A measuring device and method for measuring normal stiffness of different specifications of concrete foundation

Abstract

The application discloses a kind of measuring device and method for measuring the normal rigidity of different specifications concrete foundation, and the testing device includes back type metal frame, load loading system, displacement measurement system, information acquisition system.Back type metal frame is integrated design.Load loading system built-in hollow force sensor, real-time monitoring and acquisition can be realized, and the local uniform distribution transmission of force can be realized by the pressing block at the end of loading system, to simulate actual foundation support load.Based on laser displacement sensor, displacement measurement system is the core component, and finally through information acquisition system, non-contact measurement and accurate analysis of the normal deformation of anchor hook grouting concrete foundation are realized, the whole operation is simple, measurement is fast, the result is reliable, and it has important opening-up significance for the subsequent study of anchor hook grouting concrete foundation support normal static rigidity.

Description

Technical Field

[0001] This invention relates to the field of CNC machine tool design, and in particular to a device and method for rapidly measuring the normal stiffness of concrete foundations of different specifications. Background Technology

[0002] Static stiffness is a crucial indicator in machine tool design. Improving the static stiffness of a machine tool enhances its efficiency, machining accuracy, and surface finish. Currently, there is no specific method for measuring the normal stiffness of anchored grouted concrete foundations. The common approach is to combine the machine tool foundation and anchor pads into a simplified block-mass system, using vibration equations and measured frequency modes to inversely calculate the equivalent stiffness of the block. However, this method is costly, time-consuming, and only applicable to specific anchor supports and concrete mixes, lacking practical application value. Therefore, developing a testing device that can adjust the normal loading pressure on the anchor supports at any time, ensure uniform stress on the application surface, and accurately measure pressure and strain, along with a rapid and efficient testing method, is of paramount importance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a measuring device and method for measuring the normal stiffness of concrete foundations of different specifications. This device features real-time controllability of normal pressure loading, high stability, uniform loading of the concrete foundation, universality of concrete foundation testing, and rapid availability of concrete foundation stiffness. Furthermore, a method for testing the normal stiffness of concrete foundations is proposed based on this device.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A measuring device for measuring the normal stiffness of concrete foundations of different specifications includes a U-shaped metal frame, a load loading system, a displacement measuring system, and a signal acquisition system. The U-shaped metal frame is installed on the concrete foundation and leveled by anchor blocks. The U-shaped metal frame is integrally cast from cast steel. Two support frames are installed parallel to each other on the lower inner surface of the U-shaped metal frame to support concrete foundation test blocks of different specifications. The top of the U-shaped metal frame is provided with a normal pressure cylinder hole for connecting the load loading system.

[0006] The displacement measurement system includes a linear guide rail, a slider, a laser displacement sensor, and a U-shaped mounting bracket. The upper and lower surfaces inside the U-shaped metal frame are respectively symmetrically mounted with linear guide rails. A slider is slidably connected to the linear guide rail. A U-shaped mounting bracket is mounted on the slider. A laser displacement sensor is mounted on the U-shaped mounting bracket.

[0007] The connecting load loading system includes, from top to bottom, a hydraulic cylinder, a flange, a sensor base, a sensor housing, and a pressure head that are connected to each other in sequence. Hollow force sensors are installed in the sensor base and the sensor housing. The hydraulic cylinder is fixed to the normal pressure cylinder hole through the flange.

[0008] Laser displacement sensors and hollow force sensors are connected to the signal acquisition system via wires to achieve non-contact measurement and acquisition of normal deformation of concrete foundations of different specifications.

[0009] Furthermore, the linear guide rail is located 150 mm from the center of the inner surface of the U-shaped metal frame.

[0010] Furthermore, the support frame consists of two rectangular profiles measuring 100*200*1000mm, which are bolted to the lower inner surface of the U-shaped metal frame.

[0011] Furthermore, a laser displacement sensor located below the concrete foundation test block is used to measure the deformation of the lower surface of the concrete foundation test block, and a laser displacement sensor located above the concrete foundation test block is used to measure the deformation of the upper surface of the concrete foundation test block. The difference between the two is the normal deformation of the concrete foundation test block.

[0012] The present invention also provides a method for measuring the normal stiffness of concrete foundations of different specifications, comprising the following steps:

[0013] (1) Place the concrete foundation test block to be tested in the U-shaped metal frame and adjust its position. At the same time, install two laser displacement sensors on two U-shaped mounting brackets and adjust them. Use the load loading system to manually adjust the normal pressure and preload the concrete foundation test block. The preload force is the maximum load on the concrete foundation test block. Collect the corresponding force signal through the signal acquisition system and monitor the loading force to eliminate the influence of the initial gap of the concrete foundation test block on the normal stiffness of the concrete foundation test block.

[0014] (2) Maintain the initial load for 10-20 minutes. After the residual stress in the U-shaped mounting frame is completely released, that is, when the displacement change obtained by the signal acquisition system no longer fluctuates with the trend of rising or falling over time, calibrate the hollow force sensor and the laser displacement sensor, and collect force and displacement information.

[0015] (3) Gradually unload the normal force on the concrete foundation test block, and after the loading force is stabilized in the range of 4500N to 5500N, carry out the loading test. After each 5000N force is applied, the signal acquisition system collects the corresponding load and displacement information.

[0016] (4) Export the information collected by the signal acquisition system to Excel or Matlab software for data processing, apply the stiffness definition formula for fitting, and then output the static stiffness test curve of the concrete foundation test block under different loading conditions.

[0017] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0018] 1. Due to the static analysis and optimization employed, the overall structure of this invention is lightweight, compact, and easy to assemble while meeting the stiffness requirements of the experiment. Furthermore, both the loading system and the measurement and acquisition system are modularly mounted on the main structure, making them easy to disassemble, maintain, and adjust.

[0019] 2. By using a simulated foundation test block for measurement, compared to the traditional method of assembling the entire machine and identifying the stiffness of the bed support, this device offers advantages in measuring the normal stiffness of the machine tool foundation: speed, accuracy, and ease of operation. Furthermore, in actual experiments, the stiffness curve fitted by relevant software from the collected data corresponds well with the stiffness under actual working conditions, with an error not exceeding 10%, thus meeting the expectations and requirements of measurement at the current stage.

[0020] 3. The hollow force sensor in the device is connected to the signal acquisition system through wires, which can realize real-time monitoring and acquisition of the loaded load. At the same time, the ball-groove pressure block that contacts the end of the load loading system can realize the local uniform distribution of force. The simulated foot on the anchored grouting concrete foundation test block can simulate the actual anchored grouting concrete foundation support load.

[0021] 4. The displacement measurement system in this device uses a laser displacement sensor as its core component to achieve non-contact measurement and acquisition of the normal deformation of grouted concrete foundations with anchor hooks.

[0022] Simultaneously, signals acquired by the laser displacement sensor and the hollow force sensor are input to the signal acquisition system via wires. These signals are then processed by the acquisition card integrated into the acquisition box within the system and transmitted to LabVIEW software for visualization. Based on the changes in force and displacement information obtained through software processing, the loading and measurement system can be easily and quickly debugged and corrected. Based on the structure of this device and the stiffness definition formula, this invention enables rapid measurement and accurate analysis of the normal stiffness of anchored grouting concrete foundations of different specifications.

[0023] 5. The main frame of this invention adopts a U-shaped frame structure with a closed force curve, which has high rigidity. The support frame on the lower inner side of the U-shaped frame has high versatility and can meet the measurement of the rigidity of grouting concrete foundations with anchor hooks of different specifications.

[0024] 6. In the load loading system, the air force sensor is built into the sensor base and sensor housing, realizing a compact combination of hydraulic cylinder, air force sensor and pressure head.

[0025] 7. The test method of this invention avoids the influence of the initial gap of the anchored grouting concrete foundation support on the stiffness, and it is simple, efficient and versatile. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the measuring device of the present invention.

[0027] Figure 2 This is a schematic diagram of the U-shaped metal frame structure;

[0028] Figure 3 This is a structural schematic diagram of the load loading system;

[0029] Figure 4 This is a schematic diagram of a displacement measurement system.

[0030] Reference numerals: 1-U-shaped metal frame, 2-load loading system, 3-displacement measurement system, 4-signal acquisition system, 5-concrete foundation test block, 6-simulated anchor, 7-pressure block, 101-support frame, 102-flange, 103-normal cylinder bore, 201-hydraulic cylinder, 202-flange, 203-sensor base, 204-hollow force sensor, 205-sensor housing, 206-pressure head, 301-linear guide rail, 302-U-shaped mounting bracket, 303-laser displacement sensor. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0032] See Figure 1This is a schematic diagram of the overall structure of the measuring device for measuring the normal stiffness of concrete foundations of different specifications provided in this embodiment. It includes a U-shaped metal frame 1, a load loading system 2, a displacement measuring system 3, and a signal acquisition system 4. The U-shaped metal frame 1 is installed on the concrete foundation and leveled using anchor blocks. The U-shaped metal frame 1 is integrally cast from cast steel. Two support frames 101 are installed parallel to each other on the lower inner surface of the U-shaped metal frame to support concrete foundation test blocks 5 of different specifications. A flange 102 and a normal pressure cylinder hole 103 are provided on the top of the U-shaped metal frame 1 for connecting the load loading system 2. In this embodiment, the concrete foundation test block 5 is a grouted concrete foundation with anchor hooks. The laser displacement sensor 303 and the hollow force sensor 204 are connected to the signal acquisition system 4 via wires to achieve non-contact measurement and acquisition of the normal deformation of concrete foundations of different specifications.

[0033] Figure 1 As can be seen from the diagram, the overall structure of the measuring device in this embodiment is compact and the modules are clearly defined, ensuring rapid and accurate measurement of the normal stiffness of the grouting concrete foundation with anchor hooks. The signal acquisition system is mainly responsible for monitoring and extracting pressure and displacement data during the experiment. Using the signal acquisition system and matching software, the electrical signals are amplified and converted into electronic signals, which are then acquired by the computer via a USB interface, achieving the purpose of real-time monitoring and acquisition of pressure and displacement.

[0034] See Figure 2 The U-shaped metal frame 1 serves as the platform and foundation of the measuring device, making its rigidity and reliability paramount. Therefore, the U-shaped metal frame 1 is constructed entirely of cast steel. Furthermore, considering that the U-shaped metal frame 1 is a primary load-bearing component, and to ensure better structural stability during the experiment, optimize material utilization efficiency, and increase personnel safety, it is designed as a U-shaped frame and integrally cast from cast steel. Symmetrically positioned on the lower inner surface of the U-shaped metal frame 1, suitable metal support frames of specification 101 are bolted together according to the specifications of the anchored grouting concrete foundation used in the experiment. This structural design ensures rapid installation and commissioning of other components of the test bench and the anchored grouting concrete foundation, while also providing better structural stability compared to non-frame structures. A normal pressure cylinder hole 103 is pre-drilled at the center of the inner surface of the upper side of the U-shaped metal frame 1, and a flange 102 is installed thereon. A hydraulic cylinder 201 is connected to the flange. During the test, the normal pressure is applied to the grouting concrete foundation with anchor hooks on the U-shaped metal frame 1 to meet the loading requirements for measuring the normal stiffness of the grouting concrete foundation with anchor hooks.

[0035] The displacement measurement system 3 includes a linear guide rail 301, a slider, a laser displacement sensor 303, and a U-shaped mounting bracket 302. The linear guide rail 301 is symmetrically mounted on the upper and lower surfaces inside the U-shaped metal frame 1. A slider is slidably connected to the linear guide rail 301, and a U-shaped mounting bracket 302 is mounted on the slider. The laser displacement sensor 303 is mounted on the U-shaped mounting bracket 302. When the two linear guide rails 301 are installed, they are kept on the same vertical plane. The upper and lower laser displacement sensors 303 are always on the same vertical line during the measurement process, which provides a mounting path for possible measuring instruments and ensures the stability and accuracy of the measurement.

[0036] See Figure 3 The diagram illustrates the structure of the load loading system. Specifically, to better simulate the pressure loading of the machine tool bed on the grouting concrete foundation with anchor hooks in actual working conditions, the loading force method was optimized through simulation using ANSYS software. Finally, the pressure was applied by using a series of hydraulic cylinders, hollow force sensors, and pressure heads to push the pressure blocks. The hydraulic cylinder 201 of the load loading system 2 and the normal cylinder bore 103 on the upper part of the U-shaped metal frame 1 are connected by a flange 202. Simultaneously, the sensor base 203 is embedded in the end of the hydraulic cylinder 201, and the hollow force sensor 204 is connected to the sensor base 203 in the same way. The sensor housing 205 is bolted to the sensor base 203 to protect the hollow force sensor 204. Finally, the load generated by the hydraulic cylinder 201 is applied to the pressure block 7 through the pressure head 206, completing the load transfer. During the test, when the normal load is manually applied, the pressure generated by the hydraulic cylinder 201 fixed on the test bench is evenly applied to the simulated foundation anchor 6 and the anchored grouting concrete foundation specimen 5 through the optimized pressure block. Meanwhile, the hollow force sensor 204 built into the load loading system collects the applied load in real time into the corresponding program in the acquisition system. This connection method ensures that the measured load value is consistent with the load generated by the hydraulic cylinder, is stable and reliable, and is easy to install and disassemble.

[0037] Figure 4The structure and working principle of the displacement measurement system are illustrated below. To avoid inaccurate positioning of the upper and lower pair of laser displacement sensors, which would lead to errors in the measurement results, the laser displacement sensor 303 is mounted on a U-shaped mounting bracket 302 to ensure that the two measuring points of the displacement measurement system are on a vertical straight line. The U-shaped mounting bracket 302 is formed by bolting a U-shaped profile frame and a linear guide rail 301. The upper and lower lengths of the U-shaped mounting bracket 302 are equal, and the hole positions are the same, ensuring the stability of the two measuring points of the laser displacement sensor 303. In this embodiment, the measuring point of one laser displacement sensor 303 is located 150mm from the central axis on the upper surface of the concrete foundation specimen, and the measuring point of the other laser displacement sensor 303 is located 150mm from the central axis on the lower surface of the concrete foundation specimen. The two measuring points are on the same side (right side) relative to the central axis. As the load is applied, the lower measuring point measures the deformation of the lower surface of the concrete foundation specimen, and the upper measuring point measures the deformation of the upper surface of the concrete foundation specimen. The difference between the two is the normal deformation of the foundation specimen.

[0038] Based on the above-mentioned measuring device, this embodiment also proposes a method for measuring the normal stiffness of grouted concrete foundations with anchor hooks of different specifications, including the following steps:

[0039] Step 1: Place the foundation test block to be tested in the main frame and adjust its position. At the same time, use the sensor fixing device to install the laser displacement sensor on the mounting frame and debug it. Use the load loading system to manually adjust the normal pressure to preload the foundation test block. The preload force is the maximum load that the foundation test block can withstand. The data collected and processed by the signal acquisition system is used to monitor the loading force in order to eliminate the influence of the initial gap of the foundation test block on the normal stiffness of the foundation test block.

[0040] Step 2: Maintain the initial load for a period of time until the residual stress in the mounting frame is completely released, that is, when the displacement change processed by the signal acquisition system no longer fluctuates with the trend of rising or falling over time, calibrate the hollow force sensor and displacement sensor, and collect force and displacement information.

[0041] Step 3: Gradually unload the normal force on the foundation test block. After unloading to about 5000N, conduct a loading test. After each load is applied, the signal acquisition system collects the corresponding load and displacement information.

[0042] Step 4: Export the information acquired by the signal acquisition system to the corresponding software, apply the stiffness definition formula for fitting, and then output the static stiffness test curves of the foundation test blocks under different loading conditions.

[0043] In summary, the normal stiffness measuring device for grouting concrete foundation with anchor hooks of the present invention can not only quickly and accurately apply loads, but also accurately measure the corresponding deformation displacement. Furthermore, the stiffness curve fitted by relevant software from the collected test data deviates from the stiffness under actual working conditions by no more than 10%. Therefore, it can be said that the normal stiffness of grouting concrete foundation with anchor hooks can be quickly and accurately measured under existing conditions.

[0044] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A measuring device for measuring the normal stiffness of concrete foundations of different specifications, characterized in that, It includes a U-shaped metal frame, a load loading system, a displacement measurement system, and a signal acquisition system. The U-shaped metal frame is installed on the concrete foundation and leveled by anchor blocks. The U-shaped metal frame is integrally cast from cast steel. Two support frames are installed parallel to each other on the lower inner surface of the U-shaped metal frame to support concrete foundation test blocks of different sizes. The top of the U-shaped metal frame is provided with a normal pressure cylinder hole for connecting the load loading system. The displacement measurement system includes a linear guide rail, a slider, a laser displacement sensor, and a U-shaped mounting bracket. The upper and lower surfaces inside the U-shaped metal frame are respectively symmetrically mounted with linear guide rails. A slider is slidably connected to the linear guide rail. A U-shaped mounting bracket is mounted on the slider. A laser displacement sensor is mounted on the U-shaped mounting bracket. The load loading system comprises, from top to bottom, a hydraulic cylinder, a flange, a sensor base, a sensor housing, and a pressure head connected in sequence. Hollow force sensors are installed in the sensor base and the sensor housing. The hydraulic cylinder is fixed to the normal pressure cylinder hole through the flange. Laser displacement sensors and hollow force sensors are connected to the signal acquisition system via wires to achieve non-contact measurement and acquisition of normal deformation of concrete foundations of different specifications.

2. The measuring device for measuring the normal stiffness of concrete foundations of different specifications according to claim 1, characterized in that, The linear guide rail is located 150mm from the center of the inner surface of the U-shaped metal frame.

3. The measuring device for measuring the normal stiffness of concrete foundations of different specifications according to claim 1, characterized in that, The support frame consists of two rectangular profiles, each 100*200*1000mm in length, bolted to the lower inner surface of the U-shaped metal frame.

4. The measuring device for measuring the normal stiffness of concrete foundations of different specifications according to claim 1, characterized in that, A laser displacement sensor located below the concrete foundation specimen is used to measure the deformation of the lower surface of the concrete foundation specimen, and a laser displacement sensor located above the concrete foundation specimen is used to measure the deformation of the upper surface of the concrete foundation specimen. The difference between the two is the normal deformation of the concrete foundation specimen.

5. A method for measuring the normal stiffness of concrete foundations of different specifications, based on the measuring device described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Place the concrete foundation test block to be tested in the U-shaped metal frame and adjust its position. At the same time, install two laser displacement sensors on two U-shaped mounting brackets and adjust them. Use the load loading system to manually adjust the normal pressure and preload the concrete foundation test block to be tested. The preload force is the maximum load on the concrete foundation test block to be tested. Collect the corresponding force signal through the signal acquisition system and monitor the loading force to eliminate the influence of the initial gap of the concrete foundation test block on the normal stiffness of the concrete foundation test block. (2) Maintain the initial load for 10-20 minutes. After the residual stress in the U-shaped mounting frame is completely released, that is, when the displacement change obtained by the signal acquisition system no longer fluctuates with the trend of rising or falling over time, calibrate the hollow force sensor and the laser displacement sensor, and collect force and displacement information. (3) Gradually unload the normal force on the concrete foundation test block, and after the loading force is stabilized in the range of 4500N to 5500N, carry out the loading test. After each 5000N force is applied, the signal acquisition system collects the corresponding load and displacement information. (4) Export the information collected by the signal acquisition system to Excel or Matlab software for data processing, apply the stiffness definition formula for fitting, and then output the static stiffness test curves of concrete foundation test blocks under different loading conditions.

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