CN217931198U - Device for testing impact shear resistance of concrete-rock interface for Hopkinson pressure bar - Google Patents
Device for testing impact shear resistance of concrete-rock interface for Hopkinson pressure bar Download PDFInfo
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- CN217931198U CN217931198U CN202221517256.6U CN202221517256U CN217931198U CN 217931198 U CN217931198 U CN 217931198U CN 202221517256 U CN202221517256 U CN 202221517256U CN 217931198 U CN217931198 U CN 217931198U
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Abstract
The utility model discloses a device and a method for testing the impact shear resistance of a concrete-rock interface of a Hopkinson pressure bar, wherein the device comprises a lower shearing box fixed on an equipment support through a fixing device, the lower shearing box comprises two symmetrically arranged steel plates, one of the two steel plates is a slidable steel plate of the lower shearing box, and the other steel plate is integrally arranged with the fixing device; an upper shearing box is arranged above the lower shearing box and comprises two steel plates which are symmetrically arranged, an incident rod is arranged on the outer side of one steel plate, and a transmission rod is arranged on the outer side of the other steel plate. Compared with the prior art, the utility model has the advantages of it is following: the device optimizes the overall structure, mostly adopts a detachable installation mode, and integrally arranges the incident rod and the upper shearing box to ensure that the incident rod and the upper shearing box move together when a load is applied; the device and the method can directly measure the shear load under different impact rates; and the device is suitable for test pieces with multiple sizes, and realizes the pressure reduction damage under complex stress.
Description
Technical Field
The utility model belongs to concrete material test field relates to a concrete-rock interface shear test device, specifically is a device that is used for the test concrete-rock interface impact shear behavior of hopkinson depression bar.
Background
The interface performance of the dam heel of the dam is influenced by the combined action of the rock and the concrete, and the research on the bonding performance of the two materials, namely the concrete and the rock, is very important for evaluating and mastering the reinforcement and anti-seismic performance of the dam heel of the dam in hydraulic engineering.
At present, static loading is mostly carried out in the interface shear test. In practical situations, the structure can bear earthquake load and impact load, such as impact of river water; at present, the research on the shearing performance of a concrete-rock interface under dynamic loading, particularly impact load, is very little. One reason is that the interface shear test under impact has higher requirements on equipment and data acquisition is more difficult. How to use the existing test device to carry out impact loading of an interface shear test becomes a difficult point.
At present, a plurality of methods for testing the bonding performance of concrete and rock are available, such as a closed box type direct shear box and a cube oblique shear, but the two methods are not applied to an interface shear test of a two-phase material on a Hopkinson pressure bar. From the application difficulty point of view: on one hand, the fitting degree between the closed box type direct shear box and the test piece influences the test result, and on the other hand, the shearing and compression loads of the oblique shear test are controlled by the interface angle, so that the change range is limited. Therefore, both of these methods have certain disadvantages in testing impact shear resistance.
SUMMERY OF THE UTILITY MODEL
The technical problem to be solved is as follows: in order to overcome the not enough of prior art, solve the problem of loading rate restriction and data acquisition difficulty that concrete-rock interface shear behavior test exists, realize testing different impact rate and the interface shear failure under the different compressive stress, the utility model provides a test concrete-rock interface impact shear performance's device for hopkinson depression bar.
The technical scheme is as follows: the device for testing the impact shear resistance of the concrete-rock interface of the Hopkinson pressure bar comprises a lower shear box fixed on an equipment support through a fixing device, wherein the lower shear box comprises two symmetrically arranged steel plates, one of the steel plates is a lower shear box slidable steel plate, and the other steel plate is integrally arranged with the fixing device; an upper shearing box is arranged above the lower shearing box and comprises two steel plates which are symmetrically arranged, wherein an incident rod is arranged on the outer side of one steel plate, a transmission rod is arranged on the outer side of the other steel plate, a PVDT dynamic pressure sensor is arranged between the incident rod and the steel plates, and a strain gauge is arranged on the incident rod; and a bearing plate is arranged in the upper shearing box, a tension and compression sensor is arranged above the bearing plate, and the sensor is connected with a digital display instrument.
Preferably, all be equipped with the shearing box screw rod on last shearing box and the lower shearing box, on four angles of steel sheet were located to the shearing box screw rod, and run through two steel sheets.
Preferably, a connecting piece is arranged between the upper shearing box and the incident rod, and the incident rod and the connecting piece are fixedly connected through a glue layer.
Preferably, the attachment is secured to the steel plate by a shear box screw.
Preferably, a screw hole position corresponding to the lower shearing box and the fixing device is formed between the lower shearing box and the fixing device and is fixedly connected with the lower shearing box through a bolt.
Preferably, a concrete-rock test piece is arranged in the lower shear box, and the interface of the concrete-rock test piece is higher than the interface of the steel plate of the lower shear box.
Preferably, the bearing plate is arranged on the concrete-rock test piece, and the interface of the concrete-rock test piece is lower than the interface of the upper shear box steel plate; and the interface of the concrete-rock test piece is positioned on the horizontal middle line of the lower shear box steel plate interface and the upper shear box steel plate interface.
The method for testing the impact shear performance of the concrete-rock interface for the Hopkinson pressure bar as described in any one of the above, comprising the steps of:
s1, pretreating a bonding surface of a rock test piece, putting the rock test piece into a prepared test mold, pouring concrete, and curing to the age to be detected to obtain a concrete-rock test piece;
s2, calibrating the PVDT dynamic pressure sensor, regarding the sensor as a common compression-resistant cylindrical test piece, pasting the test piece between an incident rod and a transmission rod, impacting by utilizing Hopkinson pressure bar equipment, and obtaining stress at different impact speeds by adjusting bullet speeds to finish calibration of the sensor;
s3, adhering a PVDT dynamic pressure sensor on a steel plate on one side of the upper shearing box, fixing a connecting piece on the incident rod by adopting a glue layer, aligning threaded holes on the connecting piece and the steel plate of the upper shearing box, penetrating through a screw rod of the shearing box, and fixing the incident rod and the connecting piece on the steel plate of the upper shearing box through bolts;
s4, fixing the lower shearing box on the equipment support through a fixing device, placing a concrete-rock test piece, adjusting a screw rod of the shearing box, moving a slidable steel plate of the lower shearing box to clamp the test piece, and ensuring that the test piece and the lower shearing box cannot slide relatively;
s5, adjusting the height of the incident rod to enable the distance between the upper shearing box and the interface of the concrete-rock test piece to be equal to the distance between the lower shearing box and the interface of the concrete-rock test piece;
s6, adjusting a shearing box screw on the upper shearing box to enable a steel plate on the upper shearing box to clamp the concrete-rock test piece;
s7, connecting the tension-compression sensor and the bearing plate, placing the connected tension-compression sensor and the bearing plate on the upper surface of the test piece in the S6, and applying pressure stress through a separated hydraulic jack;
and S8, carrying out impact loading by adopting a Hopkinson pressure bar, and adjusting the bullet speed to obtain a shear stress-displacement curve of the concrete-rock test piece interface under different impact speeds and compressive stresses.
When the device and the method are used for testing the impact shear resistance of the concrete-rock interface, impact load is transmitted to the upper shear box through the incident rod, and the incident rod and the upper shear box move together when the load is applied; the load is transferred to the concrete by the upper shear box while the rock below the concrete-rock interface is restrained from displacement by the lower shear box fixed to the equipment support, so that the interface between the concrete and the rock is in shear stress. The pressure stress is transmitted to the concrete-rock test piece by the jack through the bearing plate. The lower shear box is fixed on the equipment support through a fixing device, and the movement of the concrete-rock test piece in the loading direction is restrained together, so that the interface is subjected to shear failure under the impact load. The shear displacement is obtained by measuring a strain gauge, and the calculation formula is as follows:
wherein, c 0 The propagation speed of the wave in the rod is 5060-5100m/s, epsilon i For incident strain,. Epsilon r Is the reflection strain; the impact load F is measured by a PVDT dynamic pressure sensor, and a schematic diagram of the measurement of the PVDT dynamic pressure sensor is shown in FIG. 1; the normal load P is measured by a tension-compression sensor and is read by an external digital display instrument. The finally obtained shear stress-displacement curve of the concrete-rock test piece interface is shown in fig. 2, wherein the shear strength is obtained by dividing the impact load F by the bonding area As of the PVDT dynamic pressure sensor and the steel plate, and the compressive stress is obtained by dividing the normal load P by the loading area A on the bearing plate.
Has the advantages that: (1) The device of the utility model optimizes the whole structure, mostly adopts a detachable installation mode, and integrally sets the incident rod and the upper shearing box, thereby ensuring that the incident rod and the upper shearing box move together when applying load, and further being capable of calculating shearing displacement through incident pulse and reflected pulse; (2) The device and the method can be suitable for testing the impact shear resistance of the concrete-rock interface by the Hopkinson pressure bar, and directly measuring the shear load at different impact rates; and the device is suitable for test pieces with multiple sizes, and realizes the pressure reduction damage under complex stress.
Drawings
FIG. 1 is a PVDT voltage acquisition circuit diagram;
FIG. 2 is a shear stress-shear displacement graph of a concrete-rock specimen interface;
fig. 3 is a schematic three-dimensional structure of the device of the present invention;
fig. 4 is a schematic two-dimensional structure diagram of the device of the present invention, wherein (a) is a top view and (b) is a front view;
FIG. 5 is a two-dimensional view of the connection between the upper shear box and the entrance bar, wherein (a) is a top view and (b) is a front view;
FIG. 6 is a two-dimensional view of the attachment between the lower shear box and the equipment support, wherein (a) is a top view and (b) is a left side view;
wherein, 1, the connecting piece; 2, a glue layer; 3, mounting a cutting box; 4, shearing a box screw; 5, a bearing plate; 6, pulling and pressing the sensor; 7, an incident rod; 8, a strain gauge; 9, a transmission rod; 10, PVDT dynamic pressure sensors; 11, a lower shear box slidable steel plate; 12, a lower cutting box; 13, a fixing device; 14, a concrete-rock test piece interface, 15, an equipment support, 16, a digital display instrument, 17, and a screw hole position corresponding to the lower shear box and the fixing device.
Detailed Description
The following examples further illustrate the invention but are not to be construed as limiting the invention. Modifications and substitutions to methods, steps or conditions of the present invention may be made without departing from the spirit and substance of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.
Example 1
As shown in fig. 3 to 6, the apparatus for testing the impact shear resistance of a concrete-rock interface for a hopkinson pressure bar comprises a lower shear box 12 fixed on an equipment support 15 by a fixing device 13, wherein the lower shear box 12 comprises two symmetrically arranged steel plates, one of which is a lower shear box slidable steel plate 11, and the other of which is integrally arranged with the fixing device 13; an upper shearing box 3 is arranged above the lower shearing box 12, the upper shearing box 3 comprises two steel plates which are symmetrically arranged, an incident rod 7 is arranged on the outer side of one steel plate, a transmission rod 9 is arranged on the outer side of the other steel plate, a PVDT dynamic pressure sensor 10 is arranged between the incident rod 7 and the steel plates, and a strain gauge 8 is arranged on the incident rod 7; a bearing plate 5 is arranged in the upper shearing box 3, a tension and compression sensor 6 is arranged above the bearing plate 5, and the sensor is connected with a digital display instrument 16.
All be equipped with shearing box screw rod 4 on going up shearing box 3 and the lower shearing box 12, shearing box screw rod 4 is located on four angles of steel sheet, and runs through two steel sheets.
Be equipped with connecting piece 1 between last shear box 3 and the incident pole 7, incident pole 7 and connecting piece 1 pass through glue layer 2 fixed connection.
The connecting piece 1 is fixed on a steel plate through a shearing box screw rod 4.
And a screw hole position 17 corresponding to the lower shearing box and the fixing device is arranged between the lower shearing box 12 and the fixing device 13 and is fixedly connected with the lower shearing box through a bolt.
The lower shear box 12 is internally provided with a concrete-rock test piece, and the interface 14 of the concrete-rock test piece is higher than the interface of a steel plate of the lower shear box 12.
The bearing plate 5 is arranged on the concrete-rock test piece, and the interface 14 of the concrete-rock test piece is lower than the interface of the steel plate of the upper shear box 3; and the interface 14 of the concrete-rock test piece is located on the horizontal midline of the steel plate interface of the lower shear box 12 and the steel plate interface of the upper shear box 3.
The method for testing the impact shear performance of the concrete-rock interface of the Hopkinson pressure bar comprises the following steps:
s1, pretreating a bonding surface of a rock test piece, putting the rock test piece into a prepared test mold, pouring concrete, and curing to the age to be tested to obtain a concrete-rock test piece;
s2, calibrating a PVDT dynamic pressure sensor 10, regarding the sensor as a common compression-resistant cylindrical test piece, pasting the test piece between an incident rod 7 and a transmission rod 9, impacting by utilizing Hopkinson pressure bar equipment, and obtaining stress at different impact speeds by adjusting bullet speeds to finish calibration of the sensor;
s3, adhering a PVDT dynamic pressure sensor 10 on a steel plate on one side of the upper shearing box 3, fixing the connecting piece 1 on the incident rod 7 by adopting a glue layer 2, aligning threaded holes in the connecting piece 1 and the steel plate of the upper shearing box 3, penetrating through a shearing box screw rod 4, and fixing the incident rod 7 and the connecting piece 1 on the steel plate of the upper shearing box 3 through bolts;
s4, fixing the lower shearing box 12 on the equipment support 15 through the fixing device 13, placing a concrete-rock test piece, adjusting the shearing box screw rod 4, moving the lower shearing box slidable steel plate 11 to clamp the test piece, and ensuring that the test piece and the lower shearing box 12 cannot slide relatively;
s5, adjusting the height of the incident rod 7 to enable the distance, which is higher than the interface 14 of the concrete-rock test piece, of the upper shearing box 3 to be equal to the distance, which is lower than the interface 14 of the concrete-rock test piece, of the lower shearing box 12;
s6, adjusting a shear box screw rod 4 on the upper shear box 3 to enable a steel plate on the upper shear box 3 to clamp the concrete-rock test piece;
s7, connecting the tension and compression sensor 6 and the bearing plate 5, placing the connected sensors on the upper surface of the test piece in the S6, and applying pressure stress through a separated hydraulic jack;
and S8, adopting a Hopkinson pressure bar to carry out impact loading, and adjusting the bullet speed to obtain a shear stress-displacement curve of the concrete-rock test piece interface under different impact speeds and compressive stresses.
When the device and the method are used for testing the impact shear resistance of the concrete-rock interface, impact load is transmitted to the upper shear box 3 through the incident rod 7, and the incident rod 7 and the upper shear box 3 move together when load is applied; the load is transferred to the concrete by the upper shear box 3 while the rock below the concrete-rock interface 14 is constrained against displacement by the lower shear box 12 which is fixed to the equipment support 15 so that the interface between the concrete and the rock is under shear stress. Compressive stress ofThe jack is transferred to the concrete-rock test piece through the bearing plate 5. The lower shear box 12 is fixed on the equipment support 15 through a fixing device 13, and the movement of the concrete-rock test piece in the loading direction is restrained together, so that the interface is subjected to shear failure under impact load. The shear displacement is measured by the strain gauge 8, and the calculation formula is as follows:
wherein, c 0 The propagation speed of the wave in the rod is 5060-5100m/s, epsilon i For incident strain,. Epsilon r Is the reflection strain; the impact load F is measured by the PVDT dynamic pressure sensor 10, and a schematic diagram of the measurement of the PVDT dynamic pressure sensor 10 is shown in FIG. 1; the normal load P is measured by the tension and compression sensor 6 and is read by an external digital display instrument 16. The finally obtained shear stress-displacement curve of the concrete-rock test piece interface 14 is shown in fig. 2, wherein the shear strength is obtained by dividing the impact load F by the bonding area As of the PVDT dynamic pressure sensor 10 and the steel plate, and the compressive stress is obtained by dividing the normal load P by the loading area a on the force bearing plate 5.
Claims (7)
1. The device for testing the impact shear resistance of the concrete-rock interface of the Hopkinson pressure bar is characterized by comprising a lower shear box (12) fixed on an equipment support (15) through a fixing device (13), wherein the lower shear box (12) comprises two symmetrically arranged steel plates, one of the two steel plates is a lower shear box slidable steel plate (11), and the other steel plate is integrally arranged with the fixing device (13); an upper shearing box (3) is arranged above the lower shearing box (12), the upper shearing box (3) comprises two steel plates which are symmetrically arranged, an incident rod (7) is arranged on the outer side of one steel plate, a transmission rod (9) is arranged on the outer side of the other steel plate, a PVDT dynamic pressure sensor (10) is arranged between the incident rod (7) and the steel plates, and a strain gauge (8) is arranged on the incident rod (7); a bearing plate (5) is arranged in the upper shearing box (3), a tension and compression sensor (6) is arranged above the bearing plate (5), and the sensor is connected with a digital display instrument (16).
2. The device for testing the impact shear performance of the concrete-rock interface of the Hopkinson pressure bar according to claim 1, wherein the shearing box screws (4) are arranged on the upper shearing box (3) and the lower shearing box (12), and the shearing box screws (4) are arranged on four corners of the steel plate and penetrate through the two steel plates.
3. The device for testing the impact shear performance of the concrete-rock interface of the Hopkinson pressure bar according to claim 1, wherein the connecting piece (1) is arranged between the upper shear box (3) and the incident rod (7), and the incident rod (7) and the connecting piece (1) are fixedly connected through the glue layer (2).
4. The apparatus for testing impact shear performance of a concrete-rock interface for a Hopkinson pressure bar as recited in claim 3, wherein the connecting member (1) is fixed to the steel plate by a shear box screw (4).
5. The device for testing the impact shear performance of the concrete-rock interface of the Hopkinson pressure bar as recited in claim 1, wherein a screw hole site (17) corresponding to the lower shear box and the fixing device is formed between the lower shear box (12) and the fixing device (13) and is fixedly connected with the lower shear box and the fixing device through a bolt.
6. The apparatus for testing impact shear performance of a concrete-rock interface for a Hopkinson pressure bar as recited in claim 1, wherein the lower shear box (12) is provided therein with a concrete-rock test piece, and the interface (14) of the concrete-rock test piece is higher than the interface of the steel plate of the lower shear box (12).
7. The device for testing the impact shear performance of the concrete-rock interface of the Hopkinson pressure bar according to claim 1, wherein the force bearing plate (5) is arranged on the concrete-rock test piece, and the interface (14) of the concrete-rock test piece is lower than the interface of the steel plate of the upper shear box (3); and the interface (14) of the concrete-rock test piece is positioned on the horizontal middle line of the steel plate interface of the lower shearing box (12) and the steel plate interface of the upper shearing box (3).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221517256.6U CN217931198U (en) | 2022-06-16 | 2022-06-16 | Device for testing impact shear resistance of concrete-rock interface for Hopkinson pressure bar |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202221517256.6U CN217931198U (en) | 2022-06-16 | 2022-06-16 | Device for testing impact shear resistance of concrete-rock interface for Hopkinson pressure bar |
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