Method for monitoring and evaluating underground leakage of hydraulic structure

Abstract

The invention discloses a hydraulic structure underground leakage monitoring and evaluation method, which belongs to the field of structural health monitoring and comprises an optical fiber sensor arrangement method, a defect shape reconstruction method based on optical fiber sensor strain signals, a leakage infiltration range reconstruction method based on optical fiber sensor temperature signals and a leakage evaluation method. According to the method, optical fiber sensors are arranged on the surface of the hydraulic structure prone to leakage, then the defect shape and the leakage infiltration range are reconstructed according to optical fiber signals, and finally the leakage amount is evaluated by combining the soil moisture content, the leakage time and other information. The method has the advantage of accurately monitoring the leakage amount of the hydraulic structure in real time.

Description

Technical Field

[0001] The invention belongs to the field of structural health monitoring, in particular to a disease monitoring technology in hydraulic structure engineering, and more particularly to a method for monitoring and evaluating underground leakage of hydraulic structures. Background Art

[0002] Hydraulic structures often undertake a variety of key livelihood functions such as flood control, water supply, and power generation. However, hydraulic structures have long been affected by complex internal and external factors, and their performance has continued to deteriorate, gradually evolving into a major engineering safety issue that endangers people's lives and property safety and social operations. Among them, the leakage problem of hydraulic structures is one of the main reasons that affect their structural safety, cause water resource waste and serious environmental pollution, and must be monitored in real time and repaired in a timely manner.

[0003] Traditional methods for monitoring underground leakage in hydraulic structures mainly rely on regular manual inspections and local instrument measurements. These methods have problems such as low monitoring efficiency, discontinuous data, and difficulty in reflecting leakage in real time. In addition, due to the complex structure of hydraulic structures, the location of leakage points and the assessment of leakage have always been technical difficulties. Although the existing technology has achieved the identification and location of leakage points to a certain extent, it still needs to be improved in the accurate monitoring and assessment of leakage, which makes it difficult to control the scale of leakage in hydraulic structures in real time and determine the appropriate emergency repair plan in time.

[0004] In view of the above problems, the present invention aims to propose a method for monitoring and evaluating underground leakage of hydraulic structures. The method monitors the leakage points and leakage amount of hydraulic structures based on distributed optical fiber sensors, and accurately evaluates the real-time leakage amount of the leakage point after the leakage occurs by establishing the leakage point area-leakage time-leakage amount relationship, thereby realizing continuous monitoring and accurate evaluation of the leakage amount, thereby improving the monitoring efficiency and accuracy. This method can overcome the limitations of traditional methods, help to evaluate the underground leakage amount and leakage degree of hydraulic structures in real time, and provide more reliable technical support for the safe operation of hydraulic structures.

[0005] After review, very few of the published patents involve monitoring and evaluation of underground leakage of hydraulic structures. Some related patents are as follows:

[0006] CN116183461B discloses a method for monitoring seepage in a deep overburden of dam foundation erosion, wherein deep piezometers are arranged at possible erosion sites and technical piezometers are set along the entire seepage path to monitor seepage, but this method cannot monitor the amount of seepage; CN113758650B discloses a dam leakage detection system and a detection method thereof, wherein leakage data is collected by setting a leakage collection channel and a leakage collection pool in conjunction with a dam leakage detection sensor assembly, and the method can accurately measure the dam leakage, but cannot identify and locate the leakage point; CN118863269A discloses a method, device, equipment and medium for monitoring reservoir leakage, wherein the leakage loss parameter and the reference leakage loss parameter are used to determine whether there is abnormal leakage in the pumped storage power station reservoir Phenomenon, but this method cannot be applied to leakage monitoring of some complex buried hydraulic structures; CN114152391B discloses a leakage performance characterization method for composite pressure vessels based on optical fiber sensing, which mentions the need to establish a structural strain-leakage performance correlation, however, the leakage of some water transfer projects usually depends on unilateral water pressure, soil properties, leakage time, etc., and is not strongly correlated with structural strain, and the correspondence between the structural surface strain field and the crack width, depth, etc. is a nonlinear relationship, and it is expected that there will be significant errors in the implementation process; CN118623242A discloses a DMA regional leakage monitoring and management method and system based on a water supply network, which evaluates the leakage by monitoring the water supply network model through an algorithm, but it still needs to be compared with the actual situation to determine its reliability. Summary of the invention

[0007] According to the problem that the existing methods mentioned above are difficult to test the leakage of hydraulic structures, a method for monitoring and evaluating underground leakage of hydraulic structures is provided to provide more reliable technical support for the safe operation of hydraulic structures.

[0008] The present invention provides a method for monitoring and evaluating underground leakage of hydraulic structures, which is characterized in that the steps of monitoring and evaluating underground leakage of hydraulic structures are as follows:

[0009] Step 1: Place the fiber optic sensor on the hydraulic structure; Step 2: Reconstruct the defect shape of the hydraulic structure based on the strain signal of the fiber optic sensor; Step 3: Reconstruct the leakage infiltration range based on the temperature signal of the fiber optic sensor; Step 4: Calculate the underground leakage of the hydraulic structure.

[0010] Preferably, the method can be used for leakage monitoring of hydraulic structures such as dams, sluices, pumping stations, water diversion (supply) tunnels, aqueducts, water pipelines, channels, revetments, hydropower station buildings, breakwaters, and ship locks, and can also be used for anti-seepage monitoring of civil engineering buildings such as basements, underground parking floors, bridges, tunnels, subways, and underground passages.

[0011] Furthermore, the step 1 will adopt a method for arranging optical fiber sensors, including: containing water inside the outer wall of the hydraulic structure, when the outer wall of the hydraulic structure is damaged, the water at the damaged part of the hydraulic structure flows out and penetrates into the soil, and forms a leakage infiltration range; a No. 1 distributed strain and temperature optical fiber sensor group is pasted on the surface of the outer wall of the hydraulic structure, and a No. 1 distributed temperature optical fiber sensor, a No. 2 distributed temperature optical fiber sensor, and a No. 3 distributed temperature optical fiber sensor are arranged in sequence from near to far in the soil around the outer wall of the hydraulic structure.

[0012] Preferably, the distributed strain and temperature optical fiber sensor group No. 1 adopts a dual-mounted optical fiber that can measure strain and temperature separately, but it is also possible to choose a method of arranging a strain sensing optical fiber and a temperature sensing optical fiber in parallel, or any other sensor that can distinguish between strain signals and temperature signals.

[0013] Preferably, the No. 1 distributed temperature fiber optic sensor, the No. 2 distributed temperature fiber optic sensor, and the No. 3 distributed temperature fiber optic sensor should adopt armored temperature fiber optic sensors, or any temperature fiber optic sensor or demodulation technology that can shield strain signals.

[0014] Preferably, the number of the distributed temperature optical fiber sensors is at least three, and more than three may be arranged depending on the amount of water inflow to the hydraulic structure.

[0015] Furthermore, the distributed strain and temperature optical fiber sensor group No. 1 includes distributed strain and temperature optical fiber sensor group No. 1, distributed strain and temperature optical fiber sensor group No. 2, and distributed strain and temperature optical fiber sensor group No. 3, all of which are closely connected to the outer wall of the hydraulic structure.

[0016] Preferably, the number of the No. 1 distributed strain and temperature optical fiber sensor group is at least 3. Depending on the scale of the hydraulic structure and the area to be monitored, more than 3 sensors may be arranged. The arrangement may also be in a variety of ways including parallel array, orthogonal grid, and diamond grid.

[0017] Furthermore, the step 2 adopts a defect shape reconstruction method based on the strain signal of the optical fiber sensor, including: identifying the connection area of ​​the intersection point 1 between the leakage surface of the hydraulic structure and the No. 1 distributed strain and temperature optical fiber sensor group, the intersection point 2 between the leakage surface of the hydraulic structure and the No. 1 distributed strain and temperature optical fiber sensor group, the intersection point 3 between the leakage surface of the hydraulic structure and the No. 1 distributed strain and temperature optical fiber sensor group, and the intersection point 4 between the leakage surface of the hydraulic structure and the No. 1 distributed strain and temperature optical fiber sensor group as the leakage area, and the location of each intersection is determined by the peak position of the strain curve measured by the No. 1 distributed strain and temperature optical fiber sensor group;

[0018] As a preferred method, the strain transfer theory can be used to directly interpret the width of the damage surface, such as the second-order Gaussian crack width calculation formula:

[0019]

[0020] The strain curve is fitted into the above formula, and the obtained Δt is the crack width, and λ is the shear hysteresis coefficient of the optical fiber sensor.

[0021] The first-order Gaussian crack width calculation formula can also be used:

[0022] y=Δt·e -λx

[0023] Furthermore, the step three will adopt a leakage infiltration range reconstruction method based on the temperature signal of the optical fiber sensor, including: identifying the range of change in the temperature curve of the No. 1 distributed temperature optical fiber sensor, the No. 2 distributed temperature optical fiber sensor, and the No. 3 distributed temperature optical fiber sensor as the leakage infiltration range.

[0024] Furthermore, the step 4 will adopt a method for calculating underground leakage of hydraulic structures, and the calculation formula for the leakage is:

[0025]

[0026] Among them, V leak is the leakage, A hole is the leakage area (m 2 ), ρ is the density of water (kg / m 3 ), ΔP is the water pressure (Pa), and f(k) is a function that takes into account the influence of soil permeability and is related to the specific structure.

[0027] Preferably, the best conditions for using the above formula are: the soil is saturated, homogeneous, and conforms to Darcy's seepage law; the complex seepage in the soil around the leakage port can be simplified to a spherical leakage model with the leakage port as the point source; the surface of the hydraulic structure is considered to be an impermeable boundary.

[0028] Preferably, if the hydraulic structure refers to a water transmission and regulation pipeline, the formula for obtaining f(k) is:

[0029]

[0030] Among them, d p is the diameter of the pipe.

[0031] Preferably, if the hydraulic structure refers to a dam, f(k) can be determined by a numerical simulation method.

[0032] As a preference, if the difference between the actual flow rate and the theoretical flow rate is taken into account, the seepage flow calculation formula can be changed to:

[0033]

[0034] Among them, C d is a dimensionless coefficient that indicates the operating efficiency of the fluid system, C d =Q a / Q t , where Q a is the actual flow rate, Q t is the theoretical flow rate.

[0035] Compared with the prior art, the advantages and positive effects of the present invention are:

[0036] The present invention provides a method for monitoring and evaluating underground leakage of hydraulic structures. Compared with the prior art, the present invention uses distributed optical fiber sensor technology to achieve continuous monitoring of leakage points and leakage amounts of hydraulic structures, which is more efficient than traditional intermittent or periodic monitoring methods. The present invention establishes a relationship model between leakage point area, leakage time and leakage amount, and can accurately evaluate the real-time leakage amount after leakage occurs, thereby improving the accuracy of leakage assessment. The present invention can evaluate the underground leakage amount and leakage degree of hydraulic structures in real time, providing timely technical support for the safe operation of hydraulic structures. By timely discovering and evaluating leakage problems, corresponding maintenance measures can be taken, thereby extending the service life of hydraulic structures, reducing unnecessary maintenance work, and thus reducing maintenance costs. When leakage occurs, by using the technology involved in the present invention, a rapid response to leakage diseases can be achieved, and measures can be taken in time to reduce potential safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced one by one below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0038] Figure 1 A schematic side view of an optical fiber arrangement for monitoring leakage in a hydraulic structure provided in Example 1;

[0039] Figure 2 A surface schematic diagram of an optical fiber arrangement for monitoring leakage in a hydraulic structure provided in Example 1;

[0040] Figure 3 A schematic diagram of monitoring leakage in a water supply and drainage pipeline provided in Example 2;

[0041] Figure 4 A schematic diagram of dam leakage monitoring provided in Example 3.

[0042] In the above figures, 1. Water body; 2. Outer wall of hydraulic structure; 3. Water body at the damaged part of hydraulic structure; 4. No. 1 distributed strain and temperature optical fiber sensor group; 5. No. 1 distributed temperature optical fiber sensor; 6. No. 2 distributed temperature optical fiber sensor; 7. No. 3 distributed temperature optical fiber sensor; 8. Leakage and infiltration range; 9. Soil body; 10. Water body in pipeline; 11. Outer wall of pipeline; 12. Water body at the damaged part of pipeline; 13. Pipeline leakage and infiltration range; 14. Soil body around pipeline; 15. No. 1 distributed strain and temperature optical fiber sensor around pipeline; 16. No. 1 distributed temperature optical fiber sensor around pipeline; 17. No. 2 distributed temperature optical fiber sensor around pipeline; 18. No. 3 distributed temperature optical fiber sensor around pipeline; 19. Water body at the damaged part of dam; 20. No. 1 distributed strain and temperature optical fiber sensor on dam body surface; 21. No. 1 distributed temperature optical fiber sensor on dam body surface ; 22. No. 2 distributed temperature optical fiber sensor on the dam body surface; 23. No. 3 distributed temperature optical fiber sensor on the dam body surface; 24. Leakage and infiltration range of the dam body; 25. Water body upstream of the reservoir area; 26. Dam body; 27. Water body downstream of the reservoir area; 28. Soil around the dam foundation; 41. No. 1 distributed strain and temperature optical fiber sensor in group; 42. No. 2 distributed strain and temperature optical fiber sensor in group; 43. No. 2 distributed strain and temperature optical fiber sensor in group; 44. Leakage surface of hydraulic structure; 45. Intersection point 1 of the leakage surface of hydraulic structure and No. 1 distributed strain and temperature optical fiber sensor group; 46. Intersection point 2 of the leakage surface of hydraulic structure and No. 1 distributed strain and temperature optical fiber sensor group; 47. Intersection point 3 of the leakage surface of hydraulic structure and No. 1 distributed strain and temperature optical fiber sensor group; 48. Intersection point 4 of the leakage surface of hydraulic structure and No. 1 distributed strain and temperature optical fiber sensor group. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0044] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0045] Example 1: This example is intended to implement an example of an optical fiber arrangement that can be used for monitoring leakage in hydraulic structures. Figures 1-2When arranging the optical fiber sensor, the following steps need to be followed to ensure the availability of leakage monitoring:

[0046] 1. Clean the outer wall of the hydraulic structure (2) and conduct a preliminary inspection to see if there is any damage, as well as water (3) and soil infiltrated by leakage at the damaged part of the hydraulic structure.

[0047] 2. A distributed strain and temperature optical fiber sensor group (4) is pasted or fixed on the cleaned surface of the outer wall (2) of the hydraulic structure by adhesive or mechanical device, wherein the group includes at least three optical fiber sensors: a distributed strain and temperature optical fiber sensor group No. 1 (41), a distributed strain and temperature optical fiber sensor group No. 2 (42), and a distributed strain and temperature optical fiber sensor group No. 3 (43), and the spacing between them generally does not exceed 1 / 20 of the building height.

[0048] 3. Excavate the soil of the outer wall (2) of the hydraulic structure, and then arrange the No. 1 distributed temperature optical fiber sensor (5), the No. 2 distributed temperature optical fiber sensor (6), the No. 3 distributed temperature optical fiber sensor (7), etc. from near to far, and control the spacing of the sensors by means of brackets, etc., and the spacing does not exceed 1 / 2 of the structure thickness and a minimum value of 20 cm.

[0049] 4. After the arrangement is completed, connect the optical fiber demodulator to test the operation of the No. 1 distributed strain and temperature optical fiber sensor group (4), the No. 1 distributed temperature optical fiber sensor (5), the No. 2 distributed temperature optical fiber sensor (6), and the No. 3 distributed temperature optical fiber sensor (7) to ensure that the sensors are operating well.

[0050] 5. After the trial run, bury the sensors and hydraulic structures.

[0051] Example 2: This example is intended to implement a leakage monitoring example for water supply and drainage pipelines. Figure 3 During the monitoring process, the following steps need to be followed to ensure the reliability of the monitoring results of the leakage of the drainage pipeline:

[0052] 1. Clean the outer wall of the pipeline (11) and conduct a preliminary inspection to see if there is any damage, as well as water (12) and soil infiltrated by leakage at the damaged part of the pipeline.

[0053] 2. A distributed strain and temperature optical fiber sensor group (15) is attached or fixed to the cleaned outer wall (11) of the pipeline by adhesive or mechanical means, wherein the group includes at least three optical fiber sensors, and the spacing between the sensors does not exceed 1 / 10 of the radius of the pipeline.

[0054] 3. Excavate the soil of the outer wall (11) of the pipeline, and then arrange the distributed temperature optical fiber sensor (16) on the circumference of the pipeline, the distributed temperature optical fiber sensor (17) on the circumference of the pipeline, the distributed temperature optical fiber sensor (18) on the circumference of the pipeline, etc. from near to far, and control the spacing of the sensors by means of brackets, etc., and the spacing is generally not more than 1 / 2 of the thickness of the pipeline wall.

[0055] 4. After the arrangement is completed, connect the optical fiber demodulator to test the operation of the distributed strain and temperature optical fiber sensor group (15) on the first tube, the distributed temperature optical fiber sensor (16) on the first tube, the distributed temperature optical fiber sensor (17) on the second tube, and the distributed temperature optical fiber sensor (18) on the third tube to ensure that the sensors are operating well.

[0056] 5. After the trial operation, bury the sensors and water supply and drainage pipelines, connect the fiber optic sensors and fiber optic demodulators, and start monitoring the leakage of the water supply and drainage pipelines during operation.

[0057] 6. When abnormal fluctuations in optical fiber values ​​occur, check whether the strain and temperature signals change at the same time.

[0058] 7. The reconstruction method is used to calculate the size of the pipeline surface leakage area and the leakage infiltration range (13) over time.

[0059] 8. Calculate the amount of pipeline leakage from the beginning of leakage to the present.

[0060] 19. Water at the damaged part of the dam; 20. No. 1 distributed strain and temperature optical fiber sensor on the dam surface; 21. No. 1 distributed temperature optical fiber sensor on the dam surface; 22. No. 2 distributed temperature optical fiber sensor on the dam surface; 23. No. 3 distributed temperature optical fiber sensor on the dam surface; 24. Leakage and infiltration range of the dam body; 25. Water upstream of the reservoir; 26. Dam body; 27. Water downstream of the reservoir; 28. Soil around the dam foundation;

[0061] Example 3: This example is intended to implement a dam leakage monitoring example. Figure 4 During the monitoring process, the following steps need to be followed to ensure the reliability of the dam leakage monitoring results:

[0062] 1. Isolate the water body downstream of the reservoir (27), excavate the soil around the dam foundation (28), clean the dam body (26), and conduct a preliminary inspection to see if there is any damage, as well as the water body (19) and the soil body that has been leaked and infiltrated at the damaged part of the dam.

[0063] 2. A distributed strain and temperature optical fiber sensor (20) is adhered or fixed to the cleaned surface of the dam body (11) by adhesive or mechanical device, wherein the sensor comprises at least three optical fiber sensors, and the spacing between the sensors does not exceed 1 / 20 of the height of the dam body.

[0064] 3. Excavate the soil on the surface of the dam body (11), and then arrange the first distributed temperature optical fiber sensor (21) on the dam body surface, the second distributed temperature optical fiber sensor (22) on the dam body surface, the third distributed temperature optical fiber sensor (23) on the dam body surface, etc. from near to far, and control the spacing of the sensors by means of brackets, etc., and the spacing is generally not more than 1 / 5 of the thickness of the dam body.

[0065] 4. After the arrangement is completed, connect the optical fiber demodulator to test the operation of the No. 1 distributed strain and temperature optical fiber sensor (20) on the dam body surface, the No. 1 distributed temperature optical fiber sensor (21) on the dam body surface, the No. 2 distributed temperature optical fiber sensor (22) on the dam body surface, and the No. 3 distributed temperature optical fiber sensor (23) on the dam body surface to ensure that the sensors are operating well.

[0066] 5. After the trial operation, bury the sensor and the dam body, connect the fiber optic sensor and the fiber optic demodulator, and start leakage monitoring of the dam during operation.

[0067] 6. When abnormal fluctuations in optical fiber values ​​occur, check whether the strain and temperature signals change at the same time.

[0068] 7. The reconstruction method is used to calculate the time-varying curves of the leakage area on the dam surface and the leakage infiltration range (24).

[0069] 8. Calculate the amount of leakage from the beginning of the dam leakage to the present.

Claims

1. A method for monitoring and evaluating underground leakage of hydraulic structures, characterized in that: The method for monitoring and evaluating underground leakage of hydraulic structures comprises the following steps: S1: Arrange the optical fiber sensor on the hydraulic structure; S2: Reconstruction of the defect shape of hydraulic structures based on the strain signal of optical fiber sensors; S3: Reconstruct the leakage infiltration range based on the temperature signal of the optical fiber sensor; S4: Calculate underground leakage of hydraulic structures.

2. A method for monitoring and evaluating underground leakage of hydraulic structures according to claim 1, characterized in that: The step S1 also includes a method for arranging optical fiber sensors; the method for arranging optical fiber sensors includes: a water body (1) is contained inside the outer wall (2) of a hydraulic structure; when the outer wall (2) of the hydraulic structure is damaged, the water body (3) at the damaged part of the hydraulic structure flows out and infiltrates into the soil (9), and forms a leakage infiltration range (8); a first distributed strain and temperature optical fiber sensor group (4) is attached to the surface of the outer wall (2) of the hydraulic structure; a first distributed temperature optical fiber sensor (5), a second distributed temperature optical fiber sensor (6), and a third distributed temperature optical fiber sensor (7) are arranged in sequence from near to far in the soil (9) around the outer wall (2) of the hydraulic structure; the first distributed strain and temperature optical fiber sensor group (4) includes a first distributed strain and temperature optical fiber sensor (41), a second distributed strain and temperature optical fiber sensor (42), and a third distributed strain and temperature optical fiber sensor (43), all of which are closely connected to the outer wall (2) of the hydraulic structure.

3. A method for monitoring and evaluating underground leakage of hydraulic structures according to claim 1, characterized in that: The step S2 also includes a defect shape reconstruction method based on the strain signal of the optical fiber sensor, the defect shape reconstruction method based on the strain signal of the optical fiber sensor includes: identifying the connection area of ​​the intersection 1 (45) of the hydraulic structure leakage surface and the first distributed strain and temperature optical fiber sensor group, the intersection 2 (46) of the hydraulic structure leakage surface and the first distributed strain and temperature optical fiber sensor group, the intersection 3 (47) of the hydraulic structure leakage surface and the first distributed strain and temperature optical fiber sensor group, and the intersection 4 (48) of the hydraulic structure leakage surface and the first distributed strain and temperature optical fiber sensor group as the leakage area, and the location of each intersection is determined by the peak position of the strain curve measured by the first distributed strain and temperature optical fiber sensor group (4).

4. A method for monitoring and evaluating underground leakage of hydraulic structures according to claim 1, characterized in that: The step S3 also includes a method for reconstructing a leakage infiltration range based on a temperature signal of an optical fiber sensor; the method for reconstructing a leakage infiltration range based on a temperature signal of an optical fiber sensor includes: identifying a range in which a temperature curve of a No. 1 distributed temperature optical fiber sensor (5), a No. 2 distributed temperature optical fiber sensor (6), and a No. 3 distributed temperature optical fiber sensor (7) changes as a leakage infiltration range.

5. A method for monitoring and evaluating underground leakage of hydraulic structures according to claim 1, characterized in that: The step S4 also includes a method for calculating underground leakage of hydraulic structures; the leakage calculation formula is: Among them, V leak is the leakage amount (m 3 ), A hole is the leakage area (m 2 ), ρ is the density of water (kg / m 3 ), ΔP is the water pressure (Pa), and f(k) is a function that takes into account the influence of soil permeability and is related to the specific structural form.

Images