CN110749513A - Direct shear test device for rock fracture - Google Patents

Direct shear test device for rock fracture Download PDF

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Publication number
CN110749513A
CN110749513A CN201911142083.7A CN201911142083A CN110749513A CN 110749513 A CN110749513 A CN 110749513A CN 201911142083 A CN201911142083 A CN 201911142083A CN 110749513 A CN110749513 A CN 110749513A
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China
Prior art keywords
test piece
box
temperature
positioning rod
shear
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CN201911142083.7A
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CN110749513B (en
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赵志宏
陈跃都
赵星光
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Tsinghua University
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Tsinghua University
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/24Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02Details
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02Details
    • G01N3/04Chucks
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014Type of force applied
    • G01N2203/0025Shearing
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/022Environment of the test
    • G01N2203/0222Temperature
    • G01N2203/0226High temperature; Heating means
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/04Chucks, fixtures, jaws, holders or anvils
    • G01N2203/0482Chucks, fixtures, jaws, holders or anvils comprising sensing means

Abstract

The invention provides a direct shear test device for a rock fracture, which is characterized by comprising a shear box and a positioning assembly, wherein the shear box is provided with a cavity for accommodating a test piece and is formed by buckling an upper shear box and a lower shear box; the positioning assembly comprises a height positioning rod, a first protractor and a test piece clamp. Compared with the prior art, the rock fracture direct shear test device provided by the invention can fix rock test pieces with different fracture dip angles to meet the requirements of direct shear tests by arranging the positioning device capable of adjusting and measuring the angle. Through setting up the heating, can heat shear box and pour high temperature resistant cement mortar and the test piece in shear box, provide the supporting condition for developing of the direct shear test of natural cementation filling crack under the high temperature effect, have important meaning to the mechanical properties of probing the high temperature rock mass.

Description

Direct shear test device for rock fracture
Technical Field
The invention relates to the technical field of rock and rock mass mechanics, in particular to a direct shear test device for a rock fracture.
Background
Due to the development and change of the structural stress in the long geological age, cracks can be generated and expanded in the rock mass, a large number of randomly distributed natural joint crack networks are further formed, and the shear mechanical behavior and the shear strength directly influence the stability and the permeability of the local rock mass. Most natural joint cracks contain cemented fillers produced by chronogeological events, and the soft structural surface minerals weaken the shear strength of the joints, thereby complicating the shear mechanics of the natural joint cracks. In addition, for deep rock mass engineering, such as hot dry rock geothermal resource exploitation, high-level waste geological deep-burying disposal, and the like, in addition to the influence of cemented filling materials, the shearing characteristics of natural fractures are further influenced by the high-temperature environment suffered by the rock mass, so that the research on the shearing characteristics of natural joint fractures becomes increasingly difficult. Therefore, the study on the shearing behaviors such as the shearing strength, the sliding characteristic and the like of the natural cemented filling fracture under the high-temperature action is an urgent problem to be solved in the current deep high-temperature rock mechanics, and plays a vital role in controlling the deep resource exploitation efficiency and the stability of the surrounding rock.
At present, the most common method for researching the shearing mechanical behavior of the structural surface is a direct shearing test, and the collection and preparation of the structural surface can be generally divided into five types: the method comprises five methods of on-site sampling, on-site pouring, artificial splitting, indoor pouring, original rock carving and the like, wherein the on-site sampling is a main method for obtaining a soft structural surface containing natural cemented filling, and the method requires that a rock sample is prevented from being disturbed and damaged in the processes of collection, transportation and preparation and water is also prevented from being used. On the basis of obtaining the structural plane, the engineering force environment of the rock mass is simulated through indoor tests, and the deformation, the failure process and the mechanism of the jointed rock mass are analyzed, so that the method becomes an effective method for researching the jointed rock mass. At present, experts at home and abroad develop a great deal of experimental research on the direct shear property of the rock fracture and the direct shear property of the rock fracture under the action of temperature, and the related experimental device and Chinese invention patents mainly comprise: "rock specimen direct shear test device" (CN 207300761U) of Wuhan science and technology university. "a cylindrical rock sample direct shear device" of the university of Sichuan "(CN 207964511U). "loadable heating insulating layer cylinder for large-size rock direct shear test" (CN 110146371A) of Shandong science and technology university. "a device for measuring rock shear seepage at high temperature and high pressure" (CN 104596857A). "a rock direct shear test device under the action of temperature-humidity-chemical coupling" (CN 207300763U) of Shandong science and technology university. From the above, at present, a great deal of research is based on the direct shear test at normal temperature or high temperature, which is developed by artificially splitting cracks, or the simulation research on the strength and deformation characteristics of natural rock masses by prefabricating cracks in materials such as gypsum, cement mortar and the like. However, because of the problems about natural joint fractures such as random fracture inclination angles, indoor tests directly aiming at rock test pieces containing natural joints are less developed, and the disclosed invention patent does not have a direct shear test device aiming at the natural joint fractures and does not have a direct shear test device considering the natural cemented filling fractures under the action of high temperature.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a direct shear test device for rock fractures, which can be used for performing direct shear test on rock fractures of rock test pieces with different fracture inclination angles, and solves the problem that in the prior art, due to the fact that the rock fracture inclination angles of natural joints are random, the rock is difficult to fix, and the test is difficult to develop.
The invention provides a direct shear test device for a rock fracture, which comprises:
the shearing box is provided with a cavity for accommodating a test piece and is formed by buckling an upper shearing box and a lower shearing box; and
the positioning assembly comprises a height positioning rod, a first protractor and a test piece clamp, the length of the height positioning rod is adjustable, a second connecting hole is formed in one end of the height positioning rod, the test piece clamp comprises a rotating rod and a clamping portion, the clamping portion is provided with an opening capable of containing a test piece, one end of the rotating rod is vertically connected with the bottom of the clamping portion, a first connecting hole is formed in the other end of the rotating rod, and a first direction knob can penetrate through the first connecting hole and the second connecting hole to enable the test piece clamp to be detachably connected with the height positioning rod; the first protractor is arranged on the height positioning rod, and the origin of the first protractor is located on the axis of the second connecting hole.
Preferably, the positioning assembly further comprises an angle positioning rod and a second protractor, wherein a third connecting hole and a fourth connecting hole are respectively formed in two ends of the angle positioning rod, and the first direction knob can penetrate through the third connecting hole and the second connecting hole to enable one end of the angle positioning rod to be detachably connected with the height positioning rod; the second orientation knob can penetrate through the fourth connecting hole and the first connecting hole to enable the other end of the angle positioning rod to be detachably connected with the test piece fixture, and the second protractor is arranged on the angle positioning rod and the original point of the second protractor is located on the axis of the fourth connecting hole.
Preferably, the direct shear test device further comprises a heating assembly, wherein the heating assembly is used for heating the test piece to keep the temperature of the test piece constant after reaching a preset temperature.
Preferably, the heating assembly comprises an electric heating ring, a temperature sensor, a temperature raising device and a temperature acquisition device, wherein the temperature sensor is used for detecting the temperature of the test piece, and the temperature acquisition device is connected with the temperature sensor and is used for displaying the temperature measured by the temperature sensor; the electric heating ring wraps the outer wall of the shearing box, and the warming device is connected with the electric heating ring and controls the electric heating ring to warm.
Preferably, the heating assembly further comprises a flexible insulating layer, and the flexible insulating layer is wrapped on the outer side of the electric heating ring.
Preferably, a temperature monitoring hole is formed in the side wall of the shearing box, and the temperature sensor extends into the cavity of the shearing box from the outside of the shearing box through the temperature monitoring hole.
Preferably, the lower shearing box is provided with a mounting hole, the mounting hole is provided with an internal thread, the other end of the height positioning rod is provided with an external thread matched with the internal thread, and the height positioning rod and the lower shearing box can form threaded connection.
Preferably, go up the shearing box including the last box body and the upper cover plate of dismantling the connection, the shearing box is including the lower box body and the lower cover plate of dismantling the connection down, the upper cover plate with all seted up the water injection hole on the lower cover plate.
Preferably, the aperture of the water injection hole is 1-2 mm.
Preferably, the specimen holder further includes a circular holder which is surrounded on an outer wall of the holding portion.
Compared with the prior art, the rock fracture direct shear test device provided by the invention can fix rock test pieces with different fracture dip angles to meet the requirements of direct shear tests by arranging the positioning device capable of adjusting and measuring the angle. Through setting up the heating, can heat shear box and pour high temperature resistant cement mortar and the test piece in shear box, provide the supporting condition for developing of the direct shear test of natural cementation filling crack under the high temperature effect, have important meaning to the mechanical properties of probing the high temperature rock mass.
The features mentioned above can be combined in various suitable ways or replaced by equivalent features as long as the object of the invention is achieved.
Drawings
The invention will be described in more detail hereinafter on the basis of non-limiting examples only and with reference to the accompanying drawings. Wherein:
FIG. 1a is a schematic illustration of a test piece required to process a core of a hole drill having naturally cemented filling fractures to a direct shear test;
FIG. 1b is a schematic illustration of another test piece required to process a core of a hole drill having naturally cemented filling fractures to a direct shear test;
FIG. 1c is a schematic illustration of yet another test piece required to process a core of a hole drill having naturally cemented packed fractures to a direct shear test;
FIG. 2 is a schematic view of the positioning assembly and the lower shear box assembled according to one embodiment of the present invention;
FIG. 3 is a top view of a lower shear box according to one embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a direct shear test apparatus for a rock fracture with a test piece poured therein according to an embodiment of the present invention;
FIG. 5 is a schematic view of the assembly of the positioning assembly and the lower shear box when the dip angle of the test piece crack is a right angle according to the second embodiment of the present invention;
FIG. 6 is a schematic view of the positioning assembly and lower shear box assembled together when the sample crack is at a relatively large acute angle according to a second embodiment of the present invention.
Description of reference numerals:
1. a lower box body; 2. a lower cover plate; 3. fastening a bolt; 4. a test piece; 5. cementing surface; 6. high temperature resistant cement mortar; 7. mounting holes; 8. a height fixing knob; 9. a height positioning rod; 10. a first orientation knob; 11. a first protractor; 12. a clamping portion; 13. a temperature monitoring hole; 14. an upper box body; 15. an upper cover plate; 16. a second orientation knob; 17. a temperature sensor; 18. a wire; 19. an electric heating ring; 20. a flexible insulating layer; 21. a temperature acquisition device; 22. a temperature raising device; 23. a second protractor; 24. rotating the rod: 25. a circular clamp; 26. a partition plate; 27. a water injection hole; 28. an angle positioning rod; 29. and (4) drilling a rock core.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer and more complete, the following technical solutions of the present invention will be described in detail, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the specific embodiments of the present invention belong to the protection scope of the present invention.
The first embodiment is as follows:
as shown in fig. 2 to 4, the direct shear test device for rock fractures provided in the present embodiment includes a shear box, a positioning assembly, and a heating assembly.
The shear box is formed by buckling an upper shear box and a lower shear box, and has a cavity for accommodating the test piece 4. The lower shearing box and the upper shearing box are both of structures which are square outside and have thick-wall cylindrical cavities in the middle, and the cavities are used for pouring a test piece 4 with natural cemented filling rock cracks; the lower shearing box and the upper shearing box are of detachable structures, wherein the upper shearing box comprises an upper box body 14 and an upper cover plate 15 which are detachably connected through a fastening bolt 3, the lower shearing box comprises a lower box body 1 and a lower cover plate 2 which are detachably connected through a fastening bolt 3, water injection holes 27 with the diameter of 1-2 mm are formed in the upper cover plate 15 and the lower cover plate 2, cement mortar does not leak in the aperture range, and the optimal aperture is 1 mm; after the upper and lower shear boxes are packaged, the high temperature resistant cement mortar 6 in the shear box can be maintained by injecting water through the water injection holes 27.
All seted up temperature monitoring hole 13 on the lateral wall of last box body 14 and lower box body 1, temperature sensor 17 is stretched into in the cavity of shearing the box by temperature monitoring hole 13 from the outside of shearing the box.
The lower shearing box is provided with a mounting hole 7 for fixing the positioning component, and an internal thread is arranged in the mounting hole 7.
The positioning assembly is used for fixing the test piece 4 and adjusting the position of the test piece 4 suspended in the shear box. The positioning assembly comprises a height positioning rod 9, a first protractor 11 and a test piece 4 clamp.
The height positioning rod 9 is a telescopic rod with adjustable length, a second connecting hole (not shown in the figure) is formed in the upper end of the height positioning rod 9, the second connecting hole is a threaded hole, an external thread matched with the internal thread of the lower shearing box mounting hole 7 is formed in the lower end of the height positioning rod 9, and the height positioning rod 9 is detachably arranged on the lower shearing box through the thread; the middle position of the positioning rod is provided with a manuscript fixing knob, and the length of the height positioning rod 9 can be adjusted through a height fixing knob 8.
The specimen 4 jig includes a rotating rod 24, a clamping portion 12, and a circular jig 25. The clamping part 12 is provided with an opening for accommodating the test piece 4, a circular clamp 25 surrounds the outer wall of the clamping part 12, and the clamping part 12 can clamp or release the test piece 4 by adjusting the circular clamp 25, wherein the circular clamp 25 can be a hoop in the embodiment; one end of the rotating rod 24 is vertically connected to the closed end of the clamping portion 12, so that the rotating rod 24 is parallel to the axis of the test piece 4 being clamped; the other end of the rotating rod 24 is provided with a first connecting hole (not shown in the figure), and when the test piece 4 is assembled, the first orientation knob 10 passes through the first connecting hole and is screwed into the second connecting hole, so that the test piece 4 clamp and the height positioning rod 9 form detachable connection; the first protractor 11 is used for measuring an included angle between the rotating rod 24 and the horizontal direction, the first protractor 11 is arranged on the height positioning rod 9, and an original point of the first protractor 11 is located on an axis of the second connecting hole.
The heating assembly is used for heating the test piece 4 and keeping the temperature constant after the temperature of the test piece 4 reaches the preset temperature.
The heating assembly comprises an electric heating coil 19, a flexible heat-insulating layer 20, a temperature sensor 17, a temperature rising device 22 and a temperature acquisition device 21. The temperature sensor 17 extends into the cavity of the shear box from the outside of the shear box through the temperature monitoring hole 13, and the detection end of the temperature sensor 17 is in contact with the outer surface of the test piece 4 and is used for detecting the temperature of the test piece 4 in real time; the temperature acquisition device 21 is connected with the temperature sensor 17 through a lead 18, and the temperature acquisition device 21 is used for displaying the temperature of the test piece 4; the electric heating ring 19 is wrapped on the thick cylindrical outer walls of the upper shearing box and the lower shearing box, and the temperature rising device 22 is connected with the electric heating ring 19 through a lead 18 for rising temperature. The flexible heat-insulating layer 20 wraps the outer side of the electric heating ring 19, the flexible heat-insulating layer 20 plays a heat-insulating role, and meanwhile, the flexible heat-insulating layer can also bear certain shearing deformation so as to meet the requirement of shearing dislocation in the direct shear test process.
The following example one is used as a reference to describe how a direct shear test apparatus for rock fractures is used to perform a direct shear test of natural cement filled rock fractures under high temperature conditions.
Step 1: test piece 4 was prepared.
Measuring the inclination angle of the cementing surface 5 in the required drill core 29 with the natural cemented filling fracture, wrapping the test piece by using a heat-shrinkable sleeve, blowing the test piece at high temperature, fastening the test piece by using the sleeve, cutting the upper part and the lower part of the drill core 29 by using a wire cutting machine, respectively enabling the upper end surface and the lower end surface of the drill core 29 to be parallel to the cementing surface 5, and cutting the heat-shrinkable sleeve by using a knife to obtain the test piece 4 with the natural cemented filling fracture required by the test, wherein the test piece 4 is shown in figures 1 a-1 c.
Step 2: the test piece 4 is mounted.
The test piece 4 is arranged in the clamping part 12, the installation depth of the test piece 4 is based on that the cementation crack of the test piece 4 is not shielded, and the circular clamp 25 is screwed down to enable the clamping part 12 to clamp the test piece 4; screwing a height positioning rod 9 into a mounting hole 7 of the lower shearing box; adjusting the rotating rod 24 to enable the included angle between the rotating rod 24 and the horizontal direction to be equal to the inclination angle of the cementing surface 5, wherein the cementing surface 5, the upper end surface and the lower end surface of the test piece 4 are parallel to the bottom of the lower shearing box; the first orientation knob 10 is tightened to keep the included angle fixed; the angle between the turning bar and the horizontal direction can be measured by the first protractor 11. The height-adjusting positioning rod 9 enables the test piece 4 to be suspended in a cavity of the lower shearing box, and the height-adjusting positioning rod 9 is adjusted through the height-determining knob 8, so that the cementing surface 5 is higher than the top of the lower shearing box by about 3 mm.
And step 3: and pouring cement mortar.
Preparing high-temperature-resistant cement mortar 6, coating a layer of lubricating oil on the inner wall surface of the shear box so as to facilitate demoulding after the shear test is finished (namely, the solidified cement mortar is conveniently taken out of the shear box), and pouring the high-temperature-resistant cement mortar 6 into a cavity of a lower shear box in which a test piece 4 is suspended; meanwhile, a temperature sensor 17 for measuring the temperature of the test piece 4 is placed in the high temperature resistant cement mortar 6, and the temperature sensor 17 is contacted with the lower side surface of the test piece 4, preferably, the contact position is close to the cementing surface 5. After the high-temperature-resistant cement is completely solidified, removing the positioning assembly, and installing a partition plate 26 above the lower shear box, wherein the partition plate 26 is a wood partition plate 26 with a through hole matched with the test piece 4, the partition plate 26 has a certain thickness (in the embodiment, the thickness of the partition plate 26 is 6mm) so that the installed partition plate 26 surrounds and covers the cementation crack of the test piece 4, and the size of the partition plate 26 can completely cover the inner cavity of the lower shear box; the upper box body 14 of the upper shear box is arranged on the partition plate 26, high-temperature-resistant cement mortar 6 is poured into the cavity of the upper box body 14, and meanwhile, a temperature sensor 17 for measuring the temperature of the test piece 4 is placed in the high-temperature-resistant cement mortar 6, so that the temperature sensor 17 is in contact with the upper side surface of the test piece 4, and preferably, the contact position is close to the cementing surface 5. After the high-temperature-resistant cement mortar 6 is completely solidified, the partition plate 26 is removed, the upper end face and the lower end face of the test piece 4 are respectively fixed in the upper shearing box and the lower shearing box by the high-temperature-resistant cement mortar 6, a gap is formed between the upper shearing box and the lower shearing box due to the blocking of the partition plate 26, the cementing surface 5 is located in the gap, and the cementing surface 5 is parallel to the bottom and the top of the shearing box, so that the direct shearing test can be conveniently carried out. After the wooden partition plate 26 is removed, water is injected into the shearing box from the water injection port every 24 hours, and the ideal curing effect of cement is achieved after one month.
The high temperature resistant cement category comprises high alumina cement, aluminate series high temperature resistant cement, N-type super early strength aluminate cement, phosphate series high temperature resistant cementing material and the like. The present example used the commercially available aluminate cement CA50-II (G6) or aluminate cement CA50-IV (G9).
And 4, step 4: the test piece 4 is heated.
Direct shear test device: the method comprises the steps of respectively wrapping two ceramic electric heating rings 19 with the wall thickness of 10mm on the peripheries of thick-walled cylinders of an upper shearing box and a lower shearing box, wrapping flexible heat insulation sleeves outside the upper ceramic electric heating ring 19 and the lower ceramic electric heating ring 19, connecting a temperature sensor 17 with a temperature acquisition device 21, and connecting the ceramic electric heating rings 19 with a temperature rise device 22, so that the direct shear test device for naturally cemented filling cracks under the high-temperature condition is completely installed.
The direct shear test device is placed on a direct shear apparatus, wherein the lower shear box is fixed on the direct shear apparatus so that the lower shear box and the direct shear apparatus do not move relatively. The heating function of the heating device 22 is started to heat the ceramic electric heating ring 19 at a speed of 3 ℃/s, and heat generated by the ceramic electric heating ring 19 is transferred to the test piece 4 through the shearing box and the high-temperature-resistant cement paste, so that the test piece 4 is heated, and the integral high-temperature environment of the shearing box can be realized. The temperature of the test piece 4 is displayed through the temperature acquisition device 21 in the temperature rising process, and when the temperature of the test piece 4 rises to 400 ℃, the constant temperature function of the temperature rising device 22 is started, and the current temperature is kept for 4 h.
And 5: and (4) direct shear test.
After keeping the constant temperature for 4 hours, starting a vertical oil cylinder of the direct shear tester, applying a normal load at a rate of 1kN/s until the normal stress reaches 20MPa and keeps the normal stress, wherein the direction of the normal stress is vertical to the cementing surface 5 and the upper and lower end surfaces of the test piece 4, and the normal stress is transmitted to the test piece 4 through an upper shear box and high-temperature resistant cement mortar 6; then, a horizontal oil cylinder of the direct shear tester is started to apply shear stress to the upper shear box, the direction of the shear stress is parallel to the cementing surface 5, and the shear stress is transmitted to the test piece 4 through the upper shear box and the high-temperature-resistant cement mortar 6; the upper and lower shear boxes are relatively displaced at a constant displacement rate of 0.2 mm/min. Collecting the changes of normal stress and shear stress and the changes of shear box displacement in the normal direction and the shear direction in the test process according to a time interval of 3s, drawing a fracture shear stress-shear displacement curve and a normal displacement-shear displacement curve, and analyzing the changes of the fracture shear strength, the shear rigidity, the residual strength and the shear expansion angle of the natural cemented filling rock. Meanwhile, a high-definition digital camera is adopted to record the change of the cemented surface 5 in the shearing process, and the crack initiation position and the failure mechanism of the natural cemented rock fracture caused by the temperature and the normal stress are analyzed.
Dismantling the lower cover plate 2 of the lower shearing box and the upper cover plate 15 of the upper shearing box, then taking out the high-temperature-resistant cement mortar 6 and the whole test piece 4 together, slightly cleaning crack surface mineral substances abraded by the shearing surface by using a brush, collecting the crack surface mineral substances, and counting the particle size distribution of abraded objects by using a laser particle size tester; and then scanning the rough features of the fracture surface by using a three-dimensional laser scanner, and analyzing the surface wear features of the natural cemented filling fracture. The test is now complete.
Example two:
on the basis of the first embodiment, an angle positioning rod 28 and a second protractor 23 are added, two ends of the angle positioning rod 28 are respectively provided with a third connecting hole (not shown in the figure) and a fourth connecting hole (not shown in the figure), wherein the fourth connecting hole is a threaded hole, and the first orientation knob 10 can pass through the third connecting hole and the second connecting hole to enable one end of the angle positioning rod 28 to be detachably connected with the height positioning rod 9; in this scheme, the first protractor 11 is used for measuring an included angle between the angle positioning rod 28 and the horizontal direction; the second orientation knob 16 can pass through the fourth connecting hole and the first connecting hole to enable the other end of the angle positioning rod 28 to be detachably connected with the clamp of the test piece 4, the second protractor 23 is arranged on the angle positioning rod 28, the original point of the second protractor 23 is located on the axis of the fourth connecting hole, and the second protractor 23 is used for measuring the included angle between the rotating rod 24 and the angle positioning rod 28. The fixing assembly in the embodiment can fix the crack filling test piece 4 with a large inclination angle, and the deflection position of the test piece 4 in the lower shear box is realized by adjusting the angle positioning rod 28 and the rotating rod 24.
As shown in fig. 5, when the inclination angle of the cementing surface 5 is a right angle and the test piece 4 is adjusted and mounted, the angle positioning rod 28 is adjusted to be perpendicular to the height positioning rod 9 and the first orientation knob 10 is screwed for fixing; and then the rotating rod 24 is adjusted to enable the rotating rod 24 to be perpendicular to the angle positioning rod 28, and the second orientation knob is screwed to be fixed, so that the cementing surface 5, the upper end surface and the lower end surface of the test piece 4 are parallel to the bottom of the lower shearing box.
As shown in fig. 6, when the inclination angle of the cementing surface 5 is θ, and the test piece 4 is adjusted and mounted, the angle-adjusting positioning rod 28 and the height-adjusting positioning rod 9 are fixed by screwing the first orientation knob 10, and the included angle θ 1 between the angle-adjusting positioning rod 28 and the height-adjusting positioning rod 9 is read; then adjust the rotary rod 24 and make the contained angle of rotary rod 24 and angle locating rod 28 be theta 2 to theta 2 equals theta-theta 1, screw up second orientation knob 16 and fix, and at this moment, the cemented surface 5, the up end and the lower terminal surface of test piece 4 all are parallel with the bottom of lower shear box.
Finally, it should be noted that: the above embodiments and examples are only used to illustrate the technical solution of the present invention, but not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments and examples, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments or examples may still be modified, or some of the technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments or examples of the present invention.

Claims (10)

1. A direct shear test device for rock fractures, the test device comprising:
the shearing box is provided with a cavity for accommodating a test piece and is formed by buckling an upper shearing box and a lower shearing box; and
the positioning assembly comprises a height positioning rod, a first protractor and a test piece clamp, the length of the height positioning rod is adjustable, a second connecting hole is formed in one end of the height positioning rod, the test piece clamp comprises a rotating rod and a clamping portion, the clamping portion is provided with an opening capable of containing a test piece, one end of the rotating rod is vertically connected with the bottom of the clamping portion, a first connecting hole is formed in the other end of the rotating rod, and a first direction knob can penetrate through the first connecting hole and the second connecting hole to enable the test piece clamp to be detachably connected with the height positioning rod; the first protractor is arranged on the height positioning rod, and the origin of the first protractor is located on the axis of the second connecting hole.
2. The direct shear test device for the rock fractures according to claim 1, wherein the positioning assembly further comprises an angle positioning rod and a second protractor, wherein a third connecting hole and a fourth connecting hole are respectively formed at two ends of the angle positioning rod, and a first orientation knob can pass through the third connecting hole and the second connecting hole to enable one end of the angle positioning rod to be detachably connected with the height positioning rod; the second orientation knob can penetrate through the fourth connecting hole and the first connecting hole to enable the other end of the angle positioning rod to be detachably connected with the test piece fixture, and the second protractor is arranged on the angle positioning rod and the original point of the second protractor is located on the axis of the fourth connecting hole.
3. The direct shear test device for rock fractures according to claim 1, further comprising a heating assembly for heating the test piece to maintain a constant temperature after the temperature of the test piece reaches a preset temperature.
4. The direct shear test device for rock fractures according to claim 3, wherein the heating assembly comprises an electric heating ring, a temperature sensor, a temperature raising device and a temperature collecting device, the temperature sensor is used for detecting the temperature of the test piece, and the temperature collecting device is connected with the temperature sensor and is used for displaying the temperature measured by the temperature sensor; the electric heating ring wraps the outer wall of the shearing box, and the warming device is connected with the electric heating ring and controls the electric heating ring to warm.
5. The direct shear test device of a rock fracture according to claim 4, wherein the heating assembly further comprises a flexible insulation layer wrapped outside the electric heating ring.
6. The direct shear test device for the rock fracture according to claim 4, wherein a temperature monitoring hole is formed in a side wall of the shear box, and the temperature sensor extends into the cavity of the shear box from the outside of the shear box through the temperature monitoring hole.
7. The direct shear test device for rock fractures according to any one of claims 1 to 6, wherein a mounting hole is formed in the lower shear box, the mounting hole is provided with an internal thread, the other end of the height positioning rod is provided with an external thread matched with the internal thread, and the height positioning rod and the lower shear box can be in threaded connection.
8. The direct shear test device for rock fractures according to any one of claims 1 to 6, wherein the upper shear box comprises an upper box body and an upper cover plate which are detachably connected, the lower shear box comprises a lower box body and a lower cover plate which are detachably connected, and water injection holes are formed in both the upper cover plate and the lower cover plate.
9. The direct shear test device for rock fractures according to claim 8, wherein the diameter of the water injection hole is 1-2 mm.
10. A direct shear test device for rock fractures according to any one of claims 1-6, characterised in that the specimen holder further comprises a circular holder encircling on the outer wall of the holding portion.
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