Water-mechanical coupling loading device and test method suitable for true triaxial Hopkinson pressure bar test

Abstract

The present invention discloses a water-mechanical coupling loading device and test method suitable for true triaxial Hopkinson pressure bar test, comprising a device body; the device body is a regular six-sided sealed cavity structure, a sample preparation rack is arranged in the inner cavity of the device body, the sample placed on the sample preparation rack is located at the inner cavity center of the device body, a through hole connected to the inner cavity is arranged in the middle of each side of the device body, one end of the pressure rod passes through the through hole and abuts against the outer side of the sample, and the other end abuts against the Hopkinson pressure bar; the inner cavity of the device body is connected to a water pressure application system, and the water pressure application system dynamically balances the internal water pressure of the device body according to the pressure value collected by a pressure sensor arranged in the inner cavity of the device body and at the same height as the sample; the pressure rod is a sleeve rod structure, the outer water-blocking rod is a hollow rod, the inner pressure rod is a solid rod, and a sponge is arranged between the outer water-blocking rod and the inner pressure rod. The present invention realizes the true triaxial Hopkinson pressure bar test under the condition of considering the coupling loading of water depth and confining pressure.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass mechanics tests, and in particular to a water-mechanical coupling loading device and a test method suitable for a true triaxial Hopkinson pressure bar test. Background Art

[0002] During deep-water rock excavation, rocks and other materials not only have to withstand high ground stress and engineering disturbances caused by blasting and excavation, but also water pressure. The deeper the water depth, the greater the water pressure. The various properties of rocks under the action of water pressure are different from those on land. At present, most of the research on the dynamic mechanical properties of rocks and other materials under high ground stress at home and abroad is based on the traditional one-dimensional or three-dimensional dynamic and static combined loading Hopkinson pressure bar test device. Although this device can carry out dynamic and static combined loading test research of rocks under equal confining pressure or three-way confining pressure conditions, it cannot consider the impact of water pressure on rock samples in real time. At present, the more common practice is to first place the rock sample in water to a saturated state, or to simulate the impact of water pressure on the rock sample by seepage, but this is obviously not in line with the actual working conditions of the rock mass under deep water conditions.

[0003] In summary, there is currently no true triaxial dynamic-static combined loading Hopkinson bar device that combines a simulated water depth system and a dynamic-static combined loading system, especially a true triaxial dynamic-static combined loading system, to consider the coupled loading of water depth and confining pressure. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention proposes a water-mechanical coupling loading device and a test method suitable for a true triaxial Hopkinson pressure bar test, which realizes a true triaxial Hopkinson pressure bar test under the condition of considering the water depth and confining pressure coupling loading.

[0005] To achieve the above-mentioned purpose, the present invention is a water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test, which is special in that it includes a device body, a pressure rod and a water pressure application system;

[0006] The device body is a six-sided sealed cavity structure, a sample preparation rack is arranged in the inner cavity of the device body, the sample placed on the sample preparation rack is located at the center of the inner cavity of the device body, a through hole communicating with the inner cavity is arranged in the middle of each side of the device body, one end of the pressure rod passes through the through hole and abuts against the outer side of the sample, and the other end of the pressure rod abuts against the Hopkinson pressure bar;

[0007] The inner cavity of the device body is connected to a water pressure application system, and the water pressure application system performs dynamic balance control on the water pressure inside the device body according to the pressure value collected by a pressure sensor arranged in the inner cavity of the device body and at the same height as the sample;

[0008] The pressure rod is a sleeve rod structure, the outer waterproof rod is a hollow rod, the inner pressure rod is a solid rod, a sponge is arranged between the outer waterproof rod and the inner pressure rod, and the outer waterproof rod is sealed and fixedly connected with the rubber sleeve.

[0009] Furthermore, the water pressure application system includes a water inlet arranged on the upper surface of the device body and a water outlet on the lower surface. The water inlet and the water outlet are connected to the water pressure control system through a water inlet pipe and a water outlet pipe respectively. The water pressure control system is electrically connected to a pressure sensor to collect the inner cavity water pressure value of the device body in real time, and the inner cavity water pressure value reaches a dynamic balance of the water pressure test value by adjusting the water flow in the water inlet pipe and the water outlet pipe.

[0010] Furthermore, a sealing rubber ring is provided on the through hole on each side of the device body, and the sealing rubber ring is sealed and fixed to the outer waterproof rod.

[0011] Furthermore, the sample preparation rack includes a bottom support rod and a sample placement tray arranged above the bottom support rod, a through hole for placing a sample is arranged in the middle of the sample placement tray, and the sample is snap-fitted with the sample placement tray.

[0012] Furthermore, a cover plate is provided on the side of the device body, the cover plate is fixed by fixing screws, and one side of the cover plate is connected to the device body by a movable hinge.

[0013] Furthermore, the cross-sections of the outer waterproof rod and the inner pressure rod are both circular.

[0014] Furthermore, the water pressure application system also includes a pressure relief valve arranged on the upper surface of the device body.

[0015] The present invention also proposes a test method of a water-mechanical coupling loading device suitable for a true triaxial Hopkinson pressure bar test, the special feature of which is that the method is implemented based on the water-mechanical coupling loading device suitable for a true triaxial Hopkinson pressure bar test, and comprises the following steps:

[0016] 1) Place the sample on the sample preparation rack;

[0017] 2) Start the Hopkinson bar pressurizing device and push the pressurizing rod toward the sample until all six sides of the sample are in contact with the pressurizing rod;

[0018] 3) Adjust the Hopkinson bar pressurizing equipment and set the confining pressure to the test value;

[0019] 4) Confirm the sealing status of the device body, start the water pressure application system, gradually increase the water pressure to the test value, and let the sample stand for the specified time according to the test requirements;

[0020] 5) Start the Hopkinson bar impact system and conduct an impact test, so that the impact bar moves at high speed under the action of impact pressure and hits the inner layer pressure rod of the pressure rod. According to the principle of force transmission, the force and shock wave of the impact bar are transmitted to the inner layer pressure rod, and the inner layer pressure rod then acts on the sample. The sample is greatly deformed and broken under the action of force and shock wave;

[0021] 6) After completing the impact test, adjust the water pressure application system to completely unload the water pressure. After the water is emptied, adjust the Hopkinson bar impact system to unload the confining pressure acting on the sample. After the confining pressure is completely unloaded, take out the impacted sample.

[0022] Preferably, the water pressure adjustment range of the water pressure application system is 0 to 200 kPa.

[0023] The water-mechanical coupling loading device for true triaxial Hopkinson pressure bar test proposed by the present invention can simulate the influence of water pressure on rock samples under different water depth conditions in real time, and can be used for explosion experiments under deep water conditions. The test method of the present invention can realize true triaxial Hopkinson pressure bar test under the condition of considering water depth and confining pressure coupling loading. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic diagram of the overall structure of a water-mechanical coupling loading device suitable for a true triaxial Hopkinson pressure bar test.

[0025] Figure 2 It is the front view of the device body.

[0026] Figure 3 A cross-sectional view of the pressure rod.

[0027] Figure 4 It is a top view of the interior of the device body.

[0028] Figure 5 This is a top view of the sample preparation rack inside the device body.

[0029] Figure 6 It is the external rear view of the device body.

[0030] Figure 7 It is a three-dimensional schematic diagram of the test of the present invention.

[0031] In the figure, there are device body 1, through hole 2, pressure rod 3, water injection port 4, water outlet 5, pressure sensor 6, sample preparation rack 7, sample 8, outer waterproof rod 9, inner pressure rod 10, sponge 11, pressure relief valve 12, water pressure control system 13, sealing rubber ring 14, cover plate 15, movable hinge 16, fixing screw 17, water inlet pipe 18, water outlet pipe 19, and rubber sleeve 20. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0033] like Figures 1 to 7 As shown, the present invention proposes a water-mechanical coupling loading device suitable for a true triaxial Hopkinson pressure bar test, comprising a device body 1, a pressure rod 3 and a water pressure application system.

[0034] The device body 1 is a six-sided sealed cavity structure. A sample preparation rack 7 is arranged in the inner cavity of the device body 1. The sample 8 placed on the sample preparation rack 7 is located at the center of the inner cavity of the device body 1. The sample preparation rack 7 includes a bottom support rod and a sample placement tray arranged above the bottom support rod. A through hole for placing the sample 8 is arranged in the middle of the sample placement tray, and the sample 8 is snap-fitted with the sample placement tray.

[0035] A through hole 2 communicating with the inner cavity is provided in the middle of each side of the device body 1, and a sealing rubber ring 14 is provided on the through hole 2. One end of the pressure rod 3 passes through the through hole 2 and abuts against the outer side of the sample 8, and the other end of the pressure rod 3 abuts against the Hopkinson pressure bar.

[0036] The inner cavity of the device body 1 is connected to the water pressure application system, and the water pressure application system dynamically balances the water pressure inside the device body 1 according to the pressure value collected by the pressure sensor 6 arranged in the inner cavity of the device body 1 at the same height as the sample 8.

[0037] like Figure 2 As shown, the water pressure application system includes a water injection port 4 and a pressure relief valve 12 arranged on the upper surface of the device body 1, and a water outlet 5 arranged on the lower surface. The water injection port 4 and the water outlet 5 are connected to the water pressure control system 13 through the water inlet pipe 18 and the water outlet pipe 19 respectively. The water pressure control system 13 is electrically connected to the pressure sensor 6 to collect the inner cavity water pressure value of the device body 1 in real time, and the inner cavity water pressure value reaches a dynamic balance of the water pressure test value by adjusting the water flow size in the water inlet pipe 18 and the water outlet pipe 19.

[0038] like Figure 3 As shown, the pressure rod 3 is a sleeve rod structure, the outer waterproof rod 9 is a hollow rod, and the inner pressure rod 10 is a solid rod. The cross-sections of the outer waterproof rod 9 and the inner pressure rod 10 are both circular. A sponge 11 for absorbing water is provided between the outer waterproof rod 9 and the inner pressure rod 10, and the outer waterproof rod 9 is sealed and fixedly connected with the rubber sleeve 20. The sealing rubber ring 14 is sealed and fixedly connected with the outer waterproof rod 9. The rubber sleeve 20 is sealed and fixedly connected with the end of the outer waterproof rod 9. The rubber sleeve 20 is elastic, which facilitates the extension and retraction of the inner rod and is waterproof. At the same time, since the rubber sleeve 20 is relatively thin, it has almost no effect on the transmission of force and waves, and has no obvious effect on the test results.

[0039] like Figure 6As shown, a cover plate 15 for taking and placing the sample 8 is provided on the side of the device body 1 . The cover plate 15 is fixed by fixing screws 17 , and one side of the cover plate 15 is connected to the device body 1 by a movable hinge 16 .

[0040] The water pressure application system can simulate a water depth of 0 to 20m, meeting the general deepwater engineering test requirements. The basic principle of the simulated water depth is: P = ρgh, P-water pressure, ρ-water density, g-gravity acceleration, generally 10m / s 2 , h-water depth; The simulation of water depth is achieved by injecting water and pressurizing it from the water inlet through the water pressure control system. The pressure sensor corresponding to the position of the sample inside the box senses the water pressure. When the water pressure reaches the test setting value, the water pressure control system stops injecting water and pressurizing it. When the water pressure exceeds the test setting value, water is discharged from the water outlet, and this process is repeated until a dynamic balance of the water pressure test value is reached.

[0041] like Figure 7 As shown, a method for performing a water-mechanical coupling loading test of a true triaxial Hopkinson pressure bar test using the water-mechanical coupling loading device suitable for a true triaxial Hopkinson pressure bar test comprises the following steps;

[0042] 1) First, open the cover 15 of the device body 1 and place the sample 8 in the middle of the sample rack 7 inside the device body 1;

[0043] 2) Start the Hopkinson bar pressurizing device, push the inner pressurizing rod 10 of the pressurizing rod 3 to slowly move toward the sample 8, until the inner pressurizing rods 10 in six directions just press the sample 8 tightly without causing deformation and breakage of the sample 8;

[0044] 3) Adjust the pressurizing equipment and slowly increase the confining pressure to the pressure value set for the test;

[0045] 4) Close the cover 15, tighten the fixing screws 17, confirm the sealing state of the device body 1, start the water pressure application system, gradually increase the water pressure to the test value, and according to the test requirements, let the sample 8 stand for a specified time; the water pressure adjustment range of the water pressure application system in this embodiment is 0 to 200 kPa.

[0046] 5) Start the Hopkinson bar impact system to conduct an impact test. The action process is that there is a stainless steel metal rod called the impact rod inside the impact system that can move quickly according to the impact pressure, so that the impact rod moves at high speed under the action of the impact pressure, and then hits the inner pressure rod 10 of the pressure rod 3. According to the principle of force transmission, the force and shock wave of the impact rod are transmitted to the inner pressure rod 10, and the inner pressure rod 10 then applies the force and shock wave to the sample. The sample 8 is greatly deformed and broken under the action of the force and shock wave. This action process is extremely short and can be used to simulate the instantaneous effect of an explosion. The outer waterproof rod 9 and sponge 11 remain stationary during this process. The sponge 11 also plays a role in absorbing the waves transmitted outward and reflected inward, preventing the transmitted waves and reflected waves from acting on the inner pressure rod 10 again and affecting the test results.

[0047] 6) After the impact test is completed, adjust the water pressure application system to completely unload the water pressure. After the water is emptied, adjust the Hopkinson bar impact system to unload the confining pressure acting on the sample. After the confining pressure is completely unloaded, take out the impacted sample 8.

[0048] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms of specific changes without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the scope of protection of the present invention.

Claims

1. A water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test, characterized in that: It comprises a device body (1), a pressure rod (3) and a water pressure application system; The device body (1) is a six-sided sealed cavity structure, a sample preparation rack (7) is arranged in the inner cavity of the device body (1), a sample (8) placed on the sample preparation rack (7) is located at the center of the inner cavity of the device body (1), a through hole (2) communicating with the inner cavity is arranged in the middle of each side surface of the device body (1), one end of the pressure rod (3) passes through the through hole (2) and abuts against the outer side surface of the sample (8), and the other end of the pressure rod (3) abuts against the Hopkinson pressure rod; The inner cavity of the device body (1) is connected to a water pressure application system, and the water pressure application system performs dynamic balance control on the water pressure inside the device body (1) according to a pressure value collected by a pressure sensor (6) arranged in the inner cavity of the device body (1) and at the same height as the sample (8); The pressure rod (3) is a sleeve rod structure, the outer water-blocking rod (9) is a hollow rod, the inner pressure rod (10) is a solid rod, a sponge (11) is provided between the outer water-blocking rod (9) and the inner pressure rod (10), and the outer water-blocking rod (9) is sealed and fixedly connected to the rubber sleeve (20); The water pressure application system comprises a water inlet (4) arranged on the upper surface of the device body (1) and a water outlet (5) arranged on the lower surface; the water inlet (4) and the water outlet (5) are respectively connected to a water pressure control system (13) via a water inlet pipe (18) and a water outlet pipe (19); the water pressure control system (13) is electrically connected to a pressure sensor (6) to collect the water pressure value of the inner cavity of the device body (1) in real time, and adjust the water flow in the water inlet pipe (18) and the water outlet pipe (19) so that the water pressure value of the inner cavity reaches a dynamic balance of the water pressure test value; The sample preparation rack (7) comprises a bottom support rod and a sample placement tray arranged above the bottom support rod, a through hole for placing a sample is arranged in the middle of the sample placement tray, and the sample is engaged with the sample placement tray.

2. The water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test according to claim 1, characterized in that: A sealing rubber ring (14) is provided on the through hole (2) on each side of the device body (1), and the sealing rubber ring (14) is sealed and fixed to the outer waterproof rod (9).

3. The water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test according to claim 1, characterized in that: A cover plate (15) is provided on the side of the device body (1), the cover plate (15) is fixed by means of fixing screws (17), and one side of the cover plate (15) is connected to the device body (1) by means of a movable hinge (16).

4. The water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test according to claim 1, characterized in that: The cross-sections of the outer waterproof rod (9) and the inner pressure rod (10) are both circular.

5. The water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test according to claim 1, characterized in that: The water pressure application system further comprises a pressure relief valve (12) arranged on the upper surface of the device body (1).

6. A test method for a water-mechanical coupling loading device suitable for a true triaxial Hopkinson pressure bar test, characterized in that: The method is implemented based on the water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test according to any one of claims 1 to 5, and comprises the following steps: 1) Place the sample (8) on the sample preparation rack (7); 2) starting the Hopkinson bar pressurizing device and pushing the pressurizing rod (3) toward the sample (8) until all six surfaces of the sample (8) are in contact with the pressurizing rod (3); 3) Adjust the Hopkinson bar pressurizing equipment and set the confining pressure to the test value; 4) Confirm the sealing status of the device body (1), start the water pressure application system, gradually increase the water pressure to the test value, and leave the sample (8) to stand for a specified time according to the test requirements; 5) starting the Hopkinson bar impact system and conducting an impact test, so that the impact bar moves at high speed under the action of the impact pressure and hits the inner pressure bar (10) of the pressure bar (3). According to the force transmission principle, the force and shock wave of the impact bar are transmitted to the inner pressure bar (10), and the inner pressure bar (10) then applies the force and shock wave to the sample. The sample (8) is greatly deformed and broken under the action of the force and shock wave. 6) After the impact test is completed, adjust the water pressure application system to completely unload the water pressure. After the water is emptied, adjust the Hopkinson bar impact system to unload the confining pressure acting on the specimen. After the confining pressure is completely unloaded, remove the impacted specimen (8).

7. The test method of the water-mechanical coupling loading device suitable for true triaxial Hopkinson pressure bar test according to claim 6, characterized in that: The water pressure adjustment range of the water pressure application system is 0~200kPa.

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