CN112945757A - Shearing device for fatigue test - Google Patents
Shearing device for fatigue test Download PDFInfo
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- CN112945757A CN112945757A CN202110245736.5A CN202110245736A CN112945757A CN 112945757 A CN112945757 A CN 112945757A CN 202110245736 A CN202110245736 A CN 202110245736A CN 112945757 A CN112945757 A CN 112945757A
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- 238000010008 shearing Methods 0.000 title claims abstract description 133
- 238000009661 fatigue test Methods 0.000 title claims abstract description 23
- 239000002689 soil Substances 0.000 claims abstract description 103
- 230000002457 bidirectional effect Effects 0.000 claims abstract description 13
- 230000005540 biological transmission Effects 0.000 claims description 28
- 230000000087 stabilizing effect Effects 0.000 claims description 15
- 239000004575 stone Substances 0.000 claims description 15
- 238000003825 pressing Methods 0.000 claims description 12
- 230000009467 reduction Effects 0.000 claims description 12
- 230000007246 mechanism Effects 0.000 claims description 7
- 238000005096 rolling process Methods 0.000 claims description 6
- 230000006835 compression Effects 0.000 claims description 3
- 238000007906 compression Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 25
- 230000008569 process Effects 0.000 abstract description 17
- 238000005259 measurement Methods 0.000 abstract description 9
- 230000009471 action Effects 0.000 abstract description 6
- 230000007547 defect Effects 0.000 abstract description 2
- 238000012360 testing method Methods 0.000 description 38
- 238000006073 displacement reaction Methods 0.000 description 17
- 229910000831 Steel Inorganic materials 0.000 description 13
- 239000010959 steel Substances 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 238000005520 cutting process Methods 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000000149 penetrating effect Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000178 monomer Substances 0.000 description 3
- 239000010963 304 stainless steel Substances 0.000 description 2
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
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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
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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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
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
- G01N3/38—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by electromagnetic means
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- 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
- G01N2203/0001—Type of application of the stress
- G01N2203/0005—Repeated or cyclic
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- 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
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- 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
- G01N2203/003—Generation of the force
- G01N2203/005—Electromagnetic means
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- 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
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0073—Fatigue
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- General Health & Medical Sciences (AREA)
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- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention relates to the technical field of shearing devices, and discloses a shearing device for a fatigue test, which comprises: support body, shearing part, two deformation measurement portions and two-way power portion, shearing part along left right direction sliding connection on the support body for fixed soil sample and shearing soil sample, two deformation measurement portions set up respectively in the left and right sides of shearing part, on two deformation measurement portions were fixed in the support body respectively, be used for measuring the deformation volume of soil sample, two-way power portion is connected with shearing part, so that shearing part slides left or right along left right direction. The invention provides a shearing device capable of considering fatigue action, which utilizes a bidirectional power part to control bidirectional shearing force, thereby changing the direction of the shearing stress of a sample in the shearing process and overcoming the defect that the strain control type direct shear in the prior art can not measure the fatigue strength of a soil sample.
Description
Technical Field
The invention relates to the technical field of shearing devices, in particular to a shearing device for a fatigue test.
Background
The fatigue of the soil body means that the soil body moves under the action of load, the strength and deformation characteristics of the soil are influenced, the strength and deformation of the soil under different dynamic loads are different, the common characteristic of the fatigue is that the soil body is influenced by the loading rate and the loading times, and the strain is increased along with the time extension.
The international development of the research on the soil fatigue starts from the material fatigue theory proposed by Bingham in 1928, and through the efforts of numerous scholars, the research on the soil fatigue obtains a great result, in the shear fatigue test, the shear fatigue test of the soil can be divided into two main types of direct methods and indirect methods according to different modes of applied load and shear force, wherein the direct methods refer to methods for directly applying shear force to carry out the fatigue test on a soil sample and comprise direct shear, torsion tests and simple shear tests; the indirect principle refers to a method for carrying out fatigue test on a soil sample by utilizing uniaxial or triaxial compression load, and comprises a uniaxial test, a triaxial shear test and the like.
All kinds of instruments have respective advantages and disadvantages: the shearing area of the torsion test is constant, but the internal and external peripheries of the soil sample stress are not uniform, and the sample preparation requirement is high; the triaxial test is relatively uniform in stress, but the manufacturing cost is high; the strain control type direct shear apparatus for the soil test instrument in China has low manufacturing cost and is widely applied, a soil sample can be applied to the apparatus under different vertical pressures by the aid of the strain control type direct shear apparatus, then the shear strength coefficient, the internal friction angle and the cohesive force of the soil are determined according to the coulomb law, the currently adopted unidirectional horizontal acting force of the apparatus reaches a required unidirectional horizontal thrust value through a pushing device of a mechanical rod and is connected with a thrust motor, unidirectional horizontal displacement of the soil sample is tested, the shear direction is invariable all the time, the shear stress is increased continuously, and the apparatus is not a strict fatigue test.
Disclosure of Invention
The invention provides a shearing device capable of considering fatigue action, which utilizes a bidirectional power part to control bidirectional shearing force, thereby changing the direction of the shearing stress of a sample in the shearing process and overcoming the defect that the strain control type direct shear in the prior art can not measure the fatigue strength of a soil sample.
The invention provides a shearing device for a fatigue test, which comprises:
the cutting part is connected to the frame body in a sliding mode along the left and right directions and used for fixing the soil sample and cutting the soil sample;
the two deformation measuring parts II are respectively arranged on the left side and the right side of the shearing part I, and are respectively fixed on the frame body and used for measuring the deformation quantity of the soil sample;
and the bidirectional power part III is connected with the shearing part I so as to enable the shearing part I to slide leftwards or rightwards along the left-right direction.
Optionally, the bidirectional power part III includes:
the transmission part is connected to the shearing part I;
and the power mechanism is connected with the transmission piece and is used for providing bidirectional power to the left or right for the transmission piece.
Optionally, the power mechanism includes:
the power box is fixed on the frame body, a motor body and a reduction gearbox are arranged inside the power box, and the output end of the motor body is connected with the reduction gearbox;
the center of the driving gear is fixedly connected with an output shaft of the reduction gearbox so as to enable the driving gear to rotate in a vertical plane;
the two driven gears are positioned below the driving gear and hinged with the power box through a rotating shaft;
the double-sided rack is connected in the power box along the left and right directions, and the driving gear and the two driven gears are respectively meshed with the tooth surfaces on the two sides of the driving gear and the two driven gears;
and the two transmission rods are fixedly connected to two ends of the double-sided rack respectively along the horizontal direction and extend out of the left side wall and the right side wall of the power box, and the transmission part is connected with the transmission rods.
Optionally, the transmission member comprises:
the two connecting rods are respectively and horizontally fixedly connected to the transmission rod;
two ends of the right-angle bent rod are respectively and vertically fixedly connected to the two connecting rods;
the straight rod is arranged along the vertical direction, one end of the straight rod is fixedly connected to the right-angle bent rod, and the other end of the straight rod is connected with the shearing part I.
Optionally, each deformation measuring part II includes:
the stabilizing frame is positioned on the left side or the right side of the shearing part I and is fixed on the frame body;
the two supporting guide wheels are respectively and symmetrically arranged at the upper part and the lower part of the maintenance frame;
the shearing ring is fixedly arranged on the frame body and is positioned on one side of the stabilizing frame, which is far away from the shearing part I;
the end of one side, close to the shearing part I, of the connecting frame extends into the space between the two supporting guide wheels, and the end of one side, far away from the shearing part I, of the connecting frame is fixedly connected with the shearing ring;
the deformation measuring meter is fixedly connected to the frame body, and one side end, close to the connecting frame, of the deformation measuring meter is in close contact with the end face of the connecting frame;
and the compression frame is fixedly arranged at one side end of the shear ring far away from the connecting frame.
Optionally, the cutting portion I includes:
the lower direct shear box is connected to the frame body and positioned between the two deformation measuring parts II;
the upper direct shear box is detachably connected to the upper end of the lower direct shear box, and a cavity body for containing permeable stones and soil samples is formed between partial space of the lower direct shear box and the upper direct shear box;
and the pressing cover is positioned at the upper end of the upper direct shear box and is used for applying vertical downward acting force to the cavity body.
Optionally, a slide rail is mounted on the end face of the frame body contacting with the lower direct shear box, rolling balls are uniformly distributed in the slide rail, and the rolling balls contact with the lower direct shear box.
Optionally, the motor further comprises a control system, and the control system is connected with the motor body.
Compared with the prior art, the invention has the beneficial effects that:
(1) in the traditional direct shear test process, an instrument only controls the shear direction to be unchanged, the shear area of a soil sample is reduced, the shear stress is increased, and the test process is not a fatigue test in the real sense;
(2) the device can meet the stress control of different shearing stresses in a fatigue shearing test, is convenient to operate and has certain precision;
(3) the device can be simply reconstructed by an old direct shear apparatus to form a simple fatigue strength measuring device, and the direct shear apparatus has simple structure, low manufacturing cost and is suitable for popularization;
(4) because the device is provided with two symmetrical shearing rings, the shearing rings and the upper shearing box are always in a relative static state, so that the shearing force generated by the soil body stress in the soil body shearing process can be directly and accurately measured, the actual shearing force can be measured, the test result is credible, and the precision can meet the engineering design requirement.
Drawings
FIG. 1 is a schematic diagram of a power device, a shearing device and a displacement measuring device according to an embodiment of the present invention;
FIG. 2 is a schematic view of the internal structure of the power mechanism;
FIG. 3 is a schematic view of the internal structure of the transmission member;
FIG. 4 is a front sectional view showing a structure of a strain measuring section;
FIG. 5 is a front sectional view of the cutout portion;
FIG. 6 is a side sectional view of the cutout portion;
fig. 7 is a schematic structural diagram of a control type fatigue test direct shear apparatus and an implementation method thereof according to an embodiment of the present invention;
fig. 8 is a circuit diagram showing the operation of the motor of the present invention.
Description of reference numerals:
i-a shearing section; II-deformation measuring part; III-a bidirectional power section; 0-shearing apparatus body; 1-a frame body; 2-a frame surface; 201-through slot; 3-a frame surface; 4-a transmission member; 401-proximity switches; 402-an operation interface; 403-a connecting rod; 404-right angle bent rod; 405-straight rods; 5-a power mechanism; 500-a power box; 501-a driving gear; 502-driven gear; 503-double-sided rack; 504-a transmission rod; 6-lower direct shear box; 602-permeable stone; 603-soil sample; hole site-604; 7-a slide rail; 8, mounting a direct shear box; 801-horizontal column; 802-a stability chamber; 803-stabilizing nails; 9-pressing the cover; 901-longitudinal slack valve; 10-a pressure applying frame; 11-dimensional stable frame; 12-a supporting guide wheel; 13-a connecting frame; 14-a shear ring; 15-deformation measuring meter; 16-deformation meter holder; 17-a pressure bearing frame; 18-a carrier table; 19-a conditioning stage; 20-a transverse elasticity valve; 21-a strut; 22-a counterweight block; 23-a scale beam; 2301-run code; 24-a bracket; 2401-a backing valve; 2402-bearing plate; 2403-longitudinal elasticity valve; 25-weight placing rack.
Detailed Description
An embodiment of the present invention will be described in detail below with reference to the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the embodiment.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing technical solutions of the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
The shearing device with the consideration of fatigue provided by the invention utilizes the motor to control the bidirectional shearing force, thereby changing the direction of the shearing stress of the sample in the shearing process, measuring the stress condition of the soil sample by adding a shearing ring device on the instrument, the corresponding comparison test is carried out on the device, the shearing stress of the device of the invention in the motion process of the soil under the action of load is detected, and the test result shows that, the simple device can simulate the fatigue effect generated in the motion process of a soil body under the action of load to a certain extent, test the change of the strain of the soil sample under a certain shearing force along with time, change the normal stress by taking the magnitude of the shearing stress as the shearing strength value of the soil sample under the given normal pressure to obtain the corresponding shearing strength, draw the relation curve of the shearing strength and the normal stress and obtain the shearing strength parameter of the sample.
As shown in fig. 1, a shearing apparatus for a fatigue test according to an embodiment of the present invention includes: support body 1, shearing part I, two deformation measurement portions II and two-way power portion III, shearing part I is along controlling direction sliding connection on support body 1 for the soil sample is cuted to the stationary soil appearance, two deformation measurement portions II set up respectively in shearing part I's the left and right sides, two deformation measurement portions II are fixed in on support body 1 respectively, a deformation volume for measuring the soil sample, two-way power portion III is connected with shearing part I, so that shearing part I slides left or right along controlling the direction.
In the traditional direct shear test process, the shear direction is controlled to be unchanged by an instrument, the shear area of the soil sample is reduced, the shear stress is increased, and the test process is not a fatigue test in the real sense.
As shown in fig. 2, the bidirectional power section III includes: driving medium 4 and power unit 5, driving medium 4 connects on shearing part I, and power unit 5 is connected with driving medium 4 for driving medium 4 provides left or right two-way power, and power unit 5 includes: the power box 500 is fixed on the frame body 1, a motor body and a reduction gearbox are arranged inside the power box 500, the output end of the motor body is connected with the reduction gearbox, the center of the driving gear 501 is fixedly connected with the output shaft of the reduction gearbox, so that the driving gear 501 rotates in a vertical plane, two driven gears 502 are located below the driving gear 501, hinged with the power box 500 through a rotating shaft, a double-sided rack 503 is connected in the power box 500 along the left and right direction, a driving gear 501 and two driven gears 502 are respectively meshed with the tooth surfaces at the two sides of the driving gear 501 and the two driven gears 502, two driving rods 504 are respectively fixedly connected at the two ends of the rack 503 along the horizontal direction, and extend out of the left and right side walls of the power box 500, the transmission member 4 is connected with the transmission rod 504, and the two driven gears 502 and the driving wheel 501 can prevent the double-sided rack 503 from swinging or falling off during operation.
As shown in fig. 3, the transmission member 4 includes: the two connecting rods 403, the right-angle bent rod 404 and the straight rod 405, wherein the two connecting rods 403 are horizontally and respectively fixedly connected to the transmission rod 504, two ends of the right-angle bent rod 404 are respectively and vertically and fixedly connected to the two connecting rods 403, the straight rod 405 is arranged in the vertical direction, one end of the straight rod is fixedly connected to the right-angle bent rod 404, and the other end of the straight rod is connected to the shearing part I.
As shown in fig. 4, the strain measurement section II includes: the device comprises a maintaining and stabilizing frame 11, two supporting guide wheels 12, a shearing ring 14, a connecting frame 13, a deformation measuring meter 15 and a pressure-bearing frame 17, wherein the maintaining and stabilizing frame 11 is positioned on the left side or the right side of a shearing part I and is fixed on a frame body 1, the two supporting guide wheels 12 are respectively and symmetrically arranged on the upper part and the lower part of the maintaining and stabilizing frame 11, the shearing ring 14 is fixedly arranged on the frame body 1 and is positioned on one side of the maintaining and stabilizing frame 11 away from the shearing part I, one side end of the connecting frame 13 close to the shearing part I extends into the space between the two supporting guide wheels 12, one side end of the connecting frame 13 far away from the shearing part I is fixedly connected with the shearing ring 14, the deformation measuring meter 15 is fixedly connected on the frame body 1, one side end of the deformation measuring meter 15 close to the connecting frame 13 is in close contact with the end surface of the connecting frame 13, the pressure-bearing frame 17 is fixedly arranged on one side end of the shearing ring 14 far, the position of the horizontal column is roughly adjusted, the transverse elasticity valve is responsible for finely adjusting the position of the connecting frame 13, so that the initial value of the measured pressure is zero, the shearing force applied to a test sample in the initial state is extremely weak and can be ignored, the accuracy of experimental data is improved, the stabilizing frame 11 is used for keeping the horizontal alignment of the shear ring 14 and the horizontal column 801, the deformation of the horizontal left or right shear ring 14 is measured in one test, the deformation measuring meter 15 is used for measuring the deformation of the shear ring 14, and the stress generated by the soil sample 603 is calculated on the premise that the elastic modulus of the shear ring 14 is known.
As shown in fig. 5 to 6, the cutout I includes: lower staight scissors box 6, go up staight scissors box 8 and the lid 9 of exerting pressure, lower staight scissors box 6 is connected on support body 1, is located between two deformation measurement portions II, goes up staight scissors box 8 and can dismantle the upper end of connecting in staight scissors box 6 down, forms the cavity body that contains pervious stone 602 and soil sample 603 between the partial space of staight scissors box 6 and the last staight scissors box 8 down, and the lid 9 of exerting pressure links firmly in the upper end of last staight scissors box 8, exerts vertical decurrent effort for pervious stone 602 and soil sample 603 in the cavity body.
The lower straight shear box 6 is provided with a space capable of containing a permeable stone 602 and a part of soil sample 603, the upper straight shear box 8 penetrates through the lower straight shear box as the center, the penetrating part is provided with another permeable stone 602, the rest part of soil sample 603 and a part of the pressure applying cover 9, and the space capable of containing a permeable stone 602 and a part of soil sample 603, the permeable stone 602, the soil sample 603, the center penetrating part of the upper straight shear box 8 and the pressure applying cover 9 in the lower straight shear box 6 are basically identical in cross-sectional area (the permeable stone 602, the soil sample 603 and the pressure applying cover 9 are slightly smaller because the three parts are to be placed in a cavity formed by the straight shear box 6 and the upper straight shear box 8), and the centroids of the cross sections of the five parts are positioned on the same plumb line.
Optionally, a slide rail 7 is installed on the end face of the frame body 1 contacting with the lower direct shear box 6, rolling balls are uniformly distributed in the slide rail 7, and the rolling balls contact with the lower direct shear box 6.
Optionally, the motor further comprises a control system, and the control system is connected with the motor body.
All the mechanical structural parts of the invention are made of 304 stainless steel and aviation steel with higher strength, thus greatly improving the corrosion resistance, the upper shearing box 8 and the lower shearing box 6 are made of 304 stainless steel, the corrosion resistance is stronger, the rigidity strength and the durability of the shearing knife edge are improved, and the service life is long.
Aiming at the problems of the existing stress type direct shear apparatus, the direct shear apparatus of the invention is mainly improved in two aspects:
firstly, a shearing force loading device of an instrument is modified, a motor is used for controlling bidirectional shearing force, so that the direction of the shearing stress of a sample in the shearing process is changed, the stress condition of a soil sample is measured by adding a shearing ring device on the instrument, and the fatigue effect generated in the motion process of a soil body under the action of load can be simulated to a certain extent;
and secondly, by improving the shear force measuring device of the instrument, two shear rings which are symmetrically distributed are adopted during a soil body shear test, the direction of the shear stress is changed during the shearing process, and the stress condition of the soil sample is measured by the improved shear ring device on the instrument.
1. The two side gear faces of the driven double gear extend outwards, the center of the driven double gear is fixed on the transmission case through the bearing, the driven double gear can be guaranteed to rotate smoothly through the design, and meanwhile, the double-sided rack can be prevented from swinging or falling off during operation.
2. The position of the lower end of the pressure applying frame on the weighing beam is set according to the analog value of the pressure applied to the soil sample and is fixed.
3. For obtaining more accurate test data, the soil sample particle size suitable for the device should not be more than 3mm, because too large particle size can not be put into the direct shear cavity and applied pressure and fixed, influence the accuracy of direct shear data.
4. The shear ring and the connecting frame guarantee the measurement accuracy of the deformation measuring meter, during early preparation, the position of the horizontal column is adjusted roughly, and the transverse elastic valve is responsible for fine adjustment of the position of the connecting frame, so that the initial value of the measured pressure is zero, and in an initial state, the shear force applied to a sample is extremely weak and can be ignored, and the accuracy of test data is improved.
The practical use result of the invention shows that the invention has the advantages of convenient operation, high stability, same speed and step displacement, convenient initial state adjustment, accurate and rapid direct shear pressure data recording, and is suitable for popularization and use in the direct shear test of fatigue determination of the real soil sample in the test chamber.
Compared with the prior art, the invention has the beneficial effects that:
(1) in the traditional direct shear test process, an instrument only controls the shear direction to be unchanged, the shear area of a soil sample is reduced, the shear stress is increased, and the test process is not a fatigue test in the real sense;
(2) the device can meet the stress control of different shearing stresses in a fatigue shearing test, is convenient to operate and has certain precision;
(3) the device can be simply reconstructed by an old direct shear apparatus to form a simple fatigue strength measuring device, and the direct shear apparatus has simple structure, low manufacturing cost and is suitable for popularization;
(4) because the device is provided with two symmetrical shearing rings, the shearing rings and the upper shearing box are always in a relative static state, the shearing force generated by the soil body stress in the soil body shearing process is directly and accurately measured, the actual shearing force can be directly measured, the test result is credible, and the precision can meet the engineering design requirement.
The invention adopts the SRM timing driving technology and is matched with various mechanical structures, thereby realizing accurate and rapid recording of the direct shear pressure data of the soil sample.
Referring to fig. 7 and 8, the complete structure of the apparatus of the present invention comprises: a main body 0 of the strain direct shear apparatus, a frame body 1, an operation table 2 and an operation table 3 are arranged on the main body 0 of the strain direct shear apparatus, the operation table 2 and the operation table 3 are fixed on the frame body 1, a proximity switch 401, a power part 4 and a power box 500 are fixedly arranged on the left side of the operation table 3, a motor body and a reduction box are arranged inside the power box 500, the output end of the motor body is connected with the reduction box, the proximity switch 401 is electrically connected with a control circuit board, an operation interface 402 is arranged on the right side of the top of the power box 500, a signal transmission port of the operation interface 402 is electrically connected with the control circuit board, a driving gear 501, a driven double-gear 502 and a double-sided rack 503 are arranged in the power box 500, the center of the driving gear 501 is fixedly connected with the output shaft of the reduction box, the transmission rod 504 and the steel connecting rod 403 are horizontally fixedly connected with each other, the steel connecting rod 403 and the steel right-angle bent rod 404 are vertically fixedly connected with each other, the steel straight rod 405 is vertically connected with the upper end of the center of the steel right-angle bent rod 404, the steel straight rod 405 is vertical to the operation table top 2, the steel straight rod 405 penetrates through the operation table top 2 through the through groove 201 and enters the hole 604 at the lower part of the lower straight shear box 6, the hole 604 is located at the center of the end face at the lower part of the operation table top 6, the through groove 201 is arranged in the middle of the operation table top 2 right below the hole 604, the transmission rod 504, the steel connecting rod 403, the steel right-angle bent rod 404, the steel straight rod 405, the through groove 201 and the hole 604 are coplanar, the formed plane is vertical to the operation table top 2 and the operation table top 3, the sliding rail 7, the stabilizing frame 11 and the pressure, an upper direct shear box 8 and a pressure applying cover 9 are placed on a lower direct shear box 6, a space capable of containing a permeable stone 602 and a part of soil sample 603 is arranged in the lower direct shear box 6, the upper direct shear box 8 penetrates through the center, the other permeable stone 602, the rest part of soil sample 603 and a part of the pressure applying cover 9 can be stored in the penetrating part, the top end of the pressure applying cover 9 is connected with a longitudinal elasticity valve 901, the longitudinal elasticity valve 901 is installed at the top end of a pressure applying frame 10, horizontal columns 801 are fixedly installed on the left side and the right side of the 8, a stabilizing frame 11 is installed on the left side and the right side of a sliding rail 7, and two supporting guide wheels 12 which are vertically arranged are arranged in the middle of; the left side and the right side of the operation table top 2 are provided with a shearing ring 14, a deformation measuring meter 15, a bearing table 18 and an adjusting table 19, the left end and the right end of the shearing ring 14 are respectively and fixedly provided with a connecting frame 13 and a pressure frame 17, the left output rod of the pressure frame 17 is provided with two deformation measuring meter holders 16, the upper ends of the two deformation measuring meter holders 16 are fixedly provided with the deformation measuring meter 15, the pressure measuring rod at the left end of the deformation measuring meter 15 is tightly contacted with the right end surface of the connecting frame 13, the left end of the connecting frame 13 extends into the space between the two supporting guide wheels 12, the pressure frame 17 is flatly arranged on the bearing table 18, the right side surface of the pressure frame 17 is sleeved with a transverse elasticity valve 20, and the transverse elasticity valve; a supporting rod 21, a scale beam 23 and a force supporting frame 24 are arranged below the operation table board 2, a balancing weight 22 is arranged at the left end point of the scale beam 23, the left end of the scale beam 23 is rotatably connected with the supporting rod 21, the left side of the scale beam 23 is rotatably connected with the lower end of the pressure applying frame 10, the right side of the scale beam 23 penetrates through the force supporting frame 24, a force supporting valve 2401 and a force supporting plate 2402 are arranged at the lower end of the force supporting frame 24, and a weight placing frame 25 is arranged at the right end point of the scale beam 23.
The use method and the working principle are as follows: in the early stage of the test, soil samples of different soil layers are classified and numbered, samples with different particle sizes are screened out from the soil sample of the same soil layer through a standard screen, and the samples are numbered and placed; according to requirements, a specimen and the weight of the specimen are selected and evenly divided into monomer soil samples (about 260g of the monomer soil samples are needed in a common single test), then, a soil compaction test is carried out to determine the optimal water content of the soil samples, water with a set proportion is evenly mixed into the monomer soil samples (the optimal water content of the soil samples determines the water adding amount), the water content of the soil samples is made to reach or approach the optimal water content as far as possible, and the optimal effect can be achieved.
The direct shear test was started with the detailed procedure as follows:
preparing soil samples 603 with the water content reaching or approaching the optimal water content and placing the prepared soil samples into a cutting ring, wherein each group of soil samples 603 is not less than 4;
aligning a lower shearing box 6 and an upper shearing box 8 of a shearing container, inserting a fixing pin 803, placing a permeable stone 602 and circular filter paper (the diameter of the circular permeable stone 602 and the circular filter paper is consistent with the inner diameter of a direct shearing cavity 601 and the diameter is the same as the inner diameter of the direct shearing cavity 601) in the lower shearing box 6, aligning the cutting edge of a cutting ring of a soil sample 603 upwards with the opening of the shearing box, carefully placing the soil sample 603 in the direct shearing cavity 601 in the shearing box, enabling half of the soil sample 603 to be located in the lower shearing box 6 and half of the soil sample 603 to be located in the upper shearing box 8 (at the moment, the soil sample 603 is not damaged and the soil sample 603 is in an integral cylinder), sequentially placing the filter paper and the permeable stone 602 on the soil sample 603 in the upper shearing box 8, shifting a pressing frame 10 aside, inserting a stabilizing nail 803 into a stabilizing cavity 802, and finally placing a;
placing the shearing container device (I) on a slide rail 7 of an operation table top 2, placing a steel straight rod 404 penetrating through the operation table top 2 in a hole position 604 at the lower part of a lower direct shear box 6, placing a pressing frame 10 above a pressing cover 9, and pressing the pressing frame 10 and the pressing cover 9 through a longitudinal tightening valve 901, wherein at the moment, the pressing cover 9 is naturally pressed in the whole process and is forbidden to be pressed by external force;
the transmission rod 504 is retracted leftwards by a reversing switch key in the operation interface 402 until the steel connecting rod is positioned at the middle position of the left touch proximity switch 401 and the right touch proximity switch 401;
the position of a pressure plate at the lower end of the pressure support frame 24 is adjusted to ensure that the weight beam 23 cannot be touched in the test, a proper weight is placed on the weight placing frame 25, the direct shear test requires that the pressure of the sample of the water and the soil is 50kN, 100kN, 200kN and 400kN in sequence, and each pressure value corresponds to one direct shear test;
after applying the vertical pressure, the stabilizing nail 803 is pulled out, and the first operation: the transmission rod 504 is moved forward rightwards through an advancing key in the operation interface 402 to shear rightwards at a shearing speed of less than 0.02mm/min, and the reading of the right deformation measuring meter 15 is measured and recorded when the soil sample 603 generates shearing displacement of 0.2-0.4 mm until the reading of the deformation measuring meter 15 has a peak value; and operation II: the driving rod 504 is retracted leftwards through a retraction key in the operation interface 402, and similarly, when the soil sample 603 generates shearing displacement of 0.2-0.4 mm, the reading of the left deformation measuring meter 15 is measured and recorded; circularly operating the first operation and the second operation until the shearing displacement of the left side and the right side is 4mm, stopping the machine, and recording a damage value;
after shearing is finished, sucking accumulated water in the shearing box, removing shearing force and vertical pressure, moving the pressing frame 10 and the pressing cover 9, taking out the soil sample 603, and measuring the water content of the soil sample 603;
replacing the weight and repeating the test; changing the particle size and testing again; replacing the soil sample and testing again; direct shear test data of all soil samples can be obtained.
The shear stress should be calculated as follows: τ ═ C · R
In the formula: τ is the shear stress; c is a correction coefficient of the dynamometer;
shear displacement is calculated as follows: Δ L ═ 20n-R
In the formula: Δ L is shear displacement 0.01 mm; n is the number of revolutions of the driving wheel 501; r is the reading of a deformation measuring meter 15;
drawing a relation curve of the shear stress and the shear displacement by taking the shear stress as a vertical coordinate and the shear displacement as a horizontal coordinate, taking a peak value of the shear stress on the curve as the shear strength, and taking the shear stress corresponding to the shear displacement of 4mm as the shear strength when the peak value does not exist;
drawing a relation curve of the normal displacement and the shearing displacement by taking the normal displacement as a vertical coordinate and the shearing displacement as a horizontal coordinate to obtain tensile strength characteristics of the soil body;
and drawing a relation curve of the shear strength and the vertical pressure by taking the shear strength as a vertical coordinate and the vertical pressure as a horizontal coordinate, wherein the dip angle of the straight line is a friction angle, and the intercept of the straight line on the vertical coordinate is cohesive force.
The invention can measure the shear strength index on the specific shearing surface of the soil body, and draw a relation curve of shear stress and normal stress, a relation curve of shear deformation and normal deformation, and a relation curve of shear stress and normal deformation, thereby obtaining the shear strength parameters of the soil body on the specific failure surface, namely the internal friction angle and cohesive force, and the tensile strength characteristic of the soil body.
The fatigue life of the soil body is related to the shear stress tau and the shear displacement delta L of the soil body, and the relation between the shear stress tau and the shear displacement delta L can be represented by a shear stress-life curve (tau-N curve) and a shear displacement-life curve (delta L-N curve). The mathematical expression can be obtained by experiments:
τ·m·N＝c
in the formula: n stress cycle number;
and m and c are material constants.
And finally, drawing all the data into a plurality of line graphs or wave graphs, so that the influence of soil layers, particle sizes and water contents on the shearing force borne by the soil sample can be analyzed more visually, the maximum shearing force borne by the soil in different soil layers in a stressed environment of the soil body can be simulated, and the particle sizes and the water contents of the soil when the maximum value is obtained, so that the technical support is provided for the construction of the soil subgrade.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
The above disclosure is only for a few specific embodiments of the present invention, however, the present invention is not limited to the above embodiments, and any variations that can be made by those skilled in the art are intended to fall within the scope of the present invention.
Claims (8)
1. The utility model provides a fatigue test's shearing mechanism, includes support body (1) and shearing portion (I), shearing portion (I) along left right direction sliding connection in on support body (1) for fixed soil sample (603) and shearing soil sample (603), its characterized in that still includes:
the two deformation measuring parts (II) are respectively arranged at the left side and the right side of the shearing part (I), and are respectively fixed on the frame body (1) and used for measuring the deformation quantity of the soil sample (603);
and the bidirectional power part (III) is connected with the shearing part (I) so as to enable the shearing part (I) to slide leftwards or rightwards along the left-right direction.
2. A shear device for fatigue testing according to claim 1, wherein said bi-directional power section (III) comprises:
a transmission member (4) connected to the shearing part (I);
and the power mechanism (5) is connected with the transmission piece (4) and is used for providing left or right bidirectional power for the transmission piece (4).
3. A shear device for fatigue testing according to claim 2, wherein the power mechanism (5) comprises:
the power box (500) is fixed on the frame body (1), a motor body and a reduction gearbox are arranged inside the power box (500), and the output end of the motor body is connected with the reduction gearbox;
the center of the driving gear (501) is fixedly connected with an output shaft of the reduction gearbox, so that the driving gear (501) rotates in a vertical plane;
the two driven gears (502) are positioned below the driving gear (501) and hinged with the power box (500) through rotating shafts;
the double-sided rack (503) is connected into the power box (500) along the left-right direction, and the driving gear (501) and the two driven gears (502) are respectively meshed with the tooth surfaces on the two sides of the driving gear;
the two transmission rods (504) are fixedly connected to two ends of the double-sided rack (503) in the horizontal direction respectively and extend out of the left side wall and the right side wall of the power box (500), and the transmission piece (4) is connected with the transmission rods (504).
4. A shear device for fatigue testing according to claim 3, wherein said transmission member (4) comprises:
the two connecting rods (403) are respectively and horizontally fixedly connected to the transmission rod (504);
two ends of the right-angle bent rod (404) are respectively and vertically fixedly connected to the two connecting rods (403);
the straight rod (405) is arranged along the vertical direction, one end of the straight rod is fixedly connected to the right-angle bent rod (404), and the other end of the straight rod is connected with the shearing part (I).
5. A shear device for fatigue testing according to claim 1, wherein each of said deformation measuring portions (II) comprises:
the maintaining and stabilizing frame (11) is positioned on the left side or the right side of the shearing part (I) and is fixed on the frame body (1);
the two supporting guide wheels (12) are respectively and symmetrically arranged at the upper part and the lower part of the stabilizing frame (11);
the shearing ring (14) is fixedly arranged on the frame body (1) and is positioned on one side, far away from the shearing part (I), of the stabilizing frame (11);
the connecting frame (13) extends into the space between the two supporting guide wheels (12) at one side end close to the shearing part (I), and one side end far away from the shearing part (I) is fixedly connected with the shearing ring (14);
the deformation measuring meter (15) is fixedly connected to the frame body (1), and one side end, close to the connecting frame (13), of the deformation measuring meter (15) is in close contact with the end face of the connecting frame (13);
and the compression frame (17) is fixedly arranged at one side end of the shear ring (14) far away from the connecting frame (13).
6. A shear device for fatigue testing according to claim 1, wherein said shear section (I) comprises:
the lower direct shear box (6) is connected to the frame body (1) and is positioned between the two deformation measuring parts (II);
the upper direct shear box (8) is detachably connected to the upper end of the lower direct shear box (6), and a cavity for containing the permeable stone (602) and the soil sample (603) is formed between partial space of the lower direct shear box (6) and the upper direct shear box (8);
and the pressing cover (9) is positioned at the upper end of the upper direct shear box (8) and is used for applying vertical downward acting force to the hollow cavity.
7. A shearing device for a fatigue test as claimed in claim 6, wherein the end face of the frame body (1) contacting with the lower straight shear box (6) is provided with a slide rail (7), rolling balls are uniformly distributed in the slide rail (7), and the rolling balls contact with the lower straight shear box (6).
8. A shear device for fatigue testing according to claim 3, further comprising a control system, said control system being connected to said motor body.
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| WO2021008009A1 (en) * | 2019-07-17 | 2021-01-21 | 深圳大学 | Dynamic shear test device and method employing single-axis two-way synchronous control electromagnetic loading |
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| CN105842086A (en) * | 2016-06-08 | 2016-08-10 | 长江水利委员会长江科学院 | Low-friction laminar ring type bidirectional dynamic shear testing machine |
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Application publication date: 20210611 |