Device and method for testing mechanical response of concrete dam structure surface under water load

Abstract

The present application belongs to the technical field of hydraulic engineering material testing, and particularly relates to a device and method for testing the mechanical response of a concrete dam structure surface under water load, comprising: a vertical mechanical loading device and a lateral water pressure loading device arranged on a dam concrete test piece. The lateral water pressure loading device comprises an integrally formed high-pressure water tank fixed on one side of the test piece, a water head pressure maintaining device is arranged in the water tank, the water head pressure maintaining device comprises a piston and a hydraulic cylinder, the piston separates the water tank into a water injection chamber and an equipment chamber, the hydraulic cylinder is arranged in the equipment chamber and is hingedly connected to the piston and the inner wall of the water tank at both ends. A structure surface damage multiscale testing device is further arranged to obtain visual data, sound data and strain data at a prefabricated crack. The present application realizes accurate testing of the mechanical response of a concrete dam structure surface under hydraulic coupling by the synergistic effect of vertical mechanical loading and water pressure loading, combined with multiscale synchronous monitoring.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic engineering material testing technology, and particularly relates to a testing device and method for testing the mechanical response of concrete dam structures under water load. Background Technology

[0002] As a major water conservancy project, the long-term operational safety of high concrete dams has always been a core research topic in the engineering field. During their service life, dams are subjected to complex load combinations, among which the coupling effect of water load and structural self-weight load is a key factor leading to stress distribution, deformation characteristics, and even potential failure modes in the dam body. In particular, hydraulic fracturing, i.e., under high water head pressure, water seeps into micro-cracks or weak surfaces in the concrete, causing crack propagation and even structural instability, has become a highly concerning and challenging frontier issue in high dam safety assessment. Laboratory physical model tests are an indispensable and crucial method for in-depth research on the performance of dam concrete materials and structures under complex loads.

[0003] However, existing testing technologies and equipment still have significant limitations in simulating the actual stress state of dams and revealing their failure mechanisms. Most mainstream material testing machines currently use rigid indenters or actuators to apply concentrated or uniform pressure to specimens. Essentially, they use solid force transmission media to simulate fluid pressure, which cannot reproduce the uniform normal force of real water loads and the seepage and splitting effects of water into the pores or cracks inside concrete under pressure. This leads to a serious disconnect between the test conditions and actual engineering conditions.

[0004] Traditional testing methods rely on attaching strain gauges or placing displacement gauges on the specimen surface. These contact-point measurement methods can only obtain macroscopic strain or displacement information on the specimen surface, making it difficult to comprehensively capture the initiation of internal micro-cracks, visually depict the dynamic propagation path of cracks, or reveal the continuous evolution process of damage from microscopic accumulation to macroscopic failure. In addition, existing hydraulic loading methods mostly use simple water supply towers or pressure vessels for indirect implementation, which suffers from problems such as low water head, poor pressure control accuracy, and insufficient stability. They are difficult to simulate the extremely high water head borne by dams of 100 meters or more, and systems that can simultaneously apply stable axial pressure to simulate self-weight are even rarer. Each subsystem often operates independently, lacking a unified closed-loop control and data synchronization mechanism. Leakage is prone to occur at the high-pressure water loading interface, which restricts the development of high-quality research.

[0005] Therefore, there is an urgent need for testing devices and methods for testing the mechanical response of concrete dam structures under water load. Summary of the Invention

[0006] The purpose of this invention is to provide a testing device and method for testing the mechanical response of concrete dam structures under water load, so as to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention provides the following solution: A testing device for the mechanical response of a concrete dam structure under water load includes: Vertical mechanical loading device and lateral water pressure loading device installed on the dam concrete specimen; The vertical mechanical loading device includes a fixed reaction frame and a vertical pressure mechanism connected to the reaction frame. The vertical pressure mechanism is used to apply a vertical load to the top of the dam concrete specimen. The lateral water pressure loading device includes an integrally molded high-pressure water tank fixed to one side of the dam concrete specimen. The integrally molded high-pressure water tank is equipped with a water head pressure holding device, which includes a piston and a hydraulic cylinder. The piston divides the integrally molded high-pressure water tank into a water injection chamber and an equipment chamber. The hydraulic cylinder is located in the equipment chamber, and one end of the hydraulic cylinder is hinged to the piston, while the other end of the hydraulic cylinder is hinged to the inner wall of the integrally molded high-pressure water tank. The water injection chamber is connected to a water source and an automatic water replenishment module. The water injection chamber is sealed to the side wall of the dam concrete specimen. A pressure acquisition system is installed inside the water injection chamber. The hydraulic cylinder is connected to a control device. A multi-scale structural surface damage testing device is also provided, which is set at the precast crack on one side of the dam concrete specimen. The multi-scale structural surface damage testing device is located inside the water injection chamber and is used to acquire visual data, sound data and strain data at the precast crack.

[0008] Optionally, the integrally molded high-pressure water tank is fixed to the dam concrete specimen by bolts.

[0009] Optionally, a sealing structure is provided at the joint between the integrally molded high-pressure water tank and the dam concrete specimen.

[0010] Optionally, the multi-scale structural surface damage testing device includes a vision module, an acoustic emission system, a strain acquisition system, and a distributed strain sensing fiber optic system.

[0011] Optionally, the pressure acquisition system includes a digital display pressure transmitter, which is connected to the control device.

[0012] Optionally, the control device includes a PLC control system and a central control box, wherein the PLC control system is connected to the hydraulic cylinder, the pressure acquisition system and the automatic water replenishment module.

[0013] Optionally, the hydraulic cylinder is connected to a hydraulic pump station, and the hydraulic pump station is connected to the PLC control system.

[0014] Optionally, the strain acquisition system includes multiple full-bridge strain gauges, which are arranged at the precast crack.

[0015] Optionally, the vertical pressure-applying mechanism is a jack.

[0016] A method for testing the mechanical response of a concrete dam structure under water load, using the aforementioned testing device for the mechanical response of a concrete dam structure under water load, includes the following steps: The precast cracks were set on the dam concrete specimen, and the multi-scale structural surface damage testing device was set at the precast cracks. The water injection chamber of the integrally molded high-pressure water tank is covered over the prefabricated crack; The water source and the automatic water replenishment module fill the water injection chamber with water, and the control device controls the extension and retraction of the hydraulic cylinder to make the piston squeeze the water injection chamber toward the dam concrete specimen. The water pressure value is displayed by the pressure acquisition system. Simultaneously, a vertical load is applied to the dam concrete specimen through the vertical mechanical loading device; Visual, acoustic, and strain data at the precast cracks are obtained using the multi-scale structural surface damage testing device.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: The test device and method for the mechanical response of concrete dam structures under water load employs a hydraulic cylinder-driven piston to apply pressure to the water in the injection chamber. Combined with feedback signals from a digital pressure transmitter, closed-loop precise control is achieved, enabling the application of a stable and adjustable high-pressure water load to the sides of the specimen, realistically simulating the water pressure effect of a high dam at different water levels. A vertical pressure mechanism on the reaction frame applies a mechanical load to the top of the specimen, simultaneously simulating the dam's self-weight, thus constructing a hydraulically coupled stress state closer to actual engineering conditions. The integrated high-pressure water tank is fixed to the specimen with bolts, and a sealing structure at the joints effectively prevents high-pressure water leakage, ensuring the reliability of the test process and the accuracy of the data. The multi-scale structural damage test device integrates a vision module, an acoustic emission system, a strain acquisition system, and a distributed strain sensing fiber optic system. It can acquire visual, acoustic, and strain data at pre-fabricated cracks in situ within the injection chamber, achieving full-scale, multi-parameter synchronous observation from macroscopic surface deformation to the initiation and propagation of internal microcracks. This device provides a highly realistic experimental means for safety assessment of dam concrete materials and structures. It is particularly suitable for studying key issues such as hydraulic fracturing, damage accumulation under long-term seepage pressure, and fracture performance under coupled loads. It can provide direct experimental basis for dam engineering design, safety early warning, and maintenance strategies. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of the present invention; Figure 3 This is a schematic diagram showing the arrangement of the acquisition ends of each module in the multi-scale structural surface damage testing device of the present invention; Figure 4 This is a system connection diagram of the present invention; The components include: 1. Integrated high-pressure water tank; 2. Water head pressure maintaining device; 3. Hydraulic pump station; 4. Pressure acquisition system; 5. PLC control system; 6. Central control box; 8. Hydraulic cylinder; 9. Automatic water replenishment module; 10. Sealing structure; 11. Multi-scale structural surface damage testing device; 12. Vision module; 13. Acoustic emission system; 14. Strain acquisition system; 15. Distributed strain sensing fiber optic system; 16. Vertical mechanical loading device; 1601. Reaction frame; 17. Dam concrete specimen; 18. Bolts. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figures 1 to 4 This invention discloses a testing device for the mechanical response of a concrete dam structure under water load, comprising: Vertical mechanical loading device 16 and lateral water pressure loading device are installed on the dam concrete specimen 17; The vertical mechanical loading device 16 includes a fixed reaction frame 1601 and a vertical pressure mechanism connected to the reaction frame 1601. The vertical pressure mechanism is used to apply a vertical load to the top of the dam concrete specimen 17. The lateral water pressure loading device includes an integrally molded high-pressure water tank 1 fixed to one side of the dam concrete specimen 17. The integrally molded high-pressure water tank 1 is equipped with a water head pressure holding device 2. The water head pressure holding device 2 includes a piston and a hydraulic cylinder 8. The piston divides the integrally molded high-pressure water tank 1 into a water injection chamber and an equipment chamber. The hydraulic cylinder 8 is installed in the equipment chamber, and one end of the hydraulic cylinder 8 is hinged to the piston, and the other end of the hydraulic cylinder 8 is hinged to the inner wall of the integrally molded high-pressure water tank 1. The water injection chamber is connected to a water source and an automatic water replenishment module 9. The water injection chamber is sealed to the side wall of the dam concrete specimen 17. The water injection chamber is equipped with a pressure acquisition system 4 and a hydraulic cylinder 8 connected to a control device. A multi-scale structural surface damage testing device 11 is also provided, which is set at the precast crack on one side of the dam concrete specimen 17. The multi-scale structural surface damage testing device 11 is located in the water injection chamber and is used to acquire visual data, sound data and strain data at the precast crack.

[0022] A vertical mechanical loading device 16 and a lateral water pressure loading device are installed on the dam concrete specimen 17. The vertical mechanical loading device 16 includes a fixed reaction frame 1601 and a vertical pressure applying mechanism connected to the reaction frame 1601. The vertical pressure applying mechanism is used to apply a vertical load to the top of the dam concrete specimen 17 to simulate its own weight. The lateral water pressure loading device includes an integrally molded high-pressure water tank 1 fixed to one side of the dam concrete specimen 17. The water tank is equipped with a water head pressure holding device 2, which includes a piston and a hydraulic cylinder 8. The piston divides the integrally molded high-pressure water tank 1 into a water injection chamber and an equipment chamber. The hydraulic cylinder 8 is located in the equipment chamber and is hinged at one end to the piston and at the other end to the inner wall of the integrally molded high-pressure water tank 1. The water injection chamber is connected to a water source and an automatic water replenishment module 9. The water injection chamber is sealed to the side wall of the dam concrete specimen 17. The water injection chamber is equipped with a pressure acquisition system 4, and the hydraulic cylinder 8 is connected to a control device. A multi-scale structural surface damage testing device 11 is installed at a precast crack on one side of the dam concrete specimen 17 and located inside the water injection chamber. It is used to acquire visual, acoustic, and strain data at the precast crack. This invention achieves hydrodynamic coupling simulation through bidirectional vertical and hydraulic loading.

[0023] As an alternative implementation, the integrally molded high-pressure water tank 1 is fixed to the dam concrete specimen 17 by bolts 18.

[0024] Bolt 18 serves as a mechanical fastener, firmly fixing the integrally molded high-pressure water tank 1 to the side wall of the dam concrete specimen 17. This ensures that the water tank will not shift or loosen under the action of high-pressure water, guaranteeing that the water load can be applied stably and vertically to the surface of the specimen. It also facilitates the installation, disassembly, maintenance, and replacement of the water tank.

[0025] As an optional implementation, a sealing structure 10 is provided at the joint between the integrally molded high-pressure water tank 1 and the dam concrete specimen 17.

[0026] Since the water injection chamber is filled with high-pressure water, the joints are the weakest points where high-pressure water is most likely to leak. The sealing structure 10 can effectively prevent high-pressure water from seeping into the specimen contact interface from the joints, ensuring that the water load is fully applied to the specimen surface. At the same time, it avoids water seepage from interfering with the structural surface and damaging the measurement results of the multi-scale testing device 11, thus ensuring the reliability of the test data.

[0027] As an optional implementation, the multi-scale structural surface damage testing device 11 includes a vision module 12, an acoustic emission system 13, a strain acquisition system 14, and a distributed strain sensing fiber optic system 15.

[0028] The vision module 12 is used to acquire surface deformation and displacement field information at the pre-fabricated crack; the acoustic emission system 13 is used to collect acoustic emission signals generated during crack propagation to locate internal cracks; the strain acquisition system 14 is used to acquire local elastic strain at the crack tip; and the distributed strain sensing fiber optic system 15 is used to measure the continuous strain distribution along the fiber optic path. These four monitoring methods work together to achieve full-scale, multi-parameter synchronous observation from macroscopic deformation to microscopic crack initiation and propagation.

[0029] As an optional implementation, the pressure acquisition system 4 includes a digital pressure transmitter, which is connected to a control device.

[0030] The digital pressure transmitter is installed inside the water injection tank or connected to the water circuit. It is used to collect the water pressure value in the water injection tank in real time and convert it into an electrical signal to be sent to the control device. The control device adjusts the hydraulic cylinder 8 accordingly, thereby realizing closed-loop precise control of water pressure and ensuring that the water load can be stably maintained at the set value.

[0031] As an optional implementation, the control device includes a PLC control system 5 and a central control box 6. The PLC control system 5 is connected to the hydraulic cylinder 8, the pressure acquisition system 4, and the automatic water replenishment module 9.

[0032] The PLC control system 5, as the core controller, receives the water pressure signal fed back by the pressure acquisition system 4, processes it through the internal PID algorithm, and outputs control commands to the hydraulic cylinder 8 to adjust the water pressure. At the same time, it controls the water replenishment frequency and timing of the automatic water replenishment module 9. The central control box 6 provides a human-machine interface for operators to set parameters and monitor the test process.

[0033] As an optional implementation, the hydraulic cylinder 8 is connected to the hydraulic pump station 3, and the hydraulic pump station 3 is connected to the PLC control system 5.

[0034] The hydraulic pump station 3 provides power oil to the hydraulic cylinder 8. The PLC control system 5 adjusts the output oil pressure by controlling the proportional relief valve in the hydraulic pump station 3, thereby precisely controlling the thrust of the piston of the hydraulic cylinder 8, and finally realizing the dynamic adjustment of the water pressure in the water injection tank, forming a complete hydraulic drive closed-loop control system.

[0035] As an optional implementation, the strain acquisition system 14 includes multiple full-bridge strain gauges arranged at the pre-fabricated crack.

[0036] The full-bridge strain gauge adopts a full-bridge circuit connection method, which can effectively compensate for the influence of temperature changes on strain measurement. Multiple full-bridge strain gauges are arranged at different positions at the crack tip and around the structural surface, which can obtain the local elastic strain changes at key positions during crack propagation, providing data support for calculating the stress intensity factor at the crack tip.

[0037] As an optional implementation, the vertical pressure mechanism is a jack.

[0038] As a common mechanical loading device, the jack is installed on the reaction frame 1601. Its jack rod extends downward and contacts the top of the dam concrete specimen 17. The jack rod is driven to press down by hydraulic or mechanical means to apply vertical load to the dam concrete specimen 17 to simulate the dam body's self-weight and other vertical sustained loads. It has the advantages of simple structure, large loading force and convenient control.

[0039] Specifically, this device aims to comprehensively test and analyze the structural response of dam concrete specimens by simulating real water loads and environmental conditions with high precision. Its technical principles and implementation methods can be systematically described as follows: 1. Device Composition: This equipment mainly consists of four parts: a real water load application device, a sealing structure, a multi-scale structural surface damage testing device, and a vertical mechanical loading device.

[0040] The real water load application device consists of the following components: 1. One-piece molded high-pressure water tank; 2. Water head pressure holding device; 3. Hydraulic pump station; 4. Pressure acquisition system: including digital display pressure transmitter, PLC control system; 5. Central control box; 6. Programmable control software; 8. Hydraulic cylinder; 9. Automatic water replenishment module.

[0041] The one-piece molded high-pressure water tank 1 is made of stainless steel and can provide a pressure of up to 5MPa (approximately 500m water head), and can be set to any pressure value within 5MPa.

[0042] The water pressure control method adopts hydraulic-piston, which is implemented through the water head pressure holding device 2. The water head pressure holding device 2 includes a piston that is slidably installed in the integrally molded high-pressure water tank 1, and a hydraulic cylinder 8 installed between the piston and the inner wall of the integrally molded high-pressure water tank 1. Automatic pressurization is achieved through the PLC control system 5 and the pressure acquisition system 4. The power of the piston is supplied by the hydraulic cylinder 8 that is hinged to it.

[0043] The digital pressure transmitter in the pressure acquisition system 4 collects the water pressure value and proportionally controls the oil pressure of the hydraulic cylinder 8, thereby achieving a precise and stable water head loading value. The water tank has an automatic water replenishment function with a replenishment frequency of 4Hz.

[0044] All key parameters, such as pressure and holding time, are precisely controlled by the PLC control system 5. These parameters, including holding time and differential pressure, can also be set directly on the equipment's touchscreen. Test data can be exported via LabVIEW software, with a data acquisition frequency of up to 5 times per second.

[0045] The sealing structure 10 adopts a dual design of "mechanical seal + chemical protection". In this embodiment, the sealing structure 10 includes a sealing ring and a sealant.

[0046] The multi-scale structural surface damage testing device 11 consists of the following subsystems: vision module 12, acoustic emission system 13, strain acquisition system 14, including full-bridge strain gauges and distributed strain sensing fiber optic system 15.

[0047] Digital image processing technology is used to monitor the deformation of the observation surface of the concrete specimen with precast cracks after pressure is applied; acoustic emission (AE) technology is used to monitor the internal damage of the concrete specimen with precast cracks. The positioning function of acoustic emission can be used to locate the internal cracks of the concrete structure, describe the crack propagation size, and determine the failure mode of the concrete damage; the strain acquisition system monitors the strain at the bonding locations by attaching full-bridge strain gauges to the crack tip and structural surface of the concrete specimen with precast cracks; the distributed strain sensing fiber optic system 15 monitors the internal strain of the concrete component by pre-embedding distributed optical fibers inside the concrete specimen.

[0048] The vertical mechanical loading device 16 mainly adopts a reaction frame 1601. The reaction frame, with its own rigidity, transforms the force exerted by loading equipment such as jacks into internal reaction forces, forming a closed force system. This provides stable reaction support for the object being inspected or constructed, meeting the requirements for force value calibration, component loading tests, etc. The rated bearing capacity of the reaction frame used in this invention is 8000KN.

[0049] The specific implementation method of this device is as follows: (1) Specimen and load simulation system A stainless steel, integrally molded high-pressure water tank 1 is fixed to the side of the dam concrete specimen 17 using bolts 18. The inner wall of the integrally molded high-pressure water tank 1 is hinged to a hydraulic cylinder 8. The hydraulic cylinder 8 acts as a power source, pushing a piston to compress water against the side wall of the dam concrete specimen 17. Controlling the extension and retraction of the hydraulic cylinder 8 dynamically applies and controls the water pressure. A high-precision digital pressure transmitter collects real-time water pressure data from the tank. Using this data as feedback, the system adjusts the oil pressure of the hydraulic cylinder 8 using proportional control, thereby achieving precise and stable pressure loading of the water head.

[0050] This closed-loop control system ensures that the water load can stably and repeatably simulate the static and fluctuating pressures on the dam body caused by real water level changes. The specific implementation of the closed-loop control involves a digital pressure transmitter installed in the water circuit between the integrated high-pressure water tank 1 and the hydraulic cylinder 8. This transmitter collects water pressure values ​​in real time and converts them into a 4-20mA electrical signal, which is then sent to the PLC control system 5. The PLC control system 5 internally runs a PID algorithm, comparing the measured water pressure with the target water pressure set on the touchscreen. It then outputs a corresponding analog control signal to the proportional relief valve of the hydraulic pump station 3, thereby dynamically adjusting the oil pressure in the hydraulic cylinder 8 and driving the piston to change the water pressure in the water tank.

[0051] The closed-loop sampling period is 50ms, and the steady-state pressure fluctuation is ≤±0.5%FS. The purpose of closed-loop control is not only to precisely regulate water pressure, but more importantly, to compensate for water pressure fluctuations caused by specimen deformation and leakage in real time, ensuring a constant water load throughout the entire test.

[0052] (2) Seepage prevention and boundary condition control A sealing structure 10 is provided on the loading surface of the water tank to prevent high-pressure water from seeping into the contact interface of the specimen during the test, ensuring that the water load is fully applied to the surface of the specimen, and avoiding water seepage interference with the measurement results. An adjustable mechanical load is applied to the upper part of the dam specimen through a reaction frame 1601 to simulate the dam's self-weight and other vertical sustained loads, thereby constructing a water-force coupling stress state that is closer to reality.

[0053] (3) Multi-scale damage observation system A multi-scale structural damage testing device 11 was deployed on both sides of the pressure zone (the area affected by water load and mechanical load) of the dam concrete specimen 17. This system integrates a vision module 12, a strain acquisition system 14, and an acoustic emission system 13 to achieve simultaneous observation of all scales and multiple parameters, from macroscopic deformation to microscopic crack initiation and propagation. By acquiring strain fields, displacement fields, and acoustic emission signals in real time, the damage evolution law, crack propagation path, and final failure mode of concrete under coupled loads can be analyzed.

[0054] (4) System integration and data fusion The entire device constitutes a comprehensive experimental platform integrating hydraulic drive, water pressure control, mechanical loading, and multi-sensor monitoring. The water pressure system and mechanical loading system can work independently or collaboratively to simulate various working conditions (such as sudden rise in water level, sustained high water level, and staged loading). All sensor data are synchronously acquired through a unified trigger signal and integrated into a unified data processing platform. Data synchronization mechanism: All sensor vision modules 12, acoustic emission system 13, strain acquisition system 14, and distributed strain sensing fiber optic system 15 support external triggering. The PLC control system 5 generates a TTL synchronization pulse signal at each loading step (or every 0.1 seconds), simultaneously triggering each sensor to acquire a frame of data. All data uses the pulse number as a time stamp to ensure alignment of multi-source data at the microsecond level. LabVIEW software is responsible for reading the water pressure and mechanical load data from the PLC and merging them with the measurement data from each sensor into a unified TDMS file. By comparing water pressure, mechanical load, and multi-scale damage data, the mechanical behavior and failure mechanism of dam concrete under complex stress states are revealed.

[0055] This invention also includes a method for testing the mechanical response of a concrete dam structure under water load, using the aforementioned testing device for the mechanical response of a concrete dam structure under water load, comprising the following steps: Precast cracks were set on the dam concrete specimen 17, and the multi-scale structural surface damage testing device 11 was set at the precast cracks. The water injection chamber of the one-piece molded high-pressure water tank 1 is covered over the precast crack; Water is injected into the water injection chamber through the water source and automatic water replenishment module 9, and the hydraulic cylinder 8 is extended and retracted by the control device to make the piston squeeze the water injection chamber toward the side of the dam concrete specimen 17, and the water pressure value is displayed through the pressure acquisition system 4. At the same time, a vertical load is applied to the dam concrete specimen 17 through the vertical mechanical loading device 16; Visual, acoustic, and strain data at the precast cracks are obtained using the multi-scale structural surface damage testing device 11.

[0056] 2.1 Typical Experimental Procedures and Data Fusion Analysis Taking precast cracked concrete specimens as an example, the test steps are as follows: 1. Pre-cast crack: An initial crack (depth and length known) is pre-cast on the surface or side of the dam concrete specimen 17.

[0057] 2. Installation and Loading: Install the specimen under the reaction frame 1601, and fix the high-pressure integrated molded high-pressure water tank 1 to the side of the specimen. Set the target water pressure value (e.g., 2MPa) and the vertical mechanical load (e.g., 500kN). Start the closed-loop control and load synchronously.

[0058] 3. Synchronous acquisition of multi-source data: The vision module 12 continuously captures speckle images of the specimen surface at a frequency of 10 Hz to obtain the surface displacement field (X1 data) and principal strain field (X2 data). The crack tip opening displacement (COD) can be extracted as a direct quantitative indicator of crack propagation.

[0059] Acoustic emission system 13: Acquires AE waveforms at a sampling rate of 1MHz, extracts cumulative impact count (Y1 data), energy release rate (Y2 data), and event location coordinates (Y3 data). Identifies the crack propagation front through three-dimensional location clusters.

[0060] Strain acquisition system 14: Strain gauges (14a) are attached to the crack tip and the front and back of the structure to acquire local elastic strain (Z1 data).

[0061] Distributed strain sensing fiber optic system 15: measures the continuous strain distribution (Z2 data) along the fiber path to identify internal strain concentration zones.

[0062] 4. Data fusion and analysis methods: Time synchronization: All sensor data are based on the clock of the PLC control system 5, and the timestamps are unified through LabVIEW software to ensure that different data streams can be aligned on the same time axis (accuracy ≤ 0.1 seconds).

[0063] Feature extraction: Crack length, width, and propagation velocity are calculated from the DIC displacement field; 3D crack surface is plotted from the AE positioning cluster; stress intensity factor KI at the crack tip is calculated from strain gauge and fiber optic data.

[0064] Multi-scale correlation: Correlation analysis is performed between macroscopic crack propagation (DIC) and microscopic AE event rate to establish a damage variable D(t) = f(AE energy, crack opening displacement). For example, grey relational analysis or Bayesian linear regression can be used to quantify the relationship between AE energy and crack propagation rate.

[0065] Target data output: Crack propagation trajectory map (fusion of DIC surface trajectory + AE internal positioning); water pressure-crack length-time curve; hydraulic fracturing threshold pressure value (water pressure corresponding to crack instability propagation); concrete damage evolution cloud map (fiber optic strain distribution).

[0066] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0067] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A testing device for the mechanical response of a concrete dam structure under water load, characterized in that, include: A vertical mechanical loading device (16) and a lateral water pressure loading device are installed on the dam concrete specimen (17); The vertical mechanical loading device (16) includes a fixed reaction frame (1601) and a vertical pressure mechanism connected to the reaction frame (1601). The vertical pressure mechanism is used to apply a vertical load to the top of the dam concrete specimen (17). The lateral water pressure loading device includes an integrally molded high-pressure water tank (1) fixed on one side of the dam concrete specimen (17). The integrally molded high-pressure water tank (1) is equipped with a water head pressure holding device (2). The water head pressure holding device (2) includes a piston and a hydraulic cylinder (8). The piston divides the integrally molded high-pressure water tank (1) into a water injection chamber and an equipment chamber. The hydraulic cylinder (8) is located in the equipment chamber. One end of the hydraulic cylinder (8) is hinged to the piston, and the other end of the hydraulic cylinder (8) is hinged to the inner wall of the integrally molded high-pressure water tank (1). The water injection chamber is connected to a water source and an automatic water replenishment module (9). The water injection chamber is sealed to the side wall of the dam concrete specimen (17). The water injection chamber is equipped with a pressure acquisition system (4). The hydraulic cylinder (8) is connected to a control device. A multi-scale structural surface damage testing device (11) is also provided, which is set at the precast crack on one side of the dam concrete specimen (17). The multi-scale structural surface damage testing device (11) is located in the water injection chamber. The multi-scale structural surface damage testing device (11) is used to acquire visual data, sound data and strain data at the precast crack.

2. The testing device for the mechanical response of a concrete dam structure under water load according to claim 1, characterized in that, The integrally molded high-pressure water tank (1) is fixed to the dam concrete specimen (17) by bolts (18).

3. The testing device for the mechanical response of a concrete dam structure under water load according to claim 1, characterized in that, A sealing structure (10) is provided at the joint between the integrally molded high-pressure water tank (1) and the dam concrete specimen (17).

4. The testing device for the mechanical response of a concrete dam structure under water load according to claim 1, characterized in that, The multi-scale testing device (11) for structural surface damage includes a vision module (12), an acoustic emission system (13), a strain acquisition system (14), and a distributed strain sensing fiber optic system (15).

5. The testing device for the mechanical response of a concrete dam structure under water load according to claim 1, characterized in that, The pressure acquisition system (4) includes a digital display pressure transmitter, which is connected to the control device.

6. The testing device for the mechanical response of a concrete dam structure under water load according to claim 1, characterized in that, The control device includes a PLC control system (5) and a central control box (6). The PLC control system (5) is connected to the hydraulic cylinder (8), the pressure acquisition system (4), and the automatic water replenishment module (9).

7. The testing device for the mechanical response of a concrete dam structure under water load according to claim 6, characterized in that, The hydraulic cylinder (8) is connected to a hydraulic pump station (3), and the hydraulic pump station (3) is connected to the PLC control system (5).

8. The testing device for the mechanical response of a concrete dam structure under water load according to claim 4, characterized in that, The strain acquisition system (14) includes multiple full-bridge strain gauges, which are arranged at the precast crack.

9. The testing device for the mechanical response of a concrete dam structure under water load according to claim 1, characterized in that, The vertical pressure-applying mechanism is a jack.

10. A method for testing the mechanical response of a concrete dam structure under water load, using the testing device for testing the mechanical response of a concrete dam structure under water load as described in any one of claims 1-9, characterized in that... Includes the following steps: The precast cracks were set on the dam concrete specimen (17), and the multi-scale structural surface damage testing device (11) was set at the precast cracks; The water injection chamber of the integrally molded high-pressure water tank (1) is covered over the prefabricated crack; The water source and the automatic water replenishment module (9) fill the water injection chamber with water, and the control device controls the hydraulic cylinder (8) to extend and retract so that the piston squeezes the water injection chamber toward the dam concrete specimen (17) and the water pressure value is displayed by the pressure acquisition system (4). At the same time, a vertical load is applied to the dam concrete specimen (17) by the vertical mechanical loading device (16); Visual data, sound data and strain data at the precast cracks are obtained through the multi-scale structural surface damage testing device (11).

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