Dam leakage positioning detection method based on water flow field disturbance

Abstract

The present application relates to a kind of dam leakage positioning detection methods based on water flow field disturbance, comprising: underwater topography scanning is carried out to dam front area;Multiple groups of test points are arranged near suspected leakage point;The flow velocity and flow direction curve of arranged test point with time are drawn;The minimum flow velocity, maximum flow velocity, average flow velocity, minimum flow direction, maximum flow direction, average flow direction of each test point are counted;According to the statistical result, whether there is leakage flow velocity characteristic in suspected leakage point is analyzed;Suspected leakage point that preliminary judgment exists leakage is retested at least once.The beneficial effects of the present application: the method can obtain the flow velocity and flow direction near the leakage position, more suitable for accurate positioning of dam leakage position, more accurate and intuitive judgment basis, while also overcome the problems of traditional Doppler flowmeter detection method range limited, insufficient precision, low resolution, low efficiency and effect is not obvious, provide important data support and reference basis for the seepage characteristics of leakage position.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dam detection, and particularly relates to a dam leakage positioning detection method based on water flow field disturbance. BACKGROUND

[0002] Leakage is a common defect in water conservancy projects, and the leakage will become more and more serious over time, thereby causing deformation or even dam collapse of the reservoir dam. Anti-seepage of hydraulic structures is a basic requirement, and the main anti-seepage system includes water retaining structures, dam foundation, dam banks and underground structures. The leakage detection of the reservoir dam is to find the specific position of the leakage channel in the above anti-seepage system, and according to the characteristics of various detection methods, detection in water, dam body or bank slope is required, and sometimes drilling method is required.

[0003] At present, the leakage detection technology of the dam can be roughly divided into the following three types: ① manual net pulling type inspection, underwater camera shooting and underwater feeling method; ② drilling and trenching method for excavation verification; ③ geophysical detection method, common ones including natural electric field method, high-density resistivity method, ground penetrating radar, transient electromagnetic method, Rayleigh surface wave method, CT technology, isotope tracing method, temperature field detection technology, induced polarization method, controllable audio frequency magnetotelluric sounding method, shallow seismic wave method and flow field fitting method detection technology. Among them, the manual net pulling type inspection and the excavation method have high cost and low efficiency, and the geophysical detection method is an indirect method, and there are many solution problems and other uncertainties in analysis. SUMMARY

[0004] The purpose of the present application is to provide a dam leakage positioning detection method based on water flow field disturbance, which overcomes the problems in the background art. The method is based on the direct detection of the weak flow field generated by the disturbance on the dam leakage.

[0005] To achieve the above purpose, the present application provides the following technical scheme: a dam leakage positioning detection method based on water flow field disturbance, comprising the following steps:

[0006] (1) a multi-beam detection method is used to scan and detect the underwater topography of the dam front area, and after obtaining the underwater topography information of the dam front area, analysis is performed to find out suspected leakage points where leakage may exist;

[0007] (2) a plurality of test points are arranged according to the spatial distribution law within a certain range near the suspected leakage point, a single-point current meter is used to test the single-point flow rate according to a certain time unit, and the single-point flow rate and flow direction information are obtained;

[0008] (3) the flow rate and flow direction curves of the test points arranged near each suspected leakage point are drawn, and the distance between the test points and the suspected leakage points is recorded;

[0009] (4) According to the single-point flow rate test result, the minimum flow rate, the maximum flow rate, the average flow rate, the minimum flow direction, the maximum flow direction, and the average flow direction of each test point are counted, and the comprehensive flow rate is estimated according to the field boundary condition;

[0010] (5) According to the statistical result, whether the suspected leakage point has a leakage flow rate feature is analyzed, and if the suspected leakage point has the leakage flow rate feature, it is preliminarily judged that the suspected leakage point has leakage.

[0011] (6) The suspected leakage point preliminarily judged to have leakage is retested at least once, and each retest narrows the range compared with the previous one, and finally the leakage position is located according to the vector field of the flow rate.

[0012] As preferred, in the step (1), the features of the suspected leakage point include collapse, deformation, and cracking.

[0013] As preferred, in the step (2), when the single-point flow rate test is performed, the data collection interval is less than or equal to 10s, and the test point spacing is 0-0.2m, and when the spatial flow rate change test is performed, the test point distance interval is 0.2-0.5cm.

[0014] As preferred, in the step (5), the leakage flow rate feature is that if the flow rate is relatively large and the flow rate decreases obviously with the increase of the distance, it is preliminarily speculated that the surrounding water flow field may have leakage; if the flow rate is relatively small and the flow rate change is not obviously related to the distance, it is preliminarily speculated that the surrounding water flow field does not have leakage.

[0015] As preferred, in the step (6), the suspected leakage point with leakage has an abnormal flow field in the water flow field, the feature of the abnormal flow field is that the vector field of the flow rate points to the leakage position, and the flow direction of the leakage center point of the leakage position is centripetal and downward, and the flow rate at different relative heights in the flow field gradually changes with time and the position away from the leakage center point.

[0016] Compared with the prior art, the method has the advantages that: the dam leakage positioning and detection method based on water flow field disturbance is a direct detection method for dam leakage based on the weak flow field generated by water flow field disturbance, which is different from the conventional geophysical detection method which indirectly infers the leakage condition by obtaining physical characteristics, and can directly obtain the flow rate and flow direction near the leakage position, is more suitable for accurate positioning of the dam leakage position, and the judgment basis is more accurate and intuitive, and also overcomes the problems of limited range, insufficient accuracy, low resolution, low efficiency and not obvious effect of the traditional Doppler flowmeter detection method, provides a new idea for dam leakage detection, and provides important data support and reference basis for the seepage characteristics of the leakage position. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1It is the schematic diagram of the measurement limit range of the single-point current meter of the present application.

[0018] Figure 2 The simulation diagram of low, medium and high speed flow field near the leakage point.

[0019] Figure 3 It is the conversion relationship between the flow direction value and the angle of the present application.

[0020] Figure 4 It is the schematic diagram of the detection site of a certain dam.

[0021] Figure 5 It is the three-dimensional terrain map of the dam front covering platform of a hydropower station in the multi-beam scanning of the implementation case.

[0022] Figure 6 It is the schematic diagram of the current meter detection point arrangement in the implementation case.

[0023] Figure 7 It is the relationship curve of the flow velocity and the flow direction of the A leakage point with time in the implementation case.

[0024] Figure 8 It is the relationship curve of the flow velocity and the flow direction of the A leakage point with time after sealing in the implementation case. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] The present application provides a dam leakage positioning and detection method based on water flow field disturbance, comprising the following steps:

[0027] (1) The multi-beam detection method is used to scan and detect the underwater terrain of the dam front area, and the underwater terrain information of the dam front area is analyzed to find out the suspected leakage point where the leakage may exist. The characteristics of the suspected leakage point are generally the abnormal phenomena such as local collapse, deformation, cracking, etc.

[0028] (2) In the vicinity of the suspected leakage point, as many test points as possible are arranged according to the spatial distribution law within a certain range, and each test point is distributed as vertically or horizontally as possible; each test point is tested by a single-point current meter according to a certain time unit to obtain single-point flow velocity and flow direction information; when the point flow velocity is tested, the data collection interval should not be greater than 10s, and the optimal test point spacing is 0-0.2m; when the spatial flow velocity variation is tested, the distance interval is preferably 0.2-0.5cm; the spatial distance can also be adjusted according to the flow velocity and the actual situation on site;

[0029] (3) The flow velocity and flow direction of each test point arranged near the suspected leakage point are plotted against time, and the distance between the test point and the suspected leakage point is recorded;

[0030] (4) According to the single-point flow velocity test results, the minimum flow velocity, maximum flow velocity, average flow velocity, minimum flow direction, maximum flow direction, and average flow direction of each test point are counted, and the comprehensive flow velocity is estimated according to the boundary conditions on site;

[0031] (5) According to the statistical results, whether the suspected leakage point has a leakage flow velocity characteristic is analyzed, the leakage flow velocity characteristic being: if the flow velocity is relatively large and the flow velocity decreases significantly with the increase of the distance, it is preliminarily inferred that there is a leakage water flow field around, and it is preliminarily judged that the suspected leakage point has leakage; if the flow velocity is relatively small and the relationship between the flow velocity variation and the distance is not obvious, it is preliminarily inferred that there is no leakage water flow field around, and it is preliminarily judged that the suspected leakage point has no leakage;

[0032] (6) The suspected leakage point with leakage has an abnormal flow field, the characteristic of the abnormal flow field being that the vector field of the flow velocity points to the leakage position, and the flow direction of the leakage center point of the leakage position is centripetal and downward, and the flow velocity at different relative heights in the flow field gradually changes with time and the position away from the leakage center point. According to the vector field pointing, the suspected leakage point preliminarily judged to have leakage is retested at least once, the range is reduced each time, and finally the leakage position is located according to the vector field of the flow velocity.

[0033] The single-point current meter uses the principle of Doppler effect to measure the flow velocity, uses an acoustic transducer as a sensor, the transducer emits an acoustic pulse wave, the acoustic pulse wave is backscattered by the unevenly distributed backscatterers such as silt particles and plankton in the water body, the signal received by the transducer is measured for Doppler frequency shift to calculate the flow velocity of several points in the measurement line range, the correlation coefficient of the rated measurement line average flow velocity and the cross section average flow velocity is obtained through field rating, the measurement line average flow velocity is calculated, and the cross section area and flow rate are calculated according to the relationship between the water level and the cross section area obtained by the field cross section measurement.

[0034] Please refer to Figure 1The present application is described in detail below in conjunction with the accompanying drawings and specific examples.

[0035] (1) As shown in the figure, the single-point current meter of the Norwegian AANDERAA company "SEAGUARD marine guard" used in this embodiment has a flow rate test range of 0-300 cm / s; a flow rate test accuracy of ±0.15 cm / s; a resolution of 0.1 mm / s; a flow direction test range of 0-360°, an accuracy of ±5°, and a resolution of 0.01°. Figure 1

[0036] (2) As shown in the figure, the leakage flow field is relatively complex, and can be numerically simulated by a finite element model of a rotating flow field, Figure 2 Figure 2 (a) (b) (c) respectively show the change characteristics of the leakage flow field under low, medium and high speed flow field conditions;

[0037] (3) As shown in the figure, the direction of the turbulence inside the water body measured by the present application is chaotic and disordered, and the direction angle value ranges from 0 to 360°. In order to facilitate description, statistics and numerical analysis, the flow direction of each measuring point is divided into a total of 12 regions (0-11), representing an angle of 0-360°, and numerically represented as 50-72. Figure 3

[0038] (4) As shown in the figure, the schematic diagram of the detection of a certain dam in the specific example of the present application is shown. Figure 4

[0039] (5) As shown in the figure, the multi-beam detection method is used to scan and inspect the underwater topography of the dam and other areas, and the data is analyzed and judged by the underwater topography and geomorphology characteristics to find out the collapse deformation area. Figure 5

[0040] (6) As shown in the figure, the single-point current meter is used to check the leakage at the collapse deformation area of the leakage platform and the surrounding 15 suspicious points. Figure 6

[0041] (7) Taking the suspected leakage point A in the figure as an example, as shown in the figure, the A leakage point (407m elevation) is located directly above the point, and the detection position is about 100-442 cm away from the leakage point position; the flow rate range detected near the point position is 2.49-100 mm / s, and the average flow rate is about 45 mm / s; the flow direction inside the water body is 360° radial flow around the periphery, and the average flow direction is SSW. The three detection positions above A point are about 140 cm, 230 cm and 435 cm away from the leakage point, respectively. As can be seen from the figure, the measured flow rate fluctuates at the same position or different positions, and the fluctuation difference is large. Figure 6 Figure 7

[0042] ​​​​​​​​(8) as shown in Figure 8 After sealing treatment of the leakage point A, the leakage point A is retested, and the leakage point A is about 104 cm away from the leakage point position; the flow rate range near the point position is detected to be 0.83-75 mm / s, and the average flow rate is about 23 mm / s; the water body internal flow direction is 360° radial flow around, and the average flow direction is to S. The average speed of the point before sealing is about 45 mm / s, which is related to the water body flow field caused by leakage; after sealing treatment, the average speed is reduced to 32 mm / s, the flow direction is gentle and less fluctuation, which is the water body internal turbulent environment flow field, clutter field and equipment system error noise field, and has no obvious leakage characteristic flow. It is proved that the leakage detection method of the present application is effective.

[0043] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for locating and detecting dam seepage based on water flow field disturbance, characterized in that, Includes the following steps: (1) Use multibeam detection method to conduct underwater topographic survey of the area in front of the dam, obtain underwater topographic information of the area in front of the dam and analyze it to find suspected leakage points that may have leakage; the characteristics of suspected leakage points include collapse, deformation and cracking. (2) Multiple test points are set up in a certain range near the suspected leakage point according to the spatial distribution pattern. Single-point current meters are used to test the single-point flow velocity at a certain time unit to obtain the single-point flow velocity and flow direction information. (3) Plot the flow velocity and flow direction curves of each test point near the suspected leakage point over time, and record the distance between the test point and the suspected leakage point. (4) Based on the single-point flow velocity test results, the minimum flow velocity, maximum flow velocity, average flow velocity, minimum flow direction, maximum flow direction, and average flow direction of each test point are calculated, and the comprehensive flow velocity is estimated based on the on-site boundary conditions. (5) Based on the statistical results, analyze whether there are leakage velocity characteristics at the suspected leakage point. If there are, it is preliminarily judged that there is leakage at the suspected leakage point. The leakage velocity characteristics are as follows: if the velocity is relatively large and the velocity decreases significantly with increasing distance, it is preliminarily inferred that there may be a leakage water flow field in the surrounding area; if the velocity is relatively small and its velocity change is not significantly related to the distance, it is preliminarily inferred that there is no leakage water flow field in the surrounding area. (6) For suspected leak points with leakage, an abnormal flow field will appear in the water flow field. The characteristics of the abnormal flow field are that the vector field of the flow velocity points to the leak location, and the flow direction of the leak center point at the leak location is centripetal and downward. The flow velocity at different relative heights in the flow field gradually changes with time and distance from the leak center point. For suspected leak points that are initially judged to have leakage, at least one retest is conducted. Each retest narrows the range compared to the previous one. Finally, the leak location is located based on the vector field of the flow velocity.

2. The dam seepage location and detection method based on water flow field disturbance as described in claim 1, characterized in that, In step (2), when performing single-point flow velocity testing, the data acquisition interval is less than or equal to 10s, and the distance between test points is 0 to 0.2m. When performing spatial flow velocity change testing, the distance between test points is 0.2 to 0.5cm.

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