Annular rock sample circumferential loading test device and method

Abstract

The invention belongs to the technical field of rock-soil body physical mechanics experiments, and particularly relates to an annular rock sample circumferential loading test device and method. The test device comprises a device frame. The circumferential pressurizing units are arranged in parallel in the axial direction of the rock sample, and the circumferential pressurizing units are arranged on the periphery of the rock sample in a sleeving mode and used for applying circumferential confining pressure to the rock sample; the annular pressurizing units at different axial positions are used for applying annular confining pressure of different magnitudes; the circumferential pressurizing unit comprises a flexible pressure equalizing plate, the flexible pressure equalizing plate surrounds the periphery of the rock sample, and after surrounding the rock sample, the flexible pressure equalizing plate is provided with mutually lapped parts; a plurality of tightening ropes surround the periphery of the flexible pressure equalizing plate, and each tightening rope at least surrounds the flexible pressure equalizing plate by one circle; and the two ends of the tightening rope are tightened to tighten the flexible pressure equalizing plate so as to apply confining pressure to the rock sample. The test device can more truly and effectively simulate the working condition that the circular shaft is subjected to peripheral ground stress and load application, so that a more accurate and effective test result is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of rock and soil physical mechanics experiments, and specifically relates to a circular ring-shaped rock sample annular loading test device and method. Background Art

[0002] Rock mechanics experiments are an important means of studying the mechanical properties of rock under different conditions and are widely used in geology, mining engineering, civil engineering and other fields. These experiments simulate the natural geological environment to help experimenters gain a deep understanding of the strength, deformation characteristics and fracture mechanism of rocks, providing a scientific basis for engineering design and disaster prevention.

[0003] The existing GCTS and SHPB test systems can only realize the loading process in one direction, but cannot realize the real simulation process of the complex ground stress in actual engineering; and it is impossible to apply circumferential load to cylindrical specimens; however, the circumferential loading of cylindrical or annular specimens can simulate the circular stress and load application conditions of circular shafts in coal mines or ground gas extraction, and there is currently no test device for this specific condition.

[0004] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Invention content

[0005] The purpose of the present invention is to provide a circular ring-shaped rock sample annular loading test device and method to at least solve the above-mentioned problems existing in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A circular ring-shaped rock sample annular loading test device, the test device comprising:

[0008] A device frame, wherein an axial loader is disposed on the top of the device frame, a top pressure plate is disposed at the output end of the axial loader, a bottom pressure plate is disposed below the corresponding top pressure plate of the device frame, and the rock sample is placed on the bottom pressure plate;

[0009] An annular pressurizing unit, wherein a plurality of annular pressurizing units are arranged in parallel along the axial direction of the rock sample, and the annular pressurizing units are sleeved on the periphery of the rock sample to apply annular confining pressure to the rock sample; the annular pressurizing units at different axial positions are used to apply annular confining pressures of different magnitudes;

[0010] The annular pressurizing unit comprises a flexible pressure equalizing plate, which surrounds the periphery of the rock sample, and has overlapping parts after the flexible pressure equalizing plate surrounds the rock sample;

[0011] A plurality of tightening ropes are arranged around the outer periphery of the flexible pressure equalizing plate, and each tightening rope is at least arranged around the flexible pressure equalizing plate once; the two ends of the tightening ropes are tightened to tighten the flexible pressure equalizing plate and apply confining pressure to the rock sample.

[0012] In the annular rock sample annular loading test device as described above, preferably, a plurality of rows of guide rings are axially arranged on the outer peripheral surface of the flexible pressure equalizing plate, and each of the tightening ropes is inserted into a row of guide rings.

[0013] As described above, the annular rock sample annular loading test device, preferably, the device frame is further provided with two steering rods, and the two steering rods are symmetrically arranged along the axis of the rock sample.

[0014] In the annular rock sample annular loading test device as described above, preferably, after the flexible pressure equalizing plate surrounds the periphery of the rock sample, a row of guide rings is provided between the axis of any steering rod and the line connecting the axis of the rock sample.

[0015] In the annular loading test device for annular rock samples as described above, preferably, after the tightening rope has wrapped around the rock sample at least once, the two ends of the tightening rope respectively pass through the guide ring between the axis of the steering rod and the axis of the rock sample, and bypass the guide ring to be connected to the tensioning unit, so that the two ends of the tightening rope passing through the guide ring are on the same straight line passing through the axis of the rock sample, and extend in opposite directions respectively.

[0016] In the annular rock sample annular loading test device as described above, preferably, the tensioning unit is a winch, and the tightening rope is a steel strand;

[0017] The two ends of the tightening rope are respectively passed around the turning rods on both sides of the rock sample and are connected to the same winch.

[0018] In the annular rock sample circumferential loading test device as described above, preferably, the winch is located on the perpendicular midline of the line connecting the axes of the two steering rods.

[0019] As described above, in the annular rock sample annular loading test device, preferably, a plurality of boreholes extending in the axial direction are arranged inside the rock sample, and a monitoring unit is arranged in each borehole.

[0020] In the annular rock sample annular loading test device as described above, preferably, the monitoring unit includes a distributed optical fiber sensor, a distributed acoustic wave sensor and an inclinometer;

[0021] The distributed optical fiber sensor is used to detect the deformation and stress of the rock sample;

[0022] The distributed acoustic wave sensor is used to detect the development and evolution of cracks in the rock sample when it is loaded;

[0023] The inclinometer is used to monitor the internal deformation and tilt data of the rock sample.

[0024] The present application also provides a circular ring-shaped rock sample annular loading test method, characterized in that the test method uses the circular ring-shaped rock sample annular loading test device mentioned above, and the test method includes:

[0025] Step 1, preparing a rock sample of a set size and drilling a hole in the rock sample;

[0026] Step 2, placing the rock sample between the bottom pressure plate and the top pressure plate of the axial loader, and adjusting the axis of the rock sample to coincide with the axis of the axial loader;

[0027] Step 3, installing multiple annular pressure units at different axial positions of the rock sample respectively; wherein, firstly, the flexible pressure equalizing plate is wrapped around the outer periphery of the rock sample, and then the tightening rope is wrapped around a row of guide rings, and after the tightening rope is wrapped around the rock sample at least once, the two ends of the tightening rope are passed around the steering rod and connected to the tensioning unit;

[0028] Step 4, applying axial pressure to the rock sample through the axial loader, and applying surrounding rock to the rock sample by tightening the tightening rope through the tightening unit; the confining pressure applied by multiple annular pressurizing units is gradually increased from top to bottom;

[0029] Step 5: When the rock sample is subjected to axial pressure and annular confining pressure, the monitoring unit is used to monitor the stress, strain, crack development process and borehole inclination of the rock sample in real time.

[0030] Beneficial effects:

[0031] In the triaxial test device, different confining pressures are applied to the rock sample by controlling multiple annular pressure units in the axial direction to simulate the actual law of gradual change of the confining pressure on the rock sample with the increase of burial depth, and the annular pressure units in the axial direction can be free from interference with each other, so that each annular pressure unit can independently and effectively apply different sizes of surrounding rock to different axial positions of the rock sample, ensuring that the circular ring-shaped rock sample annular loading test device can more realistically and effectively simulate the working conditions of the circular shaft of coal mine or ground gas extraction subjected to the surrounding ground stress and load, thereby having more accurate and effective test results.

[0032] Each tightening rope is passed through a row of guide rings so that the tightening rope can better maintain its position without a large position deviation, thereby ensuring that each tightening rope can stably and reliably play its tightening role at the preset position.

[0033] The two ends of the tightening rope pass through the guide ring and are wound around the steering rod. Since the guide ring through which the tightening rope passes is located between the axis of the steering rod and the axis of the rock sample, and the two steering rods are symmetrically arranged relative to the axis of the rock sample, that is, the two ends of the tightening rope are on the same straight line passing through the axis of the rock sample and extend in opposite directions, when the two ends of the tightening rope are tightened, while the tightening rope tightens the flexible pressure equalizing plate, the forces in opposite directions at the two ends of the tightening rope on the same straight line along the axis of the rock sample can offset each other, thereby not generating other forces that deviate from the axis of the rock sample on the rock sample, thereby ensuring the stability of the annular loading test of the circular rock sample.

[0034] The monitoring unit is used to monitor the stress, strain, crack development process and drilling inclination of the rock sample in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings constituting part of the present application are used to provide a further understanding of the invention. The exemplary embodiments and descriptions of the invention are used to explain the invention and do not constitute an improper limitation on the invention. Among them:

[0036] Figure 1 A front view of a test device for creating an embodiment of the present invention;

[0037] Figure 2 for Figure 1 A partial enlarged view of the

[0038] Figure 3 A top view of a test device for creating an embodiment of the present invention;

[0039] Figure 4 for Figure 3 A partial enlarged view of the

[0040] In the figure: 1. rock sample; 2. device frame; 3. axial loader; 4. top pressure plate; 5. bottom pressure plate; 6. flexible pressure plate; 7. guide ring; 8. tightening rope; 9. steering rod; 10. monitoring unit; 11. winch. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0042] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixedly connected or detachably connected; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0044] According to the specific embodiments of the present invention, Figure 1-4 As shown, the present invention provides a circular ring-shaped rock sample annular loading test device, the test device comprising:

[0045] The device frame 2 has an axial loader 3 on its top, a top pressure plate 4 on its output end, a bottom pressure plate 5 on the bottom of the corresponding top pressure plate 4 of the device frame 2 , and the rock sample 1 is placed on the bottom pressure plate 5 .

[0046] An annular pressurizing unit, wherein a plurality of annular pressurizing units are arranged in parallel along the axial direction of the rock sample 1, and the annular pressurizing units are sleeved on the periphery of the rock sample 1, and are used to apply annular confining pressure to the rock sample 1; the annular pressurizing units at different axial positions are used to apply annular confining pressures of different magnitudes.

[0047] The annular pressurizing unit includes a flexible pressure equalizing plate 6, which surrounds the periphery of the rock sample 1, and has overlapping parts after the flexible pressure equalizing plate 6 surrounds the rock sample 1; in this embodiment, the flexible pressure equalizing plate 6 is made of a bent iron plate or steel plate, and the flexible pressure equalizing plate 6 only overlaps each other after surrounding the rock sample 1, but is not fixed, so as to ensure that the flexible pressure equalizing plate 6 can be further tightened to apply confining pressure to the rock sample 1.

[0048] A plurality of tightening ropes 8 are arranged around the flexible pressure equalizing plate 6 , and each tightening rope 8 at least surrounds the flexible pressure equalizing plate 6 once; the ends of the tightening ropes 8 are tightened to tighten the flexible pressure equalizing plate 6 and apply confining pressure to the rock sample 1 .

[0049] In the triaxial test device, axial pressure can be applied to the rock sample 1 through the axial loader 3, and in the annular pressurizing unit, a tightening rope 8 is wrapped around the outer periphery of the flexible pressure equalizing plate 6. After the tightening rope 8 is tightened, the tightening rope 8 gradually locks the flexible pressure equalizing plate 6. As the tension of the tightening rope 8 increases, the confining pressure of the flexible pressure equalizing plate 6 on the rock sample 1 gradually increases; by controlling multiple annular pressurizing units in the axial direction to apply different sizes of confining pressure to the rock sample 1, the actual law of gradual change of the confining pressure on the rock sample 1 with the increase of the burial depth is simulated, and the annular pressurizing units in the axial direction can be achieved without interfering with each other, so that each annular pressurizing unit can independently and effectively apply different sizes of surrounding rock to different axial positions of the rock sample 1, ensuring that the annular rock sample annular loading test device can more realistically and effectively simulate the application conditions of the surrounding ground stress and load on the circular shaft of the coal mine or ground gas extraction, thereby having more accurate and effective test results.

[0050] A plurality of rows of guide rings 7 are axially arranged on the outer surface of the flexible pressure equalizing plate 6, and each tightening rope 8 is inserted in a row of guide rings 7. In one embodiment of the present application, each tightening rope 8 is inserted in a row of guide rings 7 so that the tightening rope 8 can better maintain its position without a large position deviation, thereby ensuring that each tightening rope 8 can stably and reliably play its tightening role at the preset position.

[0051] In this embodiment, at least eight guide rings 7 are provided in each row to better provide a guiding and limiting function for the tightening rope 8 .

[0052] Two steering rods 9 are also provided on the device frame 2 , and the two steering rods 9 are symmetrically arranged along the axis of the rock sample 1 .

[0053] After the flexible pressure equalizing plate 6 surrounds the periphery of the rock sample 1 , a row of guide rings 7 is provided between the axis of any steering rod 9 and the axis of the rock sample 1 .

[0054] After the tightening rope 8 has been wrapped around the rock sample 1 at least once, the two ends of the tightening rope 8 respectively pass through the guide ring 7 between the axis of the steering rod 9 and the axis of the rock sample 1, and pass around the guide ring 7 to be connected to the tensioning unit, so that the two ends of the tightening rope 8 passing through the guide ring 7 are on the same straight line passing through the axis of the rock sample 1, and extend in opposite directions respectively. In one embodiment of the present application, the two ends of the tightening rope 8 are respectively passed through the guide ring 7 and then wound around the steering rod 9. Since the guide ring 7 through which the tightening rope 8 passes is located between the axis of the steering rod 9 and the axis of the rock sample 1, and the two steering rods 9 are symmetrically arranged relative to the axis of the rock sample 1, that is, the two ends of the tightening rope 8 are on the same straight line passing through the axis of the rock sample 1, and extend in opposite directions respectively, then when the two ends of the tightening rope 8 are tightened, while the tightening rope 8 tightens the flexible pressure equalizing plate 6, the forces in opposite directions at the two ends of the tightening rope 8 on the same straight line along the axis of the rock sample 1 can offset each other, thereby not generating other forces that offset the axis of the rock sample 1 on the rock sample 1, thereby ensuring the stability of the annular loading test of the circular rock sample.

[0055] The tensioning unit is a winch 11, and the tightening rope 8 is a steel strand; both ends of the tightening rope 8 are connected to the same winch 11 after passing through the turning rods 9 on both sides of the rock sample 1. In one embodiment of the present application, both ends of a tightening rope 8 are connected to the same winch 11 after passing through the two turning rods 9 respectively. When the winch 11 rotates, the two ends of the tightening rope 8 are subjected to the same tightening force, so that the tension at both ends of the tightening rope 8 can be offset against each other.

[0056] The hoist 11 is located on the perpendicular midline of the axis connecting the two steering rods 9. In one embodiment of the present application, the arrangement is such that the distances from both ends of the tightening rope 8 to the same hoist 11 are equal, so that both ends of the tightening rope 8 can be subjected to the same tensioning force.

[0057] A plurality of boreholes extending in the axial direction are arranged inside the rock sample 1 , and a monitoring unit 10 is arranged in each borehole.

[0058] The monitoring unit 10 includes a distributed optical fiber sensor, a distributed acoustic wave sensor and an inclinometer; the distributed optical fiber sensor is used to detect the deformation and stress of the rock sample 1; so as to finally draw a distribution cloud map and numerical value of stress and strain from top to bottom, so as to record and analyze the stress and strain change law of the ring sample during the loading process.

[0059] The distributed acoustic wave sensor is used to detect the crack development and evolution process of the rock sample 1 when it is loaded; specifically, the distributed acoustic wave sensor detects the crack initiation, expansion, crack arrest, and the entire development and evolution process of the crack path inside the rock sample 1.

[0060] The inclinometer is used to monitor the internal deformation and tilt data of the rock sample 1, so as to measure and monitor the different tilt damage conditions of the rock sample 1 borehole in real time.

[0061] The present application also provides a circular ring-shaped rock sample annular loading test method, the test method uses the circular ring-shaped rock sample annular loading test device, and the test method includes:

[0062] Step 1, prepare a rock sample 1 of a set size, and drill holes in the rock sample 1; in this embodiment, the rock sample 1 can be made into a cylindrical or annular shape, wherein the cylindrical shape is a special annular shape with an inner diameter of zero; taking the cylindrical rock sample 1 as an example, its size is 50 mm (diameter) × 100 mm (height); and four holes are symmetrically drilled in the cylindrical rock sample 1;

[0063] Step 2, placing the rock sample 1 between the bottom pressure plate 5 and the top pressure plate 4 of the axial loader 3, and adjusting the axis of the rock sample 1 to coincide with the axis of the axial loader 3; to ensure that the axial load is applied in the axial direction of the rock sample 1;

[0064] Step 3, installing multiple annular pressure units at different axial positions of the rock sample 1 respectively; in this embodiment, five annular pressure units are installed in the axial direction around the rock sample 1, and the surrounding rock applied by the five annular pressure units is gradually increased; wherein, the flexible pressure equalizing plate 6 is firstly wrapped around the rock sample 1, and then the tightening rope 8 is wrapped around a row of guide rings 7, and after the tightening rope 8 wraps around the rock sample 1 for at least one circle, the two ends of the tightening rope 8 are passed around the steering rod 9 and connected to the tensioning unit;

[0065] Step 4, applying axial pressure to the rock sample 1 through the axial loader 3, and applying surrounding rock to the rock sample 1 through the tensioning unit tightening the tightening rope 8; the confining pressure applied by multiple annular pressurizing units gradually increases from top to bottom;

[0066] Step 5: When the rock sample 1 is subjected to axial pressure and annular confining pressure, the monitoring unit 10 monitors the stress, strain, crack development process and drilling inclination of the rock sample 1 in real time.

[0067] It should be understood that the above description is merely exemplary and the embodiments of the present application do not limit this.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A circular rock sample annular loading test device, characterized in that: The test device comprises: A device frame, wherein an axial loader is disposed on the top of the device frame, a top pressure plate is disposed at the output end of the axial loader, a bottom pressure plate is disposed below the corresponding top pressure plate of the device frame, and the rock sample is placed on the bottom pressure plate; An annular pressurizing unit, wherein a plurality of annular pressurizing units are arranged in parallel along the axial direction of the rock sample, and the annular pressurizing units are sleeved on the periphery of the rock sample to apply annular confining pressure to the rock sample; the annular pressurizing units at different axial positions are used to apply annular confining pressures of different magnitudes; The annular pressurizing unit comprises a flexible pressure equalizing plate, which surrounds the periphery of the rock sample, and has overlapping parts after the flexible pressure equalizing plate surrounds the rock sample; A plurality of tightening ropes are arranged around the outer periphery of the flexible pressure equalizing plate, and each tightening rope is at least arranged around the flexible pressure equalizing plate once; the two ends of the tightening ropes are tightened to tighten the flexible pressure equalizing plate and apply confining pressure to the rock sample.

2. The annular rock sample circumferential loading test device according to claim 1 is characterized in that: A plurality of rows of guide rings are axially arranged on the outer peripheral surface of the flexible pressure equalizing plate, and each of the tightening ropes is inserted into a row of guide rings.

3. The annular rock sample circumferential loading test device according to claim 2 is characterized in that: The device frame is also provided with two steering rods, which are symmetrically arranged along the axis of the rock sample.

4. The annular rock sample circumferential loading test device according to claim 3 is characterized in that: After the flexible pressure equalizing plate surrounds the periphery of the rock sample, a row of guide rings is provided between the axis of any steering rod and the axis of the rock sample.

5. The annular rock sample circumferential loading test device according to claim 4 is characterized in that: After the tightening rope has been wrapped around the rock sample at least once, the two ends of the tightening rope respectively pass through the guide ring between the axis of the steering rod and the axis of the rock sample, and pass around the guide ring to be connected to the tensioning unit, so that the two ends of the tightening rope passing through the guide ring are on the same straight line passing through the axis of the rock sample and extend in opposite directions.

6. The annular rock sample circumferential loading test device according to claim 5 is characterized in that: The tensioning unit is a winch, and the tightening rope is a steel strand; The two ends of the tightening rope are respectively passed around the turning rods on both sides of the rock sample and are connected to the same winch.

7. The annular rock sample circumferential loading test device according to claim 6 is characterized in that: The winch is located on the mid-vertical line of the line connecting the axes of the two steering rods.

8. The annular rock sample circumferential loading test device according to claim 5, characterized in that: A plurality of boreholes extending along the axial direction are arranged inside the rock sample, and a monitoring unit is arranged in each borehole.

9. The annular rock sample circumferential loading test device according to claim 8, characterized in that: The monitoring unit includes a distributed optical fiber sensor, a distributed acoustic wave sensor and an inclinometer; The distributed optical fiber sensor is used to detect the deformation and stress of the rock sample; The distributed acoustic wave sensor is used to detect the development and evolution of cracks in the rock sample when it is loaded; The inclinometer is used to monitor the internal deformation and tilt data of the rock sample.

10. A method for annular rock sample circumferential loading test, characterized in that: The test method uses the annular rock sample annular loading test device according to claim 9, and the test method comprises: Step 1, preparing a rock sample of a set size and drilling a hole in the rock sample; Step 2, placing the rock sample between the bottom pressure plate and the top pressure plate of the axial loader, and adjusting the axis of the rock sample to coincide with the axis of the axial loader; Step 3, installing multiple annular pressure units at different axial positions of the rock sample respectively; wherein, firstly, the flexible pressure equalizing plate is wrapped around the outer periphery of the rock sample, and then the tightening rope is wrapped around a row of guide rings, and after the tightening rope is wrapped around the rock sample at least once, the two ends of the tightening rope are passed around the steering rod and connected to the tensioning unit; Step 4, applying axial pressure to the rock sample through the axial loader, and applying surrounding rock to the rock sample by tightening the tightening rope through the tightening unit; the confining pressure applied by multiple annular pressurizing units is gradually increased from top to bottom; Step 5: When the rock sample is subjected to axial pressure and annular confining pressure, the monitoring unit is used to monitor the stress, strain, crack development process and borehole inclination of the rock sample in real time.

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