Measuring device and method for measuring normal stiffness of concrete foundations of different specifications

Abstract

The invention discloses a measuring device and method for measuring normal stiffness of concrete foundations of different specifications. The measuring device comprises a concentric-square-shaped metal frame, a load loading system, a displacement measuring system and an information collecting system. Wherein the concentric-square-shaped metal frame is integrally designed. A hollow force sensor is arranged in the load loading system, real-time monitoring and collecting of loading can be achieved, a pressing block at the tail end of the loading system can achieve local uniform distribution and transmission of force, and actual foundation supporting load is simulated. The displacement measurement system takes a laser displacement sensor as a core component, and finally realizes non-contact measurement and accurate analysis of normal deformation of the grouting concrete foundation with the anchor hook through the information acquisition system, so that the overall operation is simple, the measurement is quick, and the accuracy is high. The result is reliable, and the method has important development significance for subsequent research on the normal static rigidity of the grouting concrete foundation support with the anchor hook.

Description

Technical Field

[0001] The invention relates to the field of numerical control machine tool design, and in particular to a device and a method for quickly measuring the normal stiffness of concrete foundations of different specifications. Background Art

[0002] Static stiffness is one of the important indicators of machine tool design. Improving the static stiffness of machine tools is conducive to improving the efficiency, processing accuracy and surface processing quality of machine tools. However, there is no method specifically used to measure the normal stiffness of grouting concrete foundation with anchor hooks. Generally, the machine tool foundation and the anchor pad are combined to simplify it into a pad-mass block system, and the equivalent stiffness of the pad is inversely calculated through the vibration equation and the measured frequency vibration mode. However, this method has high experimental cost and long cycle, and can only analyze a certain anchor support and concrete mix ratio, and does not have good application value. Therefore, it is of great significance to develop a test device that can adjust the normal loading pressure of the anchor support at any time, make the force on the action surface uniform, and accurately obtain the measured pressure and strain, and to develop a fast and efficient testing method. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a measuring device and method for measuring the normal stiffness of concrete foundations of different specifications, the device has the characteristics of real-time controllability of normal pressure loading, high stability, uniformity of concrete foundation loading, universality of concrete foundation testing, and rapid availability of concrete foundation stiffness. At the same time, a testing method for the normal stiffness of concrete foundations is proposed based on the device.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A measuring device for measuring the normal stiffness of concrete foundations of different specifications, comprising a circular metal frame, a load loading system, a displacement measurement system and a signal acquisition system; the circular metal frame is installed on the concrete foundation through a base iron and leveled, the circular metal frame is integrally cast by cast steel material, two support frames are installed in parallel on the inner lower surface of the circular metal frame, and are used to support concrete foundation test blocks of different specifications; a normal pressure cylinder hole is arranged on the top of the circular metal frame, and is used to connect 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 frame. The upper and lower surfaces of the inner part of the circular metal frame are symmetrically mounted with linear guide rails, the slider is slidably connected to the linear guide rail, the U-shaped mounting frame is mounted on the slider, and the laser displacement sensor is mounted on the U-shaped mounting frame.

[0007] The connection load loading system comprises, from top to bottom, a hydraulic cylinder, a flange, a sensor base, a sensor housing and a pressure head which are connected to each other in sequence, wherein a hollow force sensor is arranged in the sensor base and the sensor housing, and the hydraulic cylinder is fixed to the normal pressure cylinder hole through a flange;

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

[0009] Furthermore, it is characterized in that the linear guide rail is 150 mm away from the center of the inner surface of the circular metal frame.

[0010] Furthermore, the support frame is two 100*200*1000mm rectangular profiles and is bolted to the inner lower surface of the circular metal frame.

[0011] Furthermore, the 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 the 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) The concrete foundation test block to be tested is placed in a U-shaped metal frame and adjusted in position. At the same time, two laser displacement sensors are respectively installed on two U-shaped mounting frames and debugged. The normal pressure is manually adjusted using the load loading system to preload the concrete foundation test block. The preload force is the maximum load on the concrete foundation test block. The corresponding force signal is collected through the signal acquisition system and the loading force is monitored 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 in an upward or downward trend over time, calibrate the hollow force sensor and laser displacement sensor, and collect force and displacement information;

[0015] (3) Gradually unload the normal force on the concrete foundation test block, and then conduct a loading test after the loading force stabilizes in the range of 4500N to 5500N. After each loading of 5000N, the signal acquisition system collects the corresponding load and displacement information;

[0016] (4) The information collected in the signal acquisition system is exported to Excel or Matlab software for data processing, and the stiffness definition formula is used for fitting, and then the static stiffness experimental curve of the concrete foundation specimen under different loading conditions is output.

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

[0018] 1. The overall structure of the present invention is designed and optimized by static analysis, and has the characteristics of light weight, small volume and easy assembly while meeting the rigidity required for the test. At the same time, the loading system and the measurement and acquisition system are installed on the main structure in a modular manner, which is easy to disassemble, maintain and adjust.

[0019] 2. Due to the use of simulated foundation test blocks for normal load measurement, compared with the traditional method of assembling the whole machine and identifying the stiffness of the bed support, this device has the advantages of fast, accurate and highly operable in measuring the normal stiffness of the machine tool foundation. In addition, in the actual experimental process, the stiffness curve fitted by the relevant software based on the collected data corresponds well to the stiffness in the actual working conditions, with an error of no more than 10%, which meets the expectations and requirements of the measurement at the current stage.

[0020] 3. The hollow force sensor in the device is connected to the signal acquisition system through a wire, which can realize real-time monitoring and acquisition of the loading load. At the same time, the pressure block with a ball groove in contact with the end of the load loading system can realize local uniform transmission of force. The simulated foot on the anchor hook grouted concrete foundation test block can simulate the actual anchor hook grouted concrete foundation support load.

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

[0022] At the same time, the signals collected by the laser displacement sensor and the hollow force sensor are input into the signal acquisition system through wires, and the acquisition card integrated in the acquisition box of the signal acquisition system is used for signal processing and transmitted to the Labview software in the signal acquisition system for visualization processing. According to the changes in the force and displacement information obtained by the software processing, the loading and measurement system can be debugged and corrected conveniently and quickly. Based on the structure of the device and the stiffness definition formula, the present invention can realize the rapid measurement and accurate analysis of the normal stiffness of grouting concrete foundations with anchor hooks of different specifications.

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

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

[0025] 7. The testing method of the present invention avoids the influence of the initial gap of the anchor hook grouting concrete foundation support on the stiffness, and its operation is simple, efficient and highly versatile. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 2 It is a structural diagram of a circular metal frame;

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

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

[0030] Figure markings: 1-reinforced 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 pressure cylinder hole, 201-hydraulic cylinder, 202-flange, 203-sensor base, 204-hollow force sensor, 205-sensor housing, 206-pressure head, 301-linear guide, 302-U-shaped mounting frame, 303-laser displacement sensor. DETAILED DESCRIPTION

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

[0032] See Figure 1, 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, including a circular metal frame 1, a load loading system 2, a displacement measurement system 3 and a signal acquisition system 4; the circular metal frame 1 is installed on the concrete foundation through the anchor pad and leveled, the circular metal frame 1 is integrally cast and formed by cast steel material, and two support frames 101 are installed in parallel on the inner lower surface of the circular metal frame to support concrete foundation test blocks 5 of different specifications; the top of the circular metal frame 1 is provided with a flange 102 and a normal pressure cylinder hole 103 for connecting the load loading system 2; the concrete foundation test block 5 in this embodiment is a grouted concrete foundation with an anchor hook. The laser displacement sensor 303 and the hollow force sensor 204 are connected to the signal acquisition system 4 through a wire to realize non-contact measurement and acquisition of normal deformation of concrete foundations of different specifications.

[0033] Figure 1 It can be seen that the overall structure of the measuring device of this embodiment is compact and the modules are clear, which can ensure the 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 the pressure data and displacement data during the experiment. The signal acquisition system and matching software are used to amplify the electrical signal and convert it into an electronic signal, which is collected on the computer through the USB interface to achieve the purpose of real-time monitoring and collection of pressure and displacement.

[0034] See Figure 2 The circular metal frame 1 is the platform and foundation of the measuring device, so the reliability of its rigidity is particularly important. Therefore, the circular metal frame 1 is made of cast steel as a whole. In addition, considering that the circular metal frame 1 is the main force-bearing part, in order to achieve better structural stability during the experiment, optimize material utilization efficiency, and increase the safety of personnel during the experiment, it is designed as a circular frame and cast in one piece with cast steel material. And at the symmetrical position on the lower inner surface of the circular metal frame 1, according to the specifications of the experimental anchor hook grouting concrete foundation, a suitable metal support frame 101 is selected for bolting and installation to support the anchor hook grouting concrete foundation. This structural design not only ensures the rapid installation and commissioning of other components of the test bench and the anchor hook grouting concrete foundation, but also has better structural stability compared with the non-frame structure. A normal pressure cylinder hole 103 is reserved at the center of the upper inner surface of the circular metal frame 1, and a flange 102 is installed, on which a hydraulic cylinder 201 is connected through the flange. During the test, normal pressure is loaded on the anchor-grouted concrete foundation on the circular metal frame 1 to meet the loading requirements for measuring the normal stiffness of the anchor-grouted concrete foundation.

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

[0036] See Figure 3 , which illustrates the structure of the load loading system. Specifically, in order 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 is optimized through the simulation of ANSYS software, and finally the pressure loading is carried out by adopting the method of hydraulic cylinder-hollow force sensor-pressure head in series to push the pressure block. The hydraulic cylinder 201 of the load loading system 2 and the normal pressure cylinder hole 103 on the upper part of the return metal frame 1 are connected through the flange 202, and the sensor base 203 is embedded in the end of the hydraulic cylinder 201. The hollow force sensor 204 is also connected to the sensor base 203 in the same way. The sensor housing 205 and the sensor base 203 are bolted to complete the protection of 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 to complete the load transfer. During the test, when the normal load is manually loaded, the pressure generated by the hydraulic cylinder 201 fixed on the test bench will eventually apply the force evenly to the simulated foot 6 and the grouting concrete foundation test block 5 with anchor hook through the optimized design of the pressure block. At the same time, the hollow force sensor 204 built into the load loading system will collect the loaded load in real time into the corresponding program of the acquisition system. The above connection method ensures that the load measurement 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, specifically as follows. In order to avoid inaccurate positioning of the upper and lower pairs of laser displacement sensors, which in turn causes errors in the measurement results, the laser displacement sensor 303 is installed on a U-shaped mounting frame 302 to ensure that the two measuring points of the displacement measurement system are on a vertical line. The U-shaped mounting frame 302 is bolted together by a U-shaped profile frame and a linear guide rail 301. The upper and lower lengths of the U-shaped mounting frame 302 are equal and the hole positions are the same, ensuring that the two measuring points of the laser displacement sensor 303 are stable. In this embodiment, the measuring point where one laser displacement sensor 303 is located is located at 150 mm from the center axis of the upper surface of the concrete foundation test block, and the measuring point where the other laser displacement sensor 303 is located is located at 150 mm from the center axis of the lower surface of the concrete foundation test block, and the two measuring points are on the same side (right side) relative to the center axis. As the load is loaded, the lower measuring point measures the deformation of the lower surface of the concrete foundation test block, and the upper measuring point measures the deformation of the upper surface of the concrete foundation test block. The difference between the two is the normal deformation of the foundation test block.

[0038] Based on the above measuring device, this embodiment also proposes a method for measuring the normal stiffness of grouting concrete foundations with anchor hooks of different specifications, comprising 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 on the foundation test block. The loading force is monitored by the data collected and processed by the signal acquisition system 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. After the residual stress in the mounting frame is completely released, that is, when the displacement change obtained by the signal acquisition system no longer fluctuates in an upward or downward trend over time, calibrate the hollow force sensor and displacement sensor, and collect information on force and displacement.

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

[0042] Step 4: Export the information collected in the signal acquisition system to the corresponding software, apply the stiffness definition formula for fitting, and then output the static stiffness experimental curve of the foundation test block 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 realize accurate loading of loads, but also accurately measure its corresponding deformation displacement. The deviation between the stiffness curve fitted by relevant software from the collected test data and the stiffness under actual working conditions does not exceed 10%. It can be said that the normal stiffness of the grouting concrete foundation with anchor hooks can be quickly and accurately measured under existing conditions.

[0044] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A measuring device for measuring the normal stiffness of concrete foundations of different specifications, characterized in that: It includes a circular metal frame, a load loading system, a displacement measurement system and a signal acquisition system; the circular metal frame is installed on a concrete foundation through a base iron and leveled, the circular metal frame is integrally cast using cast steel material, two support frames are installed in parallel on the inner lower surface of the circular metal frame, and are used to support concrete foundation test blocks of different specifications; a normal pressure cylinder hole is provided on the top of the circular metal frame, and is used to connect the load loading system; The displacement measurement system includes a linear guide rail, a slider, a laser displacement sensor and a U-shaped mounting frame. The upper and lower surfaces of the inner part of the circular metal frame are symmetrically mounted with linear guide rails, the slider is slidably connected to the linear guide rail, the U-shaped mounting frame is mounted on the slider, and the laser displacement sensor is mounted on the U-shaped mounting frame. The connection load loading system comprises, from top to bottom, a hydraulic cylinder, a flange, a sensor base, a sensor housing and a pressure head which are connected to each other in sequence, wherein a hollow force sensor is arranged in the sensor base and the sensor housing, and the hydraulic cylinder is fixed to the normal pressure cylinder hole through a flange; The laser displacement sensor and the hollow force sensor are connected to the signal acquisition system through wires to achieve non-contact measurement and acquisition of normal deformation of concrete foundations of different specifications.

2. A measuring device for measuring the normal stiffness of concrete grouting foundations of different specifications according to claim 1, characterized in that: The linear guide is 150mm away from the center of the inner surface of the circular metal frame.

3. A measuring device for measuring the normal stiffness of concrete grouting foundations of different specifications according to claim 1, characterized in that: The support frame is two 100*200*1000mm rectangular profiles and is bolted to the lower surface of the inner side of the circular metal frame.

4. A measuring device for measuring the normal stiffness of concrete grouting foundations of different specifications according to claim 1, characterized in that: The 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 the 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.

5. A method for measuring the normal stiffness of concrete foundations of different specifications, based on the measuring device according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) The concrete foundation test block to be tested is placed in a U-shaped metal frame and adjusted in position. At the same time, two laser displacement sensors are respectively installed on two U-shaped mounting frames and debugged. The normal pressure is manually adjusted using the load loading system to preload the concrete foundation test block. The preload force is the maximum load on the concrete foundation test block. The corresponding force signal is collected through the signal acquisition system and the loading force is monitored 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 in an upward or downward trend over time, calibrate the hollow force sensor and laser displacement sensor, and collect force and displacement information; (3) Gradually unload the normal force on the concrete foundation test block, and then conduct a loading test after the loading force stabilizes in the range of 4500N to 5500N. After each loading of 5000N, the signal acquisition system collects the corresponding load and displacement information; (4) The information collected in the signal acquisition system is exported to Excel or Matlab software for data processing, and the stiffness definition formula is used for fitting, and then the static stiffness experimental curve of the concrete foundation specimen under different loading conditions is output.

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