Equipment, method and storage medium for determining fracture parameters of full-graded concrete specimens

Abstract

The present application provides a device, method and storage medium for determining fracture parameters of a full-graded concrete specimen. The device includes a controller, a power component, a first steel disc and a second steel disc symmetrically arranged, a first spherical hinge, a second spherical hinge, a tension sensor and a plurality of extensometers; the controller is configured to drive a fixing member to move away from the ground through a control driving member of the power component, so that the first steel disc moves away from the second steel disc, so as to axially stretch the full-graded concrete specimen; the controller is further configured to determine a tension-displacement relationship curve based on the displacements of the crack openings of the full-graded concrete specimen measured by the respective extensometers at multiple moments, and the tension of the full-graded concrete specimen measured by the tension sensor at the corresponding moments; and determine the fracture parameters of the full-graded concrete specimen according to the tension-displacement relationship curve. The method of the present application can improve the accuracy of the fracture parameters of the full-graded concrete specimen.

Description

Technical Field

[0001] This application relates to the technology of fracture parameter testing, and particularly to an apparatus, method and storage medium for determining the fracture parameters of full-scale concrete specimens. Background Art

[0002] As a heterogeneous material, concrete often has a large number of microcracks on its surface and inside. With the development of fracture parameter testing technology, in order to ensure that concrete meets the usage requirements of buildings, methods for determining the fracture parameters of full-scale concrete specimens have emerged.

[0003] Currently, the methods for determining the fracture parameters of full-scale concrete specimens mainly involve conducting three-point bending tests or wedge splitting tests on full-scale concrete specimens to determine the fracture performance of full-scale concrete specimens under tensile forces (i.e., the fracture parameters of concrete), so as to determine the applicable scenarios of full-scale concrete specimens.

[0004] However, when making larger full-scale concrete specimens for three-point bending tests, they are not easy to handle and may break during handling. Most importantly, the self-weight of the specimens has a great impact on the test results. In the wedge splitting test, the vertical load will cause additional moments, which will affect the stress field at the crack tip and may affect the fracture parameters of the test. Summary of the Invention

[0005] This application provides an apparatus, method and storage medium for determining the fracture parameters of full-scale concrete specimens to solve the technical problem of low accuracy in determining the fracture parameters of full-scale concrete specimens in the prior art.

[0006] In a first aspect, this application provides an apparatus for determining the fracture parameters of full-scale concrete specimens, including: a controller, a power component, a first steel disc and a second steel disc symmetrically arranged, a first spherical hinge, a second spherical hinge, a tensile force sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tensile force sensor and each extensometer respectively; the power component is connected to the first spherical hinge through a fixing member;

[0007] The first steel disc is fixedly installed at one end of the first spherical hinge. The second steel disc is installed on the base of the apparatus for determining the fracture parameters of full-scale concrete specimens through the second spherical hinge. The base is fixedly connected to the ground. The first steel disc and the second steel disc are respectively fixedly connected to one end of the full-scale concrete specimen through epoxy glue. The tensile force sensor is fixedly arranged on the fixing member. The extensometers are fixedly arranged along the opening of the prefabricated crack of the full-scale concrete specimen;

[0008] The controller is configured to control the power component to drive the fixing member to move away from the ground, so that the first steel disc moves away from the second steel disc, so as to axially stretch the full-graded concrete specimen;

[0009] The tensile force sensor is configured to measure the tensile force of the full-graded concrete specimen at multiple moments during the process that the controller controls the full-graded concrete specimen to be axially stretched;

[0010] The extensometer is configured to measure the displacement of the crack opening of the full-graded concrete specimen at multiple moments during the process that the full-graded concrete specimen is axially stretched;

[0011] The controller is further configured to determine a tensile force-displacement relationship curve based on the displacements of the crack openings of the full-graded concrete specimen at multiple moments respectively measured by each extensometer and the tensile force of the full-graded concrete specimen at the corresponding moment measured by the tensile force sensor; and determine the fracture parameters of the full-graded concrete specimen according to the tensile force-displacement relationship curve, where the tensile force-displacement relationship curve characterizes the relationship between the displacement of the crack opening and the tensile force of the full-graded concrete specimen.

[0012] In a second aspect, the present application provides a method for determining the fracture parameters of a full-graded concrete specimen, including:

[0013] A controller applied to the device for determining the fracture parameters of the full-graded concrete specimen, where the device for determining the fracture parameters of the full-graded concrete specimen further includes a power component, a first steel disc and a second steel disc arranged symmetrically, a first spherical hinge, a second spherical hinge, a tensile force sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tensile force sensor and each extensometer respectively; the power component is connected to the first spherical hinge through a fixing member; the first steel disc is fixedly installed at one end of the first spherical hinge, the second steel disc is installed on the base of the device for determining the fracture parameters of the full-graded concrete specimen through the second spherical hinge, the base is fixedly connected to the ground, and the first steel disc and the second steel disc are respectively fixedly connected to one end of the full-graded concrete specimen through epoxy glue; the tensile force sensor is fixedly arranged on the fixing member, and the extensometers are fixedly arranged along the opening of the prefabricated crack of the full-graded concrete specimen; the method includes:

[0014] Controlling the power component to drive the fixing member to move away from the ground, so that the first steel disc moves away from the second steel disc, so as to axially stretch the full-graded concrete specimen;

[0015] Based on the displacements of the crack openings of the full-graded concrete specimens at multiple moments measured by multiple extensometers, and the tensile forces of the full-graded concrete specimens at the corresponding moments measured by the tensile force sensors, determine the tensile force-displacement relationship curve; the tensile force-displacement relationship curve characterizes the relationship between the displacement of the crack opening of the full-graded concrete specimen and the tensile force;

[0016] According to the tensile force-displacement relationship curve, determine the fracture parameters of the full-graded concrete specimen.

[0017] In a third aspect, the present application provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, they are used to implement the method described in the second aspect.

[0018] Equipment, method and storage medium for determining fracture parameters of full-graded concrete specimens provided by the present application. The equipment for determining fracture parameters of full-graded concrete specimens includes: a controller, a power component, a first steel disc and a second steel disc symmetrically arranged, a first spherical hinge, a second spherical hinge, a tensile sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tensile sensor and each extensometer respectively; the power component is connected to the first spherical hinge through a fixing member; the first steel disc is fixedly installed at one end of the first spherical hinge, and the second steel disc is installed on the base of the equipment for determining fracture parameters of full-graded concrete specimens through the second spherical hinge. The base is fixedly connected to the ground. The first steel disc and the second steel disc are respectively fixedly connected to one end of the full-graded concrete specimen through epoxy glue; the tensile sensor is fixedly arranged on the fixing member, and the extensometers are fixedly arranged along the opening of the prefabricated crack of the full-graded concrete specimen; the controller is used to drive the fixing member to move away from the ground by controlling the power component, so that the first steel disc moves away from the second steel disc, so as to axially stretch the full-graded concrete specimen; the tensile sensor is used to measure the tensile force of the full-graded concrete specimen at multiple moments during the process of axially stretching the full-graded concrete specimen controlled by the controller; the extensometers are used to measure the displacement of the crack opening of the full-graded concrete specimen at multiple moments during the process of axially stretching the full-graded concrete specimen; the controller is further used to determine the load-displacement relationship curve based on the displacements of the crack openings of the full-graded concrete specimen measured by each extensometer at multiple moments and the tensile force of the full-graded concrete specimen measured by the tensile sensor at the corresponding moment; according to the load-displacement relationship curve, determine the fracture parameters of the full-graded concrete specimen. The load-displacement relationship curve characterizes the relationship between the displacement of the crack opening of the full-graded concrete specimen and the tensile force. Since the axial stretching method can obtain very accurate results when determining the material mechanical parameters of concrete specimens, such as elastic modulus and Poisson's ratio. Since the fracture parameters of concrete specimens are affected by the material mechanical parameters of concrete specimens (material properties), the axial stretching method can be applied to determine the fracture parameters of concrete specimens. Moreover, the method of axially stretching concrete specimens will not cause additional moments due to vertical loads in the prior art, which will affect the stress field at the crack tip. Therefore, accurate fracture parameters of concrete specimens can be obtained. In addition, the concrete specimens tested by the axial stretching method are easier to manufacture and easier to handle during the test. Description of the Drawings

[0019] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0020] Figure 1 A structural schematic diagram of a device for determining fracture parameters of a full-graded concrete specimen according to an embodiment of this application;

[0021] Figure 2 A layout schematic diagram of extensometers on a full-graded concrete specimen according to an embodiment of this application;

[0022] Figure 3 A flowchart of a method for determining fracture parameters of a full-graded concrete specimen according to an embodiment of this application;

[0023] Figure 4 A flowchart of a method for determining fracture parameters of a full-graded concrete specimen according to another embodiment of this application;

[0024] Figure 5 A flowchart of a method for determining fracture parameters of a full-graded concrete specimen according to yet another embodiment of this application.

[0025] Through the above-mentioned accompanying drawings, specific embodiments of this application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0026] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with this application. On the contrary, they are merely examples of devices and methods consistent with some aspects of this application as detailed in the appended claims.

[0027] To clearly understand the technical solution of this application, the solutions of the prior art will be introduced in detail first.

[0028] In the traditional method, the method for determining the fracture parameters of a full-graded concrete specimen mainly involves conducting a three-point bending test or a wedge splitting test on the full-graded concrete specimen to determine the fracture performance of the full-graded concrete specimen under tensile force (i.e., the fracture parameters of the concrete), so as to determine the applicable occasions of the full-graded concrete specimen. However, when making a relatively large full-graded concrete specimen for the three-point bending test, it is not easy to handle and may break during handling. Most importantly, the self-weight of the specimen has a great impact on the test results. In the wedge splitting test, the vertical load will cause additional moments, which will affect the stress field at the crack tip and may affect the fracture parameters of the test.

[0029] Therefore, in the face of the technical problems of the existing technology, the inventor found through creative research that in order to improve the accuracy of determining the fracture parameters of the full-graded concrete specimen. Since the axial tension method can obtain very accurate results when determining the material mechanics parameters of the concrete specimen, such as the elastic modulus and Poisson's ratio. Since the fracture parameters of the concrete specimen are affected by the material mechanics parameters of the concrete specimen (material properties), the axial tension method can be applied to determine the fracture parameters of the concrete specimen. Moreover, the method of axially tensioning the concrete specimen will not have the situation in the existing technology where the vertical load will cause additional moments, which will affect the stress field at the crack tip, so accurate fracture parameters of the concrete specimen can be obtained. In addition, the concrete specimen tested by the axial tension method is easier to manufacture and easier to handle during the test.

[0030] As Figure 1 shown, the device for determining the fracture parameters of the full-graded concrete specimen provided in the embodiment of the present application includes: a controller 10, a power component 20, a first steel disc 30 and a second steel disc 40 arranged symmetrically, a first spherical hinge 50, a second spherical hinge 52, a tension sensor 60 and a plurality of extensometers 70. The controller 10 is electrically connected to the power component 20, the tension sensor 60 and each extensometer 70 respectively. The power component 20 is connected to the first spherical hinge 50 through a fixing member 51. The first steel disc 30 is fixedly installed at one end of the first spherical hinge 50 of the device for determining the fracture parameters of the full-graded concrete specimen. The second steel disc 40 is installed on the base 90 of the device for determining the fracture parameters of the full-graded concrete specimen through the second spherical hinge 52. The base 90 of the fracture parameter determination device is fixed on the ground. The first steel disc 30 and the second steel disc 40 are respectively fixedly connected to one end of the full-graded concrete specimen 80 through epoxy glue. The tension sensor 60 is fixedly arranged on the fixing member 51, and the extensometer 70 is fixedly arranged along the opening of the prefabricated crack of the full-graded concrete specimen 80. Figure 1The portal shape therein is a bracket, and the bracket is provided with a plurality of columns 100. The controller 10 and the power component 20 are arranged on the housing 200. The housing 200 is fixedly connected with a plurality of collars 300, and each collar 300 is sleeved on the corresponding column 100. When the power component 20 drives the first ball hinge 50 to move, the full-size concrete specimen 80 can be driven to move longitudinally.

[0031] When axially stretching the full-size concrete specimen 80, the controller 10 controls the power component 20 to drive the fixing member 51 to move away from the ground, and indirectly makes the first steel disc 30 move away from the second steel disc 40 through the first ball hinge 50, so that the full-size concrete specimen 80 is axially stretched.

[0032] During the process of axially stretching the full-size concrete specimen 80, the tensile force of the full-size concrete specimen 80 at multiple moments can be measured by the tensile force sensor 60. At the same time, the displacements of the crack openings of the full-size concrete specimen 80 at multiple moments are respectively measured by a plurality of extensometers 70.

[0033] When the controller 10 obtains the displacements of the crack openings of the full-size concrete specimen 80 at multiple moments respectively measured by each extensometer 70, and the tensile force of the full-size concrete specimen 80 at the corresponding moment measured by the tensile force sensor 60, a tensile force-displacement relationship curve can be generated. And based on the tensile force-displacement relationship curve, the fracture parameters of the full-size concrete specimen 80 are determined.

[0034] The following uses specific embodiments to elaborate in detail on the technical solution of the present application and how the technical solution of the present application solves the above technical problems. These several specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the drawings.

[0035] The fracture parameter determination device for a full-size concrete specimen provided by an embodiment of the present application includes: a controller, a power component, a first steel disc and a second steel disc arranged symmetrically, a first ball hinge, a second ball hinge, a tensile force sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tensile force sensor and each extensometer respectively; the power component is connected to the first ball hinge through a fixing member;

[0036] The first steel disc is fixedly installed at one end of the first ball hinge. The second steel disc is installed on the base of the device for determining the fracture parameters of the fully graded concrete specimen through the second ball hinge. The base is fixedly connected to the ground. The first steel disc and the second steel disc are respectively fixedly connected to one end of the fully graded concrete specimen through epoxy glue. The tensile sensor is fixedly arranged on the fixing member, and the extensometer is fixedly arranged along the opening of the prefabricated crack of the fully graded concrete specimen.

[0037] The controller is configured to drive the fixing member to move away from the ground by controlling the power component, so that the first steel disc moves away from the second steel disc, so as to axially stretch the fully graded concrete specimen.

[0038] The tensile sensor is configured to measure the tensile force of the fully graded concrete specimen at multiple moments during the process that the controller controls the fully graded concrete specimen to be axially stretched.

[0039] The extensometer is configured to measure the displacement of the crack opening of the fully graded concrete specimen at multiple moments during the process that the fully graded concrete specimen is axially stretched.

[0040] The controller is further configured to determine the tensile force-displacement relationship curve based on the displacements of the crack openings of the fully graded concrete specimen at multiple moments respectively measured by each extensometer and the tensile force of the fully graded concrete specimen at the corresponding moment measured by the tensile sensor; and determine the fracture parameters of the fully graded concrete specimen according to the tensile force-displacement relationship curve, where the tensile force-displacement relationship curve characterizes the relationship between the displacement of the crack opening of the fully graded concrete specimen and the tensile force.

[0041] Wherein, the controller is electrically connected to the power component, the tensile sensor and each extensometer respectively.

[0042] Specifically, the first steel disc and the second steel disc refer to discs made of steel material and in a circular shape, and the surface areas of the two satisfy that they can bear the fully graded concrete specimen.

[0043] The first steel disc and the second steel disc are symmetrically arranged, and their thicknesses and shapes are exactly the same. The first steel disc is fixedly installed at one end of the first spherical hinge of the equipment for determining the fracture parameters of the full-graded concrete specimen and can move along with the movement of the first spherical hinge. The second steel disc is installed on the base of the equipment for determining the fracture parameters of the full-graded concrete specimen through the second spherical hinge. Taking the ground as a reference, the second steel disc is closer to the ground than the first steel disc, that is, the first steel disc is located above the second steel disc. The second steel disc is always in a fixed state, and the first steel disc can move relative to the second steel disc in the longitudinal direction under the action of the power component, the fixing piece and the first spherical hinge.

[0044] Since the dams in water conservancy projects have high requirements for water storage capacity and flood discharge capacity, it is necessary to conduct experimental analysis on the fracture parameters of the concrete used for building dams. Before conducting the tensile fracture test on the full-graded concrete specimen, epoxy glue can be applied to the first steel disc and the second steel disc, and the full-graded concrete specimen can be placed between the first steel disc and the second steel disc, and the first steel disc and the second steel disc are respectively abutted against both ends of the full-graded concrete specimen, so that the first steel disc, the second steel disc and the full-graded concrete specimen are tightly bonded together through the epoxy glue. In order to prevent the full-graded concrete specimen from breaking at the glue surface of the epoxy glue during the tensile process, after the epoxy glue between the first steel disc, the second steel disc and the full-graded concrete specimen is completely fixed, the tensile fracture test is carried out. After the epoxy glue is cured, the strength of the epoxy glue is much greater than the tensile strength of the full-graded concrete specimen.

[0045] In a specific test, during the pretreatment process before placing the full-graded concrete specimen between the first steel disc and the second steel disc, for example, when selecting materials, a full-graded concrete specimen in the shape of a cylinder with a diameter of 450 mm and a height of 450 mm can be used, and a cutting machine can be used to cut a prefabricated crack with a groove depth of 45 mm around the outer circumference of the full-graded concrete specimen at the middle position of the full-graded concrete specimen to ensure that the full-graded concrete specimen breaks from the middle during the tensile process. After cutting, the crack is rinsed.

[0046] The tensile force sensor is fixed on the fixing piece and can be used to measure the tensile force of the full-graded concrete specimen at multiple moments during the tensile process.

[0047] During the test process of determining the fracture parameters of the full-graded concrete specimen, the extensometer is mainly used to measure the displacement of the crack opening of the full-graded concrete specimen at multiple moments during the process of the full-graded concrete specimen being stretched along the axial direction. Before the test, multiple extensometers are arranged, and each extensometer is fixedly arranged on the outer surface of the full-graded concrete specimen along the opening of the prefabricated crack of the full-graded concrete specimen. AsFigure 2 As shown in the cross-section of the full-graded concrete specimen, 4 extensometers are fixedly arranged at equal intervals on the outer periphery of the circular cross-section.

[0048] The power component refers to a power device that is controlled by a controller and can control the movement of the ball joint. For example, it can be a hydraulic cylinder, a pneumatic cylinder, or a motor, etc. Taking the power component as a motor as an example, it is illustrated how the power component is connected to the first ball joint through a fixing member. Specifically: the output shaft of the motor is fixedly connected to one end of the fixing member, and the other end of the fixing member is fixedly connected to the end of the first ball joint away from the ground. Therefore, when the controller controls the power component to drive the fixing member to move away from the ground, the first steel disc can move away from the second steel disc. During the process of the first steel disc moving away from the second steel disc, the full-graded concrete specimen fixed between the first steel disc and the second steel disc is stretched along the axial direction.

[0049] During the process of the controller controlling the full-graded concrete specimen to be stretched along the axial direction, the tensile forces of the full-graded concrete specimen at multiple moments measured by the tensile force sensor are transmitted back to the controller, and the displacements of the crack openings of the full-graded concrete specimen at multiple moments measured by the multiple extensometers are also transmitted back to the controller. Thus, the controller can determine the tensile force-displacement relationship curve based on the displacements of the crack openings of the full-graded concrete specimen at multiple moments measured by each extensometer and the tensile force of the full-graded concrete specimen at the corresponding moment measured by the tensile force sensor. The tensile force-displacement relationship curve characterizes the relationship between the displacement of the crack opening of the full-graded concrete specimen and the tensile force. After obtaining the tensile force-displacement relationship curve, the fracture parameters of the full-graded concrete specimen can be determined according to this tensile force-displacement relationship curve. The fracture parameters of the full-graded concrete specimen refer to the parameters related to the fracture performance of the concrete. Optionally, the fracture parameters of the full-graded concrete specimen include the energy absorption capacity of the full-graded concrete specimen, the fracture energy of the full-graded concrete specimen, the fracture toughness of the full-graded concrete specimen, and the characteristic length of the full-graded concrete specimen.

[0050] After obtaining the fracture parameters of the full-graded concrete specimen, it can be determined whether the fracture parameters of the concrete prepared by the same configuration method as the full-graded concrete specimen are applicable to the dam in the water conservancy project.

[0051] In this application, the device for determining the fracture parameters of the fully graded concrete specimen includes: a controller, a power component, a first steel disc and a second steel disc arranged symmetrically, a first spherical hinge, a second spherical hinge, a tensile sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tensile sensor and each extensometer respectively. The first steel disc is fixedly installed at one end of the first spherical hinge. The second steel disc is installed on the base of the device for determining the fracture parameters of the fully graded concrete specimen through the second spherical hinge. The first steel disc and the second steel disc are respectively fixedly connected to one end of the fully graded concrete specimen through epoxy glue. The tensile sensor is fixedly arranged on the fixing piece. The extensometers are fixedly arranged along the opening of the prefabricated crack of the fully graded concrete specimen. The controller is used to control the power component to drive the fixing piece to move away from the ground, so that the first steel disc moves away from the second steel disc, so as to axially stretch the fully graded concrete specimen. The tensile sensor is used to measure the tensile force of the fully graded concrete specimen at multiple moments during the process of axially stretching the fully graded concrete specimen controlled by the controller. The extensometers are used to measure the displacement of the crack opening of the fully graded concrete specimen at multiple moments during the process of axially stretching the fully graded concrete specimen. The controller is further used to determine the load-displacement relationship curve based on the displacements of the crack openings of the fully graded concrete specimen at multiple moments measured by each extensometer respectively, and the tensile force of the fully graded concrete specimen at the corresponding moment measured by the tensile sensor. According to the load-displacement relationship curve, determine the fracture parameters of the fully graded concrete specimen, which characterize the relationship between the displacement of the crack opening and the tensile force of the fully graded concrete specimen. Since the axial tension method can obtain very accurate results when determining the material mechanical parameters of concrete specimens, such as elastic modulus and Poisson's ratio. Since the fracture parameters of concrete specimens are affected by the material mechanical parameters of concrete specimens (material properties), the axial tension method can be applied to determine the fracture parameters of concrete specimens. Moreover, the method of axially stretching concrete specimens will not cause additional moments due to vertical loads in the prior art, which will affect the stress field at the crack tip, so accurate fracture parameters of concrete specimens can be obtained. In addition, the concrete specimens tested by the axial tension method are easier to manufacture and easier to handle during the test.

[0052] Since the dams in water conservancy projects usually adopt fully graded concrete, the fully graded concrete is used in the test analysis of this application, which can ensure that the test analysis results can be accurately applied to the parameter analysis of dam concrete. In one embodiment, the method for configuring the fully graded concrete specimen includes: selecting three types of stones, namely large stones, medium stones and small stones, where the particle size of the small stones is greater than 5 mm and the particle size of the large stones does not exceed 80 mm. The specimen is poured in a fabricated steel mold, and after being vibrated thoroughly with a flat vibrator and an internal vibrator and then smoothed, a cotton quilt is placed to prevent water loss. Demolding is carried out 3 days after completion, and the fully graded concrete specimen is placed in a curing room at a temperature of 20 °C and a humidity of 98% for 90 days of curing. As shown in Table 1, it is the mix ratio of each material for preparing the fully graded concrete specimen.

[0053] Table 1 Concrete Mix Ratio

[0054]

[0055] The material mechanical parameters of the fully graded concrete specimen obtained based on this configuration method are shown in Table 2:

[0056] Table 2 Concrete Material Mechanical Parameters

[0057]

[0058] In one embodiment, when determining the tensile-displacement relationship curve, the controller is specifically configured to: take the average of the displacements of multiple crack openings of the fully graded concrete specimen measured by each extensometer at each moment to obtain the average displacement of the crack opening at each moment; construct a tensile-displacement relationship curve based on the average displacement of the crack opening at each moment and the tensile force measured by the tensile force sensor at the corresponding moment.

[0059] Among them, an extensometer is arranged at each position of the prefabricated crack of the fully graded concrete specimen, so that the displacement change of the crack opening at multiple positions of the fully graded concrete specimen can be measured. According to the displacements of the crack openings measured by each extensometer at multiple moments and the tensile forces at the corresponding moments, a displacement-time curve of the crack opening corresponding to each extensometer can be generated. The vertical axis of the displacement-time curve of the crack opening represents the displacement of the crack opening, and the horizontal axis represents the moment. Therefore, multiple displacement-time curves of the crack opening can be obtained based on multiple extensometers.

[0060] The tensile-displacement relationship curve is the displacement-tensile curve of the crack opening. The horizontal axis represents the displacement of the crack opening, and the vertical axis represents the tensile force. The tensile-displacement relationship curve is obtained based on the displacement-time curves of the crack openings measured by multiple extensometers. Specifically, according to the displacement-time curves of the crack openings measured by multiple extensometers, the displacements of the crack openings at each moment are averaged to obtain the average displacement. For example, if the displacements of the crack openings of a fully graded concrete specimen measured by 4 extensometers at time t1 are s1, s2, s3, and s4, then the average displacement is (s1 + s2 + s3 + s4) / 4. After obtaining the average displacements at multiple moments, according to the average displacements at multiple moments and the corresponding tensile forces at these moments, the discrete points are fitted to obtain the tensile-displacement relationship curve. The method of fitting the discrete points can adopt any existing technology and will not be elaborated.

[0061] In this embodiment, when determining the tensile-displacement relationship curve, the controller is specifically configured to: average the displacements of the crack openings of the fully graded concrete specimen measured by each of the extensometers at multiple moments to obtain the average displacements of the crack openings at multiple moments; construct and obtain the tensile-displacement relationship curve according to the average displacements of the crack openings at the multiple moments and the corresponding tensile forces measured by the tensile force sensor at these moments. Since the tensile-displacement relationship curve is established based on the average of the displacements of the crack openings of the fully graded concrete specimen measured by multiple extensometers at multiple moments, and then using the average displacements of the crack openings at each moment and the corresponding tensile forces at these moments, it is relatively accurate.

[0062] In one embodiment, when determining the fracture parameters of the fully graded concrete specimen according to the tensile-displacement relationship curve, the controller is specifically configured to: determine the energy absorption capacity of the fully graded concrete specimen and the fracture energy of the fully graded concrete specimen according to the tensile-displacement relationship curve; use the extended finite element method to determine the fracture toughness of the fully graded concrete specimen; determine the characteristic length of the fully graded concrete specimen according to the fracture energy of the fully graded concrete specimen.

[0063] Among them, the energy absorption capacity of the fully graded concrete specimen is the energy absorbed by the fully graded concrete specimen before reaching the peak load (i.e., peak tensile force), that is, before failure. The energy absorption capacity of the fully graded concrete specimen can be calculated through the tensile-displacement relationship curve.

[0064] The fracture energy of the fully graded concrete specimen refers to the energy absorbed during the entire fracture process of the fully graded concrete specimen.

[0065] The fracture toughness of the fully graded concrete specimen refers to the ability of the fully graded concrete specimen to resist the unstable propagation of macroscopic cracks, reflecting the ability of the fully graded concrete specimen to resist brittle fracture. The fracture toughness of the fully graded concrete specimen can be determined by the extended finite element method.

[0066] The characteristic length of a full-graded concrete specimen can be used to evaluate the brittleness during the fracture process of concrete. The smaller the characteristic length of the full-graded concrete specimen, the more brittle the full-graded concrete specimen is and the more likely it is to fracture. To calculate the characteristic length of the full-graded concrete specimen, it is necessary to first determine the fracture energy of the full-graded concrete specimen.

[0067] In this embodiment, according to the load-displacement relationship curve, the energy absorption capacity of the full-graded concrete specimen and the fracture energy of the full-graded concrete specimen are determined; the extended finite element method is used to determine the fracture toughness of the full-graded concrete specimen; according to the fracture energy of the full-graded concrete specimen, the characteristic length of the full-graded concrete specimen is determined. Since the fracture parameters of the full-graded concrete specimen are obtained based on the load-displacement relationship curve, the extended finite element method, etc., the accuracy of the data can be guaranteed.

[0068] In one embodiment, when the controller determines the energy absorption capacity of the full-graded concrete specimen according to the load-displacement relationship curve, it is specifically configured to: obtain the area of the rising section enclosed by the rising section of the load-displacement relationship curve and the coordinate axis; obtain the rising section ratio between the area of the rising section and the net area of the fracture zone, and determine the rising section ratio as the energy absorption capacity of the full-graded concrete specimen.

[0069] Among them, the net area of the fracture zone is the area obtained by subtracting the area of the prefabricated crack from the cross-sectional area obtained by cutting the full-graded concrete specimen. In specific calculations, for example, assume that a prefabricated crack with a depth of 45 mm is cut in a cylindrical full-graded concrete specimen with a diameter of 450 mm. The cross-section obtained by cutting is circular, and its area is π * 450 * 450. The cross-section of the prefabricated crack is an annulus. Therefore, the net area of the fracture zone is π * 360 * 360.

[0070] The rising section refers to a section of the curve that is in an upward state between the initial point and the peak point in the load-displacement relationship curve. In the load-displacement relationship curve, the load corresponding to the peak point is the peak load. The area of the rising section is the area enclosed by the rising section and the horizontal axis of the coordinate axis. This part of the area represents the work done by the fracture parameter determination device of the full-graded concrete specimen when stretching the full-graded concrete specimen to the peak load. Dividing the area of the rising section by the net area of the fracture zone to obtain the rising section ratio between the area of the rising section and the fracture zone represents the energy absorbed per unit area of the full-graded concrete specimen before reaching the peak load.

[0071] In this embodiment, the rising-section area enclosed by the rising section of the tensile force-displacement relationship curve and the coordinate axes is obtained; the rising-section ratio between the rising-section area and the net area of the fracture zone is obtained, and the rising-section ratio is determined as the energy absorption capacity of the fully graded concrete specimen; the net area of the fracture zone is the total area of the fracture surface obtained after the fully graded concrete specimen fractures. Since the energy absorption capacity of the fully graded concrete specimen is determined based on the rising-section area of the tensile force-displacement relationship curve and the net area of the fracture zone, the accuracy of obtaining the energy absorption capacity of the fully graded concrete specimen can be ensured.

[0072] In one embodiment, when determining the fracture energy of the fully graded concrete specimen according to the tensile force-displacement relationship curve, the controller is specifically configured to: obtain the total curve-section area enclosed by the entire curve section of the tensile force-displacement relationship curve and the coordinate axes; obtain the total curve-section ratio between the total curve-section area and the net area of the fracture zone, and determine the total curve-section ratio as the fracture energy of the fully graded concrete specimen.

[0073] Among them, the total curve-section area refers to the area enclosed by the entire curve section of the tensile force-displacement relationship curve and the horizontal axis of the coordinate axes. The total curve-section ratio is the ratio obtained by dividing the total curve-section area by the net area of the fracture zone. The total curve-section ratio represents the fracture energy of the fully graded concrete specimen.

[0074] In this embodiment, the total curve-section area enclosed by the entire curve section of the tensile force-displacement relationship curve and the coordinate axes is obtained; the total curve-section ratio between the total curve-section area and the net area of the fracture zone is obtained, and the total curve-section ratio is determined as the fracture energy of the fully graded concrete specimen. Since the fracture energy of the fully graded concrete specimen is determined based on the entire curve section of the tensile force-displacement relationship curve and the net area of the fracture zone, the fracture energy of the fully graded concrete specimen can be ensured.

[0075] In one embodiment, the device for determining the fracture parameters of the full-graded concrete specimen further includes a plurality of laser displacement sensors; the laser displacement sensor includes a laser emitter and a receiver; the laser emitter and the receiver of each laser displacement sensor are respectively installed at both ends of the full-graded concrete specimen; when determining the fracture toughness of the full-graded concrete specimen by using the extended finite element method, the controller is specifically configured to: obtain the material mechanical parameters and dimensions of the full-graded concrete specimen; construct a constructed finite element model based on the material mechanical parameters and dimensions of the full-graded concrete specimen, and the constructed finite element model is the finite element model of the full-graded concrete specimen before axial tension; when it is determined that the peak tensile force of the full-graded concrete specimen is obtained, the deformation displacements of the full-graded concrete specimen measured by the plurality of laser displacement sensors respectively are obtained, and a plane equation is obtained by fitting according to the deformation displacements; the plane equation is applied to the upper surface of the constructed finite element model by means of displacement loading to obtain the total tensile force on the upper surface of the constructed finite element model and the fracture toughness of the constructed finite element model; and the fracture toughness of the full-graded concrete specimen is determined according to the total tensile force, the fracture toughness of the constructed finite element model, and the peak tensile force of the full-graded concrete specimen.

[0076] Among them, the laser displacement sensor is a measuring device that measures displacement by emitting and receiving laser. The laser emitter and the receiver are respectively installed at both ends of the full-graded concrete specimen. The laser emitter can be used to emit laser, and the receiver can be used to receive the laser emitted by the laser emitter. Therefore, during the tensile process of the full-graded concrete specimen, the displacement between the laser emitter and the receiver measured by the laser displacement sensor can be used to represent the overall deformation of the full-graded concrete specimen during the tensile process, that is, the deformation displacement of the full-graded concrete specimen.

[0077] The material mechanical parameters of the full-graded concrete specimen refer to the material mechanical parameters of the material when the concrete is used. The material mechanical parameters of the full-graded concrete specimen are shown in Table 2 and include elastic modulus, Poisson's ratio, density, compressive strength, tensile strength, etc.

[0078] By inputting the material mechanical parameters, dimensions and other information of the full-graded concrete specimen into the finite element analysis software of the controller, a constructed finite element model can be obtained in the finite element analysis software. Among them, the finite element analysis software can be any existing finite element analysis software, such as Abaqus, without specific limitation. The constructed finite element model is the finite element model of the full-graded concrete specimen before axial tension.

[0079] The plane equation is obtained by fitting the deformation displacement of multiple fully graded concrete specimens through mathematical calculation. For example, the four measured deformation displacements are 0.0081, 0.0141, 0.0331, and 0.02989; the height of the fully graded concrete specimen is 450 mm and the diameter is 450 mm. Taking the bottom center of the fully graded concrete specimen as the origin of the three-dimensional coordinate axis, the coordinates of the four laser displacement meters are (225, 0, 0.0081), (0, 225, 0.0141), (-225, 0, 0.0331), and (0, -225, 0.02989). Assuming that the plane equation is x+ay+bz+c=0, take (225, 0, 0.0081), (0, 225, 0.0141), (-225, 0, 0.0331) for calculation, and we can get the plane equation z=(0.3708-x-0.528y) / 18×10 3 .

[0080] Due to the existence of prefabricated cracks in the fully graded concrete specimen, eccentricity will occur in the actual tensile process. In the case of eccentricity, the tensile force at each position on the upper surface of the fully graded concrete specimen is different. Incorporating the eccentricity problem into the fracture performance study of the fully graded concrete specimen can obtain a more accurate determination of the fracture parameters of the fully graded concrete specimen.

[0081] After the above-mentioned axial tensile test is performed, eccentric loading can be realized through finite element model simulation, specifically: the plane equation is applied to the upper surface of the constructed finite element model by displacement loading. Here, it can be understood that before the plane equation is applied, the upper surface of the constructed finite element model is in the initial position before being axially stretched, and the plane equation is loaded to the upper surface of the constructed finite element model, that is, the constructed finite element model is stretched according to the axial tensile test. After the upper surface of the constructed finite element model is stretched to the position of the plane equation, it can be consistent with the displacement of the upper surface of the full-graded concrete specimen during the test process, so as to achieve the purpose of reflecting the real test results as much as possible. When the plane equation is applied to the upper surface of the constructed finite element model by displacement loading, constraints are also set for the lower surface (i.e., the bottom surface) of the constructed finite element model: the entire surface constrains the z-axis direction, and the center of the circle constrains the three directions of xyz. The purpose of this is to fix the lower end of the constructed finite element model and keep the lower surface motionless, which is consistent with the fixation of the lower end of the full-graded concrete specimen during the test.

[0082] After the plane equation is loaded onto the upper surface of the constructed finite element model by the finite element analysis software, the total tensile force on the upper surface of the constructed finite element model and the fracture toughness of the constructed finite element model can be automatically calculated. Among them, during the process of stretching the constructed finite element model to the plane equation, at each displacement where it is stretched, a corresponding stress intensity factor can be output. When it is stretched to the displacement position corresponding to the peak tensile force, the corresponding stress intensity factor is called the fracture toughness.

[0083] The ratio between the total tensile force on the upper surface of the constructed finite element model and the fracture toughness of the constructed finite element model is equal to the ratio between the peak tensile force of the fully graded concrete specimen and the fracture toughness of the fully graded concrete specimen. Based on this, when the total tensile force on the upper surface of the constructed finite element model, the fracture toughness of the constructed finite element model, and the peak tensile force of the fully graded concrete specimen are determined, the fracture toughness of the fully graded concrete specimen can be determined.

[0084] For example, after the upper surface of the constructed finite element model is stretched to the plane equation, the total tensile force on the upper surface is 100 KN. Assuming that this 100 KN is the peak tensile force, the stress intensity factor corresponding to 100 KN is 0.2 MPa*mm1 / 2. Since the fracture toughness is the stress intensity factor corresponding to the peak tensile force, the fracture toughness of the constructed finite element model is 0.2 MPa*mm1 / 2. During the axial tensile test of the fully graded concrete specimen, if the actually measured peak tensile force is assumed to be 200 KN, then the fracture toughness of the fully graded concrete specimen can be determined to be 0.4 MPa*mm1 / 2.

[0085] In one embodiment, the material mechanical parameters of the fully graded concrete specimen include the elastic modulus and the axial tensile strength; when the controller determines the characteristic length of the fully graded concrete specimen according to the fracture energy of the fully graded concrete specimen, it is specifically used for: inputting the elastic modulus, the axial tensile strength, and the fracture energy of the fully graded concrete specimen into a preset characteristic length calculation formula for calculation, and outputting to obtain the characteristic length of the fully graded concrete specimen.

[0086] Among them, the preset characteristic length calculation formula is:

[0087]

[0088] Among them, L ch is the characteristic length of the fully graded concrete specimen; E c is the elastic modulus; G f is the fracture energy of the fully graded concrete specimen; f t is the axial tensile strength of the fully graded concrete specimen.

[0089] In this embodiment, the elastic modulus, the axial tensile strength, and the fracture energy of the fully-graded concrete specimen are input into a preset characteristic length calculation formula for calculation, and the characteristic length of the fully-graded concrete specimen is obtained as the output. Since the characteristic length is calculated according to a preset characteristic length calculation formula, in combination with its own elastic modulus, axial tensile strength, and the energy absorbed during the entire fracture process, the accurate characteristic length of the fully-graded concrete specimen can be obtained.

[0090] For the limitation of the method for determining the fracture parameters of the fully-graded concrete specimen in the subsequent embodiments, please refer to the relevant description of the device for determining the fracture parameters of the fully-graded concrete specimen.

[0091] Figure 3 This is a method for determining the fracture parameters of a fully-graded concrete specimen provided in an embodiment of the present application. As Figure 4 shown, the execution subject of the method for determining the fracture parameters of the fully-graded concrete specimen provided in this embodiment is the controller of the device for determining the fracture parameters of the fully-graded concrete specimen. Then, the method for determining the fracture parameters of the fully-graded concrete specimen provided in this embodiment includes the following steps:

[0092] Step 101: Control the power component to drive the fixing member to move in a direction away from the ground, so that the first steel disc moves in a direction away from the second steel disc, so that the fully-graded concrete specimen is axially stretched.

[0093] Among them, the device for determining the fracture parameters of the fully-graded concrete specimen further includes a power component, a first steel disc and a second steel disc arranged symmetrically, a first spherical hinge, a second spherical hinge, a tension sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tension sensor, and each extensometer respectively; the first steel disc is fixedly installed at one end of the first spherical hinge of the device for determining the fracture parameters of the fully-graded concrete specimen, and the second steel disc is installed on the base of the device for determining the fracture parameters of the fully-graded concrete specimen through the second spherical hinge. The first steel disc and the second steel disc are respectively fixedly connected to one end of the fully-graded concrete specimen through epoxy glue; the tension sensor is fixedly arranged on the fixing member, and the extensometers are fixedly arranged along the opening of the prefabricated crack of the fully-graded concrete specimen.

[0094] Step 102: Based on the displacements of the crack openings of the fully-graded concrete specimen measured by a plurality of extensometers at a plurality of moments, and the tensile force of the fully-graded concrete specimen measured by the tension sensor at the corresponding moment, determine the tension-displacement relationship curve; the tension-displacement relationship curve characterizes the relationship between the displacement of the crack opening of the fully-graded concrete specimen and the tensile force.

[0095] Step 103: Determine the fracture parameters of the fully-graded concrete specimen according to the load-displacement relationship curve.

[0096] In this embodiment, since the axial tension method can obtain very accurate results when determining the material mechanical parameters of concrete specimens, such as elastic modulus and Poisson's ratio. Since the fracture parameters of concrete specimens are affected by the material mechanical parameters of concrete specimens (material properties), the axial tension method can be applied to determine the fracture parameters of concrete specimens. Moreover, the axial tension method for concrete specimens will not cause additional moments due to vertical loads in the prior art, which will affect the stress field at the crack tip. Therefore, accurate fracture parameters of concrete specimens can be obtained. In addition, the concrete specimens tested by the axial tension method are easier to fabricate and easier to handle during the test.

[0097] In one embodiment, as Figure 4 shown, Step 102 includes the following steps:

[0098] Step 201: Take the average of the displacements of the crack openings of the fully-graded concrete specimen measured by each extensometer at multiple moments to obtain the average displacement of the crack openings at multiple moments.

[0099] Step 202: Construct a load-displacement relationship curve according to the average displacement of the crack openings at the multiple moments and the load measured by the load sensor at the corresponding moments.

[0100] In one embodiment, the fracture parameters of the concrete include the energy absorption capacity of the fully-graded concrete specimen, the fracture energy of the fully-graded concrete specimen, the fracture toughness of the fully-graded concrete specimen, and the characteristic length of the fully-graded concrete specimen.

[0101] In one embodiment, as Figure 5 shown, Step 103 includes the following steps:

[0102] Step 301: Determine the energy absorption capacity of the fully-graded concrete specimen and the fracture energy of the fully-graded concrete specimen according to the load-displacement relationship curve.

[0103] Step 302: Use the extended finite element method to determine the fracture toughness of the fully-graded concrete specimen.

[0104] Step 303: Determine the characteristic length of the fully-graded concrete specimen according to the fracture energy of the fully-graded concrete specimen.

[0105] In one embodiment, determining the energy absorption capacity of the fully-graded concrete specimen in Step 301 includes the following steps:

[0106] Step 401: Obtain the area of the rising segment enclosed by the rising segment of the tensile-displacement relationship curve and the coordinate axes.

[0107] Step 402: Obtain the rising segment ratio between the area of the rising segment and the net area of the fracture zone, and determine the energy absorption capacity of the fully graded concrete specimen by the rising segment ratio; the net area of the fracture zone is the total area of the fracture surface obtained after the fully graded concrete specimen fractures.

[0108] In one embodiment, determining the fracture energy of the fully graded concrete specimen in step 301 includes the following steps:

[0109] Step 501: Obtain the area of the entire curve segment enclosed by the entire curve segment of the tensile-displacement relationship curve and the coordinate axes.

[0110] Step 502: Obtain the full curve segment ratio between the area of the full curve segment and the net area of the fracture zone, and determine the fracture energy of the fully graded concrete specimen by the full curve segment ratio.

[0111] In one embodiment, step 302 includes the following steps:

[0112] Step 601: Obtain the peak tensile force of the fully graded concrete specimen measured by the fracture parameter determination device of the fully graded concrete specimen, and the material mechanical parameters of the fully graded concrete specimen.

[0113] Step 602: Input the peak tensile force and the material mechanical parameters of the fully graded concrete specimen into a pre-constructed finite element model, and calculate and output the fracture toughness of the fully graded concrete specimen through the pre-constructed finite element model. The pre-constructed finite element model is a simulation model constructed by using the extended finite element method for the fully graded concrete specimen.

[0114] In one embodiment, the laser displacement meter includes a laser emitter and a receiver. Before step 602, the fracture parameter determination method of the fully graded concrete specimen further includes:

[0115] Step 701: Determine the deformation displacement between the laser emitter and the receiver measured by multiple laser displacement meters when the peak tensile force of the fully graded concrete specimen is obtained, and fit a plane equation based on each deformation displacement; the laser emitter and the receiver of each laser displacement meter are respectively installed on both sides of the prefabricated crack of the fully graded concrete specimen.

[0116] Step 702: Load the plane equation onto the upper surface of the initial finite element model to obtain the pre-constructed finite element model.

[0117] In one embodiment, the material mechanical parameters of the fully-graded concrete specimen include elastic modulus and axial tensile strength; step 303 specifically includes: inputting the elastic modulus, the axial tensile strength, and the fracture energy of the fully-graded concrete specimen into a preset characteristic length calculation formula for calculation, and outputting to obtain the characteristic length of the fully-graded concrete specimen.

[0118] A non-transitory computer-readable storage medium, when the instructions in the storage medium are executed by a processor of an electronic device, enables the electronic device to execute the method for determining the fracture parameters of the fully-graded concrete specimen of the above-mentioned electronic device.

[0119] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the following claims.

[0120] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. An apparatus for determining fracture parameters of a full-graded concrete specimen, characterized in that, The equipment for determining the fracture parameters of the fully graded concrete specimen includes: a controller, a power component, a first steel disc and a second steel disc arranged symmetrically, a first spherical hinge, a second spherical hinge, a tension sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tension sensor and each of the extensometers respectively; the power component is connected to the first spherical hinge through a fixing member; the material mechanical parameters of the fully graded concrete specimen include elastic modulus and axial tensile strength; The first steel disc is fixedly installed at one end of the first spherical hinge, and the second steel disc is installed on the base of the equipment for determining the fracture parameters of the fully graded concrete specimen through the second spherical hinge. The base is fixedly connected to the ground. The first steel disc and the second steel disc are respectively fixedly connected to one end of the fully graded concrete specimen through epoxy glue; the tension sensor is fixedly arranged on the fixing member, and the extensometers are fixedly arranged along the opening of the prefabricated crack of the fully graded concrete specimen; The controller is used to control the power component to drive the fixing member to move away from the ground, so that the first steel disc moves away from the second steel disc, so as to axially stretch the fully graded concrete specimen; The tension sensor is used to measure the tension of the fully graded concrete specimen at multiple moments during the process of axially stretching the fully graded concrete specimen controlled by the controller; The extensometer is used to measure the displacement of the crack opening of the fully graded concrete specimen at multiple moments during the process of axially stretching the fully graded concrete specimen; The controller is also used to determine the tension-displacement relationship curve based on the displacements of the crack openings of the fully graded concrete specimen at multiple moments measured by each of the extensometers respectively, and the tension of the fully graded concrete specimen at the corresponding moment measured by the tension sensor; according to the tension-displacement relationship curve, determine the fracture parameters of the fully graded concrete specimen. The tension-displacement relationship curve characterizes the relationship between the displacement of the crack opening of the fully graded concrete specimen and the tension; the fracture parameters of the concrete include: the energy absorption capacity of the fully graded concrete specimen, the fracture energy of the fully graded concrete specimen and the characteristic length of the fully graded concrete specimen; When determining the fracture parameters of the fully graded concrete specimen according to the tensile force-displacement relationship curve, the controller is specifically configured to: obtain the area of the rising section enclosed by the rising section of the tensile force-displacement relationship curve and the coordinate axes, and the area of the entire curve section enclosed by the entire curve section of the tensile force-displacement relationship curve and the coordinate axes; obtain the rising section ratio between the area of the rising section and the net area of the fracture zone, and determine the energy absorption capacity of the fully graded concrete specimen as the rising section ratio; the net area of the fracture zone is the total area of the fracture surface obtained after the fracture of the fully graded concrete specimen; obtain the full curve section ratio between the area of the full curve section and the net area of the fracture zone, and determine the fracture energy of the fully graded concrete specimen as the full curve section ratio; input the elastic modulus, the axial tensile strength, and the fracture energy of the fully graded concrete specimen into a preset characteristic length calculation formula for calculation, and output to obtain the characteristic length of the fully graded concrete specimen.

2. The device for determining the fracture parameters of the full-graded concrete specimen according to claim 1, characterized in that, When determining the tensile force-displacement relationship curve, the controller is specifically configured to: Take the average of the displacements of the crack openings of the fully graded concrete specimen measured by each extensometer at multiple moments to obtain the average displacement of the crack openings at multiple moments; Construct a tensile force-displacement relationship curve based on the average displacement of the crack openings at multiple moments and the tensile force at the corresponding moments measured by the tensile force sensor.

3. The device for determining the fracture parameters of the fully graded concrete specimen according to claim 1, characterized in that, The fracture parameters of the concrete further include: the fracture toughness of the fully graded concrete specimen; when determining the fracture parameters of the fully graded concrete specimen according to the tensile force-displacement relationship curve, the controller is further specifically configured to: Use the extended finite element method to determine the fracture toughness of the fully graded concrete specimen.

4. The device for determining the fracture parameters of the fully graded concrete specimen according to claim 3, characterized in that, The fracture parameter determination device for the fully graded concrete specimen further includes a plurality of laser displacement sensors; the laser displacement sensor includes a laser emitter and a receiver; the laser emitter and the receiver of each laser displacement sensor are respectively installed at both ends of the fully graded concrete specimen; when using the extended finite element method to determine the fracture toughness of the fully graded concrete specimen, the controller is specifically configured to: Obtain the material mechanical parameters and dimensions of the fully graded concrete specimen; Construct a constructed finite element model based on the material mechanical parameters and dimensions of the fully graded concrete specimen, and the constructed finite element model is the finite element model of the fully graded concrete specimen before axial tension; When it is determined that the peak tensile force of the fully graded concrete specimen is obtained, obtain the deformation displacements of the fully graded concrete specimen measured by each laser displacement sensor, and fit a plane equation according to each deformation displacement; Apply the plane equation to the upper surface of the constructed finite element model through displacement loading to obtain the total tensile force on the upper surface of the constructed finite element model and the fracture toughness of the constructed finite element model; Determine the fracture toughness of the fully graded concrete specimen according to the total tensile force, the fracture toughness of the constructed finite element model, and the peak tensile force of the fully graded concrete specimen.

5. A method for determining the fracture parameters of a fully-graded concrete specimen, which is applied to the equipment for determining the fracture parameters of a fully-graded concrete specimen as described in any one of claims 1-4, characterized in that, The controller of the fracture parameter determination device for the full-graded concrete specimen. The fracture parameter determination device for the full-graded concrete specimen further includes a power component, a first steel disc and a second steel disc arranged symmetrically, a first spherical hinge, a second spherical hinge, a tension sensor and a plurality of extensometers. The controller is electrically connected to the power component, the tension sensor and each of the extensometers respectively; the power component is connected to the first spherical hinge through a fixing member; the first steel disc is fixedly installed at one end of the first spherical hinge, and the second steel disc is installed on the base of the fracture parameter determination device for the full-graded concrete specimen through the second spherical hinge. The base is fixedly connected to the ground. The first steel disc and the second steel disc are respectively fixedly connected to one end of the full-graded concrete specimen through epoxy glue; the tension sensor is fixedly arranged on the fixing member, and the extensometers are fixedly arranged along the opening of the prefabricated crack of the full-graded concrete specimen; the method includes: By controlling the power component to drive the fixing member to move in a direction away from the ground, the first steel disc is moved in a direction away from the second steel disc, so that the full-graded concrete specimen is axially stretched; Based on the displacements of the crack openings of the full-graded concrete specimen measured by the plurality of extensometers at a plurality of moments respectively, and the tensile force of the full-graded concrete specimen measured by the tension sensor at the corresponding moments, a tensile force-displacement relationship curve is determined; the tensile force-displacement relationship curve characterizes the relationship between the displacement of the crack opening of the full-graded concrete specimen and the tensile force; According to the tensile force-displacement relationship curve, the fracture parameters of the full-graded concrete specimen are determined.

6. A computer-readable storage medium, characterized in that, Computer-executable instructions are stored in the computer-readable storage medium, and when the computer-executable instructions are executed by a processor, they are used to implement the method according to claim 5.

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