Railway concrete dynamic impact performance test equipment and evaluation method

Abstract

The present invention discloses a dynamic impact performance test device and evaluation method for railway concrete. The dynamic impact performance test device is constructed based on the drop hammer test method. The device includes: a main frame, a drop hammer system, a monitoring system, a central control system and a protection system; and provides a dynamic impact performance evaluation method based on the energy dissipation principle. The device is convenient for testing the dynamic impact performance of railway concrete. The dynamic impact state of concrete is determined by using multiple parameters such as peak load and circumferential deformation, ensuring the accuracy of the dynamic performance test. The test process of the present invention has a high degree of automation and the test state determination results are accurate. It can realize the dynamic performance test of structural concrete of conventional railways, high-speed railways, heavy-load railways, etc., and its dynamic impact performance can be safely, quickly and accurately evaluated; it can also test and evaluate the impact performance of other concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of railway concrete performance testing, and in particular to railway concrete dynamic impact performance testing equipment and an evaluation method. Background Art

[0002] During their service life, concrete structures on conventional, high-speed, and heavy-haul railways, in addition to static properties like compression and bending, are sometimes subject to periodic impact loads. Under repeated impact loads, railway concrete structures are prone to sudden cracking and damage. Therefore, testing and evaluation of the dynamic impact performance of railway concrete are necessary.

[0003] At present, the main impact test schemes include Charpy pendulum impact test, sustained stress-strain test, light gas gun test, split Hopkinson pressure bar test (SHPB), and explosion test, depending on the strain rate of the impact process. However, the existing test schemes are mainly applied to fiber concrete testing, and there is little research on the dynamic performance detection and damage process evaluation of railway concrete. The existing test schemes are not suitable for railway concrete, and the test parameters lack specificity. The dynamic damage process and dynamic performance of railway concrete cannot be accurately evaluated through a simple impact life. The test system is significantly different from railway concrete subjected to impact loads, and it cannot accurately reflect the dynamic performance evolution process and damage mechanism of railway concrete. In addition, the existing methods mainly determine the specimen state through manual observation, which makes it difficult to accurately evaluate the dynamic performance of the material.

[0004] Therefore, how to achieve safe, rapid and accurate evaluation of the dynamic impact performance of railway concrete is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a railway concrete dynamic impact performance test equipment and evaluation method that solves at least some of the above-mentioned technical problems, facilitates dynamic impact performance testing of railway concrete on conventional railways, high-speed railways, heavy-load railways, etc., and facilitates rapid and accurate evaluation of the dynamic impact performance of railway concrete, thereby improving work efficiency and safety.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a railway concrete dynamic impact performance test device, which uses a drop hammer test method to perform a dynamic impact performance test on railway concrete specimens, including: a main frame, a drop hammer system, a monitoring system and a central control system, wherein:

[0008] The main frame includes: an upper plate, columns, a frame and a base connected by bolts, and is used to provide support for the drop hammer system;

[0009] The drop hammer system includes: a lifting motor, a lifting device, a grab hook, a hammer head, a moving device and a moving beam, wherein: the lifting motor controls the height of the lifting device through the settings of the central control system, and controls the height of the moving beam through the moving device; the grab hook is installed at the lower end of the lifting device for grabbing and releasing the hammer head; the moving beam is used to carry and fix the railway concrete specimen, and the moving beam is installed with a clamping device for fixing the railway concrete specimen;

[0010] The monitoring system includes: a piezoelectric dynamic force sensor and an extensometer, wherein: the piezoelectric dynamic force sensor is installed at the front end of the hammer head, and the measuring end of the extensometer is wrapped around the surface of the railway concrete specimen, respectively used to monitor and obtain the impact load change data and circumferential displacement data of the railway concrete specimen during each impact, and send the obtained data to the central control system for calculation and processing;

[0011] The central control system includes: a photoelectric position detector and a control terminal, wherein: the photoelectric position detector is used to detect the height position of the moving beam; the control terminal is used to adjust the height position of the lifting device and the moving beam during the test, and calculate the impact toughness index of the railway concrete based on the data sent by the monitoring system, and evaluate and determine the dynamic impact performance of the railway concrete based on the calculated impact toughness index.

[0012] Preferably, the control terminal calculates the impact toughness index of railway concrete based on the data sent by the monitoring system, and the calculation formula is:

[0013]

[0014] Where C is the dynamic impact toughness index, E nt is the toughness energy dissipated during a single impact, F is the load during the impact, t1 is the peak load time in a single impact, t2 is the end time of the impact, s is the deformation during the impact, N is the number of dynamic impact life, E is the total energy absorbed by the concrete specimen after N drop hammer impacts; m is the mass of the drop hammer; g is the acceleration of gravity; h is the drop hammer height.

[0015] Preferably, when the dynamic impact performance test of a railway concrete specimen is performed using the device, if one of the following conditions occurs in the railway concrete specimen, it is determined that the railway concrete specimen has reached a failure state and the test is stopped:

[0016] (1) Railway concrete specimens cracked and fell off;

[0017] (2) The load decay of the railway concrete specimen reaches a preset multiple of the peak load;

[0018] (3) The circumferential displacement of the railway concrete specimen reaches the preset value.

[0019] Preferably, the extensometers are in multiple groups, the measurement accuracy of the extensometers is less than 0.02 mm, and the maximum sampling frequency is less than 500 kHz.

[0020] Preferably, the railway concrete specimens used in the test are formed by test molds or obtained by on-site core drilling at the railway; the number of specimens in each group of impact test is not less than 6.

[0021] Preferably, the device further comprises: a protection system, which is composed of a protection frame and acrylic glass and is used to keep the device in a fully enclosed state during the test process; a protection door is installed on the protection frame, and the protection door is provided with a door limit switch.

[0022] In a second aspect, the present invention further provides a method for evaluating the dynamic impact performance of railway concrete, which is applied to the above-mentioned railway concrete dynamic impact performance test equipment to conduct dynamic impact performance experiments on railway concrete specimens and evaluate and determine their dynamic impact performance based on the experimental results. The method comprises:

[0023] Step 1: Debug the equipment through the central control system;

[0024] Step 2: Mark the center of the circle on the surface of the railway concrete specimen and place it on the moving beam, wrap the extensometer around it; and fix the railway concrete specimen with a clamping device;

[0025] Step 3: Make sure the center of the railway concrete specimen drop hammer system specimen is aligned with the hammer head;

[0026] Step 4: Set dynamic impact performance test parameters;

[0027] Step 5: Start the drop hammer system to conduct a dynamic impact performance test and collect impact test data through the monitoring system;

[0028] Step 6: Clean the concrete debris on the surface of the railway concrete specimen;

[0029] Step 7: Stop the test when the failure state is reached, and express the dynamic impact life of railway concrete by the number of dynamic impacts experienced by the concrete;

[0030] Step 8: The control terminal obtains concrete energy transfer related data based on the collected test data, calculates the impact toughness index of the concrete according to the impact energy, and evaluates and determines the dynamic impact performance of the railway concrete based on the calculated impact toughness index.

[0031] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0032] 1. The present invention provides a railway concrete dynamic impact performance test device and evaluation method. The test device has a simple and reasonable structure, which is convenient for implementing dynamic impact performance tests on railway concrete such as conventional railways, high-speed railways, and heavy-load railways. It can quickly and accurately evaluate the dynamic impact performance of railway concrete, and also improves work efficiency.

[0033] 2. The present invention provides a railway concrete dynamic impact performance test device that uses a piezoelectric dynamic force sensor and an extensometer to monitor and obtain impact load change data and circumferential displacement data of the railway concrete specimen during each impact. The test process is data-rich; the test device is easy to operate, taking into account both test accuracy and operational safety.

[0034] 3. The present invention uses multiple parameters to determine the dynamic impact state of concrete. After the test, the relevant parameters can be used to accurately derive the evolution characteristics of concrete's dynamic performance. Compared with traditional methods, this method offers advantages such as rapid determination, high automation, and accurate results. By focusing on energy dissipation, which can more accurately reflect changes in concrete properties, the present invention proposes a method for evaluating the dynamic impact performance of railway concrete using impact toughness. This method, based on parameters such as load and deformation, more comprehensively reflects the mechanism of concrete degradation, achieving truly accurate evaluation of the dynamic performance of railway concrete.

[0035] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0036] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0039] Figure 1 A schematic structural diagram of a railway concrete dynamic impact performance test device provided by an embodiment of the present invention.

[0040] Figure 2 Schematic diagram of the winding method of the extensometer provided by an embodiment of the present invention on the side of concrete.

[0041] Among them, 1-upper plate; 2-lifting motor; 3-column; 4-lifting device; 5-hammer; 6-piezoelectric dynamic force sensor; 7-extensometer; 8-clamping device; 9-moving beam; 10-frame; 11-base; 12-moving device; 13-photoelectric positioner; 14-grab hook; 15-central control computer; 16-electrical control box. DETAILED DESCRIPTION

[0042] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", "front end", "rear end", "two ends", "one side", "the other side", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0043] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood in a broad sense. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection, an electrical connection, or a communication connection; it may refer to a direct connection, an indirect connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0044] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0045] First, the working principle of the present invention is introduced:

[0046] Under the action of the drop hammer impact load, the energy applied to the railway concrete specimen is completely converted into elastic strain energy. The fracture energy and kinetic energy of the concrete during fracture are also converted from elastic strain energy. The transformation and propagation mainly go through three stages:

[0047] 1) The energy is first converted into reversible elastic strain energy, which increases continuously with the increase of impact duration;

[0048] 2) When concrete is loaded to a certain extent, some microcracks inside the concrete expand and penetrate, converting part of the stored elastic strain energy into surface energy;

[0049] 3) As the crack continues to expand, when the elastic strain energy reaches its storage limit, the elastic strain energy is released and converted into kinetic energy, surface energy, frictional heat energy and other energies of the concrete.

[0050] Analysis of the load-displacement curves shows that concrete's tough energy absorption corresponds to the second and third stages of energy transfer, and the integrated area is its tough energy absorption. The greater the tough energy absorption capacity, the lower the likelihood of sudden brittle failure of the concrete.

[0051] See also Figure 1 As shown, in order to achieve safe, rapid and accurate evaluation of the dynamic impact performance of railway concrete for conventional railways, high-speed railways, heavy-haul railways, etc., an embodiment of the present invention provides a railway concrete dynamic impact performance test device. The device uses a drop hammer test method to perform dynamic impact performance tests on railway concrete specimens. The device includes: a main frame, a drop hammer system, a monitoring system and a central control system, wherein:

[0052] The main frame includes: an upper plate 1, a column 3, a frame 10 and a base 11 connected by bolts. The various components are connected by bolts, and the structure is stable during the impact process, which is used to provide support for the drop hammer system; the preferred frame 10 is made of aluminum alloy, which is light and strong.

[0053] The drop hammer system includes a lifting motor 2, a lifting device 4, a grab hook 14, a hammer head 5, a moving device 12, and a moving beam 9. The lifting motor 2 controls the height of the lifting device 4 through the central control system, and the moving beam 9 is controlled by the moving device 12. The grab hook 14 is mounted at the lower end of the lifting device 4 to grasp and release the hammer head 5. The moving beam 9 is equipped with a clamping device 8 to support and secure the railway concrete specimen. These components enable a fully automated process, including precise hammer lifting and continuous impact testing. The clamping device 8 also prevents secondary impacts and reduces test errors.

[0054] The monitoring system includes: a piezoelectric dynamic force sensor 6 and an extensometer 7. The piezoelectric dynamic force sensor 6 is installed at the front end of the hammer head 5. The measuring end of the extensometer 7 is wrapped around the surface of the railway concrete specimen. When in use, after the measuring end is arranged, the fixed end of the extensometer 7 is fixed to the moving beam 9 by screws; the piezoelectric dynamic force sensor 6 and the extensometer 7 are respectively used to monitor and obtain the impact load change data and circumferential displacement data of the railway concrete specimen during each impact, and send the obtained data to the central control system for calculation and processing, thereby realizing an accurate assessment of the railway concrete state.

[0055] The central control system includes: a photoelectric position detector 13 and a control terminal, which are used to control the entire test process and calculate the concrete state and energy absorption and dissipation based on the data of the test process; among them, the photoelectric position detector 13 is used to detect the height position of the moving beam; the control terminal includes a central control computer 15 and an electric control box 16, the electric control box 16 is used to control the height position of the lifting device 4 and the moving beam 9 during the test process, and the central control computer 15 is used to calculate the impact toughness index of the railway concrete based on the data sent by the monitoring system, and evaluate and determine the dynamic impact performance of the railway concrete based on the impact toughness index.

[0056] In a specific embodiment, the control terminal calculates and obtains the impact toughness index of railway concrete based on the data sent by the monitoring system. The calculation process includes:

[0057] According to the load-displacement curve during the impact process, an impact toughness evaluation model based on energy transfer and dissipation characteristics is established. The total impact energy absorbed by concrete should be calculated according to formula (1):

[0058] E=Nmgh(1)

[0059] Where: N is the dynamic impact life (times), E is the total energy absorbed by the concrete specimen after N drop hammer impacts (J); m is the mass of the drop hammer (kg); g is the acceleration of gravity (km / s 2 ); h is the height of the falling hammer (mm);

[0060] The toughness energy dissipated by a single impact can be calculated according to formula (2):

[0061]

[0062] Where: s is the deformation during the impact (mm); F is the load during the impact (kN); En t is the toughness energy dissipated during a single impact (J); t1, t2 are the peak load time and the end time of the impact in the single impact load-displacement curve (μs);

[0063] The dynamic impact toughness index can be calculated according to formula (3):

[0064]

[0065] Where: C is the dynamic impact toughness index;

[0066] In this embodiment, the load-displacement curve and the dynamic impact toughness index C can be automatically calculated by the central control computer 15, and no further details will be given.

[0067] In this embodiment, optionally, when powdering occurs on the surface of the specimen and the powdering depth exceeds 5 mm, the test data is determined to be invalid; the peak load Fma collected in the test x When the difference between the maximum or minimum value of the impact life N and the average value exceeds 30%, the arithmetic mean of the remaining 5 results is used as the result, and the peak load Fma x Accurate to 0.1kN, impact life N is accurate to 1 time; if there is still a measured value in the remaining results that is greater than ±30% of the arithmetic mean of the 5 results, then this measured value will be eliminated and the arithmetic mean of the remaining 4 results will be used as the result; the valid test data of each group of impact tests should not be less than 4 groups. When any of the 4 measured values ​​exceeds ±30% of the arithmetic mean of the group, the results of this group will be invalid.

[0068] In this embodiment, when one of the following situations occurs during the dynamic impact performance test, it can be determined that the railway concrete specimen has reached a failure state and the test is stopped:

[0069] (1) When the specimen is obviously cracked or falling off;

[0070] (2) The specimen load attenuation reaches 0.4 times the peak load (0.4F max )hour;

[0071] (3) When the circumferential deformation δ of the specimen reaches the preset value at failure;

[0072] In this embodiment, the cracking and falling state of the specimen can be observed; the peak load F max The piezoelectric dynamic force sensor placed on the hammer head can be used for measurement. The test data is displayed on the central control computer. The load range during the test should be no less than 100kN, the measurement accuracy should be no greater than 0.01kN, and the maximum sampling frequency should be no less than 2MHz. The circumferential deformation δ can be measured by two sets of extensometers wrapped around the side of the specimen. For the wrapping method, see Figure 2 As shown; the measurement result is the average value of the two groups of extensometers. The extensometer measurement accuracy should not be greater than 0.02mm, the maximum sampling frequency should not be less than 500kHz, and the preset value of the circumferential deformation δ at the time of concrete failure should be specified according to different test systems.

[0073] In this embodiment, the railway concrete specimens used in the impact test can be formed by a test mold or obtained by on-site core drilling. Their diameter ranges from 100 mm to 200 mm, the specimen height ranges from 50 mm to 100 mm, and the ratio of the specimen height to the diameter is 1:2. The number of specimens in each group of impact tests should be no less than 6.

[0074] As a further improvement of this example, the equipment also includes: a protective system consisting of a protective frame and acrylic glass, which is used to keep the equipment in a fully enclosed state during the test process; the protective frame is preferably made of aluminum, and a protective door is installed on the protective frame. The protective door is preferably provided with a door limit switch to prevent concrete specimen fragments from splashing due to impact, thereby improving test safety.

[0075] Furthermore, based on the above-mentioned railway concrete dynamic impact performance test equipment, an embodiment of the present invention also provides a railway concrete dynamic impact performance evaluation method, which mainly includes the following steps when implemented:

[0076] Step 1: Turn on the dynamic impact performance test equipment, debug the equipment on the electric control box, set the moving beam to rise and fall 50mm, and the hammer to rise and fall 1500mm, and cycle the operation three times;

[0077] Step 2: Mark the center of the circle on the surface of the concrete specimen and place it on the moving beam. Wrap the extensometer around it. After tightening the extensometer, fix the extensometer to the moving beam with screws. Then fix the specimen with the clamping device.

[0078] Step 3: Align the railway concrete. The center of the specimen should coincide with the hammer. After the first alignment is completed, lower the hammer to contact the specimen for a second alignment.

[0079] Step 4: Set the dynamic impact performance test parameters, including impact mode, impact number, drop height, hammer mass, etc. The drop height is 300mm to 1500mm, and the drop mass is adjusted by weights in the range of 5kg to 15kg. The maximum impact energy should not be less than 200J.

[0080] Step 5: Conduct dynamic impact performance test and collect impact test data;

[0081] Step 6: When using the single impact mode, observe the surface of the specimen and use a vacuum cleaner to clean it if there are concrete debris on the surface; when using the cyclic impact mode, preferably use a vacuum cleaner to clean it every 5 impacts;

[0082] Step 7: The dynamic load and dynamic deformation during the impact process are collected by the monitoring system and recorded by the central control system. The test is stopped when the failure state is reached, and the dynamic impact life N of the railway concrete is expressed by the number of dynamic impacts experienced by the concrete;

[0083] Step 8: The energy transfer of concrete is obtained based on the collected test data, and the impact toughness of concrete is calculated based on the impact energy. The dynamic impact performance of railway concrete is evaluated and determined based on the impact toughness value.

[0084] Furthermore, the device and method of the present invention are described in detail below with reference to specific embodiments.

[0085] In this embodiment, an impact test system is formulated based on the actual service conditions of railway concrete. The impact test system is divided into conventional railway, high-speed railway, and heavy-haul railway. The preset value of the circumferential deformation δ is set according to different test systems:

[0086] (1) Conventional railway: drop weight height 300mm-500mm, drop weight mass 5kg, circumferential deformation δ 0.80mm;

[0087] (2) High-speed railway: drop height 500 mm, drop weight 5 kg, circumferential deformation δ 1.00 mm;

[0088] (3) Heavy-load railway: drop height 500mm~750mm, drop weight 6kg, circumferential deformation δ is 1.10mm.

[0089] Furthermore, in this embodiment, the present invention optionally divides the dynamic impact performance of railway concrete based on the dynamic impact toughness index C according to the service performance requirements of railway concrete for conventional railways, high-speed railways, and heavy-haul railways. The specific division results can be seen in Table 1:

[0090] Table 1 Classification of dynamic impact performance of railway concrete

[0091] conventional railway 0.55 0.5 0.45 High-speed rail 0.6 0.55 0.5 heavy-haul railway 0.65 0.6 0.55

[0092] Example 1:

[0093] The specific implementation process of this embodiment is as follows:

[0094] (1) Turn on the dynamic impact performance tester and debug the equipment on the electric control box. Use the test parameters of conventional railways, set the moving beam to rise and fall by 50 mm, and the hammer to rise and fall by 1500 mm, and cycle the operation three times.

[0095] (2) After the specimen is aligned and fixed, the extensometer is wrapped around the side of the concrete. A concrete specimen with a strength grade of C40, a diameter of 150 mm, and a height of 75 mm is selected.

[0096] (3) Set the dynamic impact performance test parameters, using the conventional railway test parameters, specifically the cyclic impact mode, the drop hammer height of 500 mm, and the hammer mass of 5 kg;

[0097] (4) Turn on the dynamic impact performance test equipment, collect impact test data, and clean it with a vacuum cleaner after 5 impact cycles;

[0098] (5) The dynamic load and dynamic deformation during the impact process were collected by the monitoring system and recorded by the central control system. The results of the 6 impact tests were all valid, with an average peak load of 36.0 kN and no breakage or fragmentation. When the load dropped to 20.3 kN and the circumferential displacement δ = 0.72 mm, the specimen was judged to have reached the failure state and the test was stopped. The average dynamic impact life N = 31 times;

[0099] (6) Based on the collected test data, the energy transfer of concrete is obtained, and the impact toughness of concrete is calculated based on the impact energy. The total impact energy absorbed by concrete is:

[0100] E=Nmgh31×5×9.8×500=759500J

[0101] Calculate the dynamic impact toughness index:

[0102]

[0103] The railway concrete was evaluated based on the divided dynamic impact performance requirements of conventional railways, and it was found that the impact toughness of the railway concrete met the Level I requirement.

[0104] Example 2:

[0105] The specific implementation process of this embodiment is as follows:

[0106] (1) Turn on the dynamic impact performance tester and debug the equipment on the electric control box. Use the test parameters of conventional railways, set the moving beam to rise and fall by 50 mm, and the hammer to rise and fall by 1500 mm, and cycle the operation three times.

[0107] (2) After the specimen is aligned and fixed, the extensometer is wrapped around the side of the concrete. A concrete specimen with a strength grade of C60, a diameter of 150 mm, and a height of 75 mm is selected.

[0108] (3) Set the dynamic impact performance test parameters, using the heavy-load railway test parameters, specifically the cyclic impact mode, the drop hammer height of 750 mm, and the hammer mass of 6 kg;

[0109] (4) Turn on the dynamic impact performance test equipment, collect impact test data, and clean it with a vacuum cleaner after 5 impact cycles;

[0110] (5) The dynamic load and dynamic deformation during the impact process were collected by the monitoring system and recorded by the central control system. The results of the 6 impact tests were all valid, with an average peak load of 53.4 kN and no breakage. When the load dropped to 35.1 kN and the circumferential displacement δ = 1.12 mm, the specimen was judged to have reached the failure state and the test was stopped. The average dynamic impact life N = 42 times;

[0111] (6) Based on the collected test data, the energy transfer of concrete is obtained, and the impact toughness of concrete is calculated based on the impact energy. The total impact energy absorbed by concrete is:

[0112] E=Nmgh42×6×9.8×750=1.8522×10J

[0113] The dynamic impact toughness index can be calculated according to formula (3):

[0114]

[0115] The railway concrete was evaluated based on the divided dynamic impact performance requirements of heavy-load railways, and it was found that the impact toughness of the concrete met the Level II requirement.

[0116] Comparing the impact toughness of the railway concretes in Examples 1 and 2 reveals that while C60 concrete has a higher strength grade and absorbs more total energy, its impact toughness is slightly lower than that of C40, indicating a greater likelihood of brittle failure under impact loads. Furthermore, it can be concluded that the impact toughness of C60 concrete under heavy train loads needs to be further improved.

[0117] As can be seen from the above embodiments, the railway concrete dynamic impact performance test equipment and evaluation method provided by the present invention have the following beneficial effects:

[0118] 1. The present invention facilitates dynamic impact performance testing of railway concrete for conventional railways, high-speed railways, heavy-load railways, etc., and facilitates rapid and accurate evaluation of the dynamic impact performance of railway concrete, thereby improving work efficiency.

[0119] 2. The present invention provides a railway concrete dynamic impact performance test device that uses a piezoelectric dynamic force sensor and an extensometer to monitor and obtain impact load change data and circumferential displacement data of the railway concrete specimen during each impact. The test process is data-rich and easy to operate, taking into account both test accuracy and operational safety.

[0120] 3. This method uses multiple parameters to determine the dynamic impact state of concrete. After the test, the relevant parameters can be used to accurately derive the dynamic performance evolution characteristics of concrete. Compared with traditional methods, this method offers advantages such as rapid determination, high automation, and accurate results. Furthermore, this method proposes a concrete dynamic performance testing system tailored to different railway structures, ensuring the accuracy of dynamic performance testing.

[0121] 4. The present invention takes energy dissipation, which can more accurately reflect the changes in concrete performance, as the starting point, and proposes a method for evaluating the dynamic impact performance of railway concrete using impact toughness. Based on parameters such as load and deformation, it more comprehensively reflects the mechanism of concrete performance degradation and realizes a truly accurate evaluation of concrete dynamic performance.

[0122] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0123] It should be noted that the word "comprising" does not exclude the presence of components or steps not listed in a claim. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer.

[0124] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A railway concrete dynamic impact performance test equipment, characterized in that: The test equipment uses the drop hammer test method to conduct dynamic impact performance tests on railway concrete specimens, including: main frame, drop hammer system, monitoring system and central control system, including: The main frame includes: an upper plate, columns, a frame and a base connected by bolts, and is used to provide support for the drop hammer system; The drop hammer system includes: a lifting motor, a lifting device, a grab hook, a hammer head, a moving device and a moving beam, wherein: the lifting motor controls the height of the lifting device through the settings of the central control system, and controls the height of the moving beam through the moving device; the grab hook is installed at the lower end of the lifting device for grabbing and releasing the hammer head; the moving beam is used to carry and fix the railway concrete specimen, and the moving beam is installed with a clamping device for fixing the railway concrete specimen; The monitoring system includes: a piezoelectric dynamic force sensor and an extensometer, wherein: the piezoelectric dynamic force sensor is installed at the front end of the hammer head, and the measuring end of the extensometer is wrapped around the surface of the railway concrete specimen, respectively used to monitor and obtain the impact load change data and circumferential displacement data of the railway concrete specimen during each impact, and send the obtained data to the central control system for calculation and processing; The central control system includes: a photoelectric position detector and a control terminal, wherein: the photoelectric position detector is used to detect the height position of the movable crossbeam; the control terminal is used to adjust the height position of the lifting device and the movable crossbeam during the test, and calculates the impact toughness index of the railway concrete based on the data sent by the monitoring system, and evaluates and determines the dynamic impact performance of the railway concrete based on the calculated impact toughness index; The control terminal calculates the impact toughness index of railway concrete based on the data sent by the monitoring system, and the calculation formula is: Where C is the dynamic impact toughness index, E nt is the toughness energy dissipated during a single impact, F is the load during the impact, t1 is the peak load time in a single impact, t2 is the end time of the impact, s is the deformation during the impact, N is the number of dynamic impact life, E is the total energy absorbed by the concrete specimen after N drop hammer impacts; m is the mass of the drop hammer; g is the acceleration of gravity; h is the drop hammer height.

2. The railway concrete dynamic impact performance test equipment according to claim 1, characterized in that: When using this equipment to conduct dynamic impact performance tests on railway concrete specimens, if any of the following situations occur in the railway concrete specimens, it is determined that the railway concrete specimens have reached a failure state and the test is stopped: (1) Railway concrete specimens cracked and fell off; (2) The load decay of the railway concrete specimen reaches a preset multiple of the peak load; (3) The circumferential displacement of the railway concrete specimen reaches the preset value.

3. The railway concrete dynamic impact performance test equipment according to claim 1, characterized in that: The extensometers are in multiple groups, the measurement accuracy of the extensometers is less than 0.02 mm, and the maximum sampling frequency is less than 500 kHz.

4. The railway concrete dynamic impact performance test equipment according to claim 1, characterized in that: The railway concrete specimens used in the test are formed by test molds or obtained by drilling cores on the railway site; the number of railway concrete specimens in each group of impact tests is multiple.

5. The railway concrete dynamic impact performance test equipment according to claim 1, characterized in that: The device also includes: a protection system, which is composed of a protection frame and acrylic glass and is used to keep the device in a fully enclosed state during the test process; a protection door is installed on the protection frame, and the protection door is provided with a door limit switch.

6. A method for evaluating the dynamic impact performance of railway concrete, characterized in that: A railway concrete dynamic impact performance test device according to any one of claims 1 to 5 is used to perform a dynamic impact performance test on a railway concrete specimen, and to evaluate and determine its dynamic impact performance based on the test results, the method comprising: Step 1: Debug the equipment through the central control system; Step 2: Mark the center of the circle on the surface of the railway concrete specimen and place it on the moving beam, wrap the extensometer around it; and fix the railway concrete specimen with a clamping device; Step 3: Make the center of the railway concrete specimen coincide with the center of the hammer head; Step 4: Set dynamic impact performance test parameters; Step 5: Start the drop hammer system to conduct a dynamic impact performance test and collect impact test data through the monitoring system; Step 6: Clean the concrete debris on the surface of the railway concrete specimen; Step 7: Stop the test when the failure state is reached, and express the dynamic impact life of railway concrete by the number of dynamic impacts experienced by the concrete; Step 8: The control terminal obtains concrete energy transfer related data based on the collected test data, calculates the impact toughness index of the concrete according to the impact energy, and evaluates and determines the dynamic impact performance of the railway concrete based on the calculated impact toughness index; The control terminal calculates the impact toughness index of railway concrete based on the data sent by the monitoring system, and the calculation formula is: Where C is the dynamic impact toughness index, E nt is the toughness energy dissipated during a single impact, F is the load during the impact, t1 is the peak load time in a single impact, t2 is the end time of the impact, s is the deformation during the impact, N is the number of dynamic impact life, E is the total energy absorbed by the concrete specimen after N drop hammer impacts; m is the mass of the drop hammer; g is the acceleration of gravity; h is the drop hammer height.

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