Large-size fully-graded concrete axial tension test piece, manufacturing mold, testing device and testing method

Abstract

The invention discloses a large-size fully-graded concrete axial tension test piece, a manufacturing mold, a testing device and a testing method, and belongs to the technical field of mechanical properties of dam concrete.The test piece comprises a test piece body formed by pouring fully-graded concrete; the two pre-embedded steel plates are pre-embedded in the test piece body, and the two pre-embedded steel plates are arranged in parallel and oppositely; the two pre-embedded threaded rods and the two pre-embedded steel plates are arranged in a one-to-one correspondence mode, one end of each pre-embedded threaded rod is fixedly connected with the corresponding pre-embedded steel plate, and the other end of each pre-embedded threaded rod extends to the outer side of the test piece body. Through collaborative optimization of the mold, the test piece, the device and the method, the technical problem of axial tension test of the large-size fully-graded concrete is solved, high-precision and high-safety axial tension performance evaluation is realized, a scientific basis is provided for concrete service life prediction of water conservancy projects such as dams, and the method has remarkable engineering practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical properties of dam concrete, and in particular relates to a large-size fully-graded concrete axial tension test piece, a manufacturing mold, a testing device and a testing method. Background Art

[0002] In the field of water conservancy engineering, the concrete material for pouring dams is mostly fully graded concrete with a maximum aggregate size of 150mm. According to the concrete test principle, the minimum boundary size of the specimen is not less than 3 times the maximum aggregate size, that is, 450mm. Therefore, the specimen size of the mechanical property test of fully graded concrete is huge, and there are technical difficulties in many aspects, such as test difficulties and inconsistent test methods.

[0003] For dam concrete, it is usually subjected to high tensile stress during its long-term service. The experimental technology of axial tension performance testing of fully-graded concrete has become an important problem for evaluating and predicting the service form and life of dam concrete. Therefore, there is an urgent need for a test device and method that can accurately test the axial tension constitutive relationship of fully-graded concrete. Summary of the invention

[0004] In order to provide a test device and method capable of accurately testing the axial tension constitutive relationship of fully graded concrete, the present invention adopts the following technical scheme:

[0005] A large-size fully graded concrete axial tension specimen, comprising:

[0006] The specimen body is formed by pouring full-graded concrete;

[0007] 2 embedded steel plates, the two embedded steel plates are embedded in the specimen body, and the two embedded steel plates are arranged parallel and opposite to each other;

[0008] Two embedded threaded rods are arranged in one-to-one correspondence with the two embedded steel plates, wherein one end of the embedded threaded rod is fixedly connected to the corresponding embedded steel plate, and the other end extends to the outside of the specimen body.

[0009] Furthermore, the size of the specimen body is 450 mm×450 mm×900 mm.

[0010] Furthermore, the center line of the specimen body in the length direction, the normal center line of the embedded steel plate and the center axis of the embedded threaded rod are collinear.

[0011] A large-sized fully-graded concrete axial tensile test piece manufacturing mold, used for manufacturing any of the large-sized fully-graded concrete axial tensile test pieces described above, the manufacturing mold comprising:

[0012] Base plate;

[0013] Two edge side panels are arranged opposite to each other, the two edge side panels are respectively arranged at the edges of the bottom plate in the width direction, and one end of the edge side panel close to the bottom plate is fixedly connected to the bottom plate through a bottom plate fixing bolt;

[0014] Two bottom side panels are arranged opposite to each other, the two bottom side panels are respectively fixedly mounted on the edges of the bottom plate in the length direction, and together with the bottom plate and the two edge side panels, form a casting space with one end open;

[0015] Among them, the two bottom side panels are fixedly connected to the bottom plate by bottom plate fixing bolts, and the two ends of the bottom side panels are fixedly connected to the two edge side panels by side plate fixing screws and nuts; the bottom side panels are provided with reserved holes adapted to the embedded threaded rods.

[0016] Furthermore, the bottom side panel is fixedly connected to the two edge side panels by two side panel fixing screws, wherein the two side panel fixing screws are arranged in parallel, and both ends of the side panel fixing screws pass through the connecting flange of the bottom side panel, the corresponding edge side panel and the nut in sequence; the through hole on the bottom side panel adapted to the embedded threaded rod is arranged between the two side panel fixing screws.

[0017] A large-size fully-graded concrete axial tension performance testing device is used for the axial tension performance testing of the large-size fully-graded concrete axial tension test piece described in any one of the above items, and the performance testing device comprises:

[0018] A loading base, wherein the loading base is fixed on a rigid base by base fixing bolts; a base ball joint is embedded in the center of the loading base, and a connecting rod of the base ball joint extends to the outside of the loading base and is threadedly connected to a pre-embedded threaded rod of the large-size fully graded concrete axial tension test piece;

[0019] A combined sleeve, a first end of which is threadedly connected to another pre-embedded threaded rod of the large-size fully-graded concrete axial tension test piece;

[0020] A load sensor connected to the second end of the combined sleeve;

[0021] A tensile ball joint, wherein the ball seat of the tensile ball joint is connected to the load sensor, and the connecting rod of the tensile ball joint is connected to the tensile testing machine;

[0022] A displacement meter mounting frame, which is sleeved on the outside of the specimen body and is clamped and fixed on the specimen body by tightening bolts of the displacement meter mounting frame;

[0023] A displacement meter is installed on the displacement meter mounting frame.

[0024] Furthermore, it also includes a protective bracket, which is sleeved on the outside of the connecting rod of the base ball joint and fixedly connected to the loading base.

[0025] A method for testing the axial tension performance of large-size fully graded concrete, the testing method comprising the following steps:

[0026] S10, assembling the above-mentioned large-size fully-graded concrete axial tension test piece production mold, and placing it in the casting and molding area of ​​the large-size fully-graded concrete axial tension test piece;

[0027] S20, welding the embedded steel plate and the embedded threaded rod to form an embedded part, and placing it in the manufacturing mold of the large-size fully-graded concrete axial tensile test piece, wherein the embedded threaded rod passes through the reserved hole on the bottom side plate;

[0028] S30, pouring fully graded concrete into the mold for making the large-sized fully graded concrete axial tension test piece, removing the mold for making the large-sized fully graded concrete axial tension test piece after curing for 3 days, and then curing to the test age to form the large-sized fully graded concrete axial tension test piece according to claims 1 to 3;

[0029] S40, fix the loading base in the above-mentioned large-size fully-graded concrete axial tension performance test device on a rigid base through base fixing bolts; install the protective bracket on the loading base, install the combined sleeve on the end of the pre-embedded threaded rod on one side of the large-size fully-graded concrete axial tension test piece; hoist the large-size fully-graded concrete axial tension test piece through the combined sleeve, and install the pre-embedded threaded steel rod on the other end of the large-size fully-graded concrete axial tension test piece into the central threaded hole of the base ball joint; the upper part of the combined sleeve is connected to the load sensor, and the upper part of the load sensor is connected to the tensile ball joint; the upper part of the tensile ball joint is connected to the tensile testing machine;

[0030] S50, start the tensile testing machine to start the full-graded concrete axial tensile performance test, obtain the load-displacement curve during the test through the load sensor and the displacement meter, and further obtain the stress-strain relationship curve of the full-graded concrete axial tensile performance test.

[0031] Further, in step S10, assembling the mold for making the large-size fully-graded concrete axial tension test piece includes the following steps:

[0032] S11, placing the base plate in the casting and forming area of ​​the large-sized fully graded concrete axial tension test piece;

[0033] S12, fixing the bottom side plate and the edge side plate on the bottom plate by bolts; fixing the two edge side plates by using side fixing bolts, and tightening the bolts to press and fix the bottom side plate between the two edge side plates;

[0034] In step S20, the distance between the embedded steel plate and the bottom side plate on the corresponding side is 150 mm.

[0035] Beneficial effects:

[0036] The present invention solves the technical difficulties in axial tension testing of large-scale fully-graded concrete through the coordinated optimization of molds, test pieces, devices and methods, realizes high-precision and high-safety axial tension performance evaluation, provides a scientific basis for predicting the service life of concrete in water conservancy projects such as dams, and has significant engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the structure of a large-sized fully graded concrete axial tension test piece provided by the present invention;

[0038] Figure 2 A schematic diagram of the structure of a large-sized fully graded concrete axial tensile test piece mold provided by the present invention;

[0039] Figure 3 A schematic diagram of the structure of a large-scale fully graded concrete axial tension performance testing device provided by the present invention;

[0040] Among them: 1. Bottom side panel; 2. Embedded steel plate; 3. Embedded threaded rod; 4. Edge side panel; 5. Side panel fixing screw; 6. Bottom plate fixing bolt; 7. Bottom plate; 8. Tensile ball joint; 9. Load sensor; 10. Combination sleeve; 11. Displacement meter; 12. Specimen body; 13. Displacement meter mounting bracket; 14. Protective bracket; 15. Base ball joint; 16. Loading base; 17. Base fixing bolt. DETAILED DESCRIPTION

[0041] Example 1

[0042] refer to Figure 1 , a large-size fully graded concrete axial tension specimen, including:

[0043] The specimen body is formed by pouring full-graded concrete;

[0044] Two embedded steel plates 2, the two embedded steel plates 2 are embedded in the specimen body 12, and the two embedded steel plates 2 are arranged parallel and opposite to each other;

[0045] Two embedded threaded rods 3 are arranged in one-to-one correspondence with the two embedded steel plates 2 , wherein one end of the embedded threaded rod 3 is fixedly connected to the corresponding embedded steel plate 2 , and the other end extends to the outside of the specimen body 12 .

[0046] In this embodiment, the size of the specimen body 12 is preferably 450 mm×450 mm×900 mm.

[0047] In this embodiment, the center line of the specimen body 12 in the length direction, the normal center line of the embedded steel plate 2 and the center axis of the embedded threaded rod 3 are collinear.

[0048] In this embodiment, the embedded threaded rod 3 is preferably a threaded steel rod, and the specification of the threaded steel rod is an M33 embedded threaded steel rod.

[0049] Specifically, embedded steel plates 2 are symmetrically embedded inside the two ends of the specimen body 12, the embedded steel plates 2 are welded to the embedded threaded rods 3 as a whole, and the embedded threaded rods 3 extend out of the specimen body 12, that is, the two embedded threaded rods 3 are symmetrically arranged at the two ends of the specimen body 12 for axial tensile loading.

[0050] The large-sized fully graded concrete axial tension test specimen provided in this embodiment has the following technical effects:

[0051] (1) The specimen size of 450 mm × 450 mm × 900 mm is designed to meet the three-fold size requirement of the maximum aggregate particle size of 150 mm. The test results can reflect the performance of the actual fully graded concrete.

[0052] (2) The pre-embedded threaded steel rod is welded to the steel plate as a whole and extends out of the specimen, which can simplify the installation process and improve the stability of the loading connection, avoiding stress concentration or data distortion caused by the pre-embedded offset of traditional specimens.

[0053] Example 2

[0054] refer to Figure 2 A large-sized fully graded concrete axial tensile test piece manufacturing mold is used to manufacture the large-sized fully graded concrete axial tensile test piece provided in Example 1. The manufacturing mold includes:

[0055] Bottom plate 7;

[0056] Two edge side panels 4 are arranged opposite to each other, and the two edge side panels 4 are respectively arranged at the edges of the bottom plate 7 in the width direction, and one end of the edge side panel 4 close to the bottom plate 7 is fixedly connected to the bottom plate 7 by a bottom plate fixing bolt 6;

[0057] Two bottom side panels 1 are arranged opposite to each other, and the two bottom side panels 1 are respectively fixedly installed at the edges of the bottom plate 7 in the length direction, and together with the bottom plate 7 and the two edge side panels 4, form a casting space with one end open;

[0058] Among them, the two bottom side panels 1 are fixedly connected to the bottom plate 7 through the bottom plate fixing bolts 6, and the two ends of the bottom side panels 1 are fixedly connected to the two edge side panels 4 through the side panel fixing screws 5 and nuts; the bottom side panels 1 are provided with reserved holes adapted to the embedded threaded rods 3.

[0059] Specifically, the bottom plate fixing bolts 6 are M16 high-strength bolts.

[0060] In this embodiment, the bottom side panel 1 is fixedly connected to the two edge side panels 4 by two side panel fixing screws 5, wherein the two side panel fixing screws 5 are arranged in parallel, and the two ends of the side panel fixing screws 5 pass through the connecting flange of the bottom side panel, the corresponding edge side panel 4 and the nut in sequence; the through hole on the bottom side panel 1 that is adapted to the embedded threaded rod 3 is arranged between the two side panel fixing screws 5.

[0061] Specifically, the side plate fixing screw is an M16 high-strength screw used in conjunction with an M16 nut.

[0062] In this embodiment, the distance between the embedded steel plate 2 and the corresponding bottom side plate 1 is 150 mm.

[0063] The mold for making large-sized fully-graded concrete axial tension test pieces provided in this embodiment adopts a modular design, which is easy to disassemble and reuse, while reducing mold loss.

[0064] Example 3

[0065] refer to Figure 3 A large-size fully-graded concrete axial tensile performance testing device is used for the axial tensile performance testing of the large-size fully-graded concrete axial tensile specimen provided in Example 1. The performance testing device comprises:

[0066] A loading base 16 is fixed on the rigid base by base fixing bolts 17; a base ball joint 15 is embedded in the center of the loading base 16, and a connecting rod of the base ball joint 15 extends to the outside of the loading base and is threadedly connected to a pre-embedded threaded rod 3 of a large-size fully graded concrete axial tension test piece;

[0067] A combined sleeve 10, a first end of which is threadedly connected to another pre-embedded threaded rod 3 of a large-size fully-graded concrete axial tension test piece;

[0068] A load sensor 9 connected to the second end of the combined sleeve 10;

[0069] A tensile ball joint 8, a ball seat of the tensile ball joint 8 is connected to a load sensor 9, and a connecting rod of the tensile ball joint 8 is connected to a tensile testing machine;

[0070] The displacement meter mounting frame 13 is sleeved on the outside of the specimen body 12 and is clamped and fixed on the specimen body 12 by tightening bolts of the displacement meter mounting frame 13;

[0071] The displacement meter 11 is mounted on a displacement meter mounting frame 13 .

[0072] In this embodiment, the base fixing bolts 17 are preferably M18 high-strength bolts.

[0073] In this embodiment, the upper part of the loading base 16 is a cylindrical steel barrel with a diameter of 300 mm, and a base ball joint 15 is embedded in the center. The center of the base ball joint 15 is a threaded hole with a specification of M33.

[0074] The present embodiment provides a large-scale fully-graded concrete axial tension performance testing device, which also includes a protective bracket 14 . The protective bracket 14 is sleeved on the outside of the connecting rod of the base ball joint 15 and is fixedly connected to the loading base 16 .

[0075] Specifically, the protective bracket 14 is fixedly connected to the loading base 16 through a plurality of M10 threaded steel rods. This embodiment provides a large-sized fully-graded concrete axial tension performance test device, wherein a ball joint is configured at the connection of a large-sized fully-graded concrete axial tension specimen to achieve centrally symmetrical tensile loading, and a load sensor and a displacement meter are configured to collect stress-strain curves in the fully-graded concrete axial tension test.

[0076] The large-scale fully graded concrete axial tension performance testing device provided in this embodiment has the following technical effects:

[0077] (1) Tensile ball joints and base ball joints are configured at both ends to eliminate the influence of eccentric loading, ensure the uniformity of axial stretching, and avoid test errors caused by uneven stress distribution.

[0078] (2) Integrate load sensors and displacement meters to monitor load-displacement changes in real time and directly generate stress-strain curves, providing reliable data for evaluating the axial-tension constitutive relationship of concrete.

[0079] (3) The protective bracket design effectively prevents accidental breakage of the specimen or damage to the equipment, ensuring the safety of the test process.

[0080] Example 4

[0081] A method for testing the axial tension performance of large-size fully graded concrete, the testing method comprising the following steps:

[0082] S10, assembling the mold for making the large-sized fully-graded concrete axial tensile test piece provided in Example 2, and placing it in the casting and molding area of ​​the large-sized fully-graded concrete axial tensile test piece;

[0083] Specifically, assembling a large-size fully graded concrete axial tensile test piece manufacturing mold comprises the following steps:

[0084] S11, placing the base plate in the casting and forming area of ​​the large-sized fully graded concrete axial tension test piece;

[0085] S12, fixing the bottom side plate and the edge side plate on the bottom plate by means of the first base fixing bolts; fixing the two edge side plates by means of the side fixing bolts, and tightening the bolts to press and fix the bottom side plate between the two edge side plates;

[0086] S20, welding the embedded steel plate and the embedded threaded rod to form an embedded part, and placing it in a mold for making a large-size fully graded concrete axial tension test piece, and the embedded threaded rod passes through the reserved hole on the bottom side plate;

[0087] Among them, the distance between the embedded steel plate and the bottom side plate on the corresponding side is 150mm.

[0088] S30, pouring fully graded concrete into a mold for making a large-sized fully graded concrete axial tension test piece, removing the mold for making the large-sized fully graded concrete axial tension test piece after curing for 3 days, and then curing to a test age to form a large-sized fully graded concrete axial tension test piece provided in Example 1;

[0089] S40, fix the loading base in the large-size fully-graded concrete axial tension performance test device provided in Example 3 on the rigid base through the base fixing bolts; install the protective bracket on the loading base, install the combined sleeve on the end of the pre-embedded threaded rod on one side of the large-size fully-graded concrete axial tension test piece; hoist the large-size fully-graded concrete axial tension test piece through the combined sleeve, and install the pre-embedded threaded steel rod on the other end of the large-size fully-graded concrete axial tension test piece into the central threaded hole of the base ball joint; connect the upper part of the combined sleeve to the load sensor, and the upper part of the load sensor is connected to the tensile ball joint; the upper part of the tensile ball joint is connected to the tensile testing machine;

[0090] S50, start the tensile testing machine to start the full-graded concrete axial tensile performance test, obtain the load-displacement curve during the test through the load sensor and the displacement meter, and further obtain the stress-strain relationship curve of the full-graded concrete axial tensile performance test.

[0091] The large-scale fully graded concrete axial tensile performance testing method provided in this embodiment has the following technical effects:

[0092] (1) From mold assembly, specimen casting, maintenance to test device installation, the steps are clear and systematic, which reduces human operation errors and improves the repeatability of test results.

[0093] (2) It is stipulated that the side panels shall be removed after 3 days of initial curing and curing shall be continued until the test age, which complies with the law of concrete strength development and ensures the stability of specimen performance.

[0094] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A large-size fully graded concrete axial tension specimen, characterized in that: include: The specimen body is formed by pouring full-graded concrete; 2 embedded steel plates, the two embedded steel plates are embedded in the specimen body, and the two embedded steel plates are arranged parallel and opposite to each other; Two embedded threaded rods are arranged in one-to-one correspondence with the two embedded steel plates, wherein one end of the embedded threaded rod is fixedly connected to the corresponding embedded steel plate, and the other end extends to the outside of the specimen body.

2. The large-size fully graded concrete axial tension test piece according to claim 1 is characterized in that: The dimensions of the specimen body are 450 mm×450 mm×900 mm.

3. The large-size fully graded concrete axial tension test piece according to claim 2 is characterized in that: The center line of the specimen body in the length direction, the normal center line of the embedded steel plate and the center axis of the embedded threaded rod are collinear.

4. A mold for making a large-size fully graded concrete axial tensile test piece, characterized in that: Used to make the large-sized fully graded concrete axial tension test piece according to any one of claims 1 to 3, the making mold comprises: Base plate; Two edge side panels are arranged opposite to each other, the two edge side panels are respectively arranged at the edges of the bottom plate in the width direction, and one end of the edge side panel close to the bottom plate is fixedly connected to the bottom plate through a bottom plate fixing bolt; Two bottom side panels are arranged opposite to each other, the two bottom side panels are respectively fixedly mounted on the edges of the bottom plate in the length direction, and together with the bottom plate and the two edge side panels, form a casting space with one end open; Among them, the two bottom side panels are fixedly connected to the bottom plate by bottom plate fixing bolts, and the two ends of the bottom side panels are fixedly connected to the two edge side panels by side plate fixing screws and nuts; the bottom side panels are provided with reserved holes adapted to the embedded threaded rods.

5. The mold for making a large-size fully graded concrete axial tensile test piece according to claim 4 is characterized in that: The bottom side panel is fixedly connected to the two edge side panels by two side panel fixing screws, wherein the two side panel fixing screws are arranged in parallel, and both ends of the side panel fixing screws pass through the connecting flange of the bottom side panel, the corresponding edge side panel and the nut in sequence; the through hole on the bottom side panel adapted to the embedded threaded rod is arranged between the two side panel fixing screws.

6. A large-scale fully graded concrete axial tension performance testing device, characterized in that: Used for the axial tension performance test of the large-sized fully graded concrete axial tension specimen according to any one of claims 1 to 3, the performance testing device comprises: A loading base, wherein the loading base is fixed on a rigid base by base fixing bolts; a base ball joint is embedded in the center of the loading base, and a connecting rod of the base ball joint extends to the outside of the loading base and is threadedly connected to a pre-embedded threaded rod of the large-size fully graded concrete axial tension test piece; A combined sleeve, a first end of which is threadedly connected to another pre-embedded threaded rod of the large-size fully-graded concrete axial tension test piece; A load sensor connected to the second end of the combined sleeve; A tensile ball joint, wherein the ball seat of the tensile ball joint is connected to the load sensor, and the connecting rod of the tensile ball joint is connected to the tensile testing machine; A displacement meter mounting frame, which is sleeved on the outside of the specimen body and is clamped and fixed on the specimen body by tightening bolts of the displacement meter mounting frame; A displacement meter is installed on the displacement meter mounting frame.

7. The large-scale fully graded concrete axial tension performance testing device according to claim 6 is characterized in that: It also includes a protective bracket, which is sleeved on the outside of the connecting rod of the base ball joint and fixedly connected to the loading base.

8. A method for testing the axial tensile properties of large-scale fully graded concrete, characterized in that: The test method comprises the following steps: S10, assembling the mold for making the large-sized fully-graded concrete axial tensile test piece according to any one of claims 4 to 5, and placing it in the casting and molding area of ​​the large-sized fully-graded concrete axial tensile test piece; S20, welding the embedded steel plate and the embedded threaded rod to form an embedded part, and placing it in the manufacturing mold of the large-size fully-graded concrete axial tensile test piece, wherein the embedded threaded rod passes through the reserved hole on the bottom side plate; S30, pouring fully graded concrete into the mold for making the large-sized fully graded concrete axial tension test piece, removing the mold for making the large-sized fully graded concrete axial tension test piece after curing for 3 days, and then curing to the test age to form the large-sized fully graded concrete axial tension test piece according to claims 1 to 3; S40. Fix the loading base in the large-size fully-graded concrete axial tension performance test device described in any one of claims 6 to 7 on a rigid base through base fixing bolts; install a protective bracket on the loading base, and install a combined sleeve on the end of the pre-embedded threaded rod on one side of the large-size fully-graded concrete axial tension test piece; hoist the large-size fully-graded concrete axial tension test piece through the combined sleeve, and install the pre-embedded threaded steel rod at the other end of the large-size fully-graded concrete axial tension test piece into the central threaded hole of the base ball joint; connect the upper part of the combined sleeve to the load sensor, and the upper part of the load sensor is connected to the tensile ball joint; the upper part of the tensile ball joint is connected to the tensile testing machine; S50, start the tensile testing machine to start the full-graded concrete axial tensile performance test, obtain the load-displacement curve during the test through the load sensor and the displacement meter, and further obtain the stress-strain relationship curve of the full-graded concrete axial tensile performance test.

9. The method for testing the axial tension performance of large-scale fully graded concrete according to claim 8, characterized in that: In step S10, assembling the mold for making the large-size fully-graded concrete axial tension test piece includes the following steps: S11, placing the base plate in the casting and forming area of ​​the large-sized fully graded concrete axial tension test piece; S12, fixing the bottom side plate and the edge side plate on the bottom plate by bolts; fixing the two edge side plates by using side fixing bolts, and tightening the bolts to press and fix the bottom side plate between the two edge side plates; In step S20, the distance between the embedded steel plate and the bottom side plate on the corresponding side is 150 mm.

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