CN111189722A - Coal rock circulating friction-gas seepage coupling test device and test method - Google Patents
Coal rock circulating friction-gas seepage coupling test device and test method Download PDFInfo
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- CN111189722A CN111189722A CN202010094401.3A CN202010094401A CN111189722A CN 111189722 A CN111189722 A CN 111189722A CN 202010094401 A CN202010094401 A CN 202010094401A CN 111189722 A CN111189722 A CN 111189722A
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- 239000003245 coal Substances 0.000 title claims abstract description 68
- 239000011435 rock Substances 0.000 title claims abstract description 67
- 230000008878 coupling Effects 0.000 title claims abstract description 22
- 238000010168 coupling process Methods 0.000 title claims abstract description 22
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 22
- 238000010998 test method Methods 0.000 title claims abstract description 18
- 238000012360 testing method Methods 0.000 title claims description 81
- 238000007789 sealing Methods 0.000 claims abstract description 20
- 238000002347 injection Methods 0.000 claims abstract description 19
- 239000007924 injection Substances 0.000 claims abstract description 19
- 238000005065 mining Methods 0.000 claims abstract description 9
- 239000003921 oil Substances 0.000 claims description 196
- 238000006073 displacement reaction Methods 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 9
- 239000010687 lubricating oil Substances 0.000 claims description 6
- 239000004677 Nylon Substances 0.000 claims description 4
- 239000002390 adhesive tape Substances 0.000 claims description 4
- 238000009499 grossing Methods 0.000 claims description 4
- 229920001778 nylon Polymers 0.000 claims description 4
- 238000005498 polishing Methods 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 238000010008 shearing Methods 0.000 abstract description 5
- 238000013461 design Methods 0.000 abstract description 3
- 238000013508 migration Methods 0.000 abstract 2
- 230000005012 migration Effects 0.000 abstract 2
- 238000004088 simulation Methods 0.000 abstract 1
- 125000004122 cyclic group Chemical group 0.000 description 7
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- 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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- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- 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
- G01N2203/02—Details not specific for a particular testing method
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- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0676—Force, weight, load, energy, speed or acceleration
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- 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
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Abstract
The invention discloses a gas-containing coal circulating friction-gas migration coupling experimental device and a test method, wherein the problem of difficult sealing of the device is solved emphatically by combining and analyzing the field practical situation related to mining and rock mechanics and by the design of a clamping cushion block with a groove and a nested axial loading oil cylinder, so that the coupling analysis of the coal-rock circulating friction and seepage problems is realized. The device mainly comprises a gas-containing coal circulating friction system, a gas injection and pressurization system and a data real-time acquisition system, can realize simultaneous implementation of circulating friction sliding behavior and gas seepage of coal rock mass, and utilizes the data real-time acquisition system to monitor and acquire data of a coal rock circulating friction shearing sliding state and gas migration characteristics, thereby realizing real simulation of coal rock circulating sliding-gas seepage coupling characteristics.
Description
Technical Field
The invention relates to the field of mining and rock mechanics, in particular to a coal-rock circulating friction-gas seepage coupling test device and a test method.
Background
In the mining process of a mine, due to the existence of fault or through crack and other structural surfaces, the coal rock mass often generates a friction sliding phenomenon along the structural surfaces under mining disturbance, particularly under the complex mining disturbance condition, the structural surfaces are usually in a cyclic loading state, the coal rock mass generates more complex cyclic friction sliding behavior under the action of cyclic shear load, the mechanical property of the coal rock is obviously changed, and the stability of a coal rock structural body is influenced.
Gas seepage is always an important problem in the scientific mining process of coal resources, and the gas seepage characteristics inside coal are basic contents for researching gas dynamic disasters, gas extraction and other related fields. Especially for structural planes with weak mechanical properties such as coal faults or through cracks, the friction slip behavior (such as fault activation slip induction protrusion) under the action of cyclic shear load becomes a main factor for inducing coal rock dynamic disasters, and the problem is further complicated by gas seepage accompanied in the cyclic friction slip process. Therefore, the research on the coal rock mass circulating friction slip-gas seepage coupling mechanism has important significance.
In rock mechanics related research, the friction phenomenon of rock structural surfaces or fractures is also called joint shear; at present, partial scholars adopt a coal rock structural plane to carry out a cyclic joint shearing test, but the effect of gas (fluid) is not considered due to the difficulty of sealing; the existing seepage-joint shearing test device can only carry out shearing slippage of a single path, and cannot describe the effect of the damage of the coal rock sample contact surface under the circulating shearing slippage on the friction slippage characteristic and the seepage characteristic.
In summary, the research on the coal body friction slip characteristic and permeability evolution under the "circulation friction-gas seepage" coupling mechanism of the coal rock mass is necessary, but a test device capable of effectively describing the "circulation friction-gas seepage" coupling characteristic of the coal rock mass is still lacking at present. Therefore, it is necessary to overcome the defects of the prior art and design a test device and a test method capable of describing the coal rock mass circulating friction-gas seepage coupling law.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a coal-rock circulating friction-gas seepage coupling test device and a test method thereof.
In order to achieve the purpose, the invention adopts the technical scheme that: a coal-rock circulating friction-gas seepage coupling test device and a test method comprise a coal-rock circulating friction system, a gas injection and pressurization system and a data real-time acquisition system, wherein the coal-rock circulating friction system comprises a device shell, a first axial loading oil cylinder, a second axial loading oil cylinder, a sealing rubber membrane, a confining pressure chamber, a test chamber and a clamping cushion block; the first axial loading oil cylinder and the second axial loading oil cylinder are respectively provided with two independently controlled oil cylinders and are respectively positioned at two sides of the device, wherein the second axial loading oil cylinder is nested in the first axial loading oil cylinder; the test chamber is positioned at the midpoint of the device, and the clamping cushion block is positioned between the inner side end of the axial loading oil cylinder and the test chamber; the sealing rubber film wraps part of the clamping cushion block and the test chamber, and a space between the sealing rubber film and the outer shell is a confining pressure chamber; the gas injection and pressurization system comprises 1 gas injection pipeline, 1 confining pressure loading oil way and 4 axial loading oil ways; the interior of the air injection pipeline is communicated with the test chamber and is externally connected with an air pump; the inside of the confining pressure loading oil path is communicated with a confining pressure chamber and is externally connected with a confining pressure pump; the axial loading oil way comprises 2 ways of a first axial loading oil way and a second axial loading oil way; the data real-time acquisition system comprises a stress sensor, a displacement sensor, a flowmeter, a PC and the like.
The second axial loading oil cylinder is nested in the first axial loading oil cylinder, one end, close to the outer side, of the first axial loading oil cylinder is a slender hollow cylinder, one end, close to the test chamber, of the first axial loading oil cylinder is of a side concave structure, and a sliding groove space is reserved between the inner bottom end of the side concave structure of the first axial loading oil cylinder and the inner end of the second axial loading oil cylinder; a sliding groove space is also arranged between the outside of the first axial loading oil cylinder and the outer shell, and the maximum space distances of the 2 sliding grooves are equal.
The first and second axial loading oil cylinder assembly structure is similar to a two-stage telescopic oil cylinder, but each oil cylinder adopts an independent control mode; the sliding grooves are arranged in the device, so that the axial loading oil cylinders on two sides of the device can independently reciprocate to achieve the effect of circular friction, and in addition, the spatial distance of the sliding grooves in the initial state of the testing device is the maximum distance.
The clamping cushion blocks are divided into two first clamping cushion blocks and two second clamping cushion blocks respectively, wherein the second clamping cushion blocks are arranged on the left lower side and the right upper side of the test chamber, the first clamping cushion blocks are arranged on the left upper side and the right lower side, and seepage channels are arranged at the friction interfaces of the upper clamping cushion block and the lower clamping cushion block; the first clamping cushion block is a cuboid, and the outer end of the first clamping cushion block is always contacted with the end part of the side plate of the concave structure at the side of the first axial loading cylinder at the same side; the outer end of the second clamping cushion block is provided with a groove corresponding to the position of the side plate of the concave structure at the side of the first axial loading cylinder at the same side, the two can be embedded with each other, and the groove is always contacted with the end part of the second axial loading cylinder at the same side.
The constant contact between the outer end of the first clamping cushion block and the end part of the side plate of the first axial loading cylinder on the same side and between the outer end of the second clamping cushion block and the end part of the second axial loading cylinder on the same side describes the corresponding position states of the clamping cushion block and the axial loading cylinder in the device circulating friction, namely, in the friction circulation, different relative motions can be generated between the clamping cushion blocks and the loading cylinder, but the first clamping cushion block is only directly pushed by the first axial loading cylinder on the same side, and the second clamping cushion block is only directly pushed by the second axial loading cylinder on the same side.
The effect of centre gripping cushion includes: firstly, the upper cushion block and the lower cushion block are provided with seepage channels on the friction interface, so that gas (or other gas or fluid) is provided for the pattern friction surface; the auxiliary sealing function is realized, and the sealing ring arranged at the corresponding position in each axial loading oil cylinder and the device is matched to form a sealing seepage cavity formed by the inner side end surface of the axial loading oil cylinder, the lower surface of the upper clamping cushion block, the upper surface of the lower clamping cushion block and the outer end surface of the test piece part, so that the pattern friction surface is ensured to be a unique seepage path; thirdly, fixing the pattern and corresponding to the motion of the loading oil cylinder through a groove designed on the second cushion block so as to realize the function of controlling the friction of the pattern in the device; taking the initial state as an example: the style is located in the middle, the first clamping cushion block is always contacted with the end part of the side plate of the side concave type structure of the first axial loading oil cylinder, and the position of the second clamping cushion block, which corresponds to the end part of the first axial loading oil cylinder, is a groove and can be embedded, therefore, when the first axial loading oil cylinder on the right moves, the first clamping cushion block can be directly pushed to drive the lower style to slide, and in the process, the side plate of the side concave type structure of the first axial loading oil cylinder on the right is embedded into the groove of the second clamping cushion block, namely, the positions of the second clamping cushion block and the upper style are kept unchanged, so that the effect of frictional sliding of the upper style and the; in addition, the clamping cushion block is made of high-strength rigid materials and can bear the load applied by the loading oil cylinder.
The maximum space distance of the sliding grooves formed in each position of the first axial loading oil cylinder and the second axial loading oil cylinder is equal to the length of the groove of the second clamping cushion block.
The groove of the second clamping cushion block can be used for realizing indirect control of the axial loading oil cylinder on the pattern, and the equal length of the groove and the maximum distance of the sliding groove can ensure accurate control of the friction sliding motion of each axial loading oil cylinder, the pattern and the clamping cushion block.
The friction contact surfaces of the structures such as the sealing rubber film, the clamping cushion block, the axial loading oil cylinder and the like are subjected to smoothing treatment and lubricating oil is added, so that the friction of the internal structure of the test device is reduced as much as possible.
The oil inlets of the 2 first axial loading oil paths are respectively positioned at the right upper part and the left lower part of the outer shell, and the interior of the oil path is communicated with the first axial loading oil cylinder; the oil inlets of the 2 second axial loading oil paths are respectively positioned at the outer side ends of the two first axial loading oil cylinders and are accessed from a gap arranged in the first axial loading oil cylinders, and the interior of the oil path is communicated with the second axial loading oil cylinders; the 4 axial loading oil ways are externally connected with 1 axial loading pump.
The first axial loading oil cylinder and the second axial loading oil cylinder respectively adopt different oil inlets and oil passages to realize independent control on each loading oil cylinder, and the second axial loading oil passage passes through the inside of the pore of the first axial loading oil cylinder but does not act on the first axial loading oil cylinder, so that 4 axial loading oil passages and oil inlets are totally corresponding to 4 axial loading oil cylinders; however, the 4 axial loading oil paths are externally connected with the same axial loading pump, and each axial loading oil path is provided with a corresponding valve so as to realize the control of each axial loading oil cylinder by 1 axial loading pump.
And the air inlet and outlet of the air injection pipeline are respectively positioned at the outer side ends of the two second axial loading oil cylinders and are finally communicated with the test chamber through a gap arranged in the second axial loading oil cylinders.
The gas injection pipeline passes through a gap arranged in the second axial loading oil cylinder but does not act on the second axial loading oil cylinder.
The test procedure was as follows:
s1: obtaining a sample, and preparing a coal rock block matched with a test instrument through processing;
obtaining a coal rock mass required by a test in a mining area; cutting block coal and rock samples with uniform texture and set size, manually polishing a friction interface of the coal and rock samples to reach set roughness, performing smoothing treatment on a non-friction interface, and smearing lubricating oil; after the preparation, the coal sample is wrapped by nylon adhesive tape, only the contact surface of the coal sample is exposed, and the two wrapped coal and rock samples are placed in a test chamber.
The functions of increasing friction and controlling roughness can be realized by polishing the pattern friction contact surface, but the friction between the pattern and the sealing rubber film can be reduced as much as possible by smoothly processing the non-friction interface and coating lubricating oil, so that the test precision is improved; the coal sample is wrapped by nylon adhesive tape, and only the contact surface of the coal sample is exposed, so that seepage gas can be ensured to pass through the friction slip surface as far as possible.
S2: preparing a test;
placing the glass substrate in a set constant temperature environment, checking the air tightness, and then carrying out vacuum-pumping treatment.
S3: carrying out a test;
firstly, applying preset confining pressure to a coal rock sample through a confining pressure pump, then applying preset gas pressure to a set value, and keeping the gas pressure unchanged to enable the coal sample to be fully adsorbed for 24 hours; and then opening the air outlet and starting a data acquisition system, and starting a speed step length sliding test with the sliding speed of 1-10 mu m/s-1-10 mu m/s after the flow of the air outlet is stable.
S4: the specific operation steps of the axial loading oil cylinder are as follows: the first step is as follows: the right first axial loading oil cylinder pushes the right lower first clamping cushion block and drives the lower pattern, the left lower second clamping cushion block and the left second axial loading oil cylinder to move leftwards for the maximum distance of the sliding chute, the friction sliding distance between the patterns is the maximum distance of the sliding chute, and at the moment, the distance of the sliding chute between the inner bottom end of the side concave structure of the left first axial loading oil cylinder and the inner end part of the inner second axial loading oil cylinder is 0; the second step is that: then the first axial loading oil cylinder on the left side pushes all other axial loading oil cylinders, the clamping cushion block and the two test samples to integrally move to the right by half of the maximum distance of the sliding chute, and the axial loading oil cylinders are symmetrical about the center of the device; the third step: then the left second axial loading oil cylinder pushes the left lower second clamping cushion block and drives the lower pattern, the right lower first clamping cushion block and the right first axial loading oil cylinder to move to the right by half of the maximum distance of the sliding chute, and at the moment, the right first axial loading oil cylinder returns to the initial position; the fourth step: finally, the right second axial loading oil cylinder pushes the right upper second clamping cushion block and drives the upper sample, the left upper first clamping cushion block and the left first axial loading oil cylinder to move to the left by half of the maximum distance of the sliding chute, at the moment, all structures and coal and rock samples in the whole test device return to the initial positions to complete a friction sliding cycle, and only the second step of the step is not subjected to friction sliding displacement; and subsequently, the steps are continued to finish the required friction cycle number according to the needs, and the friction force, the sliding displacement and the seepage flow at each moment are continuously monitored and recorded.
S5: and after one test period is finished, replacing the coal rock sample, and continuing the processes S3 and S4 by changing the applied gas pressure and the normal stress again.
The invention has the following beneficial effects: a coal rock circulating friction-gas seepage coupling test device and a test method are disclosed, wherein a clamping cushion block with a groove is arranged to indirectly control the circulating friction slippage of a sample, and the problem that the coal rock is difficult to seal well in the circulating friction slippage process is solved, so that the coal rock circulating slippage-gas seepage coupling characteristic can be truly simulated.
Drawings
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings, in which:
FIG. 1 is a diagram of a test apparatus according to the present invention;
FIG. 2 is a schematic diagram of the insufflation/pressurization system and the real-time data acquisition system of the present invention
FIG. 3 is a schematic diagram showing the dimensions of the axial loading cylinder and the second clamping pad groove of the present invention.
FIG. 4 is a left side view of the seepage passage of the gripping pad of the present invention.
FIG. 5 is a flow chart of the control of the axial loading cylinder in the cyclic friction test according to the present invention.
In the figure: 1-device outer shell, 2-first axial loading cylinder, 201-left first axial loading cylinder, 202-right first axial loading cylinder, 3-second axial loading cylinder, 301-left second axial loading cylinder, 302-right second axial loading cylinder, 4-sealing rubber membrane, 5-confining pressure chamber, 6-test chamber and coal rock pattern, 601-pattern friction interface, 7-clamping cushion block, 701-left first clamping cushion block, 702-right first clamping cushion block, 703-left second clamping cushion block, 704-right second clamping cushion block, 8-axial loading oil way, 801-first axial loading oil way left lower oil inlet, 802-first axial loading oil way right upper oil inlet, 803-second axial loading oil way left oil inlet, 804-right oil inlet of a second axial loading oil path, 9-confining pressure loading oil path, 10-gas injection pipeline, 1001-gas inlet, 1002-gas outlet, 11-valve, 12-flowmeter, 13-stress sensor, 14-displacement sensor, 15-pump, 1501-gas pump, 1502-confining pressure pump, 1503-axial loading pump, 16-PC, 17-sealing ring and 18-seepage channel.
The specific implementation mode is as follows:
as shown in fig. 1 and 2, a coal-rock circulating friction-gas seepage coupling test device and a test method include a coal-rock circulating friction system, a gas injection and pressurization system and a data real-time acquisition system, wherein the coal-rock circulating friction system includes a device outer shell 1, a first axial loading oil cylinder 2, a second axial loading oil cylinder 3, a sealing rubber membrane 4, a confining pressure chamber 5, a test chamber 6 and a clamping cushion block 7; the first axial loading oil cylinder 2 and the second axial loading oil cylinder 3 are respectively provided with two independently controlled oil cylinders and are respectively positioned at two sides of the device, wherein the second axial loading oil cylinder 3 is nested in the first axial loading oil cylinder 2; the test chamber 6 is positioned at the midpoint of the device, and the clamping cushion block 7 is positioned between the inner side ends of the axial loading oil cylinders 2 and 3 and the test chamber 6; the sealing rubber film 4 wraps part of the clamping cushion block 7 and the test chamber 6, and the space between the sealing rubber film 4 and the outer shell 1 is a confining pressure chamber 5; the gas injection and pressurization system comprises 1 gas injection pipeline 10, 1 confining pressure loading oil way 9 and 4 axial loading oil ways 8; the interior of the air injection pipeline 10 is communicated with the test chamber 6 and is externally connected with an air pump 1501; the confining pressure loading oil path 9 is internally communicated with a confining pressure chamber 5 and is externally connected with a confining pressure pump 1502; the axial loading oil way 8 comprises 2 ways of a first axial loading oil way and a second axial loading oil way respectively; the data real-time acquisition system comprises a stress sensor 13, a displacement sensor 14, a flow meter 12 and a PC 16.
As shown in fig. 2, each path in the gas injection and pressurization system is provided with a stress sensor 13, each branch (4 paths in total) of the axial loading oil path 8 is provided with a displacement sensor 14 in addition to the stress sensor 13, each branch is provided with a valve 11, and when a certain path of valve 11 is opened, the action of the axial loading oil cylinder of the path can be independently controlled, and corresponding displacement and stress values are recorded through the sensors.
For example, when the dimension of the axial loading cylinder is given, as shown in fig. 3, the left side schematic diagram of the test device in the initial state is shown, and the chute space distance is the maximum chute space distance; the second axial loading oil cylinder 301 is nested inside the first axial loading oil cylinder 201, one end, close to the outer side, of the first axial loading oil cylinder 201 is a hollow cylinder with the length of 100mm and the inner/outer diameter of 18/40mm, one end, close to the test chamber 6, of the first axial loading oil cylinder 201 is a side concave structure with the length of 40mm and the thicknesses of the upper side and the lower side of 10mm, and a sliding groove space is reserved between the inner bottom end of the side concave structure of the first axial loading oil cylinder 201 and the inner end of the second axial loading oil cylinder 301 inside; a chute space is also arranged between the outside of the first axial loading oil cylinder 201 and the outer shell 1, and the maximum space distance of the 2 chutes is 20 mm.
The clamping cushion block 7 is divided into two clamping cushion blocks 701 and 702 and two clamping cushion blocks 703 and 704, wherein the lower left side 703 and the upper right side 704 of the test chamber are the second clamping cushion block, and the upper left side 701 and the lower right side 702 are the first clamping cushion block, as shown in fig. 4: the friction interface of the upper and lower clamping cushion blocks is provided with a seepage channel 18; the outer ends of the first clamping cushion blocks 701 and 702 are always contacted with the end parts of the side plates of the first axial loading oil cylinders 201 and 202 on the same side in the concave structure; the outer ends of the second clamping cushion blocks 703 and 704 are provided with grooves corresponding to the side plates of the first axial loading cylinders 201 and 202 on the same side and in the concave structure, and the grooves can be embedded with the side plates and are always contacted with the end parts of the second axial loading cylinders 301 and 302 on the same side.
For example, when the dimensions of the grooves of the second nip pads 703 and 704 are given, as shown in fig. 3, which is a left side schematic view of the test apparatus, the maximum spatial distances of the respective sliding grooves provided in the first axial loading cylinder 201 and the second axial loading cylinder 301 are equal to the groove length of the second nip pad 703, and are both 20mm, and the groove width of the second nip pad 703 is equal to the width of the "concave" type structural side plate on the first axial loading cylinder 201 side, and is both 10 mm. The design and size matching of the sliding grooves of the axial loading oil cylinders 2 and 3 and the grooves of the second clamping cushion blocks 703 and 704 enables the device to flexibly and accurately control the sliding of the sample and realize the circulating friction sliding.
In addition, as shown in fig. 3, "always contact" between the outer end of the first clamping pad 701 and the end of the side plate of the "concave" type structure on the first axial loading cylinder 201 side on the same side, and the outer end of the second clamping pad 703 and the end of the second axial loading cylinder 301 on the same side describes the corresponding position state of the clamping pad 7 and the axial loading cylinders 2 and 3 in the device circulation friction, that is, in the friction circulation, each clamping pad 7 and the loading cylinders 2 and 3 will generate different relative motions, but the first clamping pad 701 is directly pushed only by the first axial loading cylinder 201 on the same side, and the second clamping pad 703 is directly pushed only by the first axial loading cylinder 301 on the same side.
The friction interface of the upper clamping cushion block 7 and the lower clamping cushion block 7 is provided with a seepage channel 18, so that gas (or other gas or fluid) is provided for the pattern friction surface 601;
the clamping cushion blocks 7 can also fix the pattern and correspond to the movement of the axial loading oil cylinders 2 and 3 through grooves designed in each cushion block 7 so as to realize the friction effect of the pattern 6 in the control device; taking the initial state as an example: as shown in fig. 1, the pattern 6 is located in the middle, the first clamping pads 701, 702 are always in contact with the end of the side plate of the side-recessed structure of the first axial loading cylinder 2, and the second clamping pads 703, 704 are recessed and can be engaged with each other corresponding to the end of the first axial loading cylinder 2, so that when the first axial loading cylinder 202 on the right moves, the first clamping pad 702 is directly pushed to drive the lower pattern 6 to slide, and in this process, the upper side plate of the side-recessed structure of the first axial loading cylinder 202 on the right is engaged with the recessed groove of the second clamping pad 704, i.e. the positions of the second clamping pad 704 and the upper pattern 6 are kept unchanged, so as to achieve the effect of frictional sliding of the upper and lower patterns; in addition, the clamping cushion block 7 is made of high-strength rigid materials and can bear the load applied by the loading oil cylinder.
The friction contact surfaces of the structures such as the sealing rubber film 4, the clamping cushion block 7, the axial loading oil cylinders 2 and 3 are subjected to smoothing treatment and lubricating oil is added, so that the friction of the internal structure of the test device is reduced as much as possible.
The 2 first axial loading oil path oil inlets 801 and 802 are respectively positioned at the left lower part and the right upper part of the outer shell 1, and the interior of the oil path is communicated with the first axial loading oil cylinders 201 and 202; the 2 second axial loading oil path oil inlets 803 and 804 are respectively positioned at the outer side ends of the two first axial loading oil cylinders 2 and are accessed from a gap arranged in the first axial loading oil cylinders 2, and the insides of the oil paths are communicated with the second axial loading oil cylinders 301 and 302; the 4 oil paths are collected into an axial loading oil path 8 and externally connected with 1 axial loading pump 1503. Therefore, the axial loading oil path 8 controls the action of each axial loading oil cylinder 201, 202, 301, 302 by controlling the valve 11 on each branch to open the corresponding oil inlet 801, 802, 803, 804.
The air inlet and outlet 1001 and 1002 of the air injection pipeline 10 are respectively positioned at the outer ends of the 2 second axial loading oil cylinders 301 and 302, and are finally communicated with the test chamber 6 through a gap arranged inside the second axial loading oil cylinder 3.
The test procedure was as follows:
s1: obtaining a sample, and preparing a coal rock block matched with a test instrument through processing;
obtaining coal and rock mass required by a test in a mining area, wherein the test can select coal-coal friction or coal-rock friction and the like, cutting blocky coal and rock samples 6 with uniform texture and set size, wherein the surface size of the sample 6 is 25mm x 50mm, manually polishing a friction interface of the coal and rock sample to reach the set roughness, and performing smooth treatment and smearing lubricating oil on a non-friction interface; after the preparation is finished, wrapping the coal sample by using a nylon adhesive tape to expose the contact surface of the coal sample, and placing the two wrapped coal and rock samples in a test chamber 6;
s2: preparing a test;
placing the glass tube in a set constant-temperature environment, checking the air tightness, and then carrying out vacuum-pumping treatment;
s3: carrying out a test;
firstly, applying preset confining pressure to a coal rock sample through a confining pressure pump 1502, then applying preset gas pressure to a set value, and keeping the gas pressure unchanged to enable the coal sample 6 to be fully adsorbed for 24 hours; then the air outlet 1002 is opened and the data acquisition system is started, and when the flow of the air outlet is stable, a speed step sliding test with the sliding speed of 1-10 mu m/s-1-10 mu m/s is started.
S4: the specific operation steps of the axial loading oil cylinder are as follows: as shown in fig. 5, first, the apparatus is in an initial state; the first step is as follows: the right first axial loading oil cylinder 202 pushes the right lower first clamping cushion block 702 and drives the lower pattern, the left lower second clamping cushion block 703 and the left second axial loading oil cylinder 301 to move 20mm leftward, friction sliding is performed among patterns 6 at this stage for 20mm, and at this time, the chute distance between the bottom end of the left first axial loading oil cylinder 201 side in the concave structure and the inner end of the inner second axial loading oil cylinder 301 is 0; the second step is that: then the first axial loading oil cylinder 201 on the left side pushes all other axial loading oil cylinders, the clamping cushion block 7 and the two test samples 6 to integrally move rightwards for 10mm, and at the moment, the axial loading oil cylinders 2 and 3 are symmetrical about the center of the device; the third step: the left second axial loading cylinder 301 pushes the left lower second clamping pad 703 and drives the lower pattern, the right lower first clamping pad 702 and the right first axial loading cylinder 202 to move to the right by 10mm, and at this time, the right first axial loading cylinder 202 returns to the initial position; the fourth step: finally, the right second axial loading oil cylinder 302 pushes the right upper second clamping cushion block 704 and drives the upper sample, the left upper first clamping cushion block 701 and the left first axial loading oil cylinder 201 to move 10mm leftwards, all structures and coal and rock samples in the whole test device return to initial positions at the moment, a friction sliding cycle is completed, and only friction sliding displacement does not occur among the second step patterns in the steps; and subsequently, the steps are continued to finish the required friction cycle number according to the needs, and the friction force, the sliding displacement and the seepage flow at each moment are continuously monitored and recorded.
S5: and (4) after one test period is finished, replacing the coal rock sample 6, and continuing the processes of S3 and S4 by changing the applied gas pressure and the normal stress again.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions and scope of the present invention as defined in the appended claims.
Claims (7)
1. A coal rock circulating friction-gas seepage coupling test device and a test method are characterized in that: the device comprises a coal rock circulating friction system, a gas injection and pressurization system and a data real-time acquisition system, wherein the coal rock circulating friction system comprises a device shell, a first axial loading oil cylinder, a second axial loading oil cylinder, a sealing rubber film, a confining pressure chamber, a test chamber and a clamping cushion block; the first axial loading oil cylinder and the second axial loading oil cylinder are respectively provided with two independently controlled oil cylinders and are respectively positioned at two sides of the device, wherein the second axial loading oil cylinder is nested in the first axial loading oil cylinder; the test chamber is positioned at the midpoint of the device, and the clamping cushion block is positioned between the inner side end of the axial loading oil cylinder and the test chamber; the sealing rubber film wraps part of the clamping cushion block and the test chamber, and a space between the sealing rubber film and the outer shell is a confining pressure chamber; the gas injection and pressurization system comprises 1 gas injection pipeline, 1 confining pressure loading oil way and 4 axial loading oil ways; the interior of the air injection pipeline is communicated with the test chamber and is externally connected with an air pump; the inside of the confining pressure loading oil path is communicated with a confining pressure chamber and is externally connected with a confining pressure pump; the axial loading oil way comprises 2 ways of a first axial loading oil way and a second axial loading oil way; the data real-time acquisition system comprises a stress sensor, a displacement sensor, a flowmeter, a PC and the like.
2. The coal-rock circulating friction-gas seepage coupling test device and the test method according to claim 1 are characterized in that: the second axial loading oil cylinder is nested in the first axial loading oil cylinder, one end, close to the outer side, of the first axial loading oil cylinder is a slender hollow cylinder, one end, close to the test chamber, of the first axial loading oil cylinder is of a side concave structure, and a sliding groove space is reserved between the inner bottom end of the side concave structure of the first axial loading oil cylinder and the inner end of the second axial loading oil cylinder; a sliding groove space is also arranged between the outside of the first axial loading oil cylinder and the outer shell, and the maximum space distances of the 2 sliding grooves are equal.
3. The coal rock circulating friction-gas seepage coupling test device and the test method according to claim 1 or claim 2, wherein: the clamping cushion blocks are divided into two first clamping cushion blocks and two second clamping cushion blocks respectively, wherein the second clamping cushion blocks are arranged on the left lower side and the right upper side of the test chamber, the first clamping cushion blocks are arranged on the left upper side and the right lower side, and seepage channels are arranged at the friction interfaces of the upper clamping cushion block and the lower clamping cushion block; the first clamping cushion block is a cuboid, and the outer end of the first clamping cushion block is always contacted with the end part of the side plate of the concave structure at the side of the first axial loading cylinder at the same side; the outer end of the second clamping cushion block is provided with a groove corresponding to the position of the side plate of the concave structure at the side of the first axial loading cylinder at the same side, the two can be embedded with each other, and the groove is always contacted with the end part of the second axial loading cylinder at the same side.
4. The coal rock circulating friction-gas seepage coupling test device and the test method according to any one of claims 1 to 3, characterized in that: the maximum space distance of the sliding grooves formed in each position of the first axial loading oil cylinder and the second axial loading oil cylinder is equal to the length of the groove of the second clamping cushion block.
5. The coal-rock circulating friction-gas seepage coupling test device and the test method according to claim 1 are characterized in that: the oil inlets of the 2 first axial loading oil paths are respectively positioned at the right upper part and the left lower part of the outer shell, and the interior of the oil path is communicated with the first axial loading oil cylinder; the oil inlets of the 2 second axial loading oil paths are respectively positioned at the outer side ends of the two first axial loading oil cylinders and are accessed from a gap arranged in the first axial loading oil cylinders, and the interior of the oil path is communicated with the second axial loading oil cylinders; the 4 axial loading oil ways are externally connected with 1 axial loading pump.
6. The coal-rock circulating friction-gas seepage coupling test device and the test method according to claim 1 are characterized in that: and the air inlet and outlet of the air injection pipeline are respectively positioned at the outer side ends of the two second axial loading oil cylinders and are finally communicated with the test chamber through a gap arranged in the second axial loading oil cylinders.
7. The coal rock circulating friction-gas seepage coupling test device and the test method according to any one of claims 1 to 7, characterized by comprising the following steps:
s1: obtaining a sample, and preparing a coal rock block matched with a test instrument through processing;
obtaining a coal rock mass required by a test in a mining area; cutting block coal and rock samples with uniform texture and set size, manually polishing a friction interface of the coal and rock samples to reach set roughness, performing smoothing treatment on a non-friction interface, and smearing lubricating oil; after the preparation is finished, wrapping the coal sample by using a nylon adhesive tape, exposing the contact surface of the coal sample, and placing the two wrapped coal and rock samples in a test chamber;
s2: preparing a test;
placing the glass tube in a set constant-temperature environment, checking the air tightness, and then carrying out vacuum-pumping treatment;
s3: carrying out a test;
firstly, applying preset confining pressure to a coal rock sample through a confining pressure pump, then applying preset gas pressure to a set value, and keeping the gas pressure unchanged to enable the coal sample to be fully adsorbed for 24 hours; and then opening the air outlet and starting a data acquisition system, and starting a speed step length sliding test with the sliding speed of 1-10 mu m/s-1-10 mu m/s after the flow of the air outlet is stable.
S4: the specific operation steps of the axial loading oil cylinder are as follows: the first step is as follows: the right first axial loading oil cylinder pushes the right lower first clamping cushion block and drives the lower pattern, the left lower second clamping cushion block and the left second axial loading oil cylinder to move leftwards for the maximum distance of the sliding chute, the friction sliding distance between the patterns is the maximum distance of the sliding chute, and at the moment, the distance of the sliding chute between the inner bottom end of the side concave structure of the left first axial loading oil cylinder and the inner end part of the inner second axial loading oil cylinder is 0; the second step is that: then the first axial loading oil cylinder on the left side pushes all other axial loading oil cylinders, the clamping cushion block and the two test samples to integrally move to the right by half of the maximum distance of the sliding chute, and the axial loading oil cylinders are symmetrical about the center of the device; the third step: then the left second axial loading oil cylinder pushes the left lower second clamping cushion block and drives the lower pattern, the right lower first clamping cushion block and the right first axial loading oil cylinder to move to the right by half of the maximum distance of the sliding chute, and at the moment, the right first axial loading oil cylinder returns to the initial position; the fourth step: finally, the right second axial loading oil cylinder pushes the right upper second clamping cushion block and drives the upper sample, the left upper first clamping cushion block and the left first axial loading oil cylinder to move to the left by half of the maximum distance of the sliding chute, at the moment, all structures and coal and rock samples in the whole test device return to the initial positions to complete a friction sliding cycle, and only the second step of the step is not subjected to friction sliding displacement; and subsequently, the steps are continued to finish the required friction cycle number according to the needs, and the friction force, the sliding displacement and the seepage flow at each moment are continuously monitored and recorded.
S5: and after one test period is finished, replacing the coal rock sample, and continuing the processes S3 and S4 by changing the applied gas pressure and the normal stress again.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112284933A (en) * | 2020-10-20 | 2021-01-29 | 中国矿业大学(北京) | Experimental device and experimental method for measuring rock mass circulating shear seepage under high temperature and high pressure |
| CN113030429A (en) * | 2021-03-15 | 2021-06-25 | 中国矿业大学 | Multifunctional coal and gas outburst physical simulation device |
| CN113267447A (en) * | 2021-06-23 | 2021-08-17 | 天津大学 | Device for simulating dynamic friction process of original rock and manufacturing method thereof |
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| CN112284933A (en) * | 2020-10-20 | 2021-01-29 | 中国矿业大学(北京) | Experimental device and experimental method for measuring rock mass circulating shear seepage under high temperature and high pressure |
| CN112284933B (en) * | 2020-10-20 | 2022-09-16 | 中国矿业大学(北京) | Experimental device and experimental method for measuring rock mass circulating shear seepage under high temperature and high pressure |
| CN113030429A (en) * | 2021-03-15 | 2021-06-25 | 中国矿业大学 | Multifunctional coal and gas outburst physical simulation device |
| CN113267447A (en) * | 2021-06-23 | 2021-08-17 | 天津大学 | Device for simulating dynamic friction process of original rock and manufacturing method thereof |
| CN113848137A (en) * | 2021-09-22 | 2021-12-28 | 天津大学 | Submarine pipeline corrosion fatigue test device capable of dynamically adjusting environmental parameters |
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