CN103900901B - A kind of edge splitting method concrete test device - Google Patents

Abstract

The invention relates to a wedge splitting method concrete test device, which belongs to the technical field of physical measurement. The device includes a loading frame, two force transmission plates and a bottom plate; the bottom plate is provided with two spacers for placing concrete test pieces; the two force transmission plates are placed on the concrete test piece relatively flush along the middle groove of the concrete test piece Above; there are wedge plates on both sides of the loading frame; rollers are provided on both sides of the force transmission plate; the force transmission plate is composed of a pull plate and an adjustment plate stacked on each other; A plurality of first adjustment holes spaced apart from each other are provided along the length direction of the concrete test piece, second adjustment holes are provided on the adjustment plate, and the pull plate and the adjustment plate are fixedly connected to each other through bolts passing through the first adjustment hole and the second adjustment hole . The invention adopts block-type force transmission plates to realize the adjustable spacing, so that concrete test pieces of different lengths can be tested, which provides a basis for subsequent derivation formulas of concrete fracture parameters of different lengths.

Description

A kind of wedge splitting method concrete test device

technical field

The invention relates to a concrete test device, in particular to a concrete test device of wedge splitting method, which belongs to the technical field of physical measurement.

Background technique

At present, the wedge splitting method is the mainstream test method for concrete fracture parameters (mainly including toughness, fracture energy, etc.). The standard document in the industry is DL/T5332-2005 "Rules for Fracture Test of Hydraulic Concrete". According to the empirical formula in the standard, it can be calculated only by measuring the crack opening displacement and load. Compared with other methods, this method can convert a small vertical load into a large horizontal split load, thereby reducing the requirements for test stiffness, and can offset the influence of the specimen's own weight and vertical force through design, and the operation It is simple and easy to analyze, so it has unique advantages.

However, the method provided by the DL/T5332-2005 standard is not strictly accurate. First of all, the vertical load transmitted by the loading fixture to the specimen is not collinear with the self-weight of the specimen and the reaction force of the support, and the additional bending moment generated by the vertical force has a certain influence on the stress-strain field at the crack tip. The "Regulations" uses the formula for calculating the fracture toughness of compact tensile specimens to calculate the fracture toughness value of wedged split tensile specimens. The action of the force, so as to obtain the approximate value of the fracture toughness. This estimation result is not completely consistent with another method recommended in the "Regulations" - three-point bending beam, and even some opposite conclusions appear.

Secondly, this standard can only be applied to test pieces whose corresponding rollers and pads are in the same vertical plane, and the length of the test piece is about 200mm, and the width is less than 200mm. If the corresponding rollers and pads are not in the same vertical plane Estimates are made when internal and deviations are not large. In the current water conservancy, civil engineering, construction and other projects, the requirements for concrete have long been far beyond 200mm, especially for large-volume concrete, the DL/T5332-2005 standard provides a standard size of 200mm×200mm×200mm The test results of the test pieces are not applicable, and have basically lost their reference value in the industry. Whether the research results of the small-size test pieces in the laboratory can be extended to the large-volume concrete in the actual project is directly related to the significance and practical value of the test research. size. In summary, it is of great significance and application value to accurately test and calculate the fracture parameters of concrete specimens of various sizes and large sizes. A method that can accurately test the fracture parameters of multi-sized and large-sized concrete specimens is urgently needed.

Contents of the invention

The technical problem solved by the invention is to propose a wedge splitting method test device that can adapt to non-standard concrete test blocks.

In order to solve the above-mentioned technical problems, the technical solution proposed by the present invention is: a wedge-split-pull method concrete test device includes a loading frame, two force-transmitting plates with folded edges at one end and a bottom plate, and the bottom plate is provided with a Two pads of the test piece, the two pads are respectively located at 1/4 and 3/4 of the length direction of the concrete test piece; during the test, the two force transmission plates along the The middle groove of the concrete test piece is relatively evenly placed on the concrete test piece, and the folded edge is sunk into the groove; the two sides of the bottom surface of the loading frame are provided with wedge plates, and the two sides of the force transmission plate The two sides of the wedge are respectively provided with rollers, and the two sides of the wedge plate are respectively close to the two rollers on the same side; when the wedge presses the rollers downward, the respective folding The sides move oppositely to each other and act on the two inner sidewalls of the groove respectively; the axle centers of the rollers are respectively located in the same vertical plane as the axle centers of the two spacers, and the force transmission plates are controlled by each other. The stacked pull plate and the adjustment plate are composed of one end of the pull plate forming the folded edge, the rollers are fixed on both sides of the adjustment plate, and the pull plate is provided along the length direction of the concrete test piece. A plurality of first adjustment holes spaced apart from each other, the adjustment plate is provided with a second adjustment hole, the pull plate and the adjustment plate are fixedly connected to each other through bolts passing through the first adjustment hole and the second adjustment hole, when the test , by passing the bolts through different first adjustment holes and second adjustment holes that are spaced apart from each other, the pull plate and the adjustment plate form a misplaced fixed connection.

The wedge-split concrete test device provided by the present invention ensures that the axis of the roller at the corresponding position and the axis of the spacer are located in the same vertical plane, so that the vertical load transmitted by the loading fixture to the test piece It is collinear with the self-weight of the specimen and the reaction force of the support, eliminating the influence of the vertical force and making the calculation results more accurate. During the test, the present invention can select different first adjustment holes according to test blocks of different lengths, and fix the pull plate and the adjustment plate, so as to adapt to test pieces of different lengths and ensure that the axis of the roller and the axis of the spacer Centers lie in the same vertical plane. The present invention can make the geometric characteristics and stress conditions of the wedged splitting test piece exactly the same as that of the compact tensile test piece, therefore, the fracture parameter calculation formula of the compact tensile test piece can be used to accurately calculate the fracture of the wedged splitting test piece Parameters, calculation methods can refer to "Stress Intensity Factor Handbook".

A further improvement of the above solution is that: the adjusting screw holes are arranged in sequence at intervals along the moving direction of the pull plate.

A further improvement of the above solution is that: the adjusting screw holes are arranged in two rows at intervals along the moving direction of the pulling plate.

In order to make the present invention adapt to test pieces of different widths, the above-mentioned solution is further improved in that: the adjustment plate is composed of two L-shaped first plates and second plates that are separated and opposed to each other; the two sides of the adjustment plate The two rollers are respectively arranged on one arm of the first plate and the second plate, and the second adjusting hole is arranged on the other arm of the first plate and the second plate; the first adjusting hole is Waist round holes, and are arranged in two rows at intervals along the moving direction of the pull plate; the loading frame is provided with a waist round mounting hole consistent with the extension direction of the first adjustment hole; the wedge plate passes through The fasteners in the mounting holes are fixedly connected with the loading frame.

Since the wedge plate needs to withstand a relatively large pressure, in order to increase its strength, the wedge plate includes a base plate fixedly connected with the loading frame, and a reinforcement plate connected with the base plate through a fastener, which is arranged on the base Supplementary boards on both sides of the board; the supplementary board is close to the base board, and the contour formed by the two is consistent with the contour of the reinforcement board; the supplementary board and the reinforcement board are connected by fasteners.

A further improvement of the above solution is that: the distance between the first screw holes on the pulling plate is 50mm.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is a schematic structural diagram of a preferred embodiment 1 of the present invention.

Fig. 2 is a schematic diagram of the drawing plate structure in Fig. 1 .

Fig. 3 is a schematic structural diagram of the adjustment plate in Fig. 1 .

Fig. 4 is a schematic structural diagram of a preferred embodiment 2 of the present invention.

Fig. 5 is a schematic structural diagram of the adjustment plate in Fig. 4 .

Fig. 6 is a structural schematic diagram of the loading frame and the wedge plate in Fig. 4 .

Fig. 7 is a schematic structural diagram of a preferred embodiment 3 of the present invention.

Fig. 8 is a schematic diagram of the structure of the drawing plate in Fig. 7 .

Fig. 9 is a schematic structural diagram of the adjustment plate in Fig. 7 .

Fig. 10 is a schematic structural diagram of the wedge plate in Fig. 7 .

The symbols in the figure are as follows: 1-loading frame, 2-wedge plate, 3-drawing plate, 4-test piece, 5-adjusting plate, 5a-roller, 6-bottom plate, 7-pad rod, 2a-basic plate, 2b - reinforcement plate, 2c - supplementary plate.

detailed description

Example 1

This embodiment provides: a wedge splitting concrete test device, as shown in Figures 1 to 3, comprising a loading frame 1, two force transmission plates with a hem at one end and a bottom plate 6; the bottom plate 6 is provided with Backing bar 7, one of backing bar 7 is welded on the base plate 6, and two then sticks on the base plate 6, so just can adjust the distance between two backing bars 7 as required. The concrete test piece 4 is placed on the pad 7; the folded edges of the two force transmission plates are placed on the concrete test piece 4 oppositely, and the folded edges fall into the prefabricated groove at the top of the test piece 4 . The two sides of the loading frame 1 are provided with wedge plates 2; the two sides of the force transmission plate are provided with rollers 5a; The loading frame 1 is driven by a pressure device, and the wedge plate 2 separates the two force transmission plates under pressure; the force transmission plate pulls the test piece 4 . The force transmission plate is composed of a pull plate 3 and an adjustment plate 5 which are stacked and screwed together; The pulling plate 3 is provided with a plurality of first adjustment holes at a distance of 50 mm from each other along the length direction of the concrete test piece 4 , and the adjustment plate 5 is provided with second adjustment holes.

In order to simplify the analysis, the two pads 7 are respectively located at 1/4 and 3/4 of the length of the test piece 4 . The shafts of the rollers 5a on the two force transmission plates are respectively in a vertical plane with the two pads 7; like this, the downward pressure can no longer have component forces in other directions, and at the same time, the self of the test piece 4 Gravity is also just equally borne by two pad rods 7, which simplifies calculation. In order to adapt to test pieces 4 of different standards, the first adjustment holes on the pull plates 3 are divided into two rows, and the distance between the two nearest first adjustment holes on the two pull plates 3 is 100mm after they are in place. In this way, use bolts to pass through different first adjustment holes, and then pass through the second adjustment holes to fix the pull plate 3 and the adjustment plate 5 to obtain different roller 5a spacings, that is, 100mm can be used as a unit to adapt to different rollers. Test piece 4, such as 300mm, 400mm, 500mm, 600mm and 700mm and so on. By changing the type or spacing of the first adjustment holes, more sizes of test pieces 4 can be accommodated.

There is an upper and lower opening in the middle of the folded edge to accommodate the clip-type extensometer to measure the displacement of the test piece conveniently and quickly.

Applying this embodiment can make the geometric characteristics and stress conditions of the wedged split tension specimen exactly the same as that of the compact tension specimen. Therefore, the fracture parameter calculation formula of the compact tension specimen can be used to accurately calculate the wedge split tension specimen. For the fracture parameters, the calculation method can refer to the "Stress Intensity Factor Handbook".

Take the calculation of crack initiation fracture toughness as an example:

In the formula , ;

is the initiation load;

Example 2

This embodiment 2 is improved on the basis of embodiment 1, most of which are the same, and the different parts are shown in Figure 4 to Figure 6: In order to ensure the strength of the wedge plate 2, the wedge plate 2 includes The base plate 2a connected with the frame, and the reinforcement plate 2b connected with the base plate 2a by bolts are provided with supplementary plates 2c on both sides of the base plate 2a; The profile of the board 2b is consistent; the supplementary board 2c and the reinforcement board 2b are fixedly connected by bolts. In this way, by replacing the reinforcement plate 2b and supplementary plate 2c of different sizes, the adjustment of the size of the wedge plate 2 can be realized to adapt to the test pieces 4 of different lengths, avoiding the need to adapt the test pieces 4 of different lengths. 4 is made big.

At the same time, grooves for key connection are respectively added on the adjustment plate 5 and the pull plate 3, and the two plates are not only fixed by bolts, but also connected by keys to increase the strength of the connection.

Example 3

This embodiment 3 is improved on the basis of embodiment 1, most of which are the same, and the different parts are shown in Figures 7 to 10: the adjustment plate 2 is composed of an L-shaped first plate and a second plate; The first board is placed opposite to the second board. The rollers 5a are respectively arranged on one arm of the first plate and the second plate, and the second adjusting hole is arranged on the other arm of the first plate and the second plate. The first adjustment holes are waist-shaped screw holes, and are arranged in two rows at intervals along the moving direction of the pull plate 3 . The extending direction of the first adjustment hole is the width direction of the test piece 4 . The loading frame 1 is provided with a waist-circular installation hole consistent with the extension direction of the first adjustment hole; the wedge plate 2 is connected with the loading frame 1 through the installation hole. Since the first adjustment hole and the installation hole are both waist-shaped screw holes, the test piece 4 can be adapted to different widths through different fastening positions.

As shown in Figure 10, in order to ensure the strength of the wedge plate 2, the wedge plate 2 includes a base plate 2a connected to the loading frame through a mounting hole, and a reinforcing plate 2b connected to the base plate 2a by bolts, which are arranged on both sides of the base plate 2a There is a supplementary plate 2c; the supplementary plate 2c is close to the base plate 2a, and the outline formed by the two is consistent with the outline of the reinforcement plate 2b; the supplementary plate 2c and the reinforcement plate 2b are fixedly connected by bolts. In this way, by replacing the reinforcing plate 2b and supplementary plate 2c of different sizes, the size of the wedge plate 2 can be adjusted to adapt to test pieces 4 of different lengths.

The present invention is not limited to the specific technical solutions of the above embodiments, and all technical solutions formed by equivalent replacement are within the scope of protection required by the present invention.

Claims (5)

1. A kind of wedge splitting method concrete test device, comprises loading frame, two pieces of one end have force transmission plate and base plate of flanging, and described base plate is provided with two spacers for placing concrete test piece, and described two The two spacers are respectively located at 1/4 and 3/4 of the length direction of the concrete test piece; during the test, the two force transmission plates are placed relatively flush along the middle groove of the concrete test piece On the concrete test piece, the folded edge is sunk into the groove; wedge plates are provided on both sides of the bottom surface of the loading frame, rollers are respectively provided on both sides of the force transmission plate, and the wedge plates The two side edges of the two force transmission plates are respectively close to the two rollers on the same side; when the wedge plate presses the rollers downward, the respective folded edges of the two force transmission plates move in opposite directions and respectively act on the two rollers. The two inner sidewalls of the groove; it is characterized in that: the axis centers of the rollers are located in the same vertical plane as the axis centers of the two spacers, and the force transmission plates are composed of pull plates and adjustment plates stacked on each other. One end of the pull plate forms the fold, the rollers are fixed on both sides of the adjustment plate, and the pull plate is provided with a plurality of first spaced apart along the length direction of the concrete test piece. Adjustment hole, the adjustment plate is provided with a second adjustment hole, the pull plate and the adjustment plate are fixedly connected to each other through bolts passing through the first adjustment hole and the second adjustment hole, when testing, by passing the bolt through Different first adjustment holes and second adjustment holes spaced apart from each other are provided so that the pull plate and the adjustment plate form a dislocation fixed connection; the adjustment plate is composed of two L-shaped first plates and a second Composed of two plates; the two rollers on both sides of the adjustment plate are respectively set on one arm of the first plate and the second plate, and the second adjustment hole is set on the first plate and the second plate the other arm; the first adjustment hole is a waist hole, and is arranged in two rows at intervals along the moving direction of the pull plate; the loading frame is provided with a waist that is consistent with the extension direction of the first adjustment hole A circular mounting hole; the wedge plate is fixedly connected with the loading frame through a fastener passing through the mounting hole. 2 . The wedge splitting concrete test device according to claim 1 , wherein the first adjustment holes are arranged at intervals along the moving direction of the tie plate. 3 . 3 . The wedge splitting concrete test device according to claim 2 , wherein the first adjustment holes are arranged in two rows at intervals along the moving direction of the pull plate. 4 . 4. The wedge splitting method concrete test device according to any one of claims 1 to 3, characterized in that: the wedge plate comprises a base plate fixedly connected to the loading frame, and the base plate is connected to the base plate through a tight The reinforcing plate connected by the firmware is a supplementary plate arranged on both sides of the base plate; the supplementary plate is close to the base plate, and the outline formed by the two is consistent with the outline of the reinforcing plate; the supplementary plate It is connected with the reinforcing plate through fasteners. 5 . The wedge splitting concrete test device according to claim 4 , wherein the distance between the first screw holes on the tie plate is 50 mm. 6 .