A triaxial Hopkinson confining pressure loading device for bulk materials

Abstract

The present invention discloses a three-axis Hopkinson confining pressure loading device for bulk materials. The present invention includes a radial confining pressure system and an axial confining pressure system. The radial confining pressure system includes a confining pressure body, confining pressure chamber end covers arranged on both sides of the confining pressure body, an incident rod passing through the confining pressure chamber end cover on one side, and a transmission rod passing through the confining pressure chamber end cover on the other side, and a sample chamber is formed between the incident rod and the transmission rod; each of the confining pressure chamber end covers is installed with a sealing sleeve for embracing the transmission rod and the transmission rod; the axial confining pressure system includes a buffer rod and a sealing sleeve embracing the buffer rod. The present invention improves the three-axis impact device and technology in view of some problems existing in the current triaxial impact test of bulk materials. By using a built-in sealing sleeve, the pressure rod is tightly embraced after being compressed and contracted to form a seal, thereby realizing three-dimensional impact loading of bulk materials.

Description

Technical Field

[0001] The invention relates to a confining pressure loading device, in particular to a three-axis Hopkinson confining pressure loading device for bulk materials. Background Art

[0002] The Split Hopkinson-Kolsky Pressure Bar (SHPB) device is one of the main methods for studying the mechanical response of materials under medium and high strain rates. 2 -10 4 / s strain rate loading test. With the development of SHPB experimental equipment and experimental technology, it is now possible to realize not only one-dimensional impact loading but also three-dimensional impact loading under active confining pressure. Among them, the active confining pressure SHPB test technology refers to the idea of ​​a triaxial hydraulic (quasi-static) loading system. The incident rod is fixed by a limiter, an axial pressure chamber is added at the end of the transmission rod, and a confining pressure chamber is added around the specimen. Before the impact test, the initial pressure is applied to the specimen through the axial pressure chamber and the confining pressure chamber. There is also a method of using 1 incident rod and 5 transmission rods to apply three-dimensional pressure to the specimen, but whether the square cross-section specimen meets the one-dimensional stress wave propagation conditions remains to be discussed. There are barriers to the two existing active confining pressure SHPB test methods: first, constant confining pressure cannot be achieved. The main reason is that the pressure changes rapidly during the application of the impact load, and there is no such sensitive and quickly adjustable pressure system; second, the existing triaxial SHPB test system does not have an internationally recognized radial stress and radial deformation test method; third, the drainage and exhaust boundaries of the specimen cannot be controlled.

[0003] Due to the limitations of the above problems, the current active confining pressure SHPB test device is only applicable to block materials such as concrete and rock, but not to bulk materials such as sand, soil, and glass balls. The main problem is that bulk materials need to be prepared in advance, and the prepared bulk material samples should be disturbed as little as possible during the loading process. The installed samples must also be well sealed, and the radial deformation observation of the samples is very important. Because of this, the current research on the one-dimensional compression performance of bulk materials (such as soil) under passive confining pressure is relatively mature at home and abroad, but the research on compression and shear characteristics under active confining pressure is still very limited. The confining pressure state is very important for some bulk materials. Taking soil as an example, the natural soil itself is under a certain stress state. The stress state directly determines the shear expansion and shear contraction properties of the soil. Under high stress, the soil skeleton characteristics can be affected by particle crushing. Therefore, it is crucial to overcome the active confining pressure SHPB impact test technology for bulk materials. Summary of the invention

[0004] Purpose of the invention: In order to solve the problems of the prior art, the present invention improves the triaxial impact technology and devices to address some of the problems existing in the current triaxial impact, and provides a triaxial Hopkinson confining pressure loading device for bulk materials to achieve three-dimensional impact loading of bulk materials.

[0005] Technical solution: The triaxial Hopkinson confining pressure loading device for bulk materials described in the present invention comprises a radial confining pressure system and an axial confining pressure system, wherein the radial confining pressure system comprises a confining pressure body, confining pressure chamber end covers arranged on both sides of the confining pressure body, an incident rod passing through the confining pressure chamber end cover on one side, and a transmission rod passing through the confining pressure chamber end cover on the other side, wherein a sample chamber is formed between the incident rod and the transmission rod; a sealing sleeve for embracing the transmission rod and the transmission rod is installed in each of the confining pressure chamber end covers; the axial confining pressure system comprises a buffer rod and a sealing sleeve embracing the buffer rod.

[0006] As a preferred embodiment of the present invention, the radial dimension of the sample chamber is larger than the dimension of the incident rod or the transmission rod, so as to ensure that the prepared bulk material sample is installed without disturbance.

[0007] As a preferred embodiment of the present invention, the sealing sleeve includes a ring sleeve made of elastic material, a plurality of gaskets and a plurality of steel rings; the ring sleeve includes a ring sleeve body, a channel arranged in the middle of the ring sleeve body, a first concave cavity arranged on one side of the ring sleeve body and a second concave cavity arranged on the outer periphery of the ring sleeve body; a plurality of first grooves for embedding the gaskets and a plurality of second grooves for embedding the steel rings are arranged on the bottom surface of the first concave cavity, and the first grooves and the second grooves are arranged at intervals.

[0008] As a preferred embodiment of the present invention, the second cavity is communicated with a radially sealed water pipe.

[0009] As a preferred embodiment of the present invention, a first sealing edge and a second sealing edge are respectively extended outwardly from both ends of the ring sleeve body.

[0010] As a preferred embodiment of the present invention, the steel ring is provided with a connecting column fixed to the bottom surface of the second groove, and the second groove is provided with a connecting hole fixed to the connecting column; and / or the gasket includes a gasket bottom plate matching the bottom surface of the first groove and a gasket side plate fitted to the inner wall of the first concave cavity.

[0011] As a preferred embodiment of the present invention, the steel ring includes an arc-shaped block.

[0012] As a preferred embodiment of the present invention, a window cover is provided above the confining pressure loading device; and / or a window is provided on the window cover.

[0013] As a preferred embodiment of the present invention, the radial confining pressure system further includes a pressure transmitter.

[0014] As a preferred embodiment of the present invention, the radial confining pressure system is provided with a linear displacement sensor for detecting radial deformation of the specimen; and / or the linear displacement sensor is connected to the confining pressure loading device via a sealing bolt.

[0015] Beneficial effects: (1) The present invention solves the defects of the traditional active confining pressure SHPB test in the study of bulk materials. The disturbance during the sample installation process is reduced by expanding the confining pressure chamber (sample chamber), and the sealing sleeve is further used to solve the sealing problem caused by the expansion of the sample chamber. The sealing sleeve of the present invention embraces the rod to achieve the sealing of the confining pressure chamber, and at the same time realizes the simulation of the boundary without drainage and exhaust. (2) The present invention can realize the deformation observation of the sample through the confining pressure chamber window combined with high-speed camera technology. (3) The sealing sleeve of the present invention can hold the SHPB incident rod, transmission rod and buffer rod tightly under the water pressure applied by radial or axial water pipes to ensure the sealing of the confining pressure device. (4) The present invention can realize three-dimensional impact loading on materials such as rock and soil, and study their mechanical properties under complex stress environments. (5) The present invention uses water to load confining pressure on the sample, which is economical, convenient and environmentally friendly. (6) The present invention can monitor the pressure changes inside the device during the impact process in real time by installing a pressure transmitter. (7) The present invention measures the radial deformation of the sample by installing a displacement sensor. (8) The pressurization and unloading processes of the present invention are all operated through the console, which is easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the ring sleeve of the present invention;

[0017] Figure 2 is a cross-sectional view of the ring sleeve of the present invention;

[0018] Figure 3 It is a schematic diagram of the structure of the gasket of the present invention;

[0019] Figure 4 It is a schematic diagram of the structure of the gasket used in conjunction with the ring sleeve in the present invention;

[0020] Figure 5 It is a structural schematic diagram of the steel ring of the present invention;

[0021] Figure 6 This is a schematic diagram of the steel ring structure used in conjunction with the ring sleeve in the present invention;

[0022] Figure 7 It is an exploded schematic diagram of the sealing sleeve of the present invention;

[0023] Figure 8 It is an exploded schematic diagram of the sealing sleeve of the present invention;

[0024] Fig. 9 It is a schematic diagram of the combined structure of the sealing sleeve of the present invention;

[0025] Fig.10 It is a front cross-sectional view of the radial confining pressure system of the present invention;

[0026] Fig.11 It is a side cross-sectional view of the radial confining pressure system of the present invention;

[0027] Fig.12 It is a front cross-sectional view of the axial confining pressure system of the present invention;

[0028] Fig.13 It is a schematic diagram of the connection relationship between the linear displacement sensor of the present invention and the confining pressure body;

[0029] Fig.14 It is a schematic diagram of the sealing bolt structure of the present invention. DETAILED DESCRIPTION

[0030] Example 1: Figure 9-11 As shown, the triaxial Hopkinson confining pressure loading device for bulk materials of the present invention comprises a radial confining pressure system 200 and an axial confining pressure system 300. The radial confining pressure system 200 comprises a confining pressure body 201, confining pressure chamber end covers 202 arranged on both sides of the confining pressure body 201 (the confining pressure end covers 202 are arranged at both ends of the radial confining pressure body 201 and connected to the radial confining pressure body 201 through rivets 211), an incident rod 203 (SHPB incident rod) passing through the confining pressure chamber end cover 202 on one side, and a transmission rod 204 passing through the confining pressure chamber end cover 202 on the other side, and a sample chamber 400 is formed between the incident rod 203 and the transmission rod 204. A sealing sleeve 100 for embracing the incident rod 203 and the transmission rod 204 is installed in each confining pressure chamber end cover 202. The confining pressure loading device of the present invention is used for bulk materials, so the radial dimension of the sample chamber 400 of the present invention is greater than the radial dimension of the incident rod 203 or the transmission rod 204. In this embodiment, the radial dimension of the sample chamber 400 of the present invention is increased by about 2 mm compared with the radial dimension of the sample, ensuring that the prepared sample (including the sample preparation film sleeve 213) can enter and exit the sample chamber 400 without disturbance. Similarly, in order to ensure that the sample can smoothly enter the sample chamber 400, a gap is also left between the inner wall of the confining pressure chamber end cover 202 of the present invention and the incident rod 203 and the transmission rod 204. In order to achieve the sealing of the incident rod 203 and the transmission rod 204, the present invention improves the structure of the traditional end cover of the confining pressure chamber, and a sealing sleeve 100 is installed on the inner side of the place where the end cover 202 of the confining pressure chamber is engaged with the confining pressure body 201, and a first block 214 is installed on the inner side of the sealing sleeve 100 (the block is hollow for passing the rod, and the diameter of the inner wall is also increased by about 2 mm compared with the rod). The sealing sleeve 100 is used to achieve the sealing of the incident rod 203 and the transmission rod 204, which solves the problem that the device cannot be sealed due to the increase in the inner diameter.

[0031] In this embodiment, the radial confining pressure body 201 is a variable inner diameter thick-walled cylinder made of high-strength steel. The middle cylinder of the radial confining pressure body 201 forms a hydraulic chamber 209. The hydraulic chamber 209 is connected to the radial confining pressure cavity water pipe 210. The radial confining pressure cavity water pipe 210 is arranged below the hydraulic chamber 209. When the sample is sent into the sample chamber 400, the liquid sent into the radial confining pressure cavity water pipe 210 surrounds the radial side of the sample in the hydraulic chamber 209.

[0032] like Figure 1-Figure 9 As shown, the sealing sleeve 100 of the present invention comprises a sleeve 101 made of elastic material, a plurality of gaskets 102 and a plurality of steel rings 103. The sleeve body 1011 of the sleeve 101 of the present invention is made of rubber, and a channel 1012 is left in the middle of the rubber material for the rod (SHPB incident rod, transmission rod or buffer rod) to pass through. A first concave cavity 1013 is arranged on the outer side of the ring sleeve body 1011, and a first groove 1015 for embedding the gasket 1012 and a second groove 1016 for embedding the steel ring 1013 are arranged on the annular bottom surface of the first concave cavity 1013. The gasket 102 and the steel ring 103 are distributed at intervals, and a second concave cavity 1014 is arranged on the outer periphery of the ring sleeve body 1011. In this embodiment, a first sealing edge 1017 and a second sealing edge 1018 are respectively arranged on both sides of the second concave cavity 1014. The first sealing edge 1017 and the second sealing edge 1018 are pressed against the inner wall of the confining pressure body, so that the second concave cavity 1014 forms an independent space, and water is injected into the second concave cavity 1014 to generate pressure around the sealing sleeve 100. The gasket 102 includes a gasket bottom plate 1021 matched with the bottom surface of the first groove 1051 and a gasket side plate 1022 fitted with the inner wall of the first cavity 1031. The gasket bottom plate 1021 is a fan-shaped structure, and the gasket side plate 1022 fits with the side wall of the corresponding first cavity 1013. As a preferred embodiment, the height of the gasket side plate 1022 is the same as the depth of the first cavity 1013. The steel ring body of the steel ring 103 is an arc block, specifically a fan-shaped block structure. Similarly, the fan-shaped block is located between the two gaskets 102. The bottom of the fan-shaped block is provided with a connecting column 1031 fixed to the bottom surface of the second groove 1016, and the second groove 1016 is provided with a connecting hole 1019 fixed to the connecting column 1031. The state of the sealing sleeve after assembly of the present invention is as follows. Fig. 9 shown.

[0033] The radial sealing cavity water pipe 206 of the present invention is arranged above the second concave cavity 1014 (radial confining pressure sealing cavity), and the second concave cavity 1014 of the sealing sleeve 100 is connected with the radial sealing water pipe 206. After the sealing sleeve 100 is assembled, the sealing sleeve 100 applies confining pressure by entering water. At the same time, the inner diameter of the sealing sleeve 100 shrinks under the pressure injected into the second concave cavity 1014, and the steel ring hugs the SHPB pressure rod, and the radial and axial confining pressure devices start to seal, and the pressurization stops when the set confining pressure is reached.

[0034] The present invention sets a window cover 205 above the radial confining pressure system 200, and a window 207 is set on the window cover 205. Furthermore, the window 207 of the present invention is a high-strength transparent glass or acrylic embedded in the side wall of the confining pressure chamber, and the window 207 is connected to the radial confining pressure body 201 through a rivet 211 under the sealing of the window cover 202. The high-speed pressure transmitter 208 of the radial confining pressure system of the present invention is a sensor installed on the side wall of the confining pressure chamber by bolts for real-time measurement of the pressure of the confining pressure chamber; the radial confining pressure system 200 of the present invention also includes a linear displacement sensor 212, which is a sensor that penetrates the side wall of the confining pressure chamber and is used to measure the radial deformation of the sample in real time.

[0035] The linear displacement sensor 212 is sealed and fixed to the side wall of the confining pressure chamber through the sealing bolt 215. Fig.11 As shown, the present invention can simultaneously set linear displacement sensors 212 on both sides of the sample chamber 400 for mutual verification. The structure of the sealing bolt 215 is as shown in FIG. Fig.13 and Fig.14 As shown, the sealing bolt 215 is arranged on the outer periphery of the displacement transmission rod 2121 of the linear displacement sensor 212, and the sealing bolt 215 includes a bolt outer wall 2151. The concave cavity formed inside the bolt outer wall 2151 is provided with an inner seal 2152 (rubber ring), a bearing 2153 and an adjustment plug 2155 from the inside to the outside, and the bolt outer wall 2151 is provided with an outer edge on the outer wall, and an outer seal 2155 (rubber ring) is provided between the outer edge and the confining pressure body 201.

[0036] The sealing bolt 215 is an inner bolt, the outer sealing member 2155 seals the connection between the outer wall of the confining pressure body 201 and the sealing bolt 215, and the inner sealing member 2152 seals the connection between the displacement transmission rod 2121 and the bolt, so that the displacement transmission rod 2121 (with scale) can move laterally without leaking the water source of the hydraulic chamber. The bearing 2153 allows the displacement transmission rod 2121 to move in the horizontal direction without deviation. The adjustment plug 2155 is screwed into the outer wall 2511 of the bolt through the outer wall thread to seal the entire sealing bolt. Before the test, the end of the displacement transmission rod 2121 is against the specimen, and the initial reading of the displacement transmission rod 2121 is recorded. After the specimen is compressed, radial deformation occurs, and the displacement transmission rod 2121 moves outward. The reading of the displacement transmission rod 2121 at this time is recorded, and the difference between the two readings is the radial deformation of the specimen.

[0037] like Fig.12 As shown, the axial confining pressure system 300 described in the present invention includes a buffer rod 301 and a sealing sleeve 100 engaged with the buffer rod 301, and the axial confining pressure system also includes an axial confining pressure body 302, an axial pressure hydraulic chamber 303, an axial confining pressure end cover 304, an axial pressure rear cover 305, a second concave cavity 1014 (axial confining pressure sealing cavity), an axial sealing cavity water pipe 306, an axial confining pressure water pipe 307 and an axial linear displacement sensor 308 (LVDT) for detecting the axial displacement of the buffer rod 301, and a second blocking block 309 is arranged on the inner side of the sealing sleeve 100. The axial confining pressure body 302 is a variable inner diameter thick-walled cylinder made of high-strength steel. The middle cylinder constitutes the axial pressure hydraulic chamber 303. The axial confining pressure sealing cavity and the sealing sleeve 100 are arranged at the front end of the axial hydraulic chamber 303 to seal the axial hydraulic chamber; the axial confining pressure end cover 304 and the axial pressure rear cover 305 are arranged at both ends of the axial confining pressure body 302 and are connected to the axial confining pressure body 302 by rivets; the sealing sleeve 100 applies confining pressure by letting in water, and at the same time the inner diameter shrinks to fix the buffer rod 301; the axial sealing cavity water pipe 306 is arranged above the axial confining pressure sealing cavity, and the axial confining pressure cavity water pipe 307 is arranged below the axial pressure hydraulic chamber 303.

[0038] Implementation case: Taking the active confining pressure SHPB test of sand as an example, the sample 400 is loaded into the latex film and placed between the incident rod 203 and the transmission rod 204, and then the sealing and pressurization are started. The water source enters the radial confining pressure sealing cavity and the axial confining pressure sealing cavity through the radial sealing cavity water pipe 206 and the axial sealing cavity water pipe 306. The sealing sleeve 100 shrinks under the pressure, and the sealing ring hugs the SHPB pressure rod. The radial and axial confining pressure devices begin to seal, and the pressurization is stopped when the set confining pressure is reached. Then the confining pressure is started. The water source enters the confining pressure hydraulic chamber 206 through the radial confining pressure cavity water pipe 210 to apply radial confining pressure to the sample. At the same time, the water source enters the axial hydraulic chamber 303 through the axial confining pressure cavity water pipe 307 to apply axial pressure to the buffer rod 301 so that the sample is subjected to axial confining pressure. The pressurization is stopped when the set confining pressure is reached. The SHPB triaxial test is started, and the pressure change of the sample during the test is monitored by the high-speed pressure transmitter 208, and the radial and axial deformation of the sample is measured by the linear displacement sensor 212.

Claims

1. A three-axis Hopkinson confining pressure loading device for bulk materials, characterized in that: The confining pressure loading device comprises a radial confining pressure system (200) and an axial confining pressure system (300), wherein the radial confining pressure system (200) comprises a confining pressure body (201), confining pressure chamber end covers (202) arranged on both sides of the confining pressure body (201), an incident rod (203) passing through the confining pressure chamber end cover (202) on one side, and a transmission rod (204) passing through the confining pressure chamber end cover (202) on the other side, wherein a sample chamber (400) is formed between the incident rod (203) and the transmission rod (204); a sealing sleeve (100) for embracing the incident rod (203) and the transmission rod (204) is installed in each of the confining pressure chamber end covers (202); and the axial confining pressure system (300) comprises a buffer rod (301) and a sealing sleeve (100) embracing the buffer rod (301); The sealing sleeve (100) comprises a sleeve (101) made of elastic material, a plurality of gaskets (102) and a plurality of steel rings (103); the sleeve (101) comprises a sleeve body (1011), a channel (1012) arranged in the middle of the sleeve body (1011), a first concave cavity (1013) arranged on one side of the sleeve body (1011) and a second concave cavity (1014) arranged on the periphery of the sleeve body (1011); a plurality of first grooves (1015) for embedding the gaskets (102) and a plurality of second grooves (1016) for embedding the steel rings (103) are arranged on the bottom surface of the first concave cavity (1013), and the first grooves (1015) and the second grooves (1016) are arranged at intervals.

2. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 1, characterized in that: The radial dimension of the sample chamber (400) is larger than the dimension of the incident rod (203) or the transmission rod (204).

3. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 1, characterized in that: The second concave cavity (1014) is in communication with the radial sealing water pipe (206).

4. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 1, characterized in that: A first sealing edge (1017) and a second sealing edge (1018) are respectively extended outwards from both ends of the ring sleeve body (1011).

5. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 4, characterized in that: The steel ring (103) is provided with a connecting column (1031) fixed to the bottom surface of the second groove (1016), and the second groove (1016) is provided with a connecting hole (1019) fixed to the connecting column (1031); and / or the gasket (102) includes a gasket bottom plate (1021) matched with the bottom surface of the first groove (1015) and a gasket side plate (1022) fitted with the inner wall of the first cavity (1013).

6. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 1, characterized in that: The steel ring (103) comprises an arc-shaped block (1032).

7. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 1, characterized in that: A window cover (205) is provided above the confining pressure loading device; and / or a window (207) is provided on the window cover (205).

8. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 1, characterized in that: The radial confining pressure system (200) further includes a pressure transmitter (208).

9. The triaxial Hopkinson confining pressure loading device for bulk materials according to claim 1, characterized in that: The radial confining pressure system (200) is provided with a linear displacement sensor (212) for detecting radial deformation of the specimen; and / or the linear displacement sensor (212) is connected to the confining pressure loading device via a sealing bolt.

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