A buried water pipe leakage testing system and method

Abstract

The application discloses a buried water pipe leakage testing system and method, and relates to the field of water pipe leakage testing. The testing system comprises a box body, which has an accommodating cavity inside; a buried water pipe, which is arranged along the extension direction of the accommodating cavity and has both ends extending out of the box body, wherein the part of the buried water pipe located in the accommodating cavity has a leakage hole communicating with the accommodating cavity; a pump body, which is connected with one end of the buried water pipe and is configured to pump water into the buried water pipe; a strain optical fiber, which is arranged in the accommodating cavity and is coupled with an optical fiber demodulator and is configured to sense the strain of the soil in the accommodating cavity; an electrical method monitor, which is coupled with a first electrode group and a second electrode group through an electrical method instrument base station, wherein the first electrode group and the second electrode group are symmetrically arranged on both sides of the accommodating cavity in the extension direction and are configured to sense the resistivity of the soil; and soil, which is filled in the accommodating cavity and is used for burying the buried water pipe, the first electrode group, the second electrode group and the strain optical fiber located in the accommodating cavity.

Description

Technical Field

[0001] This invention relates to the field of safety monitoring technology, and in particular to a buried water pipe leakage testing system and method. Background Technology

[0002] With the advancement of urbanization and the renovation of urban pipeline networks, buried pipelines and multi-pipeline integration have become the main directions of current pipeline transformation. Constructing new urban pipeline networks necessitates further innovation in safety testing technologies for buried pipelines. For most buried pipelines, soil stability is a crucial foundation affecting pipeline safety and plays a vital role in ensuring their safe and stable operation. During use, the damage to buried pipelines caused by the media within the pipeline and the surrounding geological conditions accumulates. This accumulated damage leads to reduced strength and structural damage, further impacting the safety of pipeline transmission, inducing leaks, and affecting the mechanical properties and stability of the surrounding soil. Over time, relatively soft soil layers, under conditions of disturbance from surface structures and human factors, face an increased risk of geological collapse. Therefore, researching leak detection technologies and evaluation methods for buried pipelines, and accurately assessing the risk of pipeline leaks, has significant practical application value for pipeline stability and environmental risk control.

[0003] Currently, the main methods for detecting buried pipelines are fluid identification sensors and fluid sensing devices. Traditional detection methods require pre-embedded sensors, have complex probe structures, require repeated installation, have low reliability, and are difficult to perform leak detection without disturbing the soil around the pipeline. Summary of the Invention

[0004] This solution addresses the problems and needs raised above by proposing a buried water pipe leakage testing system and method. Due to the adoption of the following technical features, it can achieve the above-mentioned technical objectives and bring about several other technical benefits.

[0005] One object of the present invention is to provide a buried water pipe leakage testing system, comprising:

[0006] The box has an internal cavity for receiving contents;

[0007] A buried water pipe is arranged along the extension direction of the receiving cavity, with both ends extending out of the box body, wherein the buried water pipe portion located inside the receiving cavity has a hole that communicates with the receiving cavity;

[0008] A pump body, which is connected to one end of the buried water pipe, is configured to pump water into the buried water pipe;

[0009] A strain fiber is arranged inside the cavity and coupled to a fiber optic demodulator, configured to sense the strain of the soil inside the cavity.

[0010] An electrical resistivity monitoring instrument is coupled to a first electrode group and a second electrode group via an electrical resistivity instrument base station. The first electrode group and the second electrode group are symmetrically arranged on both sides of the receiving cavity in the extension direction and configured to sense the resistivity of the soil. The first electrode group includes a plurality of first electrode units spaced apart along the depth direction, and the second electrode group includes a plurality of second electrode units spaced apart along the depth direction. The depth direction and the extension direction are perpendicular to each other.

[0011] The cavity is filled with soil to bury the buried water pipe, the first electrode group, the second electrode group, and the strain optical fiber located within the cavity.

[0012] In one example of the invention, it also includes: a computer.

[0013] One end of it is coupled to the electrical resistivity monitoring instrument, and the other end is coupled to the fiber optic demodulator. It is configured to receive the strain information and resistivity information of the soil, and to determine the risk of soil collapse caused by leakage based on the strain information and resistivity information of the soil.

[0014] In one example of the invention, it also includes: a DIC camera,

[0015] It is located on one side of the box and coupled to the computer. It is configured to collect real-time image information of the soil inside the box, and the computer processes the collected image information to determine the location of soil deformation after the buried water pipe leaks.

[0016] In one example of the present invention, the strain optical fiber is arranged along the extension direction of the buried water pipe and is positioned close to the buried water pipe.

[0017] In one example of the present invention, the strained optical fiber includes:

[0018] Optical fiber body;

[0019] The fiber coating layer coated on the outer wall of the optical fiber body; and

[0020] The optical fiber cladding layer covering the outside of the optical fiber coating layer.

[0021] In one example of the present invention, it further includes: a water-permeable filter screen.

[0022] It is laid on the lower side of the buried water pipe and is configured as a drainage box for draining accumulated water from the leaks in the buried water pipe.

[0023] Another objective of this invention is to provide a method for testing leakage in buried water pipes as described above, comprising the following steps:

[0024] S10: The resistivity ρ of the soil in the initial state within the enclosure was measured using a parallel electrical resistivity analyzer. (t) Simultaneously, the strain value ε of the soil surrounding the buried water pipe in the initial state was measured by strain optical fiber. (t) ;

[0025] S20: Strain δ on the soil surface due to the leak in the buried water pipe (t) The soil conductivity ρ was obtained after water leaked from the pipe. (i) Strain value ε in soil (i) Surface strain δ (i) Establish the relationship between the risk of ground subsidence caused by buried water pipe leakage and resistivity Δρ (t) and strain rate Δε (t) The functional relationship is used to quickly determine the risk of soil collapse caused by buried water pipe leakage.

[0026] In one example of the present invention, in step S10, the soil resistivity ρ (t) With voltage U (t) and current I (t) The relational expression is as follows:

[0027]

[0028] In one example of the present invention, in step S20, the strain rate Δε of the soil (t) The axial strain change of the soil is represented by a Bragg grating, and a temperature-compensated fiber is simultaneously deployed with the strain fiber to test the strain rate Δε of the soil deformation caused by different water contents. (t) The expression is as follows:

[0029]

[0030] Where Δλ is the wavelength variable of the emitted light in the Bragg grating region, λ is the center wavelength of the reflected light from the original Bragg grating center, and l ε l is the strain influence coefficient of the optical fiber material. T ΔT represents the temperature influence coefficient of the optical fiber material, and ΔT represents the temperature change.

[0031] In one example of the present invention, in step S20, the risk of ground subsidence due to leakage of buried water pipes is established in relation to resistivity Δρ. (t) and strain rate Δε (t) The functional relationship, where, based on the strain rate Δε (t) and resistivity Δρ (t) The expression for the early warning function of soil collapse risk due to changes in buried water pipe leakage is as follows:

[0032]

[0033] Where, Δρ(t) Δε is the change in soil resistivity per unit time. (t) The change in strain per unit time, s i This is the area unit for the measurement region.

[0034] The preferred embodiments of the invention will be described in more detail below with reference to the accompanying drawings, so as to facilitate an understanding of the features and advantages of the invention. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. The drawings are merely illustrative of some embodiments of the present invention and are not intended to limit the scope of the present invention to all embodiments.

[0036] Figure 1 This is a schematic diagram of the structure of a buried water pipe leakage testing system according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of a strain-insulated optical fiber according to an embodiment of the present invention;

[0038] Figure 3 The resistivity test results are based on an embodiment of the present invention.

[0039] Figure 4 This is a time-series characteristic diagram of fiber strain at the front of the resistivity contour plot according to an embodiment of the present invention;

[0040] Figure 5 This is a time-series characteristic diagram of fiber strain in the middle of the resistivity contour plot according to an embodiment of the present invention;

[0041] Figure 6 This is a time-series characteristic diagram of fiber strain at the rear of the resistivity contour plot according to an embodiment of the present invention;

[0042] Figure 7 This is a feature diagram of the early warning curve for ground subsidence caused by buried water pipes according to an embodiment of the present invention.

[0043] List of reference numerals in the attached diagram:

[0044] Test system 100;

[0045] Box 110;

[0046] Receiving cavity 111;

[0047] 120 buried water pipes;

[0048] Vulnerability 121;

[0049] Pump body 130;

[0050] 140 strain-insulated fiber;

[0051] Fiber optic body 141;

[0052] Fiber coating layer 142;

[0053] Fiber cladding layer 143;

[0054] Fiber optic demodulator 150;

[0055] Electrical resistance monitoring instrument 160;

[0056] Electrical resistivity meter base station 170;

[0057] First electrode group 180;

[0058] First electrode unit 181;

[0059] Second electrode group 190;

[0060] Second electrode unit 191;

[0061] Soil 200;

[0062] DIC camera 210;

[0063] Computer 220;

[0064] 230mm water-permeable filter screen;

[0065] Extending direction X;

[0066] Depth direction Y. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0068] Unless otherwise defined, technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which this invention pertains. The terms "first", "second" and similar terms used in the description and claims of this patent application for invention do not denote any order, quantity or importance, but are merely used to distinguish different components. Similarly, words such as "a" or "an" do not necessarily denote a quantity limitation. Words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms "connected" or "coupled" do not necessarily limit to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right" etc. are only used to indicate relative position relationships. When the absolute position of the described object changes, the relative position relationship may also change accordingly.

[0069] A buried water pipe leakage test system 100 according to the first aspect of the present invention, as Figure 1 shown, includes:

[0070] A box body 110 having an accommodation cavity 111 inside; it should be noted that an experimental box body 110 for making the buried water pipe 120 leak. The box body 110 is a cuboid with length L × thickness B × height H. The thickness of the soil mass 200 is h, the burial height of the water pipe is H0, and the burial heights of the optical fibers are H1, H2 and are parallel to the water pipe, where H1 < H0 < H2 < h.

[0071] A buried water pipe  120 arranged along the extension direction X of the accommodation cavity 111, and both ends thereof extend out of the box body 110. Among them, the part of the buried water pipe 120 located in the accommodation cavity 111 has a leak 121 communicating with the accommodation cavity 111;

[0072] A pump body 130, which is connected to one end of the buried water pipe 120 and is configured to pump water into the buried water pipe 120;

[0073] A strain optical fiber 140 arranged in the accommodation cavity 111 and coupled to an optical fiber demodulator 150, and is configured to sense the strain of the soil mass 200 in the accommodation cavity 111;

[0074] An electrical resistivity monitoring instrument 160 is coupled to a first electrode group 180 and a second electrode group 190 via an electrical resistivity instrument base station 170. The first electrode group 180 and the second electrode group 190 are symmetrically arranged on both sides of the receiving cavity 111 in the extension direction X, configured to sense the resistivity of the soil 200. The first electrode group 180 includes a plurality of first electrode units 181 spaced apart along the depth direction Y, and the second electrode group 190 includes a plurality of second electrode units 191 spaced apart along the depth direction Y. The depth direction Y is parallel to the extension direction X. They are perpendicular to each other; that is, when the electrical resistivity monitor 160 is monitoring, one of each first electrode unit 181 and each second electrode unit 191 serves as the emitter, and the remaining first electrode units 181 and second electrode units 191 serve as the receivers. For example, the first electrode group 180 includes five first electrode units 181, and the second electrode group 190 includes five second electrode units 191. That is, when one of the first electrode units 181 serves as the emitter, the remaining four first electrode units 181 and five second electrode units 191 all serve as receivers.

[0075] For example, the first electrode group 180 and the second electrode group 190 are arranged at both ends of the housing 110, and the first electrode group 180 and the second electrode group 190 are arranged at... At this location, B is the width of the box 110, which is evenly distributed along the edge of the soil 200 with a thickness of h.

[0076] The cavity 111 is filled with soil 200 for burying the buried water pipe 120, the first electrode group 180, the second electrode group 190 and the strain optical fiber 140 located in the cavity 111.

[0077] Water is pumped into the buried water pipe 120 by the pump body 130. The water flows through the portion of the buried water pipe 120 located in the receiving cavity 111 and leaks into the soil 200 through the hole 121. During this process, the resistivity ρ of the soil 200 in the initial state in the box 110 is tested using a parallel electrical resistivity analyzer 160. (t) Simultaneously, the strain value ε of the soil 200 surrounding the buried water pipe 120 in the initial state was measured by the strain fiber 140. (t) ; with the leakage of the buried water pipe 120, the surface strain δ of the soil 200 is... (t) After a water pipe leaked, the soil conductivity ρ was measured to be 200. (i) Strain value ε within 200 mm of soil (i) Surface strain δ (i) Establish the risk of ground subsidence caused by leakage of buried water pipe 120 and its resistivity Δρ t and strain rate Δε t The functional relationship is used to quickly determine the risk of soil collapse caused by a leak in the buried water pipe 120.

[0078] This invention addresses the issue by improving the efficiency and reducing the complexity of pipeline leak detection, and by establishing a joint evaluation method for soil deformation and resistivity. It innovatively employs a simple and accurate resistivity sensor and a highly sensitive and interference-resistant fiber optic grating sensor to continuously and undisturbedly test the changes in soil resistivity and strain during buried water pipe leaks. The location of the buried water pipe leak is determined by selecting the soil resistivity and fiber optic strain test results. By comparing the soil resistivity test value with the saturated resistivity test value in the leak area, and combining this with the fiber optic strain rate change, an evaluation index for ground subsidence caused by buried water pipe leaks is established. This quantifies the relationship between the risk level of ground subsidence and resistivity and strain rate, and proposes a comprehensive evaluation method for ground subsidence caused by buried water pipe leaks. Compared with existing methods, this method has the advantages of multiple evaluation indicators, high accuracy, and quantifiability, providing important reference value for risk assessment and research on ground subsidence caused by buried water pipe leaks.

[0079] The buried water pipe 120 leakage testing system 100 has the following beneficial effects:

[0080] (1) Using the experimental device of box 110, a leak monitoring experiment of buried water pipe 120 was carried out, and a resistivity-strain risk assessment method was established to conduct a risk assessment of ground collapse caused by the leak of buried water pipe 120.

[0081] (2) Due to the concealed nature of the leak in the buried water pipe 120, the accuracy of locating the leak area was improved by using parallel electrical resistivity monitoring and fiber optic strain monitoring.

[0082] (3) A solution for the arrangement of electrodes and optical fibers for monitoring leaks in buried water pipes 120 is proposed, which helps to comprehensively monitor the leak area by utilizing its monitoring characteristics and improve the accuracy of locating the leak area.

[0083] (4) By establishing the relationship between resistivity and strain, this method provides a way to locate the leak location of the buried water pipe 120 and provide a risk warning of ground subsidence caused by the leak of the buried water pipe 120.

[0084] In one example of the present invention, a computer 220 is also included.

[0085] One end of it is coupled to the electrical resistivity monitoring instrument 160, and the other end is coupled to the fiber optic demodulator 150. It is configured to receive the strain information and resistivity information of the soil 200, and to detect the risk of soil 200 collapse caused by leakage of the strain information and resistivity information of the soil 200.

[0086] In other words, the resistivity ρ of the soil 200 in the initial state within the enclosure 110 is measured using a parallel electrical resistivity meter 160. (t)Simultaneously, the strain value ε of the soil 200 surrounding the buried water pipe 120 in the initial state was measured by the strain fiber 140. (t) ; with the leakage of the buried water pipe 120, the surface strain δ of the soil 200 is... (t) After a water pipe leaked, the soil conductivity ρ was measured to be 200. (i) Strain value ε within 200 mm of soil (i) Surface strain δ (i) Establish the risk of ground subsidence caused by leakage of buried water pipe 120 and its resistivity Δρ t and strain rate Δε t The function relationship is used to quickly determine the risk of soil collapse caused by the leakage of the buried water pipe 120; the computer 220 can accurately determine the risk of soil collapse caused by the leakage of the buried water pipe 120.

[0087] In one example of the present invention, it also includes: a DIC camera 210,

[0088] It is located on one side of the box 110 and coupled to the computer 220. It is configured to collect real-time image information of the soil 200 inside the box 110, and the computer 220 processes the collected image information to determine the location of the deformation of the soil 200 after the buried water pipe 120 leaks.

[0089] For example, the DIC camera 210 is vertically arranged directly above the experimental setup, and the parallel electrochemical electrodes are arranged on the side of the water inlet and the opposite side of the water pipe, perpendicular to the water pipe.

[0090] In short, the DIC camera 210 can capture real-time images of the soil 200 inside the housing 110. When the buried water pipe 120 leaks, the soil 200 at the leak point will shrink in volume due to the influence of water, and correspondingly, the surface of the soil 200 perpendicular to the leak point will also become depressed. The DIC camera 210 can capture the changes on the surface of the soil 200 and determine the leak location of the buried water pipe 120 based on the deformation of the soil 200. By setting the DIC camera 210, the leakage test system 100 can determine the leakage location, and it is highly reliable and more intuitive.

[0091] In one example of the present invention, the strain optical fiber 140 is arranged along the extension direction X of the buried water pipe 120 and is disposed close to the buried water pipe 120.

[0092] By arranging the strain fiber 140 close to and along the extension direction X of the buried water pipe 120, the strain fiber 140 can accurately sense the strain changes of the soil 200 near the buried water pipe 120. Once a leak occurs at a certain point in the buried water pipe 120, the strain fiber 140 can accurately sense the strain changes of the soil 200, which helps to improve the testing accuracy of the leakage testing system 100.

[0093] In one example of the present invention, such as Figure 2 As shown, the strained optical fiber 140 includes:

[0094] Fiber optic body 141;

[0095] The optical fiber coating layer 142 coated on the outer wall of the optical fiber body 141; and

[0096] An optical fiber cladding layer 143 covering the outside of the optical fiber coating layer 142;

[0097] For example, the material of the optical fiber cladding layer 143 is polyvinyl chloride plastic; the material of the optical fiber coating layer 142 is epoxy resin;

[0098] Since the strain optical fiber 140 is buried in the soil 200, it needs to withstand the effects of changes in the soil 200. By coating the outside of the optical fiber body 141 with an optical fiber cladding layer and an optical fiber covering layer 143, the load-bearing limit of the optical fiber can be increased, the strain monitoring range can be improved, and the strain optical fiber 140 can adapt to the strain change of the strain optical fiber 140 caused by the leakage of the buried water pipe 120.

[0099] In one example of the present invention, it further includes: a water-permeable filter screen 230.

[0100] It is laid on the lower end side of the buried water pipe 120 and configured to drain the accumulated water from the hole 121 of the buried water pipe 120.

[0101] For example, a leak hole is opened at the lower end of the box 110, the permeable filter 230 is arranged on the leak hole, and the soil 200 is covered on the permeable filter 230, so that the leaked water is discharged through the permeable filter 230.

[0102] Since the leakage test system 100 is tested inside the housing 110, if the buried water pipe 120 leaks inside the housing 110, the water will accumulate in the containment cavity 111 of the housing 110 over time, which will affect the accuracy of the test. To avoid the above-mentioned impact, a permeable filter 230 is installed at the lower end of the buried water pipe 120 so that the leaked water can be effectively discharged from the housing 110 through the permeable filter 230.

[0103] According to a second aspect of the present invention, a method for testing the leakage of a buried water pipe 120 as described above includes the following steps:

[0104] Another objective of this invention is to provide a method for testing the leakage of buried water pipes as described above, comprising the following steps:

[0105] S10: The resistivity ρ of the soil 200 in the initial state within the enclosure 110 was measured using a parallel electrical resistivity meter 160. (t) Simultaneously, the strain value ε of the soil 200 surrounding the buried water pipe 120 in the initial state was measured by the strain fiber 140. (t) ;

[0106] S20: Surface strain δ of soil at 200 mm following leakage from buried water pipe 120. (t) After a water pipe leaked, the soil conductivity ρ was measured to be 200. (i) Strain value ε within 200 mm of soil (i) Surface strain δ (i) Establish the risk of ground subsidence caused by leakage of buried water pipe 120 and its resistivity Δρ (t) and strain rate Δε (t) The functional relationship is used to quickly determine the risk of soil collapse caused by a leak in the buried water pipe 120.

[0107] This method, based on parallel electrical resistivity testing and combined with high-sensitivity, high-precision, and interference-resistant fiber optic sensing technology, achieves simultaneous joint testing of resistivity and strain rate of change in soil mass 200 with varying water content. It proposes strain and resistivity of soil mass 200 as evaluation indicators for leakage in buried water pipe 120, and uses the resistance and strain changes of saturated soil mass 200 as a reference. Finally, a comprehensive risk assessment method for soil mass 200 collapse is established.

[0108] The 120mm leakage test method for buried water pipes has the following beneficial effects:

[0109] (1) Using the experimental device of box 110, a leak monitoring experiment of buried water pipe 120 was carried out, and a resistivity-strain risk assessment method was established to conduct a risk assessment of ground collapse caused by the leak of buried water pipe 120.

[0110] (2) Due to the concealed nature of the leak in the buried water pipe 120, the accuracy of locating the leak area was improved by using parallel electrical resistivity monitoring and fiber optic strain monitoring.

[0111] (3) A solution for the arrangement of electrodes and optical fibers for monitoring leaks in buried water pipes 120 is proposed, which helps to comprehensively monitor the leak area by utilizing its monitoring characteristics and improve the accuracy of locating the leak area.

[0112] (4) By establishing the relationship between resistivity and strain, this method provides a way to locate the leak location of the buried water pipe 120 and provide a risk warning of ground subsidence caused by the leak of the buried water pipe 120.

[0113] In one example of the present invention, in step S10, the soil resistivity ρ200 is... (t) With voltage U (t)and current I (t) The relational expression is as follows:

[0114]

[0115] In one example of the present invention, in step S20, the strain Δε of the soil 200 (t) The axial strain change of soil 200 is represented by a Bragg grating, and a temperature-compensated fiber is simultaneously arranged with the strain fiber 140 to test the strain Δε of soil 200 caused by different water contents. (t) The expression is as follows:

[0116]

[0117] Where Δλ is the wavelength variable of the emitted light in the Bragg grating region, λ is the center wavelength of the reflected light from the original Bragg grating center, and l ε l is the strain influence coefficient of the optical fiber material. T ΔT is the temperature influence coefficient of the optical fiber material, where ΔT is the temperature change.

[0118] In other words, a tightly packed grating sensor is used, with a coating and external fiber cladding to improve the tensile strength and measurement limit of the grating, to test the strain Δε of soil at a depth of 200 mm. (t) The strain Δε of the soil 200 is measured by a Bragg grating reflecting the axial strain change of the soil 200, and by a temperature-compensated fiber arranged simultaneously with the strain fiber 140, to measure the strain Δε of the soil 200 induced by different water contents. (t) .

[0119] In one example of the present invention, in step S20, the risk of ground subsidence caused by leakage of the buried water pipe 120 is established in relation to the resistivity Δρ. (t) and strain rate Δε (t) The functional relationship, where, based on the strain rate Δε (t) and resistivity Δρ (t) The expression for the early warning function of the risk of leakage of 120 buried water pipe and 200 soil collapse is as follows:

[0120]

[0121] Where, Δρ (t) Δε is the change in soil resistivity per unit time over a distance of 200 mm. (t) The change in strain per unit time, s i This is the area unit for the measurement region.

[0122] When Y (t) When exhibiting irregular fluctuations, this is reflected in the continuous increase of soil saturation strain as the soil moisture content increases, Y (t)When the soil moisture content increases steadily and tends to remain constant, it reflects that the soil moisture content remains constant and the strain also tends to remain stable, thus providing a risk warning for the collapse of buried water pipes.

[0123] A leakage warning is issued when the rate of change of strain and the rate of change of resistivity increase in a certain region per unit time, or when the strain shows an increasing trend and the resistivity shows a decreasing trend in a certain monitoring region. Specific Implementation

[0125] a. Constructing the experimental chamber 110 (see...) Figure 1 The dimensions of the manufactured box 110 are length L × thickness B × height H = 2000mm × 600mm × 1000mm. Water pipe arrangement holes are cut on the side of the box 110, and the height of the water pipe arrangement holes from the bottom of the box 110 is H0 = 500mm.

[0126] b. The arrangement of the grating and electrodes in the embodiment is shown in the figure. Figure 1 The specific process is as follows: First, a soil layer with a thickness of H0 = 500 mm is laid in the box 110, making it level with the height of the water pipe. Then, the strain monitoring fiber and temperature compensation fiber are buried at this height, and the soil is covered until the box 110 is full of soil.

[0127] Meanwhile, during the process of covering the enclosure 110 with soil, as the soil layer covers both ends of the enclosure 110, the electrodes used for resistivity testing are evenly distributed. The first electrode group 180 is arranged at the right end of the enclosure 110, and the second electrode group 190 is arranged at the left end. The electrodes are replaced with conductive copper sheets and are arranged at the interface between the soil 200 and the enclosure wall.

[0128] Afterwards, a thin layer of white paint was evenly sprayed onto the surface of the soil layer 110 of the container as a background color. After it dried, a thin layer of black paint was sprayed on as markers to form random black and white speckles. The images were then captured by camera 5 and stored for later analysis.

[0129] c. Conduct a 120mm leakage test experiment on buried water pipes. Specifically, a pressure water pump is used as the pressure source for water pipe leakage. The water pipe buried in the soil is filled with water at a constant pressure of 0.14 MPa for 200mm.

[0130] d. Simultaneously record the monitoring data of the grating and resistivity, and the DIC image of the soil surface at 200 mm during the water filling process.

[0131] e. Plot the time-series curve of fiber optic strain versus water pipe leakage based on the experimental data collected in step d (see...). Figure 4 ) and the final soil resistivity contour map of the water pipe leak (see Figure 3 ).

[0132] in, Figure 4 This represents the fiber strain time-series characteristics at the front of the resistivity contour plot. Figure 5 The resistivity contour plot shows the time-series characteristics of fiber strain in the optical fiber. Figure 6 This represents the fiber strain timing characteristics at the back of the resistivity contour plot.

[0133] Based on the characteristics of strain rate of change and resistivity rate of change, a functional relationship is established for the ground subsidence induced by the buried water pipe 120 based on the changes of both:

[0134]

[0135] like Figure 7 As shown, when the experiment was about 12,000 seconds in, the leakage of the buried water pipe 120 reached the point where the soil in the leakage area 200 was saturated with water, resulting in a high risk of ground collapse. Thereafter, the risk level continued to increase as the water pipe leaked.

[0136] Integrated buried water pipe 120 leakage resistivity cloud map ( Figure 3 This allows for a direct determination of the location of water pipe leaks and the area affected by water, based on the time-series characteristics of fiber optic strain changes in different regions. Figure 4 It can be seen that the fiber strain in the leakage region (the middle of the resistivity contour plot) shows an upward fluctuating trend, while in the influence zone before and after the leakage region, the fiber strain shows an increasing trend over time.

[0137] The foregoing description, with reference to preferred embodiments, details exemplary implementations of the buried water pipe 120 leakage testing system 100 and method proposed in this invention. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of this invention, and various combinations can be made to the various technical features and structures proposed in this invention without exceeding the protection scope of this invention, which is determined by the appended claims.

Claims

1. A method for testing leakage in buried water pipes, characterized in that, The testing system includes: The box (110) has an internal cavity (111). A buried water pipe (120) is arranged along the extension direction (X) of the receiving cavity (111) and both ends extend out of the box (110), wherein the buried water pipe (120) located in the receiving cavity (111) has a hole (121) that communicates with the receiving cavity (111). A pump body (130) is connected to one end of the buried water pipe (120) and is configured to pump water into the buried water pipe (120); A strain fiber (140) is arranged in the cavity (111) and coupled to a fiber demodulator (150) for sensing the strain of the soil (200) in the cavity (111). An electrical resistivity monitoring instrument (160) is coupled to a first electrode group (180) and a second electrode group (190) via an electrical resistivity instrument base station (170). The first electrode group (180) and the second electrode group (190) are symmetrically arranged on both sides of the receiving cavity (111) in the extension direction (X) and configured to sense the resistivity of the soil (200). The first electrode group (180) includes a plurality of first electrode units (181) arranged at intervals along the depth direction (Y), and the second electrode group (190) includes a plurality of second electrode units (191) arranged at intervals along the depth direction (Y). The depth direction (Y) and the extension direction (X) are perpendicular to each other. The cavity (111) is filled with soil (200) for burying the buried water pipe (120), the first electrode group (180), the second electrode group (190) and the strain optical fiber (140) located in the cavity (111). The testing method includes the following steps: S10: The resistivity of the soil (200) in the initial state within the enclosure (110) was tested using a parallel electrical resistivity meter (160). Simultaneously, the strain values ​​of the soil (200) surrounding the buried water pipe (120) in the initial state were measured by the strain fiber (140). ; S20: Surface strain of soil (200) due to leakage from buried water pipe (120). The conductivity of the soil (200) was obtained after water leaked from the water pipe. Strain values ​​within the soil (200) Surface strain Establish the risk of ground subsidence caused by leakage of buried water pipe (120) and resistivity. and strain rate The functional relationship is used to quickly determine the risk of soil (200) collapse caused by leakage of buried water pipe (120); Among them, the risk of ground subsidence caused by leakage of buried water pipe (120) and resistivity were established. and strain rate The functional relationship, where, based on strain rate and resistivity The expression for the early warning function of the risk of collapse of the soil (200) due to leakage from the changing buried water pipe (120) is as follows: in, This represents the change in soil resistivity (200) per unit time. The change in strain per unit time. This is the area unit for the measurement region.

2. The method for testing leakage in buried water pipes according to claim 1, characterized in that, Also includes: computers (220), One end of it is coupled to the electrical resistivity monitoring instrument (160), and the other end is coupled to the fiber optic demodulator (150). It is configured to receive the strain information and resistivity information of the soil (200), and to determine the risk of soil (200) collapse caused by the leakage of the buried water pipe (120) based on the strain information and resistivity information of the soil (200).

3. The method for testing leakage in buried water pipes according to claim 2, characterized in that, Also included: DIC camera (210). It is located on one side of the box (110) and coupled to the computer (220). It is configured to collect real-time image information of the soil (200) inside the box (110), and the computer (220) processes the collected image information to determine the location of the deformation of the soil (200) after the buried water pipe (120) leaks.

4. The method for testing leakage in buried water pipes according to claim 1, characterized in that, The strain optical fiber (140) is arranged along the extension direction (X) of the buried water pipe (120) and is positioned close to the buried water pipe (120).

5. The method for testing leakage in buried water pipes according to claim 1, characterized in that, The strained optical fiber (140) comprises: Optical fiber body (141); An optical fiber coating layer (142) coated on the outer wall of the optical fiber body (141); and The optical fiber cladding layer (143) covering the outside of the optical fiber coating layer (142).

6. The method for testing leakage in buried water pipes according to claim 1, characterized in that, Also includes: Water-permeable filter screen (230). It is laid on the lower end side of the buried water pipe (120) and configured to drain the accumulated water from the hole (121) of the buried water pipe (120) into the drain box (110).

7. The method for testing leakage in buried water pipes according to claim 1, characterized in that, In step S10, the resistivity of the soil (200) With voltage and current The relational expression is as follows: 。 8. The method for testing leakage in buried water pipes according to claim 1, characterized in that, In step S20, the strain rate of the soil (200) The axial strain change of the soil (200) is represented by a Bragg grating, and a temperature-compensated fiber is simultaneously arranged with the strain fiber (140) to test the strain rate of the soil (200) induced by different water contents. The expression is as follows: in, For the wavelength variation of the emitted light center in the Bragg grating region, The center wavelength of the light reflected from the center of the original Bragg grating. The strain influence coefficient of the optical fiber material. This refers to the temperature influence coefficient of the optical fiber material. This represents the change in temperature.

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