measuring device is installed on the defective pipe and is used to measure the water pressure inside the defective pipe. Multiple second pressure measuring elements are provided. These multiple second pressure measuring elements are arranged sequentially above the rupture opening along the height direction of the sand box. The second pressure measuring element located at the bottom is in contact with the rupture opening. These multiple second pressure measuring elements are used to measure the water pressure at different heights from the rupture opening. An image acquisition device is located on the outside of the sand box and is used to acquire images of the sand bed inside the sand box. An overflow collection device, connected to the overflow outlet, is used to collect and count the volume of fluid overflowing from the overflow outlet; A sand collection device is installed on the first or second water pipe to collect sand particles inside defective pipes.

[0007] Preferably, the first water supply component further includes a first water storage tank and a first water pump; The first water tank is provided with a first partition to divide the inner cavity of the first water tank into a first water storage chamber and a first drainage chamber. The top of the first partition is reserved with a first overflow opening. The first water tank in the first water storage chamber is provided with a first water outlet and a first water inlet. One end of the first water pipe is connected to the first water outlet, and the other end of the first water pipe is connected to one end of the defective pipe. The inlet of the first water pump is connected to the first water storage tank, and the outlet of the first water pump is connected to the first water inlet through a seventh water pipe. The first drainage chamber is connected to the first water storage tank through a fourth water pipe.

[0008] Preferably, the second water supply component further includes a second water pump and a second water storage tank; The third water tank is equipped with a third partition to divide the inner cavity of the third water tank into a third water storage chamber and a third drainage chamber. A third overflow opening is reserved at the top of the third partition. The third water tank in the third water storage chamber is equipped with a third water outlet and a third water inlet. One end of the third water pipe is connected to the third water outlet, and the other end of the third water pipe is connected to the water supply port. The third drainage chamber is connected to the second water storage tank through a sixth water pipe. The second water tank is equipped with a second partition to divide the inner cavity of the second water tank into a second water storage chamber and a second drainage chamber. The second water tank in the second water storage chamber is equipped with a second water inlet and a fourth water inlet. A second overflow opening is reserved at the top of the second partition. One end of the second water pipe is connected to the second water inlet, and the other end of the second water pipe is connected to the other end of the defective pipe. The second drainage chamber is connected to the second water storage tank through a fifth water pipe. The inlet of the second water pump is connected to the second water storage tank, and the outlet of the second water pump is connected to the first branch pipe and the second branch pipe. The first branch pipe is connected to the third water inlet, and the second branch pipe is connected to the fourth water inlet. A second valve is installed on both the first and second branch pipes.

[0009] Preferably, the test device for simulating sand bed damage induced by pipeline leakage further includes a first lifting device, a second lifting device, and a third lifting device. The first lifting device is used to drive the first water tank to lift, the second lifting device is used to drive the second water tank to lift, and the third lifting device is used to drive the third water tank to lift. The first, second, third, fourth, fifth, sixth, and seventh water pipes, as well as the first and second branch pipes, are all flexible hoses.

[0010] Preferably, the rupture extends along the length of the defective pipe, and the width of the rupture gradually increases from the inside of the defective pipe to the outside of the defective pipe.

[0011] Preferably, the damaged area is covered with a sand-blocking net or water-soluble paper.

[0012] Preferably, the side wall of the sand box inside the water-containing cavity is provided with an opening that extends along the height direction of the sand box; The sand box at the opening is provided with multiple fixing holes, which are arranged in pairs. The two fixing holes in a pair are located on both sides of the overflow port, and the multiple pairs of fixing holes are arranged at intervals along the height direction of the sand box. The sand box also includes a baffle plate that covers the outside of the opening. The opening at the top of the baffle plate forms an overflow outlet. The baffle plate is provided with mounting holes corresponding to each fixing hole. Each mounting hole is fitted with a bolt, which passes through the mounting hole and the fixing hole in sequence.

[0013] Preferably, the fixing hole is a round hole, and the mounting hole is an elongated oval hole extending along the height direction of the sand box.

[0014] This invention provides a test method for simulating sand bed damage induced by pipeline leakage, using the aforementioned test apparatus for simulating sand bed damage induced by pipeline leakage, and includes the following steps: S1. Fill the sand chamber in layers, compact each layer and ensure that the soil is uniform to form a simulated sand bed; S2. The water supply pressure is adjusted by the first water supply component to create a water flow between the first water tank and the second water tank, thereby establishing an initial water pressure in the defective pipe. S3. Open the third valve and supply water from the third water tank to the water chamber through the second water supply component, so that the water pressure in the sand bed is higher than the initial water pressure in the defective pipe, and the water flows from the sand bed into the defective pipe. S4. Obtain the pressure measured by the first pressure measuring device and the second pressure measuring device, the sand bed image acquired by the image acquisition device, and the mass of sand particles collected by the sand particle collection device. S5. After the preset time is reached, close the third valve and adjust the water supply pressure of the first water supply component to allow the water in the defective pipe to permeate into the sand bed. S6. Acquire the pressure measured by the first pressure measuring device and the second pressure measuring device, the sand bed image acquired by the image acquisition device, and the fluid volume collected in the overflow acquisition device; S7. Repeat steps S2 to S6.

[0015] Compared with existing technologies, the experimental apparatus and method for simulating sand bed damage induced by pipeline leakage in this invention have the following advantages: This invention discloses an experimental apparatus and method for simulating sand bed damage induced by pipeline leakage. The defective pipeline horizontally penetrates a sand box, with its break located within the sand-containing cavity. A first water tank and a second water tank of a first water supply component are connected to both ends of the defective pipeline via first and second water pipes, respectively, allowing water to flow between the two tanks. Under external leakage conditions, the third valve is closed, and water flows through the break in the defective pipeline into the sand-containing cavity, accurately simulating the external leakage condition of water from the pipeline to the sand bed. Under internal corrosion conditions, the third valve is opened, and the water flowing between the first and second water tanks establishes initial water pressure within the defective pipeline, simulating the water pressure within a real pipeline environment, thus providing a more accurate simulation of the internal corrosion condition. The sand box is divided into a sand-containing cavity and a water-containing cavity by a partition. The partition corresponding to the water-containing cavity has multiple permeable holes. The third water tank of the second water supply component supplies water to the water-containing cavity via a third water pipe, and water can seep into the sand-containing cavity through the permeable holes, accurately simulating the internal corrosion condition of water from the sand bed to the pipeline. This invention, by adjusting the operating status of the third valve, the first water supply component, and the second water supply component, can simulate internal corrosion and external seepage conditions separately, and can also simulate the alternating effects of the two. It fully restores the real scenario in engineering practice where the sand bed is simultaneously affected by alternating internal corrosion and external seepage when the pipeline leaks, fundamentally solving the problem of the existing technology having a single test scenario and large deviation from reality.

[0016] Meanwhile, the sand box corresponding to the water-containing chamber is equipped with an overflow port, which can maintain a stable water level in the water-containing chamber and ensure that the intensity of the outflow of water seeping into the sand-containing chamber through the permeable holes is uniform, avoiding distortion of the internal corrosion simulation due to water level fluctuations; the first water supply component uses two water tanks connected to both ends of the defective pipe respectively, which can flexibly control the direction and flow rate of water in the pipe, accurately simulate the intensity of internal corrosion under different pipe operating conditions, and adapt to the test requirements of different engineering scenarios; the third valve can flexibly control the start and stop of water supply to the water-containing chamber and the water supply volume, which can realize precise switching and parameter adjustment of different operating conditions, improve the convenience of test operation, ensure the accuracy and repeatability of test data, and provide more comprehensive and reliable technical support for underground pipeline safety assessment.

[0017] In summary, this invention solves the technical problem that existing technologies can only simulate external seepage conditions and cannot reproduce the real evolution mechanism of sand bed fluidization under the alternating effects of external seepage and internal erosion. It effectively reduces the deviation between experimental results and engineering reality, and provides reliable data support for underground pipeline safety assessment. Attached Figure Description

[0018] Figure 1 This is a top view of the test apparatus according to an embodiment of the present invention; Figure 2 This is a front view of the test apparatus according to an embodiment of the present invention; Figure 3This is a schematic diagram of the third water tank according to an embodiment of the present invention; Figure 4 This is an arrangement diagram of the second pressure measuring element according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a defective pipe according to an embodiment of the present invention; Figure 6 This is an arrangement diagram of the first pressure gauge according to an embodiment of the present invention; Figure 7 This is a side view of the sand box according to an embodiment of the present invention; Figure 8 This is a three-dimensional structural diagram of the sand box according to an embodiment of the present invention.

[0019] In the diagram, 1. Sand box; 1a. Sand chamber; 1b. Water chamber; 1c. Overflow outlet; 1d. Fixing hole; 11. Divider; 12. Water baffle; 12a. Mounting hole; 13. Bolt; 2. Defective pipe; 21. Damaged opening; 22. Water-soluble paper; 3. First water supply assembly; 31a. First water pipe; 32a. Second water pipe; 33a. Fourth water pipe; 34a. Fifth water pipe; 35a. Seventh water pipe; 31. First water tank; 311. First partition; 311a. First water storage chamber; 311b. First drainage chamber; 311c. First overflow opening; 32. Second water tank; 321. Second partition; 321a. Second water storage chamber; 321b. Second drainage chamber; 321c. Second overflow opening; 33. First water storage tank; 34. First water... 35. Pump; 36. First valve; 37. First lifting device; 4. Second lifting device; 5. Second water supply assembly; 61a. Third water pipe; 42a. Sixth water pipe; 43a. First branch pipe; 44a. Second branch pipe; 41. Third water tank; 411. Third partition; 411a. Third water storage chamber; 411b. Third drainage chamber; 411c. Third overflow opening; 42. Second water pump; 43. Second water storage tank; 44. Second valve; 45. Third valve; 46. Third lifting device; 5. First pressure measuring device; 6. Second pressure measuring device; 7. Image acquisition device; 8. Overflow acquisition device; 9. Sand collection device; 10. Computer; 14. Data acquisition instrument; 15. Control console; 16. Fourth lifting device; 17. Third water inlet. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "bottom", "inner", "outer" and other terms used in this invention to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] It should be understood that the terms "first," "second," etc., are used in this invention to describe various types of information, but these terms are not limited to them; they are only used to distinguish information of the same type from one another. For example, without departing from the scope of this invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] like Figures 1 to 8 As shown, a test device for simulating sand bed damage induced by pipeline leakage according to a preferred embodiment of the present invention includes a sand box 1, a defective pipeline 2, a first water supply component 3, and a second water supply component 3.

[0025] like Figure 1 , Figure 2 , Figure 7 and Figure 8 As shown, the sand box 1 is provided with at least one partition 11. A sand-containing cavity 1a is formed between one partition 11 and the side wall of the sand box 1 or between two adjacent partitions 11, for filling with sand. In this embodiment of the invention, the sand box 1 is a cuboid box made of transparent acrylic sheet. There are two partitions 11, which are arranged at intervals along the length of the sand box 1, forming a sand-containing cavity 1a between the two partitions 11. A water-containing cavity 1b is formed between each partition 11 and the side wall of the sand box 1. The partitions 11 forming the water-containing cavity 1b are provided with multiple water-permeable holes. Specifically, in this embodiment of the invention, the partition 11 is a permeable mesh. The permeable mesh ensures water permeability while preventing sand from passing through it.

[0026] like Figure 1 , Figure 2 , Figure 7 and Figure 8As shown, each sand box 1 in the water-containing cavity 1b is provided with an overflow port 1c and a water supply port. Specifically, the water supply port is located at the bottom of the sand box 1 in each water-containing cavity 1b and is connected to the third water tank 41 through the third water pipe 41a. Under internal corrosion conditions, the second water supply component supplies water to the water-containing cavity 1b through the third water tank 41, the third water pipe 41a and the water supply port.

[0027] Specifically, such as Figure 1 , Figure 2 , Figure 7 and Figure 8 As shown, the sand box 1 inside the water-containing cavity 1b has an opening on its side wall, which extends along the height direction of the sand box 1; that is, the opening is located at both ends of the length direction of the sand box 1. The sand box 1 at the opening has multiple fixing holes 1d, which are arranged in pairs. The two pairs of fixing holes 1d are located on both sides of the overflow port 1c. The multiple pairs of fixing holes 1d are arranged at intervals along the height direction of the sand box 1. The sand box 1 also includes a baffle plate 12, which covers the outside of the opening. The opening at the top of the baffle plate 12 forms the overflow port 1c. The baffle plate 12 has mounting holes 12a corresponding to each fixing hole 1d. Each mounting hole 12a is fitted with a bolt 13, which passes through the mounting hole 12a and the fixing hole 1d in sequence. Multiple pairs of fixing holes 1d are distributed along the height direction of the sand box 1. Combined with the mounting holes 12a of the baffle plate 12 and the bolts 13, the fixing height of the baffle plate 12 can be changed by selecting fixing holes 1d of different heights, thereby adjusting the submerged water level of the sand bed under simulated external seepage and internal corrosion conditions.

[0028] Furthermore, such as Figure 7 As shown, the fixing hole 1d is a circular hole, and the mounting hole 12a is an elongated oval hole extending along the height direction of the sand box 1. The elongated mounting hole 12a, in conjunction with the circular fixing hole 1d, enables fine-tuning of the height of the baffle plate 12, improving the adjustment accuracy and thus allowing arbitrary adjustment of the simulated sand bed submersion water level.

[0029] Specifically, such as Figure 1 , Figure 2 , Figure 4 and Figure 5As shown, the defective pipe 2 horizontally penetrates the sand box 1. A break 21 is provided on the defective pipe 2, located within the sand-containing cavity 1a. The break 21 extends along the length of the defective pipe 2, and its width gradually increases from the inside to the outside of the defective pipe 2. A sand-blocking net or water-soluble paper 22 covers the break 21. When this test apparatus is used only to simulate a single external seepage condition, the sand-blocking net covers the break 21 to prevent sand from flowing into the pipe and being lost. When this test apparatus is used only to simulate a single internal corrosion condition or an external seepage-internal corrosion cycle condition, the water-soluble paper 22 covers the break 21. During sand bed filling, the water-soluble paper 22 covers the break 21 to prevent sand from entering the pipe and causing blockage before the test. After the test begins, the water-soluble paper 22 gradually dissolves, allowing sand to enter the pipe from the break 21, simulating an internal corrosion condition or an external seepage-internal corrosion cycle condition.

[0030] Specifically, such as Figure 1 and Figure 2 As shown, the first water supply component 3 includes a first water tank 31 and a second water tank 32. The first water tank 31 is connected to one end of the defective pipe 2 through a first water pipe 31a, and the second water tank 32 is connected to the other end of the defective pipe 2 through a second water pipe 32a, so that the water in the first water tank 31 or the water in the second water tank 32 can flow between the first water tank 31 and the second water tank 32. A first valve 35 is provided on both the first water pipe 31a and the second water pipe 32a.

[0031] Furthermore, such as Figure 1 and Figure 2 As shown, the first water supply assembly 3 also includes a first water storage tank 33 and a first water pump 34. The first water tank 31 is provided with a first partition 311 to divide the inner cavity of the first water tank 31 into a first water storage chamber 311a and a first drainage chamber 311b. A first overflow opening 311c is reserved at the top of the first partition 311. The first water tank 31 in the first water storage chamber 311a is provided with a first outlet and a first inlet. One end of the first water pipe 31a is connected to the first outlet, and the other end of the first water pipe 31a is connected to one end of the defective pipe 2. The inlet of the first water pump 34 is connected to the first water storage tank 33, and the outlet of the first water pump 34 is connected to the first inlet through a seventh water pipe 35a. The first drainage chamber 311b is connected to the first water storage tank 33 through a fourth water pipe 33a.

[0032] The second water tank 32 is provided with a second partition 321 to divide the inner cavity of the second water tank 32 into a second water storage chamber 321a and a second drainage chamber 321b. The second water tank 32 in the second water storage chamber 321a is provided with a second water inlet and a fourth water inlet. A second overflow opening 321c is reserved at the top of the second partition 321. One end of the second water pipe 32a is connected to the second water inlet, and the other end of the second water pipe 32a is connected to the other end of the defective pipe 2. The second drainage chamber 321b is connected to the second water storage tank 43 through a fifth water pipe 34a.

[0033] The first water pump 34 draws water from the first water tank 33 into the first water storage chamber 311a. The water then flows through the first water pipe 31a, the defective pipe 2, and the second water pipe 32a into the second water storage chamber 321a. When the first water storage chamber 311a is full, excess water flows over the first partition 311 into the first drainage chamber 311b, and then through the fourth water pipe 33a into the first water tank 33, ensuring a stable water level in the first water storage chamber 311a and thus ensuring stable and controllable pressure at the inlet of the defective pipe 2. When the second water storage chamber 321a is full, excess water flows over the second partition 321 into the second drainage chamber 321b, and then through the fifth water pipe 34a into the second water tank 43, ensuring a stable water level in the second water storage chamber 321a and thus ensuring stable and controllable pressure at the outlet of the defective pipe 2. This ensures stable and controllable water pressure differential within the defective pipe 2, guaranteeing stable test performance.

[0034] Furthermore, such as Figure 2 As shown, in this embodiment of the invention, by adjusting the relative height of the first water tank 31 and the second water tank 32, water flows between the first water tank 31 and the second water tank 32, and then flows through the defective pipe 2. Specifically, as... Figure 2 As shown, the test apparatus of this embodiment of the invention further includes a first lifting device 36 and a second lifting device 37. The first lifting device 36 is used to drive the first water tank 31 to rise and fall, and the second lifting device 37 is used to drive the second water tank 32 to rise and fall. By adjusting the height of the first water tank 31 and the second water tank 32, the magnitude of the pressure head difference in the defective pipe 2 can be controlled, thereby affecting the leakage flow rate.

[0035] Furthermore, such as Figure 1 and Figure 2 As shown, the second water supply assembly 4 includes a third water tank 41, which is connected to a water supply port via a third water pipe 41a for supplying water to the water storage chamber 1b. A third valve 45 is provided on the third water pipe 41a. Specifically, the second water supply assembly 4 also includes a second water pump 42 and a second water storage tank 43. The third water tank 41 is provided with a third partition 411 to divide the inner cavity of the third water tank 41 into a third water storage chamber 411a and a third drainage chamber 411b. The top of the third partition 411 is reserved with a third overflow opening 411c. The third water tank 41 in the third water storage chamber 411a is provided with a third outlet and a third inlet 17. One end of the third water pipe 41a is connected to the third outlet, and the other end of the third water pipe 41a is connected to the water supply port. The third drainage chamber 411b is connected to the second water storage tank 43 through a sixth water pipe 42a. The inlet of the second water pump 42 is connected to the second water storage tank 43. The outlet of the second water pump 42 is connected to a first branch pipe 43a and a second branch pipe 44a. The first branch pipe 43a is connected to the third inlet 17, and the second branch pipe 44a is connected to the fourth inlet. The first branch pipe 43a and the second branch pipe 44a are both provided with a second valve 44.

[0036] Under internal corrosion conditions, the height of the second water tank 32 is greater than that of the first water tank 31. The second water pump 42 draws water from the second water storage tank 43 and sends it through the first branch pipe 43a and the second branch pipe 44a into the third water storage chamber 411a and the second water storage chamber 321a. The water in the second water storage chamber 321a flows to the first water storage chamber 311a to simulate the initial water pressure in the defective pipe 2. Then, the third valve 45 is opened, and the water in the third water storage chamber 411a flows into the water container 1b through the third water pipe 41a for water supply to conduct the internal corrosion test. When the third water storage chamber 411a is full, the excess water passes over the third partition 411 and enters the third drainage chamber 411b, and then flows into the second water storage tank 43 through the sixth water pipe 42a to ensure the water level in the third water storage chamber 411a is stable, thereby ensuring that the pressure in the water container 1b is stable and controllable, and ensuring the smooth progress of the internal corrosion test.

[0037] Specifically, such as Figure 3 As shown, the experimental apparatus of this embodiment of the invention also includes a third lifting device 46, which is used to drive the third water tank 41 to rise and fall. By adjusting the height of the third water tank 41 and the sand box 1, the water pressure in the water-containing chamber 1b can be controlled, thereby affecting the amount of sand lost at the break 21.

[0038] Furthermore, such as Figure 2 As shown, the test apparatus of this embodiment of the invention also includes a fourth lifting device 16 and a control console 15. The first lifting device 36, the second lifting device 37, the third lifting device 46 and the fourth lifting device 16 are all electrically connected to the control console 15. The control console 15 can dynamically adjust the height of each lifting device in real time to realize the dynamic time-varying of water pressure.

[0039] Furthermore, such as Figure 1 and Figure 2As shown, the first water pipe 31a, the second water pipe 32a, the third water pipe 41a, the fourth water pipe 33a, the fifth water pipe 34a, the sixth water pipe 42a, the seventh water pipe 35a, the first branch pipe 43a, and the second branch pipe 44a are all flexible hoses, which can flexibly deform with the raising and lowering of the first water tank 31, the second water tank 32, the third water tank 41, and the sand box 1, avoiding the pipes from being rigidly stretched due to raising and lowering, and reducing the risk of pipe damage.

[0040] Furthermore, such as Figure 1 , Figure 2 and Figure 6 As shown, the test apparatus of this embodiment of the invention further includes a first pressure measuring element 5, a second pressure measuring element 6, an image acquisition device 7, an overflow acquisition device 8, and a sand collection device 9. The first pressure measuring element 5 is a first pore water pressure gauge, of which there are two. Both first pore water pressure gauges are installed on the defective pipe 2, located on the front and rear sides of the rupture opening 21, respectively, and are used to measure the water pressure inside the defective pipe 2 at its inlet and outlet.

[0041] Furthermore, such as Figure 1 , Figure 4 and Figure 6 As shown, the second pressure measuring element 6 is a second pore water pressure gauge, and multiple second pressure measuring elements 6 are arranged sequentially above the broken opening 21 along the height direction of the sand box 1, and are used to measure the water pressure at different heights from the broken opening 21; the second pressure measuring element 6 located at the bottom is in contact with the broken opening 21 and is used to measure the pore water pressure at the broken opening 21; the upper surface of the second pressure measuring element 6 located at the top is flush with the upper surface of the sand bed and is used to collect the residual water pressure after the fluid seeps through the interior of the sand bed.

[0042] The first and second pore water pressure gauges are encased in acrylic shells.

[0043] Furthermore, such as Figure 1 As shown, the image acquisition device 7 is an industrial camera, located on the outside of the sand box 1, used to acquire images of the sand bed inside the sand box 1. Specifically, by adjusting the height of the camera tripod and the camera angle, it is ensured that a complete image of the broken opening 21 of the defective pipe 2 and the sand bed above the broken opening 21 can be captured, and the movement process of the sand particles can be clearly captured.

[0044] Furthermore, such as Figure 1 and Figure 2 As shown, the overflow collection device 8 is a measuring cylinder, which is located below the overflow port 1c and connected to the overflow port 1c, and is used to collect and count the volume of fluid overflowing from the overflow port 1c.

[0045] Furthermore, such as Figure 1 and Figure 2As shown, the sand collection device 9 is a sand collector, which is installed on the first water pipe 31a and is used to collect sand particles that flow into the defective pipe 2 from the broken opening 21.

[0046] Furthermore, such as Figure 1 As shown, the experimental apparatus of this embodiment further includes a data acquisition device 14 and a computer 10. The data acquisition device 14 is a dynamic and static strain data acquisition device. Each first pressure measuring element 5 and each second pressure measuring element 6 are electrically connected to the data acquisition device 14 via transmission wires to transmit the acquired internal pressure data of the defective pipe 2 and the water pressure data at the rupture point 21 to the data acquisition device 14. The data acquisition device 14 is electrically connected to the computer 10 to transmit the internal pressure data of the defective pipe 2 and the water pressure data at the rupture point 21 to the computer 10. Simultaneously, the image acquisition device 7 is electrically connected to the computer 10 to transmit the acquired images to the computer 10.

[0047] like Figures 1 to 8 As shown, based on the above-described embodiments of the invention, an experimental apparatus for simulating sand bed damage induced by pipeline leakage is provided. The present invention also provides an experimental method for simulating sand bed damage induced by pipeline leakage, comprising the following steps: S1. Sand is filled in layers in the sand-containing cavity 1a, and each layer is compacted and made uniform to form a simulated sand bed. S2. The water supply pressure is adjusted by the first water supply component 3 to form a water flow between the first water tank 31 and the second water tank 32, thereby establishing an initial water pressure in the defective pipe 2. Simulate the internal corrosion condition: Activate the second lifting device 37 and the first lifting device 36, adjust the height of the second water tank 32 and the first water tank 31 so that the second water tank 32 is higher than the first water tank 31, and then open the first valve 35 on the first water pipe 31a and the second water pipe 32a and the second valve 44 on the second branch pipe 44a. The second water pump 42 pumps the water in the second water storage tank 43 to the second water storage chamber 321a. The water in the second water storage chamber 321a flows into the first water storage chamber 311a. The head difference between the second water tank 32 and the first water tank 31 forms the initial water pressure in the defective pipe 2, which is used to simulate the water pressure in the water supply pipe in reality.

[0048] S3. Open the third valve 45 and supply water to the water chamber 1b through the second water supply component 4, so that the water pressure in the sand bed is higher than the initial water pressure in the defective pipe 2, and the water flows from the sand bed into the defective pipe 2. Adjust the height of the baffle plate 12 so that its top is at the target height. Then, start the third lifting device 46 to adjust the height of the third water tank 41. Open the third valve 45 and the second valve 44 on the first branch pipe 43a. The second water pump 42 pumps the water in the second water tank 43 to the third water storage chamber 411a. The water in the third water storage chamber 411a enters the water receiving chamber 1b. When the water level reaches the top of the baffle plate 12, the water level in the water receiving chamber 1b reaches the target height to simulate the water pressure in the sand layer in reality.

[0049] S4. Obtain the pressure measured by the first pressure measuring element 5 and the second pressure measuring element 6, the sand bed image acquired by the image acquisition device 7, and the mass of sand particles collected by the sand particle collection device 9. Water continuously seeps into the sand layer from the water-receiving cavity 1b, causing the water pressure in the sand layer to be higher than that in the defective pipe 2. The water in the sand layer carries sand particles from the breach 21 into the defective pipe 2, and then flows with the water in the defective pipe 2 into the first water storage cavity 311a. The first pressure measuring device 5 measures the water pressure at the inlet and outlet of the defective pipe 2, the second pressure measuring device 6 measures the water pressure at different heights from the breach 21, the image acquisition device 7 acquires images of the sand bed, and the sand particle collection device 9 collects the sand particles in the first water pipe 31a. The pressure data determines the direction and driving force of internal erosion, the image data visually reveals the dynamic evolution process of soil internal structural damage, and the sand particle mass data accurately quantifies the severity of soil loss. The combination of these three methods can fully reveal the mechanism by which reverse seepage carries away sand particles, forms cavities in the soil, and ultimately leads to instability.

[0050] S5. After the preset time is reached, close the third valve 45 and adjust the water supply pressure of the first water supply component 3 so that the water in the defective pipe 2 can penetrate into the sand bed. After the preset time is reached, the internal corrosion test is completed, and the external seepage condition is simulated: the third valve 45, the second valve 44 on the first branch pipe 43a, the second valve 44 on the second branch pipe 44a, and the first valve 35 on the first water pipe 31a and the second water pipe 32a are closed. The height of the baffle plate 12 is adjusted, and the height of the first water tank 31 and the second water tank 32 are adjusted by the first lifting device 36 and the second lifting device 37 so that the height of the first water tank 31 is greater than that of the second water tank. The first water pump 34 transports the water in the first water tank 33 to the first water storage chamber 311a. The water in the first water storage chamber 311a flows through the first water pipe 31a, the defective pipe 2, and the second water pipe 32a into the second water storage chamber 321a. During this process, the water in the defective pipe 2 flows out from the broken opening 21, and the outflowing water flows into the water-containing chamber 1b through the sand bed and the separator 11.

[0051] S6. Acquire the pressure measured by the first pressure measuring device 5 and the second pressure measuring device 6, the sand bed image acquired by the image acquisition device 7, and the fluid volume collected in the overflow acquisition device 8. When the water level in the water-receiving cavity 1b is higher than the top of the baffle plate 12, excess water flows from the overflow port 1c into the overflow collection device 8. The first pressure measuring element 5 measures the water pressure at the inlet and outlet of the defective pipe 2, the second pressure measuring element 6 measures the water pressure at different heights from the damaged opening 21, the image acquisition device 7 acquires images of the sand bed, and the overflow collection device 8 collects the volume of liquid flowing out of the overflow port 1c. The driving force is obtained through pressure data, the seepage pattern is observed through image data, and the leakage result is accurately quantified through overflow volume data. Combining these three methods allows for a comprehensive analysis of how water flows through the soil and the resulting leakage under specific pressure.

[0052] Once the preset time has elapsed, the extravasation test is complete, and the next cycle begins.

[0053] S7. Repeat steps S2 to S6.

[0054] Repeat steps S2 to S6 above until the required number of cycles is reached or the sand bed is destroyed.

[0055] Furthermore, the test apparatus of this embodiment can not only simulate external seepage and internal corrosion cycles, but also perform a single internal corrosion test by executing steps S2 to S4; and perform a single external seepage test by executing steps S5 to S6.

[0056] In summary, the embodiments of the present invention provide a test device and test method for simulating sand bed damage induced by pipeline leakage. Under the external leakage condition, water flows through the broken opening 21 of the defective pipeline 2 and leaks into the sand in the sand-containing cavity 1a, accurately simulating the external leakage condition of water in the pipeline to the sand bed. Under the internal corrosion condition, the water flowing between the first water tank 31 and the second water tank 32 can establish an initial water pressure in the defective pipeline 2 to simulate the water pressure in the pipeline in the real environment, making the internal corrosion condition simulation more accurate. The sand box 1 forms a sand-containing cavity 1a and a water-containing cavity 1b through the partition 11. The partition 11 corresponding to the water-containing cavity 1b is provided with multiple water-permeable holes. The third water tank 41 of the second water supply component 4 supplies water to the water-containing cavity 1b through the third water pipe 41a. Water can seep into the sand in the sand-containing cavity 1a through the water-permeable holes, which can accurately simulate the internal corrosion condition of water in the sand bed leaking into the pipeline. This invention, by adjusting the operating states of the first valve 35, the second valve 44, the third valve 45, the first water supply component 3, and the second water supply component 4, can achieve separate simulation of internal corrosion and external seepage conditions, and can also simulate the alternating effects of the two. It fully restores the real scenario in actual engineering where the sand bed is simultaneously affected by alternating internal corrosion and external seepage when the pipeline leaks, fundamentally solving the problem of the existing technology having a single test scenario and large deviation from reality.

[0057] Meanwhile, the sand box 1 corresponding to the water chamber 1b is equipped with an overflow port 1c, which can maintain the water level in the water chamber 1b and ensure that the intensity of the outflow of water seeping into the sand chamber 1a through the permeable holes is uniform, avoiding the distortion of the internal corrosion simulation due to water level fluctuations; the first water supply component 3 uses two water tanks to connect to both ends of the defective pipe 2 respectively, which can flexibly control the direction and flow rate of water in the pipe, accurately simulate the intensity of internal corrosion under different pipe operating conditions, and adapt to the test requirements of different engineering scenarios; the third valve 45 can flexibly control the start and stop of water supply to the water chamber 1b and the water supply volume, which can realize the precise switching and parameter adjustment of different operating conditions, improve the convenience of test operation, ensure the accuracy and repeatability of test data, and provide more comprehensive and reliable technical support for underground pipeline safety assessment.

[0058] In summary, the embodiments of the present invention solve the technical problem that the prior art can only simulate external seepage conditions and cannot reproduce the real evolution mechanism of sand bed fluidization under the alternating effects of external seepage and internal erosion. It effectively reduces the deviation between experimental results and engineering reality and provides reliable data support for underground pipeline safety assessment.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A test apparatus for simulating sand bed damage induced by pipeline leakage, characterized in that, include: A sand box (1) is provided with at least one partition (11) therein, and a sand-containing cavity (1a) is formed between one of the partitions (11) and the side wall of the sand box (1) or between two adjacent partitions (11) for filling sand. At least one of the partitions (11) forming the sand chamber (1a) forms a water chamber (1b) between the partition (11) and the side wall of the sand box (1). The partition (11) forming the water chamber (1b) is provided with a plurality of water-permeable holes. The sand box (1) in each water chamber (1b) is provided with an overflow port (1c) and a water supply port. A defective pipe (2) is horizontally penetrating the sand box (1), and a broken opening (21) is provided on the defective pipe (2), which is located inside the sand-containing cavity (1a); The first water supply component (3) includes a first water tank (31) and a second water tank (32). The first water tank (31) is connected to one end of the defective pipe (2) through a first water pipe (31a), and the second water tank (32) is connected to the other end of the defective pipe (2) through a second water pipe (32a), so that the water in the first water tank (31) or the water in the second water tank (32) can flow between the first water tank (31) and the second water tank (32). The second water supply component (4) includes a third water tank (41), which is connected to the water supply port through a third water pipe (41a) and is used to supply water to the water chamber (1b). A third valve (45) is provided on the third water pipe (41a).

2. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 1, characterized in that, The experimental apparatus for simulating sand bed damage induced by pipeline leakage also includes: The first pressure measuring element (5) is installed on the defective pipe (2) and is used to measure the water pressure inside the defective pipe (2); Multiple second pressure measuring elements (6) are provided. Multiple second pressure measuring elements (6) are arranged sequentially above the break opening (21) along the height direction of the sand box (1). The second pressure measuring element (6) located at the bottom is in contact with the break opening (21). Multiple second pressure measuring elements (6) are used to measure the water pressure at different heights from the break opening (21). An image acquisition device (7) is located on the outside of the sand box (1) and is used to acquire images of the sand bed inside the sand box (1); An overflow collection device (8) is connected to the overflow port (1c) and is used to collect and count the volume of fluid overflowing from the overflow port (1c); A sand collection device (9) is installed on the first water pipe (31a) or the second water pipe (32a) for collecting sand particles in the defective pipe (2).

3. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 2, characterized in that, The first water supply component (3) also includes a first water storage tank (33) and a first water pump (34); The first water tank (31) is provided with a first partition (311) to divide the inner cavity of the first water tank (31) into a first water storage cavity (311a) and a first drainage cavity (311b). The top of the first partition (311) is reserved with a first overflow opening (311c). The first water tank (31) in the first water storage cavity (311a) is provided with a first outlet and a first inlet. One end of the first water pipe (31a) is connected to the first outlet, and the other end of the first water pipe (31a) is connected to one end of the defective pipe (2). The inlet of the first water pump (34) is connected to the first water storage tank (33). The outlet of the first water pump (34) is connected to the first inlet through a seventh water pipe (35a). The first drainage cavity (311b) is connected to the first water storage tank (33) through a fourth water pipe (33a).

4. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 3, characterized in that, The second water supply component (4) also includes a second water pump (42) and a second water storage tank (43); The third water tank (41) is provided with a third partition (411) to divide the inner cavity of the third water tank (41) into a third water storage chamber (411a) and a third drainage chamber (411b). The top of the third partition (411) is reserved with a third overflow opening (411c). The third water tank (41) in the third water storage chamber (411a) is provided with a third water outlet and a third water inlet (17). One end of the third water pipe (41a) is connected to the third water outlet, and the other end of the third water pipe (41a) is connected to the water supply port. The third drainage chamber (411b) is connected to the second water storage tank (43) through a sixth water pipe (42a). The second water tank (32) is provided with a second partition (321) to divide the inner cavity of the second water tank (32) into a second water storage chamber (321a) and a second drainage chamber (321b). The second water tank (32) in the second water storage chamber (321a) is provided with a second water inlet and a fourth water inlet. The top of the second partition (321) is reserved with a second overflow opening (321c). One end of the second water pipe (32a) is connected to the second water inlet, and the other end of the second water pipe (32a) is connected to the other end of the defective pipe (2). The second drainage chamber (321b) is connected to the second water storage tank (43) through a fifth water pipe (34a). The inlet of the second water pump (42) is connected to the second water storage tank (43), and the outlet of the second water pump (42) is connected to the first branch pipe (43a) and the second branch pipe (44a). The first branch pipe (43a) is connected to the third water inlet (17), and the second branch pipe (44a) is connected to the fourth water inlet. A second valve (44) is provided on both the first branch pipe (43a) and the second branch pipe (44a).

5. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 4, characterized in that, The test device for simulating sand bed damage induced by pipeline leakage also includes a first lifting device (36), a second lifting device (37), and a third lifting device (46). The first lifting device (36) is used to drive the first water tank (31) to rise and fall, the second lifting device (37) is used to drive the second water tank (32) to rise and fall, and the third lifting device (46) is used to drive the third water tank (41) to rise and fall. The first water pipe (31a), the second water pipe (32a), the third water pipe (41a), the fourth water pipe (33a), the fifth water pipe (34a), the sixth water pipe (42a), the seventh water pipe (35a), the first branch pipe (43a), and the second branch pipe (44a) are all flexible hoses.

6. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 1, characterized in that, The rupture (21) extends along the length of the defective pipe (2), and the width of the rupture (21) gradually increases from the inside of the defective pipe (2) to the outside of the defective pipe (2).

7. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 6, characterized in that, The damaged opening (21) is covered with a sand-blocking net or water-soluble paper (22).

8. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 1, characterized in that, An opening is provided on the side wall of the sand box (1) inside the water-containing cavity (1b), and the opening extends along the height direction of the sand box (1). The sand box (1) at the opening is provided with a plurality of fixing holes (1d). The plurality of fixing holes (1d) are arranged in pairs. The two pairs of fixing holes (1d) are located on both sides of the overflow port (1c). The plurality of fixing holes (1d) are arranged at intervals along the height direction of the sand box (1). The sand box (1) also includes a baffle plate (12), which covers the outside of the opening. The opening at the top of the baffle plate (12) forms the overflow port (1c). The baffle plate (12) is provided with mounting holes (12a) corresponding to each of the fixing holes (1d). Each mounting hole (12a) is fitted with a bolt (13), which passes through the mounting hole (12a) and the fixing hole (1d) in sequence.

9. The experimental apparatus for simulating sand bed damage induced by pipeline leakage according to claim 8, characterized in that, The fixing hole (1d) is a round hole, and the mounting hole (12a) is an elongated hole extending along the height direction of the sand box (1).

10. A test method for simulating sand bed damage induced by pipeline leakage, characterized in that, The experimental apparatus for simulating pipeline leakage-induced sand bed damage as described in claim 2 includes the following steps: S1. Sand is filled in layers in the sand-containing cavity (1a), each layer is compacted and the soil is made uniform to form a simulated sand bed; S2. The water supply pressure is adjusted by the first water supply component (3) to form a water flow between the first water tank (31) and the second water tank (32), thereby establishing an initial water pressure in the defective pipe (2); S3. Open the third valve (45) and supply water to the water chamber (1b) through the second water supply component (4) so ​​that the water pressure in the sand bed is higher than the initial water pressure in the defective pipe (2) and the water flows from the sand bed into the defective pipe (2). S4. Obtain the pressure measured by the first pressure measuring device (5) and the second pressure measuring device (6), the image of the sand bed acquired by the image acquisition device (7), and the mass of the sand collected by the sand collection device (9). S5. After the preset time is reached, the third valve (45) is closed, and the water supply pressure of the first water supply component (3) is adjusted so that the water in the defective pipe (2) can penetrate into the sand bed. S6. Obtain the pressure measured by the first pressure measuring device (5) and the second pressure measuring device (6), the sand bed image acquired by the image acquisition device (7), and the fluid volume collected in the overflow acquisition device (8); S7. Repeat steps S2 to S6.

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