A three-dimensional five-surface stress loading device based on a caustics test system and a test method thereof

Abstract

This invention discloses a triaxial five-dimensional stress loading device based on a caustic testing system for loading specimens. The device includes: a main frame located on the outside of the specimen, with a side plate installed on one side to clamp the specimen in conjunction with the main frame; a hydraulic loading system detachably mounted on the inner wall of the main frame via a connecting plate, used to clamp the specimen around its perimeter and provide power for clamping one end face of the specimen via an axial push plate; the drive end of the hydraulic loading system is equipped with a force-transmitting push plate for pressing the side of the specimen; and a double-arm clamp installed on one side of the side plate, with its two arms located at both ends of the specimen for pre-clamping the two end faces of the specimen. This invention, through this loading device, not only addresses the shortcomings of insufficient confining pressure in ordinary tests but also better simulates the stress state of the original rock underground, obtaining the evolution process of the burst crack tip under real underground stress, and thus analyzing the burst crack propagation law under triaxial five-dimensional stress.

Description

Technical Field

[0001] The invention relates to the field of underground engineering blasting technology, specifically a three-dimensional five-sided stress loading device and its testing method based on a caustic testing system. Background Technology

[0002] With the application of blasting technology in my country's water conservancy, hydropower, energy, mining, transportation and military fields, the depth of underground blasting projects is also increasing. Rock masses with initial stress are products of geological activity. In their natural, unmined and undamaged state, they have initial stresses such as self-weight stress and tectonic stress in multiple directions. In order to study their fracture mechanism, crack propagation, and dynamic stress intensity factor at the crack tip under explosive load, it is necessary to conduct caustic tests on the rock mass under a certain stress state loading.

[0003] Existing laboratory experiments do not consider confining pressure or perform triaxial five-plane pressure loading. Moreover, existing experiments apply relatively low loading pressure to the specimens, which cannot effectively simulate the stress state of rock masses with one free face. Therefore, designing a hydraulic loading device based on a caustic system under triaxial five-plane stress loading has significant theoretical and engineering value in the field of deep rock blasting technology.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is the closest prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a three-dimensional five-dimensional stress loading device and its testing method based on a causs testing system, so as to solve the problem that the existing testing schemes and testing loading devices mentioned in the background art are insufficient for the causs test research of rock materials under confining pressure and explosive loading.

[0006] To achieve the above objectives, the invention provides the following technical solution:

[0007] A triaxial five-sided stress loading device based on a caustic testing system is provided. The loading device is used to load a specimen, which is a square specimen or a circular specimen. A borehole is provided through the middle of the specimen. The two ends of the specimen are respectively provided with an axial push plate for clamping it and a filling rod for filling the opening on one side of the borehole. The axial push plate is provided with a filling protrusion at the position corresponding to the borehole for filling the opening of the borehole located on one side of the axial push plate.

[0008] The main frame is located on the outside of the specimen, and a side plate is installed on one side of it to clamp the specimen in conjunction with the main frame.

[0009] The hydraulic loading system is detachably installed on the inner wall of the main frame via a connecting plate. It is used to clamp the specimen around its perimeter and to provide power for clamping one end face of the specimen via an axial push plate. The drive end of the hydraulic loading system is equipped with a force-transmitting push plate for pressing the side of the specimen.

[0010] The double-arm clamp is installed on one side of the side plate, with its two arms located at both ends of the specimen, and is used to pre-clamp the two end faces of the specimen.

[0011] Furthermore, the force-transmitting push plate includes a slot mechanism, the slot mechanism comprising:

[0012] The switching block is slidably disposed in the slot inside the slot mechanism, and has an arc-shaped slot for clamping a circular specimen and a square slot for clamping a square specimen arranged parallel to each other on one side.

[0013] The slot spiral has threads on its outer side and is threaded to the threaded hole inside the switching block, which is used to drive the switching block to switch the position of the arc-shaped slot and the square slot.

[0014] Furthermore, the hydraulic loading system includes:

[0015] tank;

[0016] A hydraulic cylinder is located on one side of the oil tank. A piston component is slidably inserted inside the cylinder. One end of the piston component is connected to a piston rod for pushing the piston to move, and the other end is connected to an axial piston push rod for driving the axial push plate to move.

[0017] A gas filter is provided inside the hydraulic cylinder and at one end of the piston rod;

[0018] The hydraulic cylinder is located inside the axial piston rod and is connected to the oil tank via an oil inlet, a safety valve, a hydraulic controller, a hydraulic pump, and one end of the oil cylinder.

[0019] Furthermore, the side plate is fixed to a left support plate by mounting bolts, and both sides of the left support plate are provided with toothed lines for adjusting the up and down movement of the double-arm clamp.

[0020] The dual-arm clamp includes:

[0021] The positioning clamps are provided in two sets symmetrically along the tooth line, and the interior of each clamp has a clearance groove.

[0022] A sliding gear is connected to one side of the positioning clamping plate opposite to the clearance groove. The sliding gear meshes with the tooth line and is used to drive the positioning clamping plate to move up and down along the left support plate.

[0023] A rotating block is located inside the relief groove, and is internally threaded with a tension screw for adjusting the movement of the rotating block along the relief groove.

[0024] A clamping arm is connected to one end of the rotating block;

[0025] Two sets of rubber blocks are provided on the inner side of each set of clamping arms for pre-clamping the specimen.

[0026] A support plate, connected between the two sets of positioning clamps, is used to support one end of the tensioning screw.

[0027] Furthermore, the clamping arm is designed with two sections, a thick section and a thin section. The thick section is connected to the rotating block, and the thin section is slidably inserted inside the thick section, which is used for pre-clamping of specimens of different sizes.

[0028] The clamping arms are equipped with telescopic adjustment screws on the thick and thin sections, which are used to rotate and lock the clamping arms of the thin and thick sections when the thin section is extended to a position that adapts to the specimen.

[0029] Furthermore, an annular loading block is used as a transition between the axial top plate and the axial piston push rod to reduce the stress of the axial piston push rod on the axial top plate.

[0030] Furthermore, when loading the square specimen, the hydraulic loading system is provided in four sets, which are respectively connected to the four inner walls of the main frame to clamp the square specimen around its perimeter.

[0031] The dual-arm clamp is installed at the bottom of the side plate when loading the square specimen, with the clamp arms angled upwards.

[0032] Furthermore, when loading the circular specimen, the hydraulic loading system is provided in four sets, which are respectively connected to the four corners of the main frame to clamp the outer periphery of the circular specimen.

[0033] The dual-arm clamp is installed in the middle of the side plate when loading a circular specimen.

[0034] Another object of the present invention is to provide a method for conducting tests using a triaxial five-dimensional stress loading device based on a caustic testing system, comprising the following steps:

[0035] Step 1: Calculate and simulate the vertical in-situ stress, maximum horizontal in-situ stress, and minimum horizontal in-situ stress of the surrounding rock at a certain depth;

[0036] Step 2: Select a specimen. Use simulation to select a specimen of suitable size for loading test.

[0037] Step 3: Fix the specimen. Open and install the double-arm clamp on the left support plate. After selecting the appropriate position of the clamping arm on the side plate, use the positioning clamp to secure the front and rear clamping arms so that the gears on the clamping arms can engage in the tooth lines of the side plate. Use the meshing force between the gears to complete the fixing of the double-arm clamp on the side plate. Then place the specimen in the middle of the double-arm clamp and rotate the clamp's tightening screw to pre-fix the front and rear ends of the specimen. Then fix the lower end of the specimen in the slots of the left and right force transmission push plates. Then fix the upper and lower force transmission push plates of the specimen to fix the specimen in all directions. After fixing, move the filling rod at the front end of the specimen to complete the filling of the front end of the specimen's borehole.

[0038] Step 4: Adjust the force transmission push plate. After selecting the type and size of the specimen, adjust the position of the specimen so that the slot and the hydraulic cylinder behind the push plate are at the same horizontal position. This ensures that the confining pressure loading direction is concentrated on the side of the specimen. Different positions correspond to different slots. Select an axial force transmission push plate of appropriate size so that the protrusion in the middle of the axial force transmission push plate can backfill the blast hole in the specimen. Adjust the axial piston rod so that it acts on the annular loading block, which drives the annular loading block to push the axial force transmission push plate to apply axial pressure loading to the specimen on one side.

[0039] Step 5: Pressure loading. Input the calculated simulated ground stress value into the hydraulic controller, turn on the hydraulic pump to perform pressure loading, and simultaneously control the loading of the axial loading zone of the specimen so that the specimen can be subjected to stress loading in three directions and five planes.

[0040] Step Six: Detonation and Filming. Check the components in the caustic test system to ensure that each component can transmit light smoothly. Turn on the high-speed camera and set it up. Use the detonation probe to detonate and complete the caustic test under triaxial five-dimensional stress loading. After the test, further analyze and study the evolution process and propagation law of cracks on the test specimen.

[0041] Compared with existing technologies, the beneficial effects of the invention are:

[0042] 1. This invention uses a hydraulic loading system to apply confining pressure and axial pressure to the specimen, simulating the stress state of rock mass at a certain underground depth. At the same time, the dual-acting, opposite-direction hydraulic device also realizes the loading of the rock mass under triaxial and five-dimensional stress. In addition, the maximum loading strength that the specimen can withstand can be determined through theoretical calculation, thus ensuring the smooth conduct of the caustic test under triaxial and five-dimensional stress loading.

[0043] 2. The present invention uses a hydraulic loading system with a control system divided into a main control and a sub-control system. The four sub-control devices can control the intensity of confining pressure and axial pressure loading in four different directions: up, down, left, and right. This can satisfy stress loading with equal pressure in all directions as well as stress loading with unequal pressure, and can meet the needs of different test conditions and test types.

[0044] 3. Through the design of the force transmission push plate, the force transmission push plate for loading confining pressure can uniformly load confining pressure onto the test specimen, and the force transmission push plate for loading axial pressure can uniformly apply the axial pressure transmitted from the annular loading block onto the specimen, thus realizing triaxial and five-sided stress loading on the specimen. Its movable connection with the upper hydraulic press also facilitates the disassembly and replacement of the push plate.

[0045] 4. The present invention, through the design of a sliding double-arm clamp, can meet the auxiliary fixation work of different types of specimens during the test. At the same time, by adjusting the telescopic cylinder, it can also assist in fixing specimens of different sizes, avoiding the uncertainty that exists in manually fixing specimens.

[0046] 5. This invention first uses a hydraulic system to drive a force-transmitting push plate to apply confining pressure to the specimen through a slot, and then applies axial pressure through an axial force-transmitting push plate. The loading intensity can be displayed in real time on the hydraulic controller through the pressure sensing device of the hydraulic system. After loading is completed, in conjunction with a reflective caustic test system and a computer, it can better analyze the propagation of burst cracks in the specimen under triaxial five-plane stress loading. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the rear axonal side of the present invention;

[0048] Figure 2 This is a front axonometric view of the present invention;

[0049] Figure 3 This is an exploded view of the axial loading region of the present invention;

[0050] Figure 4 This is a schematic diagram of the loading process of the circular specimen of the present invention;

[0051] Figure 5 This is a schematic diagram of the loading process of the square specimen of the present invention;

[0052] Figure 6 This is a schematic diagram of the card slot mechanism of the present invention;

[0053] Figure 7 This is a schematic diagram of the double-arm clamp of the present invention clamping a circular specimen;

[0054] Figure 8 This is a schematic diagram of the double-arm clamp of the present invention clamping a square specimen;

[0055] Figure 9 This is a schematic diagram of the inner structure of the positioning clamp of the present invention;

[0056] Figure 10 This is a schematic diagram of the hydraulic loading system structure of the present invention;

[0057] Figure 11 This is a schematic diagram of the caustic testing system used in this invention.

[0058] Reference numerals: 1. Main frame; 10. Test loading platform; 101. Side plate; 102. Left side support plate; 1021. Toothed line; 2. Force transmission push plate; 201. Slot mechanism; 2011. Slot screw; 2012. Switching block; 2013. Square slot; 2014. Arc-shaped slot; 3. Hydraulic loading system; 301. Oil tank; 302. Hydraulic pump; 33. Hydraulic controller; 304. Safety valve; 305. Piston rod; 306. Piston component; 307. Hydraulic cylinder; 308. Gas filter; 309. Axial piston push rod; 311. Oil inlet; 4. Double-arm clamp; 401. Rotating block; 40 2. Tightening screw; 403. Positioning clamp; 4031. Leaving groove; 4032. Bearing plate; 404. Rubber block; 405. Telescopic cylinder adjusting screw; 406. Sliding gear; 407. Clamping arm; 5. Specimen; 501. Observation area; 502. Axial push plate; 5021. Stuffing protrusion; 503. Annular loading block; 504. Stuffing rod; 5041. Stuffing head; 6. Blast hole; 7. Mounting bolt; 8. Caustic test system; 801. Computer; 802. High-speed camera; 803. Reflector I; 804. Reflector II; 805. Point light source; 806. Field lens I; 807. Field lens II. Detailed Implementation

[0059] The technical solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0060] Example 1

[0061] Please see Figure 1-11 The present invention provides a technical solution:

[0062] A triaxial five-dimensional stress loading device based on a caustic testing system, the loading device being used to load square or circular specimens, comprising:

[0063] The specimen 5 has a borehole 6 running through its interior. At both ends of the specimen 5, there are axial push plates 502 for pressing against it and a filling rod 504 for filling the opening on one side of the borehole 6. The axial push plate 502 has a filling protrusion 5021 corresponding to the borehole 6, which is used to fill the opening of the borehole 6 located on the side of the axial push plate.

[0064] The tamping rod 504 tamps one side opening of the blast hole 6 through the tamping head 5041 provided on the upper side.

[0065] The main frame 1 is located outside the specimen 5, and a side plate 101 is installed on one side of the main frame 1 to clamp the specimen 5. The lower end of the main frame 1 is provided with a test loading table 10.

[0066] The hydraulic loading system 3 is detachably installed on the inner wall of the main frame 1 via a connecting plate. It is used to clamp the specimen 5 around its perimeter and to provide power for clamping one end face of the specimen 5 via the axial push plate 502. The drive end of the hydraulic loading system 3 is provided with a force-transmitting push plate 2 for pressing the side of the specimen 5.

[0067] The double-arm clamp 4 is installed on one side of the side plate 101, with its two arms located at both ends of the specimen 5, for pre-clamping the two end faces of the specimen 5.

[0068] As an improvement, the force-transmitting push plate 2 includes a slot mechanism 201, which includes:

[0069] The switching block 2012 is slidably disposed in the groove inside the slot mechanism 201, and has an arc-shaped slot 2014 for clamping the circular specimen 5 and a square slot 2013 for clamping the square specimen 5 arranged parallel to one side.

[0070] The specimen 5 is located on one side of the axial push plate 502 as the observation area 501;

[0071] The slot spiral 2011 has a thread on its outer side and is threadedly connected to the threaded hole inside the switching block 2012, which is used to drive the switching block 2012 to switch the position of the arc-shaped slot 2014 and the square slot 2013.

[0072] Furthermore, the hydraulic loading system 3 includes:

[0073] Fuel tank 301;

[0074] Hydraulic cylinder 307 is located on one side of oil tank 301. A piston 306 is slidably inserted inside it. One end of the piston 306 is connected to a piston rod 305 for pushing the piston to move, and the other end is connected to an axial piston push rod 309 for driving the axial push plate 502 to move.

[0075] A gas filter 308 is provided inside the hydraulic cylinder 307 and at one end of the piston rod 305;

[0076] The hydraulic cylinder 307 is located inside one end of the axial piston rod 305 and is connected to one end of the oil tank 301 via the oil inlet 311, safety valve 304, hydraulic controller 33, and hydraulic pump 302.

[0077] As an improvement, the side plate 101 is fixed to the left support plate 102 by mounting bolts 7, and both sides of the left support plate 102 are provided with toothed lines 1021 for adjusting the up and down movement of the double-arm clamp 4:

[0078] The dual-arm clamp 4 includes:

[0079] The positioning clamp 403 is symmetrically arranged in two sets along the tooth line 1021, and its interior is provided with a relief groove 4031;

[0080] A sliding gear 406 is connected to one side of the positioning clamp 403 opposite to the relief groove 4031. The sliding gear 406 meshes with the tooth line 1021 and is used to drive the positioning clamp 403 to move up and down along the left support plate 102.

[0081] A rotating block 401 is disposed inside the relief groove 4031, and is internally threaded with a tensioning screw 402 for adjusting the movement of the rotating block 401 along the relief groove 4031.

[0082] Clamping arm 407 is connected to one end of the rotating block 401;

[0083] Rubber blocks 404 are provided in two sets on the inner side of each set of clamping arms 407, for pre-clamping the specimen 5.

[0084] The support plate 4032 is connected between the two sets of positioning clamps 403 and is used to support one end of the tensioning screw 402.

[0085] Furthermore, the clamping arm 407 is configured as a two-section design, with the thick section connected to the rotating block 401 and the thin section slidably inserted inside the thick section, for pre-clamping of specimens 5 of different sizes.

[0086] The clamping arm 407 is equipped with a telescopic cylinder adjusting screw 405 on the coarse and fine sections, which is used to rotate and lock the clamping arm 407 of the fine and coarse sections when the fine section is extended to a position that adapts to the specimen 5.

[0087] Furthermore, an annular loading block 503 is used as a transition between the axial top plate and the axial piston push rod 309 to reduce the stress of the axial piston push rod 309 on the axial top plate.

[0088] As an improvement, the hydraulic loading system 3 is provided in four sets, which are respectively connected to the four inner walls of the main frame 1. When loading the square specimen 5, it is used to clamp the square specimen 5 around its perimeter. That is, the four sets of hydraulic loading systems 3 are detachably installed on the inner wall of the main frame 1 and located in the middle position through connecting plates. The connecting plates are connected to the main frame 1 by bolts. The fixed ends of the four sets of hydraulic loading systems are fixedly connected to the connecting plates. The fixed and telescopic ends of the four sets of hydraulic loading systems can be fixedly connected to the force transmission push plate 2 or detachably connected. This is not limited here.

[0089] The double-arm clamp 4 is installed at the bottom of the side plate 101 when loading the square specimen 5, and the clamping arms 407 are in an oblique upward position.

[0090] As an improvement, when loading the circular specimen 5, the hydraulic loading system 3 is provided in four sets, which are respectively connected to the four corners of the main frame 1 to clamp the outer periphery of the circular specimen 5; that is, the four sets of hydraulic loading systems 3 are detachably installed at the four corners of the main frame 1 through connecting plates and form isosceles right triangles with the corners, and the connecting plates are connected to the main frame 1 by bolts; the fixed ends of the four sets of hydraulic loading systems are fixedly connected to the connecting plates, and the fixed and telescopic ends of the four sets of hydraulic loading systems are either fixedly connected to the force transmission push plate 2 or detachably connected, which is not limited here;

[0091] The double-arm clamp 4 is installed in the middle of the side plate 101 when loading the circular specimen 5.

[0092] It should be noted that the double-arm clamp 4 device is fixed to the middle part of the left support plate 102 by the sliding gear 406 and the positioning clamp 403. After the specimen 5 is prepared, one tester places the specimen 5 in the middle of the loading table main frame 1, and another tester rotates the rotating block 401 of the double-arm clamp 4 so that the rubber block 404 of the front and rear clamp arms 407 of the specimen 5 is at the same horizontal position as the center line of the specimen 5. The telescopic cylinder adjusting screw 405 is adjusted so that the length of the clamp arm 407 is appropriate so that the rubber block 404 at the front end of the clamp arm 407 is approximately located on both sides of the blast hole 6 in the middle of the specimen 5. Then, the tensioning screw 402 is rotated so that the front end of the double-arm clamp 4 moves closer to the center of the specimen 5 under the spiral pushing action of the tensioning screw 402 until the specimen can be kept stationary by the friction of the rubber block 404.

[0093] If the test requirements change, for example, if the size of the specimen does not provide sufficient space for the clamping arms 407 of the fixture to be fixed, or for a square specimen 5 loading device, the sliding gear 406 can be operated to slide the entire double-arm clamp 4 under the side plate 101, and the clamping arms 407 can be fixed by the positioning clamping plate 403 and the sliding gear 406. After the double-arm clamp 4 has completed the overall fixation of the specimen 5, the telescopic cylinder adjusting screw 405 on the clamping arms 407 can be adjusted to make the front and rear clamping arms 407 in a suitable position and fixed on the side plate 101. This ensures that the high-friction rubber block 404 at the top of the clamping arms 407 firmly pre-fixes the specimen 5. However, during the fixing process, it should be ensured that the rubber block 404 never contacts the borehole 6 in the center of the specimen 5 to avoid damaging the borehole 6 and affecting the explosion effect. When the double-arm clamp 4 is fixed by installation in the middle of the side plate 101, it should be ensured that the clamping arms 407 and the high-friction rubber block 404 at the top of the clamping arms 407 are firmly pre-fixed to the specimen 5. Figure 7 The included angle α of the horizontal reference plane represented in the figure is less than ±10 degrees. When the fixture is fixed by the bottom of the side plate 101, the included angle b between the clamping arm 407 and the horizontal reference plane should be 45 degrees upward.

[0094] Please see Figure 10 The back of the force-transmitting push plate 2 is connected to the bottom of the hydraulic loading system 3 through a sliding groove. The force is transmitted by the piston rod 305 in the hydraulic cylinder to each force-transmitting push plate 2 under the action of hydraulic pressure, and then the force-transmitting push plate 2 is transmitted to the specimen 5 through the slot mechanism 201.

[0095] like Figure 6 As shown, before loading the confining pressure, select the corresponding slot for specimen 5. For example, when using a square specimen 5, rotate the slot screw 2011. The slot screw 2011 will slide the square slot 2013 to the middle of the hydraulic loading system 3 under the spiral propulsion force between it and the switching block 2012. When using a round specimen 5 for loading, rotate the slot screw 2011 to slide the arc-shaped slot 2014 to the middle of the hydraulic loading system 3 so that the line of action of the confining pressure provided by the loading system and the specimen 5 can be on the same plane during the loading process.

[0096] After the double-arm clamp 4 pre-fixes the specimen 5, align the specimen 5 with the slots of each force transmission push plate 2, and adjust the square slots 2013 or arc slots 2014 on the side of each force transmission push plate 2 so that the specimen 5 can be fixed in the slots until stable.

[0097] After the specimen 5 is firmly fixed, the tightening screw 402 of the double-arm clamp 4 needs to be adjusted to release the specimen 5 from the constraint of the double-arm clamp 4. At the same time, the tightening screw 402 is unscrewed from inside the rotating block 401, so that the double-arm clamp 4 hangs down naturally and is parallel to the left support plate 102, allowing the specimen 5 to expose the borehole 6. This facilitates the subsequent caustic test, allowing the light path to pass smoothly through the specimen 5 without being blocked by the rotating block 401, clamping arms 407, etc. See reference. Figure 4 When a type B loading square specimen is used and the specimen 5 has been pre-fixed according to the above process, the rotating block 401 should be adjusted and the positioning clamp 403 should be removed so that the double-arm clamp 4 can be detached from the side plate 101 without affecting the propagation of light in the caustic test.

[0098] Please see Figure 1 and Figure 3 The aforementioned triaxial five-sided stress loading, through Figure 1 The axial piston push rod 309 drives the annular loading block 503 to act on the axial push plate 502, so that the axial push plate 502 can apply axial pressure to the specimen 5, thereby loading axial pressure without damaging the specimen 5.

[0099] Before loading, the filling protrusion 5021 on the axial push plate 502 should be designed so that it can fill the blast hole 6 on the specimen 5. After completing the loading and filling preparation work on the back of the specimen 5, move the filling rod 504 on the front of the specimen 5 and adjust the filling head 5041 on the filling rod 504 to complete the filling of the blast hole 6 in the specimen in cooperation with the filling protrusion 5021 on the axial push plate 502.

[0100] In this embodiment, please refer to Figure 10 The hydraulic loading system 3 comprises an oil tank 301, a hydraulic pump 302, a hydraulic controller 33, a safety valve 304, a hydraulic cylinder 307, a gas filter 308, and an oil inlet 311. The hydraulic cylinder 307 of the double-acting axial hydraulic device contains a piston rod 305 and an axial piston push rod 309. After the specimen 5 is fixed, the calculated simulated confining pressure stress value is input into the hydraulic controller 33, and the gas filter 308 switch on the hydraulic loading system 3 is opened, allowing the hydraulic cylinder 307 to... After the gas is discharged and all the gas inside the hydraulic cylinder 307 is discharged, the gas filter 308 is closed and the hydraulic pump 302 is turned on, and the specimen 5 can be subjected to simulated confining pressure loading. The upper and lower hydraulic loading devices need to be pressurized in the axial pressure loading controller so that the axial piston push rod 309 responsible for axial pressure loading can provide axial pressure. The axial piston push rod 309 drives the annular loading block 503 to transmit the pressure to the axial push plate 502 in the axial pressure loading area of ​​the specimen 5, thereby achieving uniform pressure on the specimen 5 in the axial pressure zone.

[0101] The hydraulic loading system 3 of this invention provides a loading intensity of 0-150kN, which can simulate the stress state of rock mass in three directions and five planes at a certain depth. Moreover, the hydraulic loading system 3 of this invention can achieve loading with different pressures in different directions under the control of the hydraulic controller 33, which can meet the requirements of tests under different loading intensities and provide feasibility for the diversity of experimental research.

[0102] In this embodiment, the explosion generating device consists of a detonation probe and a detonator in the borehole 6 at the center of the specimen 5. It adopts a decoupled charge structure and uses the filling protrusion 5021 on the axial pressure push plate 502 and the filling head 5041 on the filling rod 504 to fill the borehole 6 from front to back, so as to avoid the energy of the explosive in the borehole 6 and ensure the stability and safety of the entire test.

[0103] Example 2

[0104] The present invention also provides a method for conducting tests using a triaxial five-dimensional stress loading device based on a caustic testing system, comprising the following steps:

[0105] Step 1: Calculate and simulate the vertical in-situ stress, maximum horizontal in-situ stress, and minimum horizontal in-situ stress of the surrounding rock at a certain depth;

[0106] Step 2: Select specimen 5, and conduct a loading test on specimen 5 of suitable size through simulation.

[0107] Step 3: Fix the specimen 5, open and install the double-arm clamp 4 on the left support plate 101, select the appropriate position of the clamp arm 407 on the side plate 101, and use the positioning clamp plate 403 to secure the front and rear clamp arms 407 so that the gears on the clamp arms 407 can be engaged in the tooth line 1021 of the side plate 101. Use the meshing force between the gears to complete the fixing of the double-arm clamp 4 on the side plate 101. Then place the specimen 5 in the middle of the double-arm clamp 4, and at the same time rotate the clamp's tightening screw 402 to pre-fix the front and rear ends of the specimen 5. Then fix the lower end of the specimen 5 in the slots of the left and right force transmission push plates 2, and then fix the upper force transmission push plate 2 and the lower force transmission push plate 2 of the specimen 5 so that the specimen 5 is fixed in all directions. After fixing, move the filling rod 504 at the front end of the specimen 5 to complete the filling of the front end of the borehole 6 of the specimen 5.

[0108] Step 4: Adjust the force transmission push plate 2. After selecting the type and size of the specimen 5, adjust the position of the specimen 5 so that the slot and the hydraulic cylinder 307 behind the push plate are at the same horizontal position, thereby ensuring that the confining pressure loading direction is concentrated on the side of the specimen 5. Different positions correspond to different slots. Select an axial force transmission push plate 2 of appropriate size so that the protrusion in the middle of the axial force transmission push plate 2 can backfill the borehole 6 in the specimen 5. Adjust the axial piston rod 305 so that it acts on the annular loading block 503, which can drive the annular loading block 503 to push the axial force transmission push plate 2 to perform unilateral axial pressure loading on the specimen 5.

[0109] Step 5: Pressure loading. Input the calculated simulated ground stress value into the hydraulic controller 33, turn on the hydraulic pump 302 to perform pressure loading, and at the same time control the loading of the axial loading zone of the specimen 5 so that the specimen 5 can be subjected to stress loading in three directions and five planes.

[0110] Step Six: Detonation and Photography. Check the components in the caustic test system 8 to ensure that each component can transmit light smoothly. Turn on the high-speed camera 802 and set it up. Use the detonation probe to detonate and complete the caustic test under triaxial five-dimensional stress loading. After the test, further analyze and study the evolution process and propagation law of the cracks on the specimen 5 after the test.

[0111] It should be noted that, in this embodiment, the caustic test system is an experimental system for studying the distribution of caustic lines in rock mass under triaxial five-plane stress loading. It is used to capture crack propagation information of specimens under the coupled action of triaxial five-plane stress loading and explosive load at high speed, obtain the evolution process of the explosive crack tip under the real underground stress state, and analyze the propagation law of explosive crack under triaxial five-plane stress state.

[0112] The specimens are PMMA specimens, commonly known as plexiglass, with a thickness of 5mm or 10mm. The PMMA specimens used have crack propagation patterns and fracture modes similar to those of brittle rocks. The specimen size can be selected according to the optimal size based on the test conditions.

[0113] The loading intensity required to simulate the original rock stress is obtained through calculation. The calculation method is as follows: vertical principal stress σv=ρgh, horizontal ground stress σh1=σh2=μσ / (1-μ), where; ρ is the density of the rock, g is the gravitational acceleration, h is the depth of the ground, and μ is the Poisson's ratio of the rock.

[0114] The magnitude of the applied load strength is calculated based on the size of the selected specimen 5, ensuring that the applied pressure is within the allowable resistance pressure range of the specimen 5. If the specimen 5 is damaged during the software simulation analysis, the size of the specimen 5 needs to be replaced so that the specimen 5 can withstand the pressure loading. After the calculation is completed, the calculation results are used to assign values ​​to the hydraulic controller in the triaxial five-plane stress loading.

[0115] In this embodiment, please refer to Figure 11 A schematic diagram of a caustic testing system is shown. The caustic testing system consists of a computer 801, a high-speed camera 802, a reflector I 803, a reflector II 804, a point light source 805, a field lens I 806, a loading device, a test loading stage 10, and a field lens II 807.

[0116] Before conducting the caustic test, it is essential to promptly check whether each component of the caustic test system meets the optical path requirements of the reflective caustic test. At the same time, it is also important to pay attention to whether there are any obstructions or shadow areas in the observation area 501 of the specimen 5.

[0117] In this embodiment, the stress optical constant of PMMA specimen 5 is c = 1.08 × 10⁻¹⁰ m² / N, and the density is ρ = 1183 kg / m³. 3 The specimen has a radius of 300 mm and a thickness of 10 mm. The distance from specimen 5 to reference plane 808 is z = 900 mm. After the caustic test under triaxial five-plane stress loading in the embodiment is completed, the result is determined by the formula: K II =μK I The dynamic stress intensity factor at the crack tip can be calculated, where: K Ι It is the stress intensity factor at the tip of a type I crack; K ΙΙ It is the stress intensity factor at the tip of a type II crack; D max It is the maximum diameter of the caustic line at the crack tip; μ is the stress intensity factor proportionality coefficient, which is related to the caustic line characteristic parameter D. max and D min Related; g is the numerical coefficient of stress intensity factor; z0 is the distance from the reference plane to the main frame 1 of the loading stage; c is the stress optical constant of the material; d is the actual thickness of specimen 5.

[0118] In summary, the triaxial five-dimensional stress loading device based on the caustic testing system can obtain the evolution process of the explosive crack tip under real underground stress conditions through experiments, and further analyze the crack propagation law under triaxial five-dimensional stress conditions. This is of positive significance for studying the crack propagation behavior of underground rock masses under explosive loading. Furthermore, experiments using the controlled variable method with and without triaxial five-dimensional stress loading and different loading intensities, and the crack propagation length and crack distribution captured by the high-speed 802 camera, more closely approximate the real situation and have guiding significance.

[0119] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0120] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A triaxial five-dimensional stress loading device based on a caustic testing system, wherein the loading device is used to load a specimen (5), the specimen (5) being a square specimen or a circular specimen, characterized in that, The test piece (5) has a borehole (6) running through its interior. The test piece (5) has an axial push plate (502) for pressing against it and a filling rod (504) for filling the opening on one side of the borehole (6) at both ends. The axial push plate (502) has a filling protrusion (5021) corresponding to the borehole (6) for filling the opening of the borehole (6) located on the side of the axial push plate. The main frame (1) is located on the outside of the specimen (5), and a side plate (101) is installed on one side to clamp the specimen (5) in conjunction with the main frame (1); The hydraulic loading system (3) is detachably installed on the inner wall of the main frame (1) via a connecting plate. It is used to clamp the specimen (5) around its perimeter and to provide power for clamping one end face of the specimen (5) via an axial push plate (502). The driving end of the hydraulic loading system (3) is provided with a force-transmitting push plate (2) for pressing the side of the specimen (5). A double-arm clamp (4) is installed on one side of the side plate (101), with its two arms located at both ends of the specimen (5) to pre-clamp the two end faces of the specimen (5). The side plate (101) is fixed to the left support plate (102) by mounting bolts (7). Both sides of the left support plate (102) are provided with toothed lines (1021) for adjusting the up and down movement of the double-arm clamp (4). The dual-arm clamp (4) includes: The positioning clamp (403) is provided in two sets symmetrically along the tooth line (1021), and the interior is provided with a relief groove (4031); A sliding gear (406) is connected to the side of the positioning clamp (403) opposite to the relief groove (4031). The sliding gear (406) meshes with the tooth line (1021) and is used to drive the positioning clamp (403) to move up and down along the left support plate (102). A rotating block (401) is provided inside the relief groove (4031), and is internally threaded with a tensioning screw (402) for adjusting the movement of the rotating block (401) along the relief groove (4031); A clamping arm (407) is connected to one end of the rotating block (401); Two sets of rubber blocks (404) are provided on the inner side of each set of clamping arms (407) for pre-clamping the specimen (5); The support plate (4032) is connected between the two sets of positioning clamps (403) and is used to support one end of the tensioning screw (402); The clamping arm (407) is designed with two sections, a thick section and a thin section. The thick section is connected to the rotating block (401), and the thin section is slidably inserted into the thick section. This is used to pre-clamp specimens (5) of different sizes. The clamping arm (407) is equipped with a telescopic cylinder adjusting screw (405) on the coarse and fine sections, which is used to rotate and lock the clamping arm (407) of the fine and coarse sections when the fine section is extended to a position that is compatible with the specimen (5).

2. The triaxial five-sided stress loading device based on a caustic testing system according to claim 1, characterized in that: The force-transmitting push plate (2) includes a slot mechanism (201), which includes: The switching block (2012) is slidably disposed in the groove inside the slot mechanism (201), and has an arc-shaped slot (2014) for clamping the circular specimen (5) and a square slot (2013) for clamping the square specimen (5) arranged parallel to one side. The slot spiral (2011) has a thread on its outer side and is threaded to the threaded hole inside the switching block (2012), which is used to drive the switching block (2012) to switch the position of the arc-shaped slot (2014) and the square slot (2013).

3. The triaxial five-sided stress loading device based on a caustic testing system according to claim 1, characterized in that: The hydraulic loading system (3) includes: Fuel tank (301); A hydraulic cylinder (307) is located on one side of the oil tank (301), and a piston (306) is slidably inserted inside it. One end of the piston (306) is connected to a piston rod (305) for pushing the piston to move, and the other end is connected to an axial piston push rod (309) for driving the axial push plate (502) to move. A gas filter (308) is provided inside the hydraulic cylinder (307) and at one end of the piston rod (305); The hydraulic cylinder (307) is located inside the axial piston rod (305) and is connected to one end of the oil tank (301) via the oil inlet (311), safety valve (304), hydraulic controller (33), and hydraulic pump (302).

4. The triaxial five-sided stress loading device based on a caustic testing system according to claim 3, characterized in that: An annular loading block (503) is used to transition between the axial top plate and the axial piston push rod (309) to reduce the stress of the axial piston push rod (309) on the axial top plate.

5. A triaxial five-sided stress loading device based on a caustic testing system according to claim 1, characterized in that: When loading the square specimen (5), the hydraulic loading system (3) is provided in four sets, which are respectively connected to the four inner walls of the main frame (1) to clamp the square specimen (5) around its perimeter. The double-arm clamp (4) is installed at the bottom of the side plate (101) when loading the square specimen (5), and the clamping arms (407) are in an oblique upward state.

6. The triaxial five-sided stress loading device based on a caustic testing system according to claim 1, characterized in that: When loading the circular specimen (5), the hydraulic loading system (3) is provided in four sets, which are connected to the four corners of the main frame (1) respectively, and are used to clamp the outer periphery of the circular specimen (5). The double-arm clamp (4) is installed in the middle of the side plate (101) when loading the circular specimen (5).

7. The method for conducting tests using a triaxial five-sided stress loading device based on a caustic testing system according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Simulate the surrounding rock at a certain depth and calculate the vertical ground stress, the maximum horizontal ground stress, and the minimum horizontal ground stress; Step 2: Select specimen (5), and conduct a loading test on a specimen (5) of suitable size through simulation. Step 3: Fix the specimen (5), open and install the double-arm clamp (4) on the left support plate (101), select the appropriate position of the clamping arm (407) on the side plate (101), and use the positioning clamp (403) to secure the front and rear clamping arms (407) so that the gears on the clamping arms (407) can be engaged in the tooth line (1021) of the side plate (101). Utilize the meshing force between the gears to complete the fixing of the double-arm clamp (4) on the side plate (101). Then place the specimen (5) on the side plate (101). Place the specimen (5) in the middle of the double-arm clamp (4), and at the same time rotate the clamp's tightening screw (402) to pre-fix the front and rear ends of the specimen (5). Then, first fix the lower end of the specimen (5) in the slots of the left and right force transmission push plates (2), and then fix the upper force transmission push plate (2) and the lower force transmission push plate (2) of the specimen (5) so that the specimen (5) is fixed in all directions. After the fixing is completed, move the filling rod (504) at the front end of the specimen (5) to complete the filling of the front end of the blast hole (6) of the specimen (5). Step 4: Adjust the force transmission push plate (2). After selecting the type and size of the specimen (5), adjust the position of the specimen (5) so that the slot and the hydraulic cylinder (307) behind the push plate are at the same horizontal position, so as to ensure that the direction of the confining pressure loading is concentrated on the side of the specimen (5). Different positions correspond to different slots. Select an axial force transmission push plate (2) of appropriate size so that the protrusion in the middle of the axial force transmission push plate (2) can back-fill the blast hole (6) in the specimen (5). Adjust the axial piston rod (305) so that it acts on the annular loading block (503) and drives the annular loading block (503) to push the axial force transmission push plate (2) to perform unilateral axial pressure loading on the specimen (5). Step 5: Pressure loading. Input the calculated simulated ground stress value into the hydraulic controller (33), turn on the hydraulic pump (302) to perform pressure loading, and at the same time control the loading of the axial loading zone of the specimen (5) so that the specimen (5) can be subjected to stress loading in three directions and five planes. Step 6: Detonation and filming. Check the components in the caustic test system (8) to ensure that each component can transmit light smoothly. Turn on the high-speed camera (802) and set it up. Use the detonation probe to detonate and complete the caustic test under triaxial five-dimensional stress loading. After the test is completed, analyze the evolution process and propagation law of the crack on the specimen (5) after the test.

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