CN111398016B - Soil body II type orthotic devices for fracture test - Google Patents

Soil body II type orthotic devices for fracture test Download PDF

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Publication number
CN111398016B
CN111398016B CN202010236150.8A CN202010236150A CN111398016B CN 111398016 B CN111398016 B CN 111398016B CN 202010236150 A CN202010236150 A CN 202010236150A CN 111398016 B CN111398016 B CN 111398016B
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sample
type
fracture
plate
magnetic suspension
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CN111398016A (en
Inventor
孙一清
沈振中
徐力群
甘磊
王润英
张宏伟
杨超
杨金孟
张文兵
巫纾予
刘杰卿
王梓优
杨子桐
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Hohai University HHU
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Hohai University HHU
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0025—Shearing

Abstract

The invention discloses a correcting device for a soil body II-type fracture test, which comprises two sets of correctors, wherein the two sets of correctors are symmetrically arranged on two sides of a long edge of a sample; the sample is placed on a II-type fracture device platform and is provided with two prefabricated cracks parallel to the long edge; each set of the straightener comprises a controller, a force measuring sensor, a straightening plate, a telescopic rod, a contact sensor and a displacement sensor; a controller for driving the extension and contraction movement of the correction plate; the force sensor is used for detecting the extrusion force between the correction plate and the sample; the contact sensor is used for detecting the contact condition of the correction plate and the sample; the displacement sensor is used for detecting the stretching displacement of the correcting plate; the correcting device is abutted against the left side and the right side of the sample, so that when the sample is subjected to the action of a pair of shearing forces, the sample crack tip is prevented from cracking towards the two sides of the crack, and the sample is prevented from being separated towards the two sides at the crack, so that the fracture mode is prevented from developing from type II fracture to type I-II mixed fracture, even being converted into type I fracture, and pure type II fracture is realized.

Description

Soil body II type orthotic devices for fracture test
Technical Field
The invention relates to a soil test device, in particular to a correction device for a soil body II-type fracture test.
Background
Fracture is a destructive process due to the initiation of new cracks or the propagation of existing cracks, and is one of the failure modes of materials and structures. In fracture mechanics, crack propagation can be divided into three basic types according to its stress state, namely: open (i.e., type I), slide (i.e., type ii) and tear (i.e., type III), respectively, as shown in fig. 1. The invention mainly relates to type I and type II fractures in soil fracture damage, and is mainly suitable for the research of pure type II fractures.
The invention discloses a Chinese patent with application number CN201210518436.0, and the invention name thereof is 'soil shear fracture failure test device and method', comprising a base, a front baffle, a thrust providing device, a load sensor, a displacement sensor and a data acquisition unit; the tip at the base is installed to the preceding baffle, the thrust provides the device and installs on the base, the power take off end of thrust provides the device and passes through the load sensor and be connected with the thrust plate, displacement sensor sets up between thrust plate and thrust provides the device, the thrust plate sets up on the base through first slide rail, be used for laying the second slide rail on the base of sample between thrust plate and preceding baffle, thrust plate and preceding baffle are located the cracked left and right sides of sample respectively, the data output end of displacement sensor and load sensor is connected with data collection station's data receiving terminal.
The above patent application, although capable of loading type II fractures, has the following disadvantages, yet to be further improved:
when the sample is promoting forward, do not have the keep out of left and right sides, cause the prefabricated crack tip of sample to the both sides fracture very easily to make the fracture mode follow II type fracture to I-II type mixed fracture development, nevertheless if apply the load in the left and right sides and prevent sample crack tip to crack of crack both sides, thereby can make the increase of the most advanced frictional force of crack and cause the cracked fracture toughness KIC grow of two types, cause the phenomenon that the measured value is bigger than normal.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art and provides a soil mass II-type fracture test correcting device which is abutted against the left side and the right side of a sample, so that the sample is prevented from cracking towards the two sides of a crack at the tip of the sample crack under the action of a pair of shearing forces, the sample is prevented from being separated towards the two sides at the crack, the fracture mode is prevented from developing from II-type fracture to I-II-type mixed fracture, even the fracture mode is changed into I-type fracture, and pure II-type fracture is realized.
In order to solve the technical problems, the invention adopts the technical scheme that:
the utility model provides a soil body II type orthotic devices for fracture test, includes two sets of unscrambler, and two sets of unscrambler symmetry set up the long limit both sides at the sample. The sample is placed on a type II fracture device platform and has two pre-fabricated cracks parallel to the long edges.
Each set of the straightener comprises a controller, a force measuring sensor, a straightening plate, a telescopic rod, a contact sensor and a displacement sensor.
And the controller is used for driving the stretching movement of the correcting plate.
The force sensor is used for detecting the extrusion force between the correction plate and the sample.
The correcting plates are used for limiting and blocking the lateral displacement of the left side and the right side of the sample, and the sample is prevented from cracking towards two sides.
The displacement sensor is used for detecting the stretching displacement of the correction plate.
The contact sensor is arranged on the correction plate adjacent to one side of the sample and used for detecting the contact condition of the correction plate and the sample.
The controller is fixed in position and is connected with the correction plate through the telescopic rod.
The controller, the force measuring sensor, the correcting plate, the telescopic rod, the contact sensor and the displacement sensor in each set of the corrector are respectively provided with two, the force measuring sensor and the displacement sensor are both arranged on the corresponding telescopic rods, and the contact sensor is arranged on the correcting plate corresponding to the telescopic rods and adjacent to one side of the sample.
The controller is controlled by a speed regulating motor.
The type II breaking device platform is a magnetic suspension device, the magnetic suspension device comprises three magnetic suspension platforms, the three magnetic suspension platforms are arranged in parallel, can lift and suspend under the action of magnetic force, and keep the same height. And a gap is formed between every two adjacent magnetic suspension platforms and corresponds to the position of a prefabricated crack on the sample.
The invention has the following beneficial effects:
1. the correcting plates are abutted against the left side and the right side of the sample, so that when the sample is subjected to the action of a pair of shearing forces, the sample is prevented from cracking from the crack tip to the two sides of the crack, and the sample is prevented from being separated from the crack to the two sides, so that the fracture mode is prevented from developing from type II fracture to type I-II mixed fracture and even being changed into type I fracture, and pure type II fracture is realized.
2. The magnetic suspension platform and the magnetic suspension support are used, so that the magnetic suspension platform for supporting the sample is completely separated from the test platform, the friction force is eliminated, and the test accuracy is improved. The magnetic suspension effect is realized by utilizing the principle that like poles repel each other and opposite poles attract each other, the friction force on the lower side of the sample is completely eliminated, the motion mode of the magnetic suspension platform can be limited, the magnetic suspension platform can only slide along the length direction of the magnetic suspension platform, and the influence of the shaking of the magnetic suspension platform on the test result is prevented.
3. The two prefabricated cracks are arranged on the sample, the cracks penetrate into the total length of the sample for a certain distance, and the two prefabricated cracks in the middle of the sample are aligned with the gaps in the two magnetic suspension platforms no matter how the size of the sample is, so that the samples with different sizes can be tested, and the application range is wide.
4. The invention can simultaneously test two prefabricated cracks on the same sample and compare the test results.
Drawings
Figure 1 shows several fracture type patterns of the test specimens.
Fig. 2 shows a schematic structural diagram of the correcting device for the soil body II-type fracture test.
FIG. 3 shows a schematic representation of a sample according to the present invention.
Figure 4 shows a schematic view of the arrester of the invention when the telescopic pole is in the original state.
Figure 5 shows a schematic view of the arrester of the invention when the telescopic pole is in an extended state.
Fig. 6 shows a schematic diagram of three magnetic levitation platforms according to the present invention.
Fig. 7 shows a partial schematic view of a magnetic levitation platform of fig. 6.
FIG. 8 shows a schematic of the other equipment on the test platform of the present invention.
FIG. 9 shows a schematic of the test platform of the present invention.
Fig. 10 is a schematic view showing the telescopic rod of the straightening and extending device in the original state.
Figure 11 shows a schematic view of the extension pole of the orthosis according to the present invention in an extended state.
Among them are:
1. a sample;
2. a blocker; 2-1, fixing a base; 2-2, a controller; 2-3, a telescopic rod; 2-4, a barrier plate;
3. a corrector; 3-1 parts of a controller, 3-2 parts of a force measuring sensor, 3-3 parts of a correcting plate, 3-4 parts of a telescopic rod; 3-5, a contact sensor; 3-6, a displacement sensor;
4. a magnetic suspension platform; 4-1, a magnetic suspension platform; 4-2, vertical electromagnetic coils; 4-3, horizontal electromagnetic coil;
5. a magnetic suspension support; 5-1, T-shaped vertical plates; 5-2, a T-shaped transverse plate; 5-3, vertical magnet; 5-4, horizontal magnet;
6. a power plate; 7. a displacement sensor; 8. a stress sensor; 9. a position sensor holder;
10. pushing and pulling a power source; 11. a collector; 12. a transmission line; 13. and (4) a test platform.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific preferred embodiments.
In the description of the present invention, it is to be understood that the terms "left side", "right side", "upper part", "lower part", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and that "first", "second", etc., do not represent an important degree of the component parts, and thus are not to be construed as limiting the present invention. The specific dimensions used in the present example are only for illustrating the technical solution and do not limit the scope of protection of the present invention.
As shown in figure 2, the correcting device for the soil body II-type fracture test comprises a sample, a test platform 13, a magnetic suspension device, a stopper 2, a correcting plate 3, a push-pull power device and a data acquisition device.
The magnetic suspension device comprises three magnetic suspension platforms 4 and three magnetic suspension supports 5.
As shown in figures 6 and 7, each of the three magnetic suspension supports comprises a T-shaped support, and each of the three magnetic suspension supports comprises a T-shaped vertical plate 5-1 and a T-shaped transverse plate 5-2. The three magnetic suspension supports are arranged in parallel and equidistantly, and the bottom end of the T-shaped vertical plate of each magnetic suspension support is fixedly arranged on the test platform. Horizontal magnets 5-4 are arranged at two outer side ends of each T-shaped transverse plate, and vertical magnets 5-3 are symmetrically distributed at the bottom of each T-shaped transverse plate on each T-shaped vertical plate.
The three magnetic suspension platforms 4-1 are all C-shaped platforms which are respectively sleeved on the peripheries of the three magnetic suspension supports. Two horizontal electromagnetic coils 4-3 and two vertical electromagnetic coils 4-2 are arranged in a C-shaped inner cavity of each magnetic suspension platform, wherein the horizontal electromagnetic coils correspond to the horizontal magnets in position, and form a magnetic field after being electrified to generate horizontal repulsive force with the horizontal magnets, so that the magnetic suspension platforms are prevented from shaking; the vertical electromagnetic coil corresponds to the vertical magnet in position, and forms a magnetic field after being electrified to generate vertical attraction with the vertical magnet so as to enable the magnetic suspension platform to be separated from the T-shaped bracket and to be suspended; the length of the magnetic suspension support in the middle is larger than that of the magnetic suspension platform sleeved outside the magnetic suspension support; the upper surfaces of the three magnetic suspension platforms are the same height after being suspended when the same current is introduced, and the three magnetic suspension platforms are used for supporting the sample 1.
The structure of sample 1, as shown in fig. 3, is provided with two symmetrical pre-fabricated cracks parallel to the length direction. The crack penetrates into the total length of the sample for a certain distance, and the two prefabricated crack forms in the middle of the sample are aligned with the gaps in the two magnetic suspension platforms regardless of the size of the sample, so that the test can be performed on the samples with different sizes, and the application range is wide. In the test, the middle part of the sample is pushed, and the two sides of the sample are blocked, so that the sample is prevented from inclining and twisting in the test process, and the trend of two seams can be compared in the same group of tests; and a gap is formed between every two adjacent magnetic suspension platforms and corresponds to the position of a prefabricated crack on the sample.
And the two stoppers are arranged on the test platform corresponding to the rear end parts of the two outer magnetic suspension supports. As shown in fig. 4 and 5, each arrester includes a fixed base 2-1, a controller 2-2, a telescopic rod 2-3, and an arresting plate 2-4. The fixed seat is installed on the test platform, the controller is installed on the fixed seat and connected with the blocking plates through the telescopic rods, the blocking plates are controlled to stretch along the length direction of the magnetic suspension platform, the height of the bottoms of the blocking plates is not lower than that of the top surface of the magnetic suspension platform, and the lower edges of the two blocking plates are flush with the upper edges of the two magnetic suspension platforms on the outer sides.
The fixing seat is L-shaped, and an L-shaped vertical plate of the fixing seat is abutted against the rear end part of the corresponding outer magnetic suspension support. The height of the top surface of the L-shaped vertical plate is the same as the height of the suspended magnetic suspension platform.
The data acquisition device comprises a stress sensor 8, a displacement sensor 7, a collector 11, a position sensor holding frame 9 and a transmission line 12, wherein the collector 11, the position sensor holding frame 9 and the transmission line 12 are installed on the test platform, the stress sensor 8 and the displacement sensor 7 are respectively used for acquiring the stress and the displacement of the power plate, and the transmission line 12 is connected with the collector simultaneously. Wherein, displacement sensor installs on displacement sensor holds force frame 9, and displacement sensor holds force frame and installs on test platform.
The push-pull power device comprises a power plate 6, a power rod 3 and a thrust power source 10 arranged on the test platform, wherein the power plate corresponds to the front end position of a sample positioned right above the middle magnetic suspension support, the output end of the thrust power source is connected with a stress sensor, the stress sensor is arranged and connected with the power rod, and the power rod is connected with the power plate.
The two straightening plates are parallel to the length direction of the magnetic suspension support and used for limiting and blocking the left lateral displacement and the right lateral displacement of the sample.
A soil body slip type fracture test method based on a magnetic suspension effect comprises the following steps.
Step 1, sample preparation: the soil body to be tested is made into a soil sample with set length and width dimensions, and two parallel prefabricated cracks are prefabricated on the soil sample along the length direction to form a sample.
Step 2, assembling the magnetic suspension device: and sequentially sleeving the three magnetic suspension platforms on the peripheries of the three magnetic suspension supports, and enabling the magnetic suspension platforms to be in an initial state. Wherein, the initial state is as follows: two vertical electromagnetic coils in the three magnetic suspension platforms are not electrified, the magnetic suspension platforms are supported through T-shaped supports in the magnetic suspension supports, the heights of the top surfaces of the three magnetic suspension platforms are the same, and one ends of the three magnetic suspension platforms, which are adjacent to the thrust plate, are kept flush. Two vertical electromagnetic coils in the three magnetic suspension platforms are all electrified with currents with the same magnitude and direction, so that the three magnetic suspension platforms drive the sample to synchronously rise to a set height. Two horizontal electromagnetic coils in the middle magnetic suspension platform are supplied with currents which are equal in magnitude and same in direction and are large enough, so that the middle magnetic suspension platform is symmetrical about the axis of the middle T-shaped support and is stabilized at the position and cannot easily shake. Two horizontal electromagnetic coils in the two magnetic suspension platforms positioned at the outer sides are not electrified and are attached to the magnetic suspension platform at the middle part without gaps.
Step 3, adjusting the gap: according to the width of the sample prefabricated crack in the step 1, currents in proper directions and proper sizes are conducted to two horizontal electromagnetic coils in two outer magnetic suspension platforms, the two outer magnetic suspension platforms move towards two sides, therefore, the gap between every two adjacent magnetic suspension platforms is equal to the width of the sample prefabricated crack in the step 1, and then the magnetic suspension platforms on the two sides are stabilized at the position and cannot easily shake through adjustment of the currents and the directions of the vertical electromagnetic coils and the horizontal electromagnetic coils.
Step 4, placing a sample: and (3) placing the sample finished in the step (1) right above the three magnetic suspension platforms in the step (3), and enabling two prefabricated cracks on the sample to be located right above the two interval gaps in the step (3).
When the soil mass sample is lofted, the front end of the soil mass sample close to the power plate is preferably flush with the front end of the magnetic suspension platform, so that the lower edge of the power plate can be conveniently aligned with the lower surface of the soil mass sample and the upper surface of the magnetic suspension platform in the middle, and the soil mass sample right above the magnetic suspension platform in the middle can be conveniently pushed to move towards the direction of the stopping plate.
Step 5, clamping a soil body sample: the power plate and the two blocking plates in the two blockers move oppositely, the two blocking plates are attached and contacted with the rear end parts of the soil mass samples right above the two outer magnetic suspension platforms, and thrust is not applied to the soil mass samples. The power plate is in contact with the front end part of the soil sample right above the magnetic suspension platform in the middle in a fitting manner, and does not apply thrust to the soil sample.
The two above-mentioned arresting plates of the magnetic suspension platform are preferably respectively aligned with the outer parts of the two prefabricated cracks of the soil body sample. One side strip of the barrier plate is aligned with the position of an adjacent prefabricated crack, and the other three side edges of the barrier plate are aligned with the edges of the soil body samples which are attached and contacted with each other.
The left side and the right side of the power plate are preferably aligned with the positions of the two prefabricated cracks, the upper side of the power plate is aligned with the upper edge of the soil body sample, and the lower edge of the power plate is flush with the lower edge of the soil body sample or the upper surface of the magnetic suspension platform in the middle.
Step 6, type II fracture test: the push-pull power source is connected with a power supply to push the power plate to move forward, so that horizontal load is applied to the soil sample, the barrier plate blocks the soil sample from moving forward at the tail part, and the bottom of the soil sample and the magnetic suspension platform are relatively static. And the power plate continues to move forwards, so that the soil sample generates pure II-type fracture at the tip ends of the two prefabricated cracks.
Step 7, data acquisition and drawing: in the II-type fracture test process, the stress sensor and the displacement sensor respectively record the stress value and the displacement value of the power plate in real time and transmit the stress value and the displacement value to the computer. And drawing a stress-time and displacement-time process line graph by a computer.
And 8, stopping the test: and when the stress value collected by the stress sensor suddenly drops, the soil body sample is displayed to be broken, and the test is stopped.
And 9, repeating the steps 2 to 8 by changing the length and width of the soil mass sample and adjusting the length or width of the prefabricated crack of the soil mass sample, and searching the influence rule and the influence of the size of the soil mass sample or the size of the prefabricated crack on the type II fracture and the influence of the size and the initial crack size change on the fracture toughness of the soil mass sample.
The utility model provides a soil body II type orthotic devices for fracture test, includes two sets of unscrambler, and two sets of unscrambler symmetry set up the long limit both sides at the sample. The sample is placed on a type II fracture device platform and has two pre-fabricated cracks parallel to the long edges.
The type II fracture device platform is preferably a magnetic suspension device, the magnetic suspension device comprises three magnetic suspension platforms which are arranged in parallel and can lift and suspend under the action of magnetic force and keep the same height; and a gap is formed between every two adjacent magnetic suspension platforms and corresponds to the position of a prefabricated crack on the sample. The specific structure of the magnetic levitation device is as described above. Alternatively, the type ii fracture device platform may be a rolling support platform or a sliding pad in the background art.
Each set of the straightener comprises a controller 3-1, a force measuring sensor 3-2, a straightening plate 3-3, a telescopic rod 3-4, a contact sensor 3-5 and a displacement sensor 3-6.
And the controller is used for driving the stretching movement of the correcting plate, and is preferably controlled by adopting a speed regulating motor.
The correcting plates are used for limiting and blocking the lateral displacement of the left side and the right side of the sample, and the sample is prevented from cracking towards two sides.
The load cell is used for detecting the extrusion force between the straightening plate and the sample, and is preferably arranged on the telescopic rod.
The displacement sensor is used for detecting the telescopic displacement of the correction plate, and is preferably arranged on the telescopic rod.
The contact sensor is arranged on the correction plate adjacent to one side of the sample and used for detecting the contact condition of the correction plate and the sample.
The controller is fixed in position and is connected with the correction plate through the telescopic rod.
The controller, the force measuring sensor, the correcting plate, the telescopic rods, the contact sensors and the displacement sensors in each set of the correcting device are preferably two in number, the force measuring sensors and the displacement sensors are mounted on the corresponding telescopic rods, and the contact sensors are mounted on the correcting plate, corresponding to the telescopic rods, on the side close to the sample.
In this embodiment, the correction method of the present invention will be described in detail by taking a magnetic suspension device as an example.
A correction method for a shear type fracture test of a magnetic suspension type soil body comprises the following steps.
Step 1, preparation before correction: the vertical electromagnetic coils and the horizontal electromagnetic coils in the three magnetic suspension devices are all electrified with currents with proper magnitude and direction, so that the three magnetic suspension devices drive the soil sample to synchronously rise to a set height and are separated from the three magnetic suspension supports, the soil sample is in a suspension state, the positions of the magnetic suspension platforms are adjusted according to the prefabricated cracks, and the three magnetic suspension platforms are stabilized at the positions and cannot easily shake. And placing the soil body sample right above the three magnetic suspension devices, and aligning the prefabricated cracks to the interval gaps between the magnetic suspension platforms as far as possible.
Step 2, sample position correction: the correcting plates of the two sets of the correctors synchronously move in opposite directions according to the size of the sample under the action of the corresponding controllers, and displace in the same size, and if the sample is not positioned right above the gap, under the action of the extrusion force of the correcting plate on one side, two prefabricated cracks on the sample are positioned right above the gap. And small extrusion force is continuously applied to the sample, so that the two side correcting plates are ensured to be in uniform contact with the sample, the extrusion force is small, and the sample and the prefabricated crack cannot be influenced.
The shape and size of each straightening plate is preferably the same as the long side of the soil sample.
Step 3, correcting before testing: the two correcting plates slowly and reversely move under the action of the corresponding telescopic driving devices, and when the two correcting plates are in contact with the left side edge and the right side edge of the soil body sample but have no extrusion force, the positions are kept still to form a correcting pose. At this time, the contact sensor can detect that the correction plate is in contact with the soil sample, but the extrusion force detected by the load cell is zero.
The telescopic driving device is preferably controlled by a speed regulating motor, and the reverse movement speed of the correcting plate in the step is preferably smaller than the opposite movement speed in the step 2. In addition, the number of the extension driving devices externally connected with each straightening plate is selected according to the length of the soil body sample. In this embodiment, each straightening plate is preferably controlled by two telescopic drives.
Step 4, correction in the test: the push-pull power source is connected with a power supply to push the power plate to move forward, so that a horizontal load is applied to the sample, the barrier plate blocks the sample from moving forward at the tail part, and the bottom of the sample and the magnetic suspension platform are relatively static. And along with the continuous forward movement of the power plate, the correcting plate always keeps the correcting pose still and abuts against the left side and the right side of the soil mass sample to form a pair of opposite side shearing forces, so that the situation that the prefabricated cracks crack from the tip to the two sides and the sample is separated from the crack to the two sides is prevented, the development trend from II-type fracture to I-II-type mixed fracture is restrained, and the pure II-type fracture is generated on the tip of the two prefabricated cracks of the soil mass sample.
Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the details of the embodiments, and various equivalent modifications can be made within the technical spirit of the present invention, and the scope of the present invention is also within the scope of the present invention.

Claims (4)

1. The utility model provides a II type orthotic devices for fracture test of soil body which characterized in that: the device comprises two sets of correctors, wherein the two sets of correctors are symmetrically arranged on two sides of a long edge of a sample; placing a sample on a II-type fracture device platform, wherein the sample is provided with two prefabricated cracks parallel to the long edge;
each set of the straightener comprises a controller, a force measuring sensor, a straightening plate, a telescopic rod, a contact sensor and a displacement sensor;
a controller for driving the extension and contraction movement of the correction plate;
the force sensor is used for detecting the extrusion force between the correction plate and the sample;
the correcting plates are used for limiting and blocking the left and right lateral displacement of the sample and preventing the sample from cracking towards two sides;
the displacement sensor is used for detecting the stretching displacement of the correcting plate;
the contact sensor is arranged on the correcting plate adjacent to one side of the sample and used for detecting the contact condition of the correcting plate and the sample and ensuring that the extrusion force between the correcting plate and the sample is zero, so that the correcting plate always keeps the correcting pose still and abuts against the left side and the right side of the soil mass sample to form a pair of opposite side shearing forces, the prefabricated cracks are prevented from cracking from the tip to the two sides, and the sample is separated from the crack to the two sides, the development trend from type II cracking to type I-II mixed cracking is restrained, and the soil mass sample is enabled to generate pure type II cracking at the tip of the two prefabricated cracks;
the arrangement of the two prefabricated cracks can simultaneously test the two prefabricated cracks on the same sample, and compare the test results;
the II-type fracture device platform is a magnetic suspension device, the magnetic suspension device comprises three magnetic suspension platforms which are arranged in parallel and can lift and suspend under the action of magnetic force and keep the same height; and a gap is formed between every two adjacent magnetic suspension platforms and corresponds to the position of a prefabricated crack on the sample.
2. The soil mass type II fracture test correcting device of claim 1, wherein: the controller is fixed in position and is connected with the correction plate through the telescopic rod.
3. The soil mass type ii fracture test correcting device of claim 2, wherein: the controller, the force measuring sensor, the correcting plate, the telescopic rod, the contact sensor and the displacement sensor in each set of the corrector are respectively provided with two, the force measuring sensor and the displacement sensor are both arranged on the corresponding telescopic rods, and the contact sensor is arranged on the correcting plate corresponding to the telescopic rods and adjacent to one side of the sample.
4. The soil mass type ii fracture test correcting device of claim 2, wherein: the controller is controlled by a speed regulating motor.
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CN102980816A (en) * 2012-12-06 2013-03-20 重庆交通大学 Soil mass shearing rupture failure testing device and method
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