A dynamic detection method for earthquake damage of arch dam cross joint

Abstract

This invention provides a dynamic detection method for seismic damage to transverse joints of arch dams, belonging to the field of structural damage detection. The method includes the following steps: acquiring acceleration vibration signals at various detection locations of the arch dam under test during an earthquake; for a given detection location, selecting acceleration vibration signals from both sides of the transverse joint and performing coordinate transformation, then converting them into the tangential and normal time-frequency matrices of the transverse joint using continuous wavelet transform; calculating the normal and tangential damage indices of the responses on both sides of the transverse joint based on the tangential and normal time-frequency matrices, and determining the comprehensive damage index for that detection location; obtaining the comprehensive damage index for all detection locations, and identifying the damage state of the transverse joints of the arch dam based on the comprehensive damage index for all detection locations. This method overcomes the limitations of traditional detection methods that are unable to address the problem of transverse joint damage to arch dams caused by earthquakes.

Description

Technical Field

[0001] This invention relates to the field of structural damage detection, and specifically to a dynamic detection method for seismic damage in the transverse joints of an arch dam. Background Technology

[0002] Arch dams are spatial shell structures formed by the combined action of horizontal arches and vertical cantilever beams. Due to their excellent adaptability to terrain and overload capacity, they are widely used in hydraulic structures. Different sections of an arch dam are independently cast and connected by high-pressure grouting. However, the grouting connection points, i.e., transverse joints, are still considered weak points in arch dams under tensile and shear stresses. Earthquakes can easily damage these transverse joints, causing relative opening and sliding between adjacent dam sections, threatening the integrity and safety of the arch dam structure. Furthermore, when the displacement of the transverse joint exceeds the watertight deformation limit, the infiltration of upstream water pressure into the transverse joint will generate additional pressure on the inner wall of the dam, further exacerbating the opening of the transverse joint. Among the many key issues in arch dam safety, the problem of transverse joint damage caused by earthquakes has been listed as a key research topic.

[0003] Existing methods for detecting transverse joint damage mainly consider the following two aspects. First, static monitoring methods based on transverse joint gauges. Transverse joint gauges are the most commonly used tool for monitoring the opening of transverse joints in arch dams, but the measurement time is long, typically measured in days or months, making it difficult to determine the damage status of the transverse joints simultaneously with an earthquake. Second, damage detection methods based on forced vibration response. Transverse joint damage caused by seismic loads exhibits strong nonlinear characteristics. Theoretically, the nonlinear characteristics of subharmonics and superharmonics based on the forced vibration response of structures can be used to detect transverse joint damage. However, arch dams are enormous in scale and operate in harsh environments, making it difficult to directly apply specific loads. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a dynamic detection method for seismic damage to transverse joints of arch dams, thereby overcoming the limitations of traditional detection methods that are unable to effectively address the problem of transverse joint damage to arch dams caused by earthquakes.

[0005] To achieve the above objectives, the present invention provides the following technical solution.

[0006] A dynamic detection method for seismic damage at transverse joints of arch dams, comprising the following steps:

[0007] Acceleration vibration signals were collected at various detection locations of the arch dam under test during the earthquake.

[0008] For a certain detection position, the acceleration vibration signals on both sides of the transverse seam are selected and the coordinate transformation is performed to obtain the tangential acceleration vibration signal and the normal acceleration vibration signal of the transverse seam, respectively.

[0009] The tangential and normal acceleration vibration signals of the transverse seam are transformed into the tangential and normal time-frequency matrices of the transverse seam, respectively, through continuous wavelet transform.

[0010] Based on the tangential and normal time-frequency matrices of the transverse seam, the normal and tangential damage indices of the responses on both sides of the transverse seam are calculated respectively, and the comprehensive damage index of the detection location is determined based on the normal and tangential damage indices.

[0011] Obtain the comprehensive damage index of all detection locations, and identify the damage state of the transverse joints of the arch dam based on the comprehensive damage index of all detection locations.

[0012] Preferably, the acquisition of the acceleration vibration signal of the arch dam to be tested during an earthquake includes the following steps:

[0013] An acceleration sensing system was deployed on the arch dam to be tested.

[0014] An acceleration sensing system was used to acquire the acceleration vibration signal of the arch dam under test during an earthquake.

[0015] The acceleration sensing system includes an acceleration sensor, a real-time signal acquisition device, and a real-time signal storage device that are electrically connected to each other; wherein, at least one acceleration sensor is arranged on each of the left and right sides of each transverse slit to be detected, and multiple acceleration sensors are arranged along both sides of the transverse slit in the height direction.

[0016] Preferably, the acquisition of acceleration vibration signals on both sides of the transverse slit includes:

[0017] Taking the direction from the left bank to the right bank as the X-axis, the direction from upstream to downstream as the Y-axis, and the polar coordinate angle of the accelerometer's location as θ, then the tangential acceleration vibration signal of the transverse slit is:

[0018] T(t)=x(t)sinθ+y(t)cosθ

[0019] The transverse seam normal acceleration vibration signal is:

[0020] N(t) = x(t)cosθ - y(t)sinθ

[0021] Where x(t) and y(t) represent the acceleration vibration responses in the X and Y directions, respectively.

[0022] Preferably, the tangential time-frequency matrix of the transverse slit is calculated according to the following formula:

[0023]

[0024]

[0025] Among them, Ta (t) and T b ψ(t) represents the tangential acceleration vibration signal of the transverse slit on both sides of a certain detection position; ψ(t) represents the wavelet function, u represents the time shift factor, and s represents the scale factor; TTSR a (u,s) and TTSR b (u,s) represents the tangential time-frequency matrix on both sides of a certain detection position;

[0026] The normal time-frequency matrix is ​​calculated according to the following formulas, including the following formulas:

[0027]

[0028]

[0029] Where, N a (t) and N b (t) represents the transverse acceleration vibration signal on both sides of a certain detection position; NTSR a (u,s) and NTSR b (u,s) represents the normal time-frequency matrix on both sides of a certain detection position.

[0030] Preferably, the normal damage index CCT of the response on both sides of the transverse slit is calculated according to the following formula:

[0031]

[0032] in, Indicates TTSR a The mean, Indicates TTSR b The mean;

[0033] The tangential damage index CCN of the response on both sides of the transverse suture is calculated according to the following formula:

[0034]

[0035] in, Represents NTSR a The mean, Represents NTSR b The mean.

[0036] Preferably, the comprehensive damage index is DI = min(CCT, CCN).

[0037] Preferably, it further includes:

[0038] Based on the identified damage status of the transverse joints of the arch dam, a damage indication diagram is drawn.

[0039] Preferably, the damage indication map selects the damage area and determines the warning color according to the following principles based on the DI of each detection location; wherein:

[0040] Strong damage (DI = [0.00-0.70]), red; moderate damage (DI = [0.70-0.90]), yellow; no damage (DI = [0.90-1.00]), green;

[0041] Finally, a damage indication map is plotted on the sensor network diagram.

[0042] The beneficial effects of this invention are:

[0043] This invention proposes a dynamic detection method for seismic damage at transverse joints of arch dams. The method involves performing coordinate transformation and continuous wavelet transform on the acquired seismic response signals to obtain a time-frequency matrix. Based on this matrix, the normal and tangential damage indices of the responses on both sides of the transverse joint are calculated. Finally, a comprehensive damage index is used to assess the degree of seismic damage development at the transverse joints of the arch dam. Compared with existing technologies, this method features real-time performance, as it is directly based on the seismic response of the arch dam, avoiding the inconvenience of manually applying excitation and acquiring responses in traditional dynamic damage detection processes. Attached Figure Description

[0044] Figure 1 This is a flowchart of a method according to an embodiment of the present invention;

[0045] Figure 2 This is an experimental layout diagram of the arch dam according to an embodiment of the present invention;

[0046] Figure 3 These are artificial seismic waves according to embodiments of the present invention;

[0047] Figure 4 This is a damage indication diagram of the transverse joint of the arch dam according to an embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0049] Example 1

[0050] The present invention provides a dynamic detection method for seismic damage at transverse joints of arch dams, such as... Figure 1-4 As shown.

[0051] Using a concrete arch dam as a prototype, a scaled-down arch dam model was designed and subjected to seismic tests. The load was applied through excitation at the bottom of a shaking table, and artificial seismic waves were used to damage the arch dam.

[0052] S1: As attached Figure 2 As shown, an accelerometer system is deployed on the arch dam to be tested. This scaled-down arch dam model considers three transverse seams, with three pairs of sensors placed on each of the two side seams and four pairs on the middle seam. The accelerometers are triaxial accelerometers with a sensitivity coefficient of 10 mV / g and a measurement range of 50 g. All accelerometers are connected to a multi-channel accelerometer and a computer.

[0053] S2: As attached Figure 3 Artificial seismic wave loading was carried out using a shaking table device, and the acceleration vibration signal of the arch dam under test during the earthquake was obtained using the acceleration sensing system in S1.

[0054] S3: In this embodiment, the accelerometer is already arranged along the normal and tangential directions of the transverse joint of the arch dam, so no coordinate transformation is required.

[0055] S4: The transverse tangential acceleration vibration signals on both sides of a certain detection position are converted into the transverse tangential time-frequency matrix on both sides of the detection position using the following formula.

[0056]

[0057]

[0058] Among them, T a (t) and T b ψ(t) represents the tangential acceleration vibration signal of the transverse slit on both sides of a certain detection position. ψ(t) represents the wavelet function, u represents the time shift factor, and s represents the scaling factor.

[0059] In S4, the transverse slit tangential acceleration vibration signals on both sides of a certain detection position are converted into transverse slit normal time-frequency matrices on both sides of the detection position using the following formula.

[0060]

[0061]

[0062] Where, N a (t) and N b ψ(t) represents the normal acceleration vibration signal of the transverse slit on both sides of a certain detection position. ψ(t) represents the wavelet function, u represents the time shift factor, and s represents the scaling factor.

[0063] S5: Calculate the tangential damage index based on the transverse tangential time-frequency matrix on both sides of a certain detection position in S4, using the following formula.

[0064]

[0065] in, Indicates TTSR a The mean, Indicates TTSR b The mean.

[0066] The tangential damage index is calculated based on the tangential time-frequency matrix of the transverse seam on both sides of a certain detection position in S4, using the following formula.

[0067]

[0068] in, Represents NTSR a The mean, Represents NTSR b The mean.

[0069] S6: Select the comprehensive damage index DI for this detection location based on the tangential and normal damage indices in S5.

[0070] S7: Perform S3-S5 processes on all locations to be detected to obtain the tangential damage index CCT and normal damage index CCN for all locations to be detected, as shown in the table below.

[0071] Table 1. Statistical table of tangential damage index CCT and normal damage index CCN

[0072]

[0073] Perform the S6 process on all locations to be detected to obtain the comprehensive damage index for all locations to be detected, as shown in the table below.

[0074] Table 2. Statistical table of comprehensive damage indicators for all locations to be detected.

[0075]

[0076] S8: Identify the damage state of the transverse joints of the arch dam based on the comprehensive damage index of all locations to be inspected in S7 and draw a damage indication diagram (see appendix). Figure 4 .

[0077] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dynamic detection method for earthquake damage of an arch dam transverse joint, characterized in that, Includes the following steps: Acceleration vibration signals were collected at various detection locations of the arch dam under test during the earthquake. For a certain detection position, the acceleration vibration signals on both sides of the transverse seam are selected and the coordinate transformation is performed to obtain the tangential acceleration vibration signal and the normal acceleration vibration signal of the transverse seam, respectively. The tangential and normal acceleration vibration signals of the transverse seam are transformed into the tangential and normal time-frequency matrices of the transverse seam, respectively, through continuous wavelet transform. Based on the tangential and normal time-frequency matrices of the transverse seam, the normal and tangential damage indices of the responses on both sides of the transverse seam are calculated respectively, and the comprehensive damage index of the detection location is determined based on the normal and tangential damage indices. Obtain the comprehensive damage index of all detection locations, and identify the damage status of the transverse joints of the arch dam based on the comprehensive damage index of all detection locations. The tangential time-frequency matrix of the transverse slit is calculated according to the following formula: in, and This indicates the tangential acceleration vibration signal of the transverse slit on both sides of a certain detection position; Describing the wavelet function, Indicates the time shift factor. Indicates the scale factor; and This represents the tangential time-frequency matrix on both sides of a certain detection position; The normal time-frequency matrix is ​​calculated according to the following formulas, including the following formulas: in, and This represents the normal acceleration vibration signal of the transverse seam on both sides of a certain detection position; and Represents the normal time-frequency matrix on both sides of a certain detection position; The normal damage indexes of the responses on both sides of the transverse seam CCT Calculate using the following formula: in, express The mean, express The mean; The tangential damage indexes on both sides of the transverse seam CCN Calculate using the following formula: in, express The mean, express The mean.

2. The dynamic detection method for seismic damage at transverse joints of an arch dam according to claim 1, characterized in that, The process of collecting the acceleration vibration signal of the arch dam to be tested during an earthquake includes the following steps: An acceleration sensing system was deployed on the arch dam to be tested. An acceleration sensing system was used to acquire the acceleration vibration signal of the arch dam under test during an earthquake. The acceleration sensing system includes an acceleration sensor, a real-time signal acquisition device, and a real-time signal storage device that are electrically connected to each other; wherein, at least one acceleration sensor is arranged on each of the left and right sides of each transverse slit to be detected, and multiple acceleration sensors are arranged along both sides of the transverse slit in the height direction.

3. The dynamic detection method for seismic damage at transverse joints of an arch dam according to claim 2, characterized in that, The acquisition of acceleration vibration signals on both sides of the transverse slit includes: Taking the direction from left bank to right bank as the X-axis and the direction from upstream to downstream as the Y-axis, the polar coordinate angle of the accelerometer's location is: Then its transverse tangential acceleration vibration signal is: The transverse seam normal acceleration vibration signal is: in, and This represents the acceleration vibration response in the X and Y directions.

4. The dynamic detection method for seismic damage at transverse joints of an arch dam according to claim 1, characterized in that, The comprehensive damage index is DI=min( , ).

5. The method of claim 4, wherein the method comprises: Also includes: Based on the identified damage status of the transverse joints of the arch dam, a damage indication diagram is drawn.

6. The method of claim 5, wherein the method comprises: The damage indication map selects the damage area and determines the warning color according to the following principles based on the DI of each detection location; wherein: Strong damage (DI=[0.00-0.70)), red; moderate damage (DI=[0.70-0.90)), yellow; no damage (DI=[0.90-1.00]), green; Finally, a damage indication map is plotted on the sensor network diagram.

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