A strength test method based on SHPB disk specimen

Abstract

The present invention belongs to the technical field of material analysis, and specifically relates to a strength test method based on SHPB disc specimens, and uses a loading device of the SHPB disc specimen to perform a strength test; the loading device includes: a confining pressure cylinder, a cover body, a fixing plate, a guide rod, an incident rod, a transmission rod, and a rubber ring; the strength test includes a Brazilian splitting tensile strength test of the SHPB disc specimen, and a compression test of the SHPB disc specimen. The device involved in the present application can conveniently take out the specimen through a fixing device after the experiment is completed, which is convenient for experimental operation, weakens the artificial secondary damage that occurs when the specimen is taken out, and also reduces the error generated when studying the dynamic stress-strain characteristics and deformation-destruction characteristics of the rock after the experiment.

Description

Technical Field

[0001] The invention belongs to the technical field of material analysis, and in particular relates to a strength test method based on a SHPB disc specimen. Background Art

[0002] In recent years, with the large-scale exploitation of deep mineral resources, the stability of deep rock masses involved in deep earth engineering has gradually received attention. Studies have shown that most deep rock masses are in a complex geological environment of "three highs and one disturbance", and are subject to the coupling of high ground stress, high osmotic pressure and dynamic disturbance, which can easily induce engineering geological disasters such as leakage, blowout, and sudden water inrush, and can easily cause casualties during construction. In engineering, Hopkinson bar is often used to study the material performance parameters of rock materials under dynamic loads. Different types of SHPB systems that can apply confining pressure have been developed. By combining the application of lateral confining pressure and axial confining pressure, simulation under complex stress states and coupling of static and dynamic loads are achieved. At the same time, hydraulic effects are also considered, and a SHPB test system with controllable pore pressure and confining pressure is developed to further study the dynamic mechanical response of deep rocks under fluid-solid coupling.

[0003] At present, there are still many problems with the Hopkinson bar confining pressure loading device, including that the specimen placement position is fixed on the basis of applying confining pressure, and only one dynamic performance parameter of the fixed size specimen can be studied, which cannot meet the requirements of measuring both the dynamic compressive performance and the splitting tensile performance of the specimen; after a set of experiments, the specimen needs to be taken out from the confining pressure loading device. The common removal method is to move the transmission rod and the sleeve apart through the back-pulling device at the buffer device after unloading the axial pressure and confining pressure, and use auxiliary facilities such as thin iron wire and vacuum cleaner to take out the specimen. Therefore, it is very likely to cause secondary damage to the specimen during the removal process, seriously affecting the observation of its surface cracks and the results of particle size analysis after the experiment; after the specimen is subjected to the pore pressure, axial pressure and confining pressure at the same time, the pore pressure cannot be effectively released, and when moving the transmission rod, it is easily affected by the pore pressure and the waterproof rubber ring, and cannot be smoothly moved out, resulting in the separation of the transmission rod and the buffer device; after the specimen breaks through, it is not easy to take it out after remaining in the sleeve, and the overall damage phenomenon and surface crack lines of the specimen cannot be observed after taking it out.

[0004] At the same time, the common SHPB devices can only apply axial pressure in one direction, which cannot adapt to the complex geological environment of deep rock mass. In recent years, SHPB devices that can apply confining pressure, water pressure or temperature have appeared, but the conditions are very simple and can only meet specific geological conditions and cannot adapt to changes in the engineering environment. These problems will reduce the efficiency of the experiment and affect the accuracy of the experiment.

[0005] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0006] In order to solve the above-mentioned defects of the prior art, the present invention provides a strength test method based on SHPB disc specimens, wherein the loading device of the SHPB disc specimen involved can be regarded as a pull-out convenient device that can move and position the SHPB disc specimen. It can provide axial pressure, confining pressure, and pore pressure to act on the specimen at the same time, and the three conditions are controllable, which greatly meets the actual needs; the dynamic compressive performance and splitting tensile performance of different specimens can also be measured by adjusting the fixing device. After the experiment is completed, the specimen can be conveniently taken out through the fixing device, which is convenient for experimental operation, weakens the artificial secondary damage that occurs when the specimen is taken out, and also reduces the errors caused by studying the dynamic stress-strain characteristics and deformation and failure characteristics of the rock after the experiment.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A strength test method based on a SHPB disc specimen, the improvement of which is that the method uses a loading device of the SHPB disc specimen to perform a strength test; the loading device comprises:

[0009] The confining pressure cylinder 17 comprises a hollow cylinder; the confining pressure cylinder 17 is placed parallel to the ground; a slot is provided at the center of the side wall of the confining pressure cylinder 17 as a placement hole; the placement hole is upward and parallel to the ground;

[0010] The cover body 20 comprises an arc-shaped block matching the placement hole, and the cover body 20 is installed in the placement hole; the outer surface of the cover body 20 is integrated with the side wall surface of the confining pressure cylinder 17;

[0011] The fixing plate 21 comprises a sheet-shaped object; the fixing plate 21 is fixedly arranged on the surface of the cover body 20; the cover body 20 is bolted to the confining pressure cylinder 17 through the fixing plate 21;

[0012] The guide rod 8 includes a rod-shaped object and is arranged perpendicular to the ground; four guide rods 8 fixedly connected to the cover body 20 are evenly arranged below the cover body 20; the test piece is fixed between the guide rods 8 by the positioner 22;

[0013] The incident rod 1 comprises a rod-shaped object; the diameter of the incident rod 1 matches the inner diameter of the confining pressure cylinder 17; the first end of the incident rod 1 is arranged inside the confining pressure cylinder 17 through the first end of the confining pressure cylinder 17; the first end of the incident rod 1 contacts the specimen; the second end of the incident rod 1 extends out of the first end of the confining pressure cylinder 17;

[0014] The transmission rod 2 comprises a rod-shaped object; the diameter of the transmission rod 2 matches the inner diameter of the confining pressure cylinder 17; the first end of the transmission rod 2 is arranged inside the confining pressure cylinder 17 through the second end of the confining pressure cylinder 17; the first end of the transmission rod 2 contacts the specimen; the second end of the transmission rod 2 extends out of the second end of the confining pressure cylinder 17;

[0015] The rubber ring 15 comprises a cylindrical annular ring; the rubber ring 15 is sleeved with the first end of the incident rod 1 and the first end of the transmission rod 2 at the same time; the space between the outside of the rubber ring 15 and the confining pressure cylinder 17 forms a confining pressure chamber 6; the space inside the rubber ring 15 forms a pore pressure chamber;

[0016] The strength tests include Brazilian splitting tensile strength test of SHPB disc specimens and compression test of SHPB disc specimens;

[0017] The Brazilian splitting test method includes the following steps:

[0018] Step S1, selecting a specimen; the specimen is a disc specimen with a diameter of 48 mm to 54 mm; the ratio of the specimen height to the diameter is 2.0 to 2.5;

[0019] Step S2, placing the specimen axially perpendicular to the ground; fixing the specimen in the guide rod 8; adjusting the position of the specimen so that the center line of the specimen is collinear with the axis of the incident rod 1 and the transmission rod 2;

[0020] Step S3, placing the cover body 20 in the confining pressure cylinder 17, and fixing the fixing plate 21 to the confining pressure cylinder 17;

[0021] Step S4, indirectly applying confining pressure to the specimen through the confining pressure chamber 6; indirectly applying pore pressure to the specimen through the pore pressure chamber; moving the transmission rod 2 to apply axial pressure; applying impact air pressure through the incident rod 1 until cracks appear on the specimen; and recording the axial pressure P when cracks appear on the specimen;

[0022] Step S5, calculating the Brazilian splitting tensile strength of the specimen according to the formula σ=P / A; wherein σ is the Brazilian splitting tensile strength, P is the axial pressure when the specimen is cracked, and A is the maximum cross-sectional area of ​​the specimen;

[0023] The compression test of SHPB disc specimens includes the following steps:

[0024] Step A, selecting a specimen; the specimen is a disc specimen with a diameter of 48 mm to 54 mm; the ratio of the specimen height to the diameter is 2.0 to 2.5;

[0025] Step B, placing the specimen axially parallel to the ground; fixing the specimen in the guide rod 8; adjusting the position of the specimen so that the axis of the specimen is collinear with the axis of the incident rod 1 and the axis of the transmission rod 2;

[0026] Step C, placing the cover body 20 in the confining pressure cylinder 17, and fixing the fixing plate 21 to the confining pressure cylinder 17;

[0027] Step D, indirectly applying confining pressure to the specimen through the confining pressure chamber 6; indirectly applying pore pressure to the specimen through the pore pressure chamber; moving the transmission rod 2 to apply axial pressure; applying impact air pressure through the incident rod 1 until cracks appear on the specimen; and recording the axial pressure p when cracks appear on the specimen;

[0028] Step E, calculating the compressive strength of the specimen according to the formula p=P / a; wherein: p is the compressive strength of the specimen, P is the axial pressure when the specimen has obvious cracks, and a is the cross-sectional area of ​​the specimen.

[0029] Preferably, the loading device also includes: a slide rail 19, through which the guide rod 8 is connected to the cover body 20; the slide rail 19 includes a rod-shaped object with an axial slot; two slide rails 19 arranged parallel to the ground and parallel to each other are fixedly connected under the cover body 20; the shape of the slot matches the shape of the connecting end of the guide rod 8, and the guide rod 8 can move in the slide rail 19 through the slot.

[0030] Preferably, the positioner 22 includes a positioning piece 22-1 and a positioning bolt 22-2; the positioning piece 22-1 includes a sheet; the positioning piece is arranged perpendicular to the axis of the guide rod 8 through a gasket 22-3 arranged in contact with the guide rod 8; two positioners 22 are arranged on each guide rod 8; the positioning piece 22-1 is respectively in contact with the upper bottom surface and the lower bottom surface of the specimen;

[0031] An axial through groove matching the locator bolt 22-2 is provided on the guide rod 8; at the same time, a bolt hole matching the locator bolt 22-2 is provided on the gasket 22-3; the locator bolt 22-2 can slide on the guide rod 8 along the through groove; the locating plate 22-1 is fixedly connected to the gasket 22-3; the gasket 22-3 is fixed by the locator bolt 22-2 and then the locating plate is fixed.

[0032] Preferably, the loading device further comprises: two sealing rings 5, comprising an annular rubber ring; the inner diameter of the sealing ring 5 matches the diameter of the incident rod 1 and the transmission rod 2; the sealing ring 5 is respectively arranged at the first end of the incident rod 1; and arranged at the first end of the transmission rod 2;

[0033] The rubber ring 15 is sleeved on the first end of the incident rod 1 and the first end of the transmission rod 2 at the same time through the sealing ring 5 .

[0034] Preferably, the loading device further comprises:

[0035] The rubber plate 26 comprises: a square curved rubber plate; an opening matching the size of the placement hole is provided on the rubber ring 15; the rubber plate 26 is installed in the opening; the outer surface of the rubber plate 26 is integrated with the side wall surface of the rubber ring 15;

[0036] The sealing plate 25 comprises: a square curved hard plate; the area of ​​the sealing plate 25 is larger than the area of ​​the rubber plate 26; the curvature of the curved surface of the sealing plate 25 matches the curvature of the curved surface of the rubber plate 26; the sealing plate 25 and the rubber plate 26 are arranged on the upper surface of the rubber plate 26 in contact with each other.

[0037] Preferably, through holes are provided on both the rubber plate 26 and the sealing plate 25, and the guide rod 8 passes through both the sealing plate 25 and the rubber plate 26;

[0038] The sealing ring 7 comprises a rubber annular ring, and two sealing rings 7 are arranged on each guide rod 8 ; the sealing rings 7 pass through the guide rod 8 and are arranged on the lower surface of the rubber plate 26 and the upper surface of the sealing plate 25 respectively.

[0039] Preferably, the loading device further comprises: two sealing heads 18; each sealing head 18 comprises an annular rubber ring with a protrusion; the inner diameter of the sealing head 18 matches the diameter of the incident rod and the transmission rod; the outer diameter of the sealing head 18 matches the inner diameter of the confining pressure cylinder; the protruding inner diameter of the sealing head 18 extends axially from the inner diameter of the sealing head 18; the protruding outer diameter of the sealing head 18 matches the diameter of the sealing ring 5; the sealing heads 18 are respectively arranged at the first end of the incident rod 1 and at the first end of the transmission rod 2, and the protruding end faces of the two sealing heads 18 are arranged opposite to each other; the planar end face of the sealing head 18 is in contact with the inner wall end face of the confining pressure cylinder 17;

[0040] The rubber ring 15 is clamped between the two sealing heads 18 .

[0041] Preferably, the loading device further comprises an oil storage chamber 11 connected below the confining pressure cylinder 17; an oil delivery hole 12 is provided below the confining pressure cylinder 17; the confining pressure chamber 6 is connected to the confining pressure cylinder 17 through the oil delivery hole 12;

[0042] The oil pipeline 9 is connected to the oil storage chamber 11 ; the oil pipeline valve 10 is arranged on the oil pipeline 9 .

[0043] Preferably, the loading device further comprises a water pipe 14 , a first end of the water pipe 14 is connected to the bottom of the confining pressure chamber 6 , and a second end of the water pipe 14 is connected to a water injection device; and a water pipe valve 13 is arranged on the water pipe 14 .

[0044] Beneficial effects:

[0045] (1) The present invention can realize the joint application of axial pressure, confining pressure and water pressure, has strong feasibility, and can better fit the actual occurrence environment of deep rock mass.

[0046] (2) The present invention can measure the dynamic compressive strength or dynamic tensile strength of the specimen by adjusting the placement angle of the specimen.

[0047] (3) The present invention can greatly improve the experimental efficiency. The test piece can be quickly replaced by using the fixing device, thus avoiding the problem of the test piece getting stuck and difficult to remove after the impact test.

[0048] (4) The present invention can ensure that the central axes of the test piece, the incident rod and the transmission rod coincide with each other through a positioner, thereby avoiding large errors in the experiment.

[0049] (5) The present invention can control the input and output of hydraulic oil through the oil storage chamber, thereby achieving the purpose of repeatedly utilizing the hydraulic oil and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings constituting a part of the present application 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 an improper limitation of the present invention. Among them:

[0051] Figure 1 It is a schematic front view of the loading device according to the present invention;

[0052] Figure 2 It is a schematic cross-sectional view of a loading device according to the present invention;

[0053] Figure 3 It is a front view of a schematic diagram of the connection and fixation of a test piece involved in the present invention;

[0054] Figure 4 It is a cross-sectional view of a schematic diagram of connection and fixation of a test piece involved in the present invention;

[0055] Figure 5 It is a plane schematic diagram of the positioner involved in the present invention;

[0056] Figure 6 A schematic diagram of the connection of the positioner according to the present invention;

[0057] Figure 7 This is a schematic diagram of the guide rod connection involved in the present invention;

[0058] Figure 8 It is a three-dimensional schematic diagram of the loading device involved in the present invention;

[0059] Wherein: 1. incident rod; 2. transmission rod; 3. hole pressure chamber; 4. guide rod base; 5. sealing ring; 6. confining pressure chamber; 7. sealing ring; 8. guide rod; 9. oil pipeline; 10. oil pipeline valve; 11. oil storage chamber; 12. oil delivery hole; 13. water pipe valve; 14. water injection pipe; 15. rubber ring; 16. test piece; 17. confining pressure cylinder; 18. sealing head; 19. slide rail; 19-1. slide rail bolt; 20. cover body; 21. fixing plate; 21-1. first fixing plate; 21-2. second fixing plate; 22. positioner; 22-1. positioning plate; 22-2. positioner bolt; 22-3. gasket; 23. handle; 24. first bolt hole; 25. sealing plate; 26. rubber plate; 27. second bolt hole. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0061] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0062] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0063] like Figure 1 As shown, the present application relates to a strength test method based on a SHPB disc specimen, the improvement of which is that the test method uses a loading device of the SHPB disc specimen to perform a strength test; wherein the loading device comprises:

[0064] The confining pressure cylinder 17 includes a hollow cylinder; the confining pressure cylinder 17 is placed parallel to the ground; a slot is set in the center of the side wall of the confining pressure cylinder 17 as a placement hole; the placement hole is upward and parallel to the ground. Specifically, the confining pressure cylinder 17 is a hollow cylinder, and a through hole coaxial with the axis is set on the first bottom surface of the confining pressure cylinder 17 and the second bottom surface of the confining pressure cylinder 17. The size of the through hole matches the diameter of the incident rod 1 and the transmission rod 2 mentioned later. The placement hole is a slot set in the center of the side wall of the confining pressure cylinder 17. The size of the placement hole shall be based on the actual experimental needs, and the size of the slot shall match the size of the specimen 16, so that the specimen 16 can be placed into the confining pressure cylinder 17 through the placement hole.

[0065] The cover 20 includes an arc-shaped block that matches the placement hole; the cover 20 is installed in the placement hole; the outer surface of the cover 20 is integrated with the side wall surface of the confining pressure cylinder 17. Specifically, the material of the cover 20 is the same as that of the confining pressure cylinder, and is located in the center of the side wall of the confining pressure cylinder 17. The shape of the cover 20 needs to match the shape of the placement hole to ensure that the cover 20 is tightly connected to the placement hole.

[0066] The fixing plate 21 includes a sheet-like object; the fixing plate 21 is fixedly arranged on the upper surface of the cover body 20; the cover body 20 is bolted to the confining pressure cylinder 17 through the fixing plate 21. In order to make the cover body 20 fit tightly with the confining pressure cylinder 17, the fixing plate 21 is arranged on the side wall surface of the confining pressure cylinder 17. Bolt holes are arranged on the fixing plate 21, and slots corresponding to the bolt holes of the fixing plate 21 are also arranged on the side wall of the confining pressure cylinder. The fixing plate 21 is bolted to the side wall of the confining pressure cylinder 17. Specifically, as Figure 8 As shown, the fixing plate 21 includes a first fixing plate 21-1 and a second fixing plate 21-2. The first fixing plate 21-1 is a sheet-shaped body, which is fixedly arranged on both sides of the radial cross section of the cover body 20. An arc matching the curvature of the side wall of the confining pressure cylinder 17 is arranged on the lower surface of the first fixing plate 21-1, and a first bolt hole 24 is arranged on the first fixing plate 21-1. The confining pressure cylinder 17 and the cover body 20 are connected by bolts arranged in the first bolt hole. Preferably, in order to strengthen the connection strength between the cover body 20 and the confining pressure cylinder 17, a second fixing plate 21-2 is also fixedly arranged axially on the side wall of the cover body 20. The second fixing plate 21-2 is symmetrically arranged on the cover body 20 along the axial direction. The lower surface of the second fixing plate 21-2 is arranged with an arc matching the curvature of the side wall of the cover body 20, and is welded to the cover body 20. The length of the fixing plate 21-2 matches the length of the cover body 20, and the width of the fixing plate 21-2 is greater than the width of the radial cross-section of the cover body 20; and a second bolt hole 27 is set in the part exceeding the radial cross-section of the cover body 20, and the confining pressure cylinder 17 and the cover body 20 are also connected by bolts set in the second bolt hole.

[0067] Guide rod 8, such as Figure 8 As shown, the guide rod 8 includes a rod-shaped object, which is arranged perpendicular to the ground; four guide rods 8 fixedly connected to the cover body 20 are evenly arranged below the cover body 20; and the specimen is fixed between the guide rods 8 by the positioner 22. Specifically, four guide rods 8 of equal length are vertically arranged below the cover body 20 and placed in the placement hole, and the specimen is fixed by the positioner 22 arranged on each guide rod 8. When the specimen needs to be taken out, the guide rod and the specimen can be taken out together when the cover body 20 is loosened and taken out.

[0068] Among them, Figure 5 and Figure 6 As shown, the positioner 22 includes a positioning piece 22-1 and a positioning bolt 22-2; the positioning piece 22-1 includes a sheet; the positioning piece is arranged perpendicular to the axis of the guide rod 8 through a gasket 22-3 arranged in contact with the guide rod 8; two positioners 22 are arranged on each guide rod 8; the positioning piece 22-1 is respectively in contact with the upper surface and the lower surface of the specimen;

[0069] An axial through groove matching the locator bolt 22-2 is provided on the guide rod 8; at the same time, a bolt hole matching the locator bolt 22-2 is provided on the gasket 22-3; the locator bolt 22-2 can slide on the guide rod 8 along the through groove; the locating plate 22-1 is fixedly connected to the gasket 22-3; the gasket 22-3 is fixed by the locator bolt 22-2 and then the locating plate is fixed.

[0070] Specifically, the positioner 22 includes a positioning piece 22-1, a positioning bolt 22-2 and a gasket 22-3. The positioning piece 22-1 and the gasket 22-3 are both sheet-shaped. The positioning piece 22-1 and the gasket 22-3 are welded and connected at right angles. In order to make rational use of space, it is preferred to weld the positioning piece 22-1 to the end of the gasket 22-3. It is also necessary to set an axial through groove on the guide rod 8, the size of the through groove matches the diameter of the positioning bolt 22-2, and also set a bolt hole matching the diameter of the positioning bolt 22-2 on the gasket 22-3. When the positioner is positioned on the guide rod 8, the positioning bolt 22-2 passes through the through groove and the bolt hole of the gasket 22-3 to fix the gasket 22-3, thereby fixing the positioning piece 22-1. At the same time, the gasket 22-3 can rotate along the positioning bolt 22-2, thereby adjusting the setting angle of the positioning piece 22-1. The specimen can move axially along the guide rod 8 following the positioner 22. In order to achieve a better holding effect, two positioners 22 are provided on each guide rod 8, which are respectively placed above and below the specimen. And the positioning pieces 22-1 are respectively fixed on the upper and lower surfaces of the specimen so as to clamp the specimen.

[0071] Preferably, the positioning piece 22 - 1 may be in a diamond shape.

[0072] Preferably, in order to be able to clamp the specimen whose axis is perpendicular to the ground and the specimen whose axis is parallel to the ground, the loading device further includes: a slide rail 19, through which the guide rod 8 is connected to the cover body 20; the slide rail 19 includes a rod-shaped object with an axial notch; two slide rails 19 arranged parallel to the ground and parallel to each other are fixedly connected under the cover body 20; the shape of the notch matches the shape of the connecting end of the guide rod 8, and the guide rod 8 can move in the slide rail 19 through the notch. Specifically, as Figure 7As shown, two parallel slide rails 19 are fixedly arranged under the cover body 20. The setting direction of the slide rail 19 is not limited, and it can be arranged along the radial direction of the cover body 20, or it can be arranged along the axial direction of the cover body 20, as long as the two slide rails 19 are arranged in parallel. An axial notch is arranged in the center of the slide rail 19; an axial protrusion is arranged on both sides of the slide rail, and a bolt hole is arranged in the protrusion, and the slide rail bolt 19-1 is vertically arranged in the bolt hole of the protrusion. Among them, the shape of the notch of the slide rail 19 matches the shape of the connecting end of the guide rod 8. The connecting end of the guide rod 8 used in this application is a sphere, so the shape of the notch is an arc matching the sphere, and the guide rod 8 can be clamped in the slide rail 19. When the guide rod 8 slides in the slide rail 19 to the specified position, the slide rail bolt 19-1 is used to fix the connecting end of the guide rod 8, thereby fixing the guide rod 8. By moving the mutual distance between the four guide rods 8, the test piece 16 can be flexibly placed horizontally or vertically between the movable guide rods 8. When the specimen 16 is placed vertically, the positioning piece 22-1 is parallel to the ground and fixed to the upper and lower bottom surfaces of the specimen 16. When the specimen 16 is placed horizontally, that is, the axis is parallel to the ground, the positioning piece 22-1 is set perpendicular to the ground and fixed to the upper and lower bottom surfaces of the specimen 16.

[0073] The incident rod 1 comprises a rod-shaped object; the diameter of the incident rod 1 matches the inner diameter of the confining pressure cylinder 17; the first end of the incident rod 1 is arranged inside the confining pressure cylinder 17 through the first end of the confining pressure cylinder 17; the first end of the incident rod 1 contacts the specimen; the second end of the incident rod 1 extends out of the first end of the confining pressure cylinder 17;

[0074] The transmission rod 2 includes a rod-shaped object; the diameter of the transmission rod 2 matches the inner diameter of the confining pressure cylinder 17; the first end of the transmission rod 2 is arranged inside the confining pressure cylinder 17 through the second end of the confining pressure cylinder 17; the first end of the transmission rod 2 is in contact with the specimen; and the second end of the transmission rod 2 extends out of the second end of the confining pressure cylinder 17. Specifically, the confining pressure cylinder 17 is a hollow cylinder, and the first end of the confining pressure cylinder 17 can be regarded as the first bottom surface of the confining pressure cylinder 17. A first through hole coaxial with the axis is provided on the first bottom surface of the confining pressure cylinder 17. The diameter of the first through hole matches the diameter of the incident rod 1. The first end of the incident rod 1 penetrates into the confining pressure cylinder 17 from the first bottom surface of the confining pressure cylinder 17 and contacts the specimen; the second end of the incident rod 1 extends out of the first bottom surface of the confining pressure cylinder 17. The second end of the confining pressure cylinder 17 can be regarded as the second bottom surface of the confining pressure cylinder 17. A second through hole coaxial with the axis is provided on the second bottom surface of the confining pressure cylinder 17. The diameter of the second through hole matches the diameter of the transmission rod 2. The first end of the transmission rod 2 extends from the second bottom surface of the confining pressure cylinder 17 into the confining pressure cylinder 17 to contact the specimen; the second end of the transmission rod 2 extends out of the second bottom surface of the confining pressure cylinder 17 .

[0075] The loading device involved in the present application also includes: a rubber ring 15, including a cylindrical annular ring. Figure 1 and Figure 2As shown, the rubber ring 15 needs to be simultaneously sleeved on the first end of the incident rod 1 and the first end of the transmission rod 2. In order to enhance the sealing performance between the rubber ring 15 and the incident rod 1 and the transmission rod 2, two sealing rings 5 ​​need to be provided. The sealing ring 5 includes an annular rubber ring; the inner diameter of the sealing ring 5 matches the diameter of the incident rod 1 and the transmission rod 2, and the outer diameter of the sealing ring is designed according to the actual situation in the experiment; the sealing rings 5 ​​are respectively arranged at the first end of the incident rod 1; and at the first end of the transmission rod 2. The rubber ring 15 is simultaneously sleeved on the first end of the incident rod 1 and the first end of the transmission rod 2 through the sealing ring 5. Specifically, the rubber ring 15 is simultaneously sleeved on the two sealing rings 5 ​​to enhance the sealing performance of the incident rod 1 and the transmission rod 2.

[0076] In order to place the test piece into the confining pressure cylinder 17, an opening matching the size of the placement hole needs to be provided on the rubber ring 15. Therefore, the device also needs to be provided with a rubber plate 26, such as Figure 2 , Figure 3 and Figure 4 As shown, the rubber plate 26 includes: a square curved rubber plate. The rubber plate 26 is installed in the opening; the outer surface of the rubber plate 26 is integrated with the side wall surface of the rubber ring 15;

[0077] It is also necessary to provide a sealing plate 25 having an area larger than the rubber plate 26. The sealing plate 25 is a square curved hard plate, and the curvature of the curved surface matches the curvature of the curved surface of the rubber plate 26. The sealing plate 25 is attached to the rubber plate 26 and covers the upper surface of the rubber plate 26. The edge of the sealing plate 25 that is beyond the rubber plate 26 is attached to the rubber ring 15.

[0078] Through holes are also provided on the rubber plate 26 and the sealing plate 25, and the guide rod 8 passes through the sealing plate 25 and the rubber plate 26 at the same time. Specifically, according to the different fixed positions of the test piece, through holes corresponding to the fixed positions of the guide rod 8 need to be provided on the rubber plate 26 and the sealing plate 25, and then different rubber plates 26 and sealing plates 25 with through holes at different positions need to be selected before each experiment. At the same time, the sealing ring 7 is provided on the lower surface of the rubber plate 26 and on the upper surface of the sealing plate 25. Specifically, two additional sealing rings 7 are provided on each guide rod 8. The sealing ring 7 is a rubber sealing ring, and the inner diameter of the sealing ring 7 matches the diameter of the guide rod 8. The sealing ring 7 passes through the guide rod 8 and is fixed on the upper surface of the sealing plate 25 and the lower surface of the rubber plate 26. The use of the rubber sealing ring 7 can ensure the sealing performance of the guide rod 8 when a gap is generated when passing through the rubber plate 26 and the sealing plate 25.

[0079] Preferably, in order to prevent the positioner and the sealing ring 7 from falling off when sliding on the guide rod 8, a fixing protrusion is further provided at the free end of the guide rod 8 as the guide rod base 4.

[0080] Preferably, in order to make the loading space a more closed environment, the loading device also includes a sealing head 18; the sealing head 18 includes an annular rubber ring with a protrusion; the inner diameter of the sealing head 18 matches the diameter of the incident rod and the transmission rod; the outer diameter of the sealing head 18 matches the inner diameter of the confining pressure cylinder; the protrusion of the sealing head 18 extends axially from the inner diameter of the sealing head 18 to the end face; the protrusion inner diameter of the sealing head 18 is the inner diameter of the sealing head 18; the protrusion outer diameter of the sealing head 18 matches the diameter of the sealing ring 5; the sealing heads 18 are respectively arranged at the first end of the incident rod 1 and at the first end of the transmission rod 2, and the protrusion end faces of the two sealing heads 18 are arranged opposite to each other, and the protrusion end faces are in contact with the sealing ring 5; the sealing head 18 is a planar end face in contact with the inner wall end face of the confining pressure cylinder 17; the rubber ring 15 is clamped between the two sealing heads 18 and in contact with the protrusions of the two sealing heads 18.

[0081] Specifically, Figure 1 As shown, the loading device also includes two sealing heads 18; the sealing heads 18 are respectively arranged at the first end of the incident rod 1 and the first end of the transmission rod 2. A protrusion is arranged on one side of the sealing head 18, and the protruding end faces of the two sealing heads 18 are arranged opposite to each other, and the protruding end faces need to be in contact with the sealing ring 5; the plane end faces of the two sealing heads 18 need to be in contact with the inner wall end face of the confining pressure cylinder 17. The rubber ring 15 is clamped in the two sealing heads 18. The sealing head 18, the sealing ring 5, the rubber ring 15, the sealing plate 25 and the rubber plate 26 form a closed space in the center of the loading device as a pore pressure chamber to ensure the airtight performance of the loading experiment.

[0082] Preferably, the loading device further includes a handle 23; the handle 23 includes an arched rod, which is fixedly connected to the fixing plate 21. Specifically, the handle 23 can be used to more conveniently remove the test piece 16. The handle 23, together with the fixing plate 21, the cover 20, the rubber plate 26, the sealing plate 25, and the guide rod 8, forms a fixing device; when the test piece 16 is removed, the fixing device and the test piece 16 are removed together.

[0083] Preferably, the loading device further includes an oil storage chamber 11, which can be regarded as a storage chamber, and the oil storage chamber 11 is connected below the confining pressure cylinder 17. An oil delivery hole 12 is provided on the lower outer wall of the confining pressure cylinder 17; the oil storage chamber 11 is connected to the inside of the confining pressure cylinder 17 through the oil delivery hole 12;

[0084] The oil pipeline 9 is connected to the oil storage chamber 11; the oil pipeline valve 10 is arranged on the oil pipeline 9 to control the oil injection amount.

[0085] Preferably, the loading device also includes a water injection pipe 14, a first end of which is connected to the bottom of the rubber ring 15 inside the confining pressure cylinder 17, and a second end of which is connected to the water injection equipment; a water pipe valve 13 is arranged on the water injection pipe 14 to control the water injection amount.

[0086] The rubber ring 15 and the sealing head 18 divide the interior of the confining pressure cylinder 17 into the orifice pressure chamber 3 and the confining pressure chamber 6. The space between the outside of the rubber ring 15 and the confining pressure cylinder 17 forms the confining pressure chamber 6; the space inside the rubber ring 15 forms the orifice pressure chamber 3.

[0087] Specifically, the oil storage chamber 11 is fixed at the bottom of the confining pressure cylinder 17. A through hole is set at the central bottom of the outer wall of the confining pressure cylinder 17 as an oil delivery hole 12, connecting the interior of the confining pressure cylinder 17 with the oil storage chamber 11. In order to facilitate the input of hydraulic oil, the oil storage chamber 11 also needs to be externally connected to an oil delivery pipe 9 connected to an oil delivery device. At the same time, an oil delivery pipe valve 10 is set on the oil delivery pipe 9 to control the input and output of hydraulic oil. A water injection pipe 14 is set on the left side of the bottom of the confining pressure cylinder 17, and one end of the water injection pipe 14 passes through a rubber ring 15; the other end of the water injection pipe 14 is connected to the water injection equipment, and a water pipe valve 13 is set on the water injection pipe 14, and the water injection amount can be controlled by the water pipe valve 13.

[0088] The method of using the pull-out convenient surrounding rock loading device of the SHPB disc specimen is as follows:

[0089] Before the experimental loading, take out the fixture, adjust the position of the movable guide rod 8, adjust the positioning piece 22-1 at the positioner 22, place the specimen 16 in the middle of the positioner, fix the positioning piece 22-1 on the upper and lower surfaces of the specimen 16, and fix the specimen 16; place the fixture, the rubber plate 26 overlaps with the rubber ring 15, the rubber plate 26 is fixed by the sealing plate 25, the rubber ring 15 is in a closed loading space, and the fixing bolts set in the first bolt hole and the second bolt hole are tightened. The incident rod 1, the transmission rod 2, and the specimen 16 are in the same horizontal position; move the transmission rod 2 to apply axial pressure. Open the water pipe valve 13 to apply pore pressure. Specifically, the water injection pipe 14 injects water into the pore pressure chamber 3 through the rubber ring. The water pressure in the pore pressure chamber 3 is regarded as the pore pressure applied to the specimen. Open the oil pipeline valve 10 to apply confining pressure. Specifically, hydraulic oil is injected into the confining pressure chamber 6 through the oil pipeline. The confining pressure applied by the hydraulic oil on the rubber ring can be indirectly applied to the specimen. Then, the bullet is fired to conduct the impact test. Specifically, the incident rod 1 is connected to an air compressor, and an experimental bullet is set inside the incident rod 1. After the confining pressure, axial pressure, and water pressure are all applied, the air compressor is turned on and pressurized to a preset impact air pressure, and then the experimental bullet is fired to reach a preset impact kinetic energy. Among them, the experimental bullet launching device inside the incident rod 1 can be a bullet launching device commonly used in this experiment.

[0090] When conducting a Brazilian split experiment, the experimental steps are as follows:

[0091] Step S1, selecting a specimen; the specimen is a disc specimen with a diameter of 48 mm to 54 mm; the ratio of the specimen height to the diameter is 2.0 to 2.5;

[0092] Step S2, placing the specimen axially perpendicular to the ground; fixing the specimen in the guide rod 8; adjusting the position of the specimen so that the center line of the specimen is collinear with the axis of the incident rod 1 and the transmission rod 2;

[0093] Step S3, placing the cover body 20 in the confining pressure cylinder 17, and fixing the fixing plate 21 to the confining pressure cylinder 17 to form a closed space;

[0094] Step S4, indirectly applying confining pressure to the specimen through the confining pressure chamber 6; indirectly applying pore pressure to the specimen through the pore pressure chamber; moving the transmission rod 2 to apply axial pressure; applying impact air pressure through the incident rod 1 until cracks appear on the specimen; and recording the axial pressure P when cracks appear on the specimen;

[0095] Step S5, calculating the Brazilian splitting tensile strength of the specimen according to the formula σ=P / A; wherein σ is the Brazilian splitting tensile strength, P is the axial pressure when the crack is generated, and A is the maximum cross-sectional area of ​​the specimen, that is, the specimen diameter×the specimen height;

[0096] When conducting a compression test on a SHPB disc specimen, the experimental steps are as follows:

[0097] Step A, selecting a specimen; the specimen is a disc specimen with a diameter of 48 mm to 54 mm; the ratio of the specimen height to the diameter is 2.0 to 2.5;

[0098] Step B, placing the specimen axially parallel to the ground; fixing the specimen in the guide rod 8; adjusting the position of the specimen so that the axis of the specimen is collinear with the axis of the incident rod 1 and the axis of the transmission rod 2;

[0099] Step C, placing the cover body 20 in the confining pressure cylinder 17, and fixing the fixing plate 21 to the confining pressure cylinder 17 to form a closed space;

[0100] Step D, moving the transmission rod 2 to apply axial pressure until cracks appear on the specimen; recording the axial pressure p when obvious cracks appear;

[0101] Step E: Calculate the compressive strength of the specimen according to the formula p=P / a, where p is the compressive strength of the specimen, P is the axial pressure when obvious cracks are generated, and a is the cross-sectional area of ​​the specimen.

[0102] After the experiment, unload the axial pressure, confining pressure and hole pressure, take out the fixing bolts set in the first bolt hole and the second bolt hole, lift the handle 23 to slowly take out the fixing device, separate the rubber plate 26 from the rubber ring 15, and take out the test piece fixed by the positioner 22 along with the fixing device. After replacing the test piece, the next set of experiments can be carried out; if some fragments fall off the surface of the test piece, they can be sucked out with a vacuum cleaner; when oil leaks in the confining pressure chamber, it can return to the oil storage chamber 11 through the oil delivery hole 12 to realize the recycling of hydraulic oil.

[0103] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A strength test method based on SHPB disc specimen, characterized in that: The method uses a loading device of a SHPB disc specimen to perform a strength test; the loading device comprises: The confining pressure cylinder (17) comprises a hollow cylinder; the confining pressure cylinder (17) is placed parallel to the ground; a slot is provided at the center of the side wall of the confining pressure cylinder (17) as a placement hole; the placement hole is upward and parallel to the ground; A cover body (20) comprises an arc-shaped block matching the placement hole, and the cover body (20) is installed in the placement hole; the outer surface of the cover body (20) is integrated with the side wall surface of the confining pressure cylinder (17); A fixing plate (21) comprising a sheet-shaped object; the fixing plate (21) is fixedly arranged on the surface of the cover body (20); the cover body (20) is bolted to the confining pressure cylinder (17) via the fixing plate (21); A guide rod (8) comprises a rod-shaped object and is arranged perpendicular to the ground; four guide rods (8) fixedly connected to the cover body (20) are evenly arranged below the cover body (20); and a test piece is fixed between the guide rods (8) via a positioner (22); The incident rod (1) comprises a rod-shaped object; the diameter of the incident rod (1) matches the inner diameter of the confining pressure cylinder (17); the first end of the incident rod (1) is arranged inside the confining pressure cylinder (17) through the first end of the confining pressure cylinder (17); the first end of the incident rod (1) contacts the specimen; the second end of the incident rod (1) extends out of the first end of the confining pressure cylinder (17); The transmission rod (2) comprises a rod-shaped object; the diameter of the transmission rod (2) matches the inner diameter of the confining pressure cylinder (17); the first end of the transmission rod (2) is arranged inside the confining pressure cylinder (17) through the second end of the confining pressure cylinder (17); the first end of the transmission rod (2) contacts the specimen; the second end of the transmission rod (2) extends out of the second end of the confining pressure cylinder (17); The rubber ring (15) comprises a cylindrical annular ring; the rubber ring (15) is sleeved with the first end of the incident rod (1) and the first end of the transmission rod (2) at the same time; the space between the outside of the rubber ring (15) and the confining pressure cylinder (17) forms a confining pressure chamber (6); the space inside the rubber ring (15) forms a pore pressure chamber; The strength test includes a Brazilian splitting tensile strength test of a SHPB disc specimen and a compression test of a SHPB disc specimen; The Brazilian splitting test method includes the following steps: Step S1, selecting a specimen; the specimen is a disc specimen with a diameter of 48 mm to 54 mm; the ratio of the specimen height to the diameter is 2.0 to 2.5; Step S2, placing the specimen axially perpendicular to the ground; fixing the specimen in the guide rod (8); adjusting the position of the specimen so that the center line of the specimen is collinear with the axis of the incident rod (1) and the transmission rod (2); Step S3, placing the cover body (20) in the confining pressure cylinder (17), and fixing the fixing plate (21) to the confining pressure cylinder (17); Step S4, indirectly applying confining pressure to the specimen through the confining pressure chamber (6); indirectly applying pore pressure to the specimen through the pore pressure chamber; moving the transmission rod (2) to apply axial pressure; applying impact air pressure through the incident rod (1) until cracks are generated in the specimen; and recording the axial pressure P when cracks are generated in the specimen; Step S5, calculating the Brazilian splitting tensile strength of the specimen according to the formula σ=P / A; wherein σ is the Brazilian splitting tensile strength, P is the axial pressure when the specimen is cracked, and A is the maximum cross-sectional area of ​​the specimen; The compression test of SHPB disc specimens includes the following steps: Step A, selecting a specimen; the specimen is a disc specimen with a diameter of 48 mm to 54 mm; the ratio of the height to the diameter of the specimen is 2.0 to 2.5; Step B, placing the specimen axially parallel to the ground; fixing the specimen in the guide rod (8); adjusting the position of the specimen so that the axis of the specimen is collinear with the axes of the incident rod (1) and the transmission rod (2); Step C, placing the cover body (20) in the confining pressure cylinder (17), and fixing the fixing plate (21) to the confining pressure cylinder (17); Step D, indirectly applying confining pressure to the specimen through the confining pressure chamber (6); indirectly applying pore pressure to the specimen through the pore pressure chamber; moving the transmission rod (2) to apply axial pressure; applying impact air pressure through the incident rod (1) until cracks are generated in the specimen; and recording the axial pressure p when cracks are generated in the specimen; Step E, calculating the compressive strength of the specimen according to the formula p=P / a; wherein: p is the compressive strength of the specimen, P is the axial pressure when the specimen has obvious cracks, and a is the cross-sectional area of ​​the specimen.

2. The strength test method based on SHPB disc specimen according to claim 1, characterized in that: The loading device further comprises: a slide rail (19), wherein the guide rod (8) is connected to the cover body (20) via the slide rail (19); the slide rail (19) comprises a rod-shaped object provided with an axial notch; two slide rails (19) arranged parallel to the ground and parallel to each other are fixedly connected below the cover body (20); the shape of the notch matches the shape of the connecting end of the guide rod (8), and the guide rod (8) can move within the slide rail (19) via the notch.

3. The strength test method based on SHPB disc specimen according to claim 1, characterized in that: The positioner (22) comprises a positioning piece (22-1) and a positioning piece bolt (22-2); the positioning piece (22-1) comprises a sheet; the positioning piece is arranged perpendicularly to the axis of the guide rod (8) via a gasket (22-3) arranged in contact with the guide rod (8); two positioners (22) are arranged on each guide rod (8); the positioning piece (22-1) is respectively in contact with the upper bottom surface and the lower bottom surface of the specimen; An axial through groove matching the locator bolt (22-2) is provided on the guide rod (8); a bolt hole matching the locator bolt (22-2) is provided on the gasket (22-3); the locator bolt (22-2) can slide on the guide rod (8) along the through groove; the positioning plate (22-1) is fixedly connected to the gasket (22-3); the gasket (22-3) is fixed by the locator bolt (22-2), thereby fixing the positioning plate.

4. The strength test method based on SHPB disc specimen according to claim 1, characterized in that: The loading device further comprises: two sealing rings (5), comprising an annular rubber ring; the inner diameter of the sealing ring (5) matches the diameter of the incident rod (1) and the transmission rod (2); the sealing ring (5) is respectively arranged at the first end of the incident rod (1); and arranged at the first end of the transmission rod (2); The rubber ring (15) is simultaneously sleeved on the first end of the incident rod (1) and the first end of the transmission rod (2) through the sealing ring (5).

5. The strength test method based on SHPB disc specimen according to claim 1, characterized in that: The loading device also includes: The rubber plate (26) comprises: a square curved rubber plate; an opening having a size matching that of the placement hole is provided on the rubber ring (15); the rubber plate (26) is installed in the opening; the outer surface of the rubber plate (26) is integrated with the side wall surface of the rubber ring (15); The sealing plate (25) comprises: a square curved hard plate; the area of ​​the sealing plate (25) is larger than the area of ​​the rubber plate (26); the curvature of the curved surface of the sealing plate (25) matches the curvature of the curved surface of the rubber plate (26); the sealing plate (25) and the rubber plate (26) are arranged on the upper surface of the rubber plate (26) in contact with each other.

6. The strength test method based on SHPB disc specimen according to claim 5, characterized in that: Through holes are provided on both the rubber plate (26) and the sealing plate (25), and the guide rod (8) passes through both the sealing plate (25) and the rubber plate (26); The sealing ring (7) comprises a rubber annular ring, and two sealing rings (7) are arranged on each guide rod (8); the sealing rings (7) pass through the guide rod (8) and are respectively arranged on the lower surface of the rubber plate (26) and on the upper surface of the sealing plate (25).

7. The strength test method based on SHPB disc specimen according to claim 4, characterized in that: The loading device further comprises: two sealing heads (18); each of the sealing heads (18) comprises an annular rubber ring with a protrusion; the inner diameter of the sealing head (18) matches the diameter of the incident rod and the transmission rod; the outer diameter of the sealing head (18) matches the inner diameter of the confining pressure cylinder; the protruding inner diameter of the sealing head (18) extends axially from the inner diameter of the sealing head (18); the protruding outer diameter of the sealing head (18) matches the diameter of the sealing ring (5); the sealing heads (18) are respectively arranged at the first end of the incident rod (1) and at the first end of the transmission rod (2), and the protruding end faces of the two sealing heads (18) are arranged opposite to each other; the planar end face of the sealing head (18) is in contact with the inner wall end face of the confining pressure cylinder (17); The rubber ring (15) is clamped between the two sealing heads (18).

8. The strength test method based on SHPB disc specimen according to claim 1, characterized in that: The loading device further comprises an oil storage chamber (11) connected to the bottom of the confining pressure cylinder (17); an oil delivery hole (12) is provided below the confining pressure cylinder (17); the confining pressure chamber (6) is connected to the confining pressure cylinder (17) through the oil delivery hole (12); The oil pipeline (9) is connected to the oil storage chamber (11); and the oil pipeline valve (10) is arranged on the oil pipeline (9).

9. The strength test method based on SHPB disc specimen according to claim 1, characterized in that: The loading device further comprises a water pipe (14), a first end of the water pipe (14) being connected to the bottom of the confining pressure chamber (6), and a second end of the water pipe (14) being connected to a water injection device; a water pipe valve (13) is arranged on the water pipe (14).

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