An arch dam global horizontal displacement monitoring method

Abstract

This invention discloses a method for monitoring the horizontal displacement of the entire arch dam, including the process of obtaining the vector displacement at the arch end of the arch ring and calculating the linear displacement of the strain at any point on the arch ring to determine the horizontal displacement of the entire arch dam. This invention achieves the calculation of the linear displacement of any point using the strain distribution along the entire length of the arch ring; obtaining the vector displacement at the arch end by setting inverted sections at both ends of the arch ring; and determining the deformed position of any point based on the unchanged and continuous macroscopic shape of the arch dam, thus obtaining the vector displacement, which is further decomposed into radial and tangential displacements, thereby achieving the monitoring of the horizontal displacement of the entire arch dam.

Description

Technical Field

[0001] This invention belongs to the field of safety monitoring technology for water conservancy and hydropower projects, and particularly relates to a method for monitoring the horizontal displacement of the entire arch dam. Background Technology

[0002] In the safety monitoring of concrete arch dams, the diverse patterns of horizontal displacement reflect the actual stress state of the arch dam. Accurately grasping these patterns of change is the key to detecting abnormal deformation and preventing dam failure accidents. Horizontal displacement data can decompose influencing factors such as temperature and water level, revealing the true working state of the arch dam.

[0003] Because arch dams are curved in plan, the quasi-straight line method commonly used for straight dams is not suitable for arch dams. The main methods suitable for monitoring the horizontal displacement of arch dams are surface deformation monitoring and the plumb line method.

[0004] Surface deformation monitoring mainly involves setting up multiple measuring points on or behind the dam crest, such as the arch crown, quarter arch, and third arch, using the intersection method to monitor horizontal displacement. The intersection method has the following characteristics: ① It requires setting up multiple working benchmarks far from the deformable body, with the intersection angle between 30° and 150°, ideally 90°-109°, otherwise the error increases; ② The elevation difference between the working benchmarks and the measuring points cannot be too large. For situations where the elevation difference range of the measuring points is large, working benchmarks need to be set up in layers; ③ Geodetic methods require multiple rounds of observation to eliminate errors, resulting in long observation times; it is also highly dependent on meteorological conditions, as observations cannot be conducted in rain, snow, fog, or sunny weather, preventing true real-time monitoring; ④ Automation costs are high, with the automation cost of a single station generally around 1 million yuan, while the intersection method requires at least two stations, costing over 2 million yuan; ⑤ The intersection method can only be used to set up representative points on the arch dam for observation, and cannot achieve full-area observation.

[0005] The plumb line method mainly involves setting up positive and inverted plumb lines at the arch crown, 1 / 4 arch, and 3 / 4 arch sections for segmented observation, and then superimposing the data to calculate the horizontal displacement of the arch dam. Similar to surface deformation monitoring, the plumb line method can only select representative sections for observation and cannot achieve full-area observation. In addition, the plumb line method requires drilling to install plumb lines, which has high drilling requirements and is quite expensive, generally costing about 2,500 yuan per meter. Taking a 100m-class arch dam as an example, if the inverted plumb line penetrates 40m into the bedrock and three positive and inverted plumb lines are used, the drilling cost alone would be 140 * 3 * 2,500 = 1.05 million yuan.

[0006] Analysis of surface deformation monitoring and plumb line method shows that both methods for monitoring horizontal displacement of arch dams are currently expensive and can only achieve point-based monitoring, not full-area monitoring.

[0007] Patent application CN105890537A discloses a distributed fiber optic sensing technology solution and system for monitoring the deformation of high arch dams. Addressing the characteristics and challenges of hyperbolic arch dams, it provides two unique curved fiber optic encapsulation structures: a weakly curved beam and a micro-curved beam type fiber optic monitoring board. It offers convenient and practical deployment methods within the galleries, shafts, and adits of the arch dam and its foundation, enabling multi-dimensional, large-scale, spatiotemporal, and wide-coverage online telemetry of the three components (radial-tangential horizontal displacement and vertical displacement) of the internal deformation of the arch dam, foundation, and abutments. This document primarily discloses the installation details of the fiber optic sensing technology but does not address the technical problem of calculating the horizontal displacement across the entire arch dam area. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a method for monitoring the horizontal displacement of an arch dam across its entire area.

[0009] The present invention is achieved through the following technical solutions.

[0010] The present invention provides a method for monitoring the horizontal displacement of the entire arch dam, which includes the process of calculating the horizontal displacement of the entire arch dam by obtaining the vector displacement of the arch end and the linear displacement of the strain at any point of the arch ring through the arch ring of the arch dam.

[0011] Preferably, the arch ring of the arch dam is provided with an arch ring groove, and a strain optical cable is laid in the arch ring groove. Inverted sags are provided at both ends of the arch ring of the arch dam, and the inverted sags are perpendicular to the arch ring of the arch dam.

[0012] A method for monitoring the horizontal displacement of an arch dam across its entire area includes the following steps:

[0013] S1: Set grooves on the arch ring of the arch dam where horizontal displacement needs to be observed, and lay strain optical cables in the grooves.

[0014] S2: Install inverted sags at both ends of the arch ring of the arch dam, with the inverted sags at both ends designated as points A and B, and monitor the displacement of points A and B;

[0015] S3: Let C be any point on the arch ring of the arch dam where the horizontal displacement needs to be monitored. Measure the deformation of the arc length from point A to point C and from point B to point C, and measure the resultant displacement of point C.

[0016] S4: Calculate the radial and tangential displacements of the arch ring of the arch dam using the resultant displacement at point C, and obtain the horizontal displacement of the entire arch dam.

[0017] Preferably, the arc length from point A to point C is measured as L1, and the formula for calculating the deformation of L1 is:

[0018]

[0019] The arc length from point B to point C is measured as L2. The formula for calculating the deformation of L2 is:

[0020]

[0021] In the formula: ΔL1 is the change in horizontal length at length L1 of the structure, ΔL2 is the change in horizontal length at length L2 of the structure, and ε(L) is the strain measurement value of segment L.

[0022] Preferably, points A' and B' are obtained after monitoring the displacement and deformation of points A and B, respectively, and the arc length of A'C' is L1+ΔL1, and the arc length of B'C' is L2+ΔL2.

[0023] According to the geometric transformation method, the line segment with arc length L1+ΔL1 rotates around point A', and the line segment with arc length L2+ΔL2 rotates around point B'. The intersection of the line segment with arc length L1+ΔL1 and the line segment with arc length L2+ΔL2 is the deformed point C', and the vector length of CC' is the resultant displacement ΔC of point C.

[0024] Preferably, in calculating the radial and tangential displacements of the arch ring of the arch dam, the angle θ between point C and the dam axis of the arch ring is measured, and the resultant displacement ΔC is decomposed into the radial and tangential displacements of the arch ring. The formula for calculating the radial displacement is:

[0025] ΔCj=ΔC*sinθ

[0026] The formula for calculating tangential displacement is:

[0027] ΔCq=ΔC*cosθ

[0028] In the formula: ΔCj is the radial displacement of point C, and ΔCq is the tangential displacement of point C.

[0029] The beneficial effects of this invention are as follows:

[0030] This invention enables the calculation of linear displacement at any point by the strain distribution along the entire length of the arch ring of an arch dam; the acquisition of vector displacement at the arch end by setting inverted sags at both ends of the arch ring; and the determination of the deformed position of any point based on the unchanged and continuous macroscopic shape of the arch dam, thereby obtaining the vector displacement, which can be further decomposed into radial displacement and tangential displacement, thus realizing the monitoring of the horizontal displacement of the entire arch dam.

[0031] This invention, by employing a sag, strain optical cable, and strain demodulator, can achieve full-area horizontal displacement monitoring of the horizontal arch ring of an arch dam, breaking through the limitations of traditional point monitoring, obtaining full-area deformation of the dam, improving the dam's safety monitoring capabilities, and protecting the lives and property of people downstream. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the present invention;

[0033] Figure 2 This is a schematic diagram of the calculation principle of the present invention;

[0034] Figure 3 This is a schematic diagram of the arch ring of an arch dam;

[0035] In the diagram: 1-arch ring of the dam, 2-groove of the arch ring, 3-strain optical cable, 4-sag. Detailed Implementation

[0036] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0037] Example:

[0038] like Figure 3 As shown, the arch ring 1 of the arch dam is fixed to the bedrock. According to the bending deformation theory of "Mechanics of Materials", under the action of loads such as reservoir water pressure and temperature load, the arch ring 1 of the arch dam will experience material strain, which will cause changes in its shape deflection, i.e., horizontal displacement. Therefore, the horizontal displacement of the arch ring 1 of the arch dam can be monitored by monitoring strain.

[0039] Distributed sensing fiber optic technology enables continuous sampling at 0.5m intervals on a continuous structure, with a strain measurement accuracy of 30με for each measurement unit.

[0040] According to the bending deformation theory of "Mechanics of Materials", the deformation of a structure is a continuous integral of strain along the length direction, and the calculation formula is as follows:

[0041]

[0042] In the formula: ΔL is the change in horizontal length at length L of the structure, ε i The strain measurement value is for the i-th segment.

[0043] Based on the above theory, the implementation process of this invention is as follows:

[0044] like Figure 1 , 2 As shown, a method for monitoring the horizontal displacement of an arch dam across its entire domain includes the process of calculating the horizontal displacement of the entire arch dam by obtaining the vector displacement at the arch end of the arch ring 1 and the linear displacement of the strain at any point of the arch ring 1.

[0045] The arch ring 1 of the arch dam is provided with an arch ring groove 2, and a strain optical cable 3 is laid in the arch ring groove 2. Inverted 4s are provided at both ends of the arch ring 1 of the arch dam, and the inverted 4s are perpendicular to the arch ring 1 of the arch dam.

[0046] A method for monitoring the horizontal displacement of an arch dam across its entire area includes the following steps:

[0047] S1: Set an arch groove 2 on the arch ring 1 of the arch dam where horizontal displacement needs to be observed, and lay a strain optical cable 3 in the arch groove 2. The arch groove 2 and the strain optical cable 3 are well coupled and have consistent deformation. The deformation of the strain optical cable 3 can represent the deformation of the arch ring 1 of the arch dam. The strain at any point of the strain optical cable 3 is obtained by a strain demodulator.

[0048] S2: Set up an inverted 4 at each end of the arch ring 1 of the arch dam. The inverted 4 at both ends are designated as points A and B respectively. Monitor the displacement of points A and B, observe the horizontal displacement of the arch end of the arch ring 1 of the arch dam under the load, and provide a reference for strain integration.

[0049] S3: Let C be any point on the arch ring 1 of the arch dam where the horizontal displacement needs to be monitored. Measure the deformation of the arc length from point A to point C and from point B to point C, and measure the resultant displacement of point C.

[0050] S4: Calculate the radial and tangential displacements of the arch ring 1 of the arch dam using the resultant displacement at point C, and obtain the horizontal displacement of the entire arch dam.

[0051] The arc length from point A to point C is L1, and the formula for calculating the deformation of L1 is:

[0052]

[0053] The arc length from point B to point C is measured as L2. The formula for calculating the deformation of L2 is:

[0054]

[0055] In the formula: ΔL1 is the change in horizontal length at length L1 of the structure, ΔL2 is the change in horizontal length at length L2 of the structure, and ε(L) is the strain measurement value of segment L.

[0056] Points A' and B' are obtained after monitoring the displacement and deformation of points A and B respectively. The arc length of A'C' is L1+ΔL1, and the arc length of B'C' is L2+ΔL2.

[0057] According to the geometric transformation method, the line segment with arc length L1-ΔL1 rotates around point A', and the line segment with arc length L2+ΔL2 rotates around point B'. The intersection of the line segment with arc length L1+ΔL1 and the line segment with arc length L2+ΔL2 is the deformed point C', and the vector length of CC' is the resultant displacement ΔC of point C.

[0058] In calculating the radial and tangential displacements of the arch ring 1 of the arch dam, the angle θ between point C and the axis of the arch ring 1 is measured. The resultant displacement ΔC is decomposed into the radial and tangential displacements of the arch ring 1. The formula for calculating the radial displacement is:

[0059] ΔCj=ΔC*sinθ

[0060] The formula for calculating tangential displacement is:

[0061] ΔCq=ΔC*cosθ

[0062] In the formula: ΔCj is the radial displacement of point C, and ΔCq is the tangential displacement of point C.

[0063] The principle of the above calculation is as follows: Figure 3 As shown, in the calculation formula of this application, all arc length units are meters (m) and all displacement units are millimeters (mm). Computer-aided, fully automated processing can be achieved. This method enables horizontal displacement monitoring of any point on the arch ring 1 of the arch dam, a significant advantage over point-based monitoring. Furthermore, the method of this application has a lower cost. Taking a medium-sized dam project as an example, assuming the dam crest arc length is 200m, the total cost of the strain gauge and strain cable 3 is less than 200,000 yuan, demonstrating a clear advantage over traditional surface deformation monitoring and plumb line methods.

Claims

1. A method for monitoring the horizontal displacement of an arch dam across its entire area, characterized in that: This includes the process of calculating the horizontal displacement of the entire arch dam by obtaining the vector displacement at the arch end through the arch ring (1) and the linear displacement of the strain at any point of the arch ring (1); The arch ring (1) of the arch dam is provided with an arch ring groove (2), and a strain optical cable (3) is laid in the arch ring groove (2). Inverted sags (4) are provided at both ends of the arch ring (1), and the inverted sags (4) are perpendicular to the arch ring (1). The method for monitoring the horizontal displacement of the entire arch dam includes the following steps: S1: Set an arch groove (2) on the arch ring (1) of the arch dam where horizontal displacement needs to be observed, and lay a strain optical cable (3) in the arch groove (2). S2: Set up inverted sags (4) at both ends of the arch ring (1) of the arch dam. Set the inverted sags (4) at both ends as points A and B respectively, and monitor the displacement of points A and B. S3: Let C be any point on the arch ring (1) of the arch dam that needs to monitor the horizontal displacement. Measure the deformation of the arc length from point A to point C and from point B to point C, and measure the resultant displacement of point C. S4: Calculate the radial and tangential displacements of the arch ring (1) of the arch dam using the combined displacement at point C, and obtain the horizontal displacement of the entire arch dam. The arc length from point A to point C is L1, and the formula for calculating the deformation of L1 is: ； The arc length from point B to point C is measured as L2. The formula for calculating the deformation of L2 is: ； In the formula: This represents the change in horizontal length at point L1 of the structure. This represents the change in horizontal length at point L2 of the structure. The strain measurement value is for segment L; Monitoring the displacement deformation of points A and B respectively obtains points A' and B', the arc length of A'C' is L1+ , the arc length of B'C' is L2+ 2; According to the geometric transformation method, the arc length L1+ The line segment rotates around point A', with an arc length of L2+ Line segment 2 rotates around point B', with arc length L1+ The line segment and arc length L2+ The intersection of line segments 2 is the deformed point C', and the vector length of CC' is the resultant displacement of point C. .

2. The method for monitoring the horizontal displacement of an arch dam as described in claim 1, characterized in that: In calculating the radial and tangential displacements of the arch ring (1) of the arch dam, the angle θ between point C and the dam axis of the arch ring (1) is measured, and the resultant displacement is calculated. The displacement is decomposed into radial displacement and tangential displacement of the arch ring (1) of the arch dam. The formula for calculating the radial displacement is: ； The formula for calculating tangential displacement is: ； In the formula: The radial displacement of point C. Let C be the tangential displacement.

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