A device and method for testing the compressive strength of materials under lateral constraint

Abstract

The present invention proposes a material compressive strength testing device and method under lateral constraint, which uses a casing to perform lateral constraint on a test piece, replacing the existing oil pressure loading method. It can not only achieve test conditions under conditions of lower lateral constraint force, but also simulate test conditions under high lateral constraint force. The device is simple, easy to operate, and can greatly improve the test efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field related to material compressive strength testing, and in particular relates to a device and method for testing the compressive strength of materials under lateral limit constraints. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The compressive strength of a material is an important indicator to measure its mechanical properties. Under certain working conditions, the material is constrained by the lateral confinement force, which will greatly improve the compressive strength of the material. The triaxial pressure testing machine can accurately control and record the size of the lateral confinement force, but the application process of the triaxial confining pressure has many limitations, such as long loading and unloading time, complex test equipment, high cost, and small lateral confinement pressure range. When the test volume is large and the lateral confinement force level is high (20-40MPa), the triaxial pressure testing machine is difficult to meet the test requirements. Summary of the invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a material compressive strength testing device and method under lateral constraint, which uses casing to perform lateral constraint on the test specimen, replacing the existing oil pressure loading method. It can not only realize the test conditions under the conditions of lower lateral constraint force, but also simulate the test conditions under high lateral constraint force. The device is simple, easy to operate, and can greatly improve the test efficiency.

[0005] To achieve the above-mentioned purpose, the first aspect of the present invention provides a material compressive strength testing device under lateral limit constraint, including a testing machine body, the testing machine body including an upper pressure plate and a lower pressure plate, the test piece to be tested is arranged between the upper pressure plate and the lower pressure plate, and different parameter sleeves corresponding to different lateral limit force constraint conditions are sleeved on the outer periphery of the test piece to be tested.

[0006] A second aspect of the present invention provides a method for testing the compressive strength of a material under lateral constraint, comprising:

[0007] Determine the parameters of the casing according to the different side restraint conditions required;

[0008] Putting a sleeve with determined parameters on the test piece to be tested;

[0009] Start the testing machine and pressurize the test piece to be tested so that the contact surface of the test piece is evenly pressurized;

[0010] Record the failure load of the test piece during the pressurization process;

[0011] According to the recorded failure load, the uniaxial compressive strength of the test specimens under different lateral confinement conditions was obtained.

[0012] One or more of the above technical solutions have the following beneficial effects:

[0013] In the present invention, the test specimen is restrained by a casing, replacing the existing oil pressure loading method. Not only can the test condition under the condition of lower lateral restraint force be achieved, but also the test condition under high lateral restraint force can be simulated. The device is simple and easy to operate, which can greatly improve the test efficiency.

[0014] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 It is a schematic diagram of a compressive strength and compression performance test device under casing constraint and confinement conditions in Example 1 of the present invention;

[0017] In the figure, 1, cross beam, 2, upper pressure plate, 3, lower pressure plate, 4, base, 5, upper steel block, 6, casing, 7, lower steel block. DETAILED DESCRIPTION

[0018] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0019] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0020] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0021] Embodiment 1

[0022] The present embodiment discloses a material compressive strength testing device under lateral limit constraint, characterized in that it includes a testing machine body, the testing machine body includes an upper pressure plate 2 and a lower pressure plate 3, the test piece to be tested is arranged between the upper pressure plate 2 and the lower pressure plate 3, and different parameter sleeves 6 corresponding to different lateral limit force constraint conditions are sleeved on the outer periphery of the test piece to be tested.

[0023] like Figure 1As shown, specifically, a plastic tube or a metal tube is wrapped around the test piece to be tested, the test piece to be tested is placed on a universal testing machine, cylindrical steel blocks are placed on the upper and lower surfaces of the test piece to be tested, the diameters of the upper steel block 5 and the lower steel block 7 are slightly smaller than the inner diameter of the sleeve 6, the upper pressure plate 2 is arranged on the crossbeam 1 of the testing machine, and the lower pressure plate is arranged on the base 4 of the testing machine.

[0024] The upper steel block 5 and the lower steel block 7 are respectively placed between the upper pressure plate 2 and the specimen to be tested, and between the lower pressure plate 3 and the specimen to be tested, in order to ensure that the upper pressure plate 2 and the lower pressure plate 3 are not in direct contact with the casing 6, so as to ensure that the casing 6 is only subjected to lateral pressure. The outer diameter of the upper steel block 5 and the lower steel block 7 is slightly smaller than the inner diameter of the casing 6, and the height should ensure that the upper surface of the steel block is not lower than the upper surface of the casing, that is, relative to the upper pressure plate 2; or the lower surface is not higher than the lower surface of the casing, that is, relative to the lower pressure plate 3.

[0025] The pressure-bearing surface of the test piece to be tested is perpendicular to the top surface during molding, and the center of the test piece to be tested is aligned with the center of the lower pressure plate of the testing machine.

[0026] Design the casing material, strength and thickness according to the lateral confinement force level. The casing thickness is calculated as follows:

[0027]

[0028] Where, P is the confining pressure (unit: MPa), D is the specimen diameter (unit: mm), and f y It is the yield tensile strength of the material (unit: MPa).

[0029] The casing material is generally PVC, aluminum alloy, and steel. Its strength is related to the model. The specific value is subject to the actual measurement. The strength of the casing material can be measured by a pull-out test before calculation. The inner diameter of the casing is slightly larger than or equal to the outer diameter of the test piece to be tested.

[0030] In this embodiment, it is necessary to design sleeves of different materials, strengths and thicknesses according to different levels of lateral confinement pressures, and to implement testing of different levels of lateral confinement pressures of the test specimen through the correspondingly arranged sleeves. This not only enables test conditions under conditions of lower lateral confinement restraint forces to be achieved, but also enables test conditions under conditions of high lateral confinement restraint forces to be simulated. The device is simple, easy to operate, and can greatly improve the test efficiency.

[0031] Embodiment 2

[0032] The purpose of this embodiment is to provide a method for testing the compressive strength of materials under lateral restraint, including:

[0033] Determine the parameters of the casing according to the different side restraint conditions required;

[0034] Putting a sleeve with determined parameters on the test piece to be tested;

[0035] Start the testing machine and pressurize the test piece to be tested so that the contact surface of the test piece is evenly pressurized;

[0036] Record the failure load of the test piece during the pressurization process;

[0037] According to the recorded failure load, the uniaxial compressive strength of the test specimens under different lateral confinement conditions was obtained.

[0038] In this embodiment, the test machine is started, and when the upper pressure plate approaches the test piece or the upper pad, the ball seat is adjusted to make the contact surface evenly compressed. The load is applied continuously and evenly, and when the test piece approaches failure and begins to deform rapidly, the failure load is recorded until the test piece fails.

[0039] The uniaxial compressive strength should be calculated according to the following formula, and the arithmetic mean of the measured values ​​of the three specimens is taken to calculate the uniaxial compressive strength.

[0040]

[0041] Where: σ is the uniaxial compressive strength of the specimen (unit: MPa), which should be accurate to 0.1 MPa; P is the specimen failure load (unit: N); A is the cross-sectional area of ​​the specimen perpendicular to the loading direction (mm 2 ).

[0042] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0043] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A material compressive strength testing device under lateral constraint, characterized in that: The testing machine comprises a main body, wherein the main body comprises an upper pressure plate and a lower pressure plate, a test piece to be tested is arranged between the upper pressure plate and the lower pressure plate, and sleeves with different parameters corresponding to different lateral force constraint conditions are sleeved on the outer periphery of the test piece to be tested; The different parameter casings refer to casings designed with different materials, material yield tensile strengths and thicknesses according to the required confining pressure and the diameter of the test piece to be tested; The thickness of the casing is determined as follows: the ratio of the product of the required limit pressure and the diameter of the test piece to be tested to twice the yield tensile strength of the material of the test piece to be tested; An upper steel block and a lower steel block are respectively arranged on the upper and lower surfaces of the test piece to be tested, and the diameters of the upper steel block and the lower steel block are both smaller than the inner diameter of the casing; The sleeve is not in contact with either the upper pressure plate or the lower pressure plate.

2. A material compressive strength testing device under lateral constraint as claimed in claim 1, characterized in that: The pressure-bearing surface of the test piece to be tested is perpendicular to the top surface during molding.

3. A material compressive strength testing device under lateral constraint as claimed in claim 1, characterized in that: The center of the test piece to be tested is aligned with the center of the lower bearing plate.

4. A material compressive strength testing device under lateral constraint as claimed in claim 1, characterized in that: The sleeve material is one of PVC, aluminum alloy and steel.

5. A method for testing the compressive strength of materials under lateral restraint, characterized in that: include: Determine the parameters of the casing according to the different side restraint conditions required; The thickness of the casing is determined as follows: the ratio of the product of the required limit pressure and the diameter of the test piece to be tested to twice the yield tensile strength of the material of the test piece to be tested; Putting a sleeve with determined parameters on the test piece to be tested; Start the testing machine and pressurize the test piece to be tested so that the contact surface of the test piece is evenly pressurized; Record the failure load of the test piece during the pressurization process; According to the recorded failure load, the uniaxial compressive strength of the specimens to be tested under different lateral confinement conditions was obtained.

6. A method for testing the compressive strength of materials under lateral restraint as claimed in claim 5, characterized in that: The uniaxial compressive strength of the specimen to be tested is the ratio of the failure load of the specimen to be tested to the cross-sectional area of ​​the specimen perpendicular to the loading direction.

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