A rheological test device and test method for coal and rock mass

Abstract

The present invention discloses a rheological test device and test method for coal and rock masses. The device includes a rheological test main machine, which includes an axial loading device, a data acquisition system, a separately arranged uniaxial pressure chamber and confining pressure chamber; the confining pressure chamber includes an openable sealed chamber body, in which an upper bearing plate and a lower bearing plate are provided, and a pore sieve backing plate is provided on the upper surface of the lower bearing plate; a fluid inlet is provided on the lower bearing plate; the data acquisition system includes an axial displacement sensor and a radial displacement sensor arranged around the specimen. This application is provided with an independent uniaxial pressure chamber and confining pressure chamber, which are respectively used for uniaxial loading tests and triaxial loading tests, and can meet the mechanical property test requirements of specimens of different sizes. The confining pressure chamber can also conduct seepage tests at the same time, and various corresponding tests can be carried out on the specimen according to specific experimental schemes. The axial compression deformation and circumferential expansion deformation of coal and rock masses can be accurately measured, and the true deformation of coal and rock masses can be accurately measured.

Description

Technical Field

[0001] The present invention belongs to the technical field of rock mechanics testing, and particularly relates to a rheological test device and test method for coal and rock masses. Background Art

[0002] Deep coal and rock masses are prone to rheology under the action of high temperature and high pressure environments. The rheology of coal and rock masses is an important cause of mine accidents. Therefore, the study of the rheological properties of coal and rock masses has important value. Most of the existing technical studies focus on the rheology of rocks, and there are few studies on the rheological tests of coal and rock masses. The current rheological test devices for coal and rock masses cannot simulate the real seepage environment under deep strata, and the space of the high-pressure seepage test device is limited, and it cannot adapt to specimens of different sizes for mechanical property testing. On the other hand, the invention with the publication number of CN103760027B discloses a "continuous pressure and constant pressure rheological test device for coal and rock masses", which measures the axial displacement change amount through a light displacement sensor, but cannot measure the circumferential expansion deformation, and cannot accurately measure the real deformation of coal and rock masses, resulting in errors in test data. Summary of the Invention

[0003] The purpose of the present invention is to provide a rheological test device and test method for coal and rock masses to solve the deficiencies of the existing technology.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] A rheological test device for coal and rock masses includes a rheological test main machine, and the rheological test main machine includes an axial loading device and a data acquisition system; the rheological test main machine also includes a separately arranged uniaxial pressure chamber and a confining pressure chamber;

[0006] The uniaxial pressure chamber is used to place specimens for uniaxial loading tests;

[0007] The confining pressure chamber includes an openable airtight chamber body. An upper bearing plate and a lower bearing plate are arranged in the chamber body. A hole sieve backing plate is arranged on the upper surface of the lower bearing plate. Between the upper bearing plate and the hole sieve backing plate is used to place specimens with side seals; the placed specimens are located in the central area of the chamber body, and the surrounding area of the chamber body forms an oil cavity for filling hydraulic oil. The oil cavity is provided with an oil inlet for filling hydraulic oil to apply confining pressure to the specimens; a fluid inlet is arranged on the lower bearing plate for injecting fluid into the interior of the specimens for seepage tests;

[0008] The data acquisition system includes an axial displacement sensor and a radial displacement sensor arranged around the specimens, which are respectively used to detect the axial displacement and radial displacement of the specimens under test conditions.

[0009] Preferably, the axial loading device is used to apply axial pressure to the specimen, and from top to bottom, it includes an axial loading pressure cylinder, an axial pressing piston, a heat insulation plate, and an upper pressing head connected in sequence;

[0010] The data acquisition system further includes a normal displacement sensor and an axial pressure sensor;

[0011] The normal displacement sensor is located above the axial loading pressure cylinder and is used to detect the displacement of axial loading;

[0012] The axial pressure sensor is located on the axial pressing piston and is used to detect the magnitude of the axial loading pressure;

[0013] The top of the upper bearing plate is connected with a lower pressing head passing through the top of the chamber body, and the lower pressing head is used to receive the pressure of the axial loading device.

[0014] Preferably, the uniaxial pressure chamber includes a first base and a plurality of detachable pads located on the first base, and the height of the pads is adjusted to adapt to specimens of different sizes.

[0015] Preferably, the coal and rock mass rheological test device as described above further includes a reaction frame;

[0016] The reaction frame includes a support and a reaction beam located in a partial side area of the support;

[0017] The axial loading device is arranged on the reaction beam;

[0018] A turntable is arranged on the support, and the uniaxial pressure chamber and the confining pressure chamber are detachably installed on the turntable. By rotating the turntable, the position of the uniaxial pressure chamber or the confining pressure chamber can be adjusted to place the uniaxial pressure chamber or the confining pressure chamber below the axial loading device on the reaction beam.

[0019] Preferably, the chamber body is composed of a cylinder cover and a bottom plate; a tightening hoop is arranged between the lower side of the cylinder cover and the bottom plate for fixing the cylinder cover;

[0020] The upper bearing plate is in a T shape and includes a horizontal section and a vertical section located in the central area of the horizontal section; the lower bearing plate is in an inverted T shape; the length of the horizontal section is slightly smaller than that of the cylinder cover, and an oil cavity is formed between the side surface of the vertical section and the side wall of the cylinder cover; the vertical sections of the upper bearing plate and the lower bearing plate are arranged oppositely, and the pore sieve pad is arranged on the upper surface of the vertical section of the lower bearing plate.

[0021] Preferably, a fluid inlet channel and an oil inlet channel are arranged on the lower bearing plate, and a fluid discharge channel is arranged on the upper bearing plate; an oil outlet port communicated with the oil cavity is arranged above the outer side of the cylinder cover, and a fluid discharge port is arranged on the side of the upper bearing plate;

[0022] A plurality of through holes are provided on the bottom plate, and a fluid inlet interface, a fluid discharge interface, and an oil inlet interface are arranged in the through holes;

[0023] The inlet end of the fluid inlet interface is used to connect to an external fluid source, and the outlet end is communicated with the inlet of the fluid inlet channel. The outlet of the fluid inlet channel, that is, the fluid inlet, is aligned with the pore sieve backing plate; the outlet of the fluid discharge channel is connected with a fluid discharge pipe, and the fluid discharge pipe is connected with the inlet end of the fluid discharge interface. The outlet end of the fluid discharge interface is communicated to the outside for discharging the fluid after the seepage test is completed;

[0024] The inlet end of the oil inlet interface is used to connect to an external oil source, and the outlet end is connected with the oil inlet channel. The other end of the oil inlet channel, that is, the oil inlet, is communicated with the oil cavity.

[0025] Preferably, a sealing device is provided between the lower bearing plate and the bottom plate;

[0026] A second base is provided below the bottom plate;

[0027] A protective cover is provided between the inner side of the cylinder cover and the upper bearing plate and the lower bearing plate.

[0028] Preferably, there are two axial displacement sensors, which are respectively arranged on both sides of the horizontal section of the lower bearing plate around the left and right sides of the specimen, and the radial displacement sensors are sleeved around the circumference of the specimen;

[0029] The data acquisition system further includes an acoustic emission device and a first temperature sensor; the acoustic emission device and the first temperature sensor are located on both sides of the horizontal section of the lower bearing plate.

[0030] Preferably, the confining pressure chamber further includes a high-temperature loading system; the high-temperature loading system is used to heat the specimen to conduct a high-temperature loading test;

[0031] The high-temperature loading system includes a detachable flexible heating sleeve and a heat insulation device;

[0032] The detachable flexible heating sleeve is sleeved on the outside of the chamber body; a heating element is arranged in the detachable flexible heating sleeve;

[0033] The heat insulation device is sleeved on the outside of the detachable flexible heating sleeve, and the heat insulation device adopts a nano-aerogel device.

[0034] The present invention also provides a test method for the coal and rock mass rheological test device as described above, using the uniaxial pressure chamber to conduct a uniaxial loading test or using the confining pressure chamber to conduct a triaxial loading and seepage test;

[0035] The uniaxial loading test includes the following steps:

[0036] Put the specimen into the uniaxial pressure chamber. When the uniaxial pressure chamber is not below the axial loading device, adjust the uniaxial pressure chamber to be located below the axial loading device, apply preloading through the axial loading device, and then apply axial load through the axial loading device until the test ends;

[0037] The triaxial loading and seepage test includes the following steps:

[0038] Take a specimen, seal the side, and then place the specimen between the upper bearing plate and the hole sieve backing plate in the chamber body, and install the axial displacement sensor and the radial displacement sensor around the specimen; when the confining pressure chamber is not below the axial loading device, adjust the confining pressure chamber to be located below the axial loading device;

[0039] Fill the oil cavity with hydraulic oil through the oil inlet to apply pre-confining pressure to the specimen; apply axial preloading through the axial loading device; then apply axial load and confining pressure with preset target values until the test ends to conduct a triaxial loading test;

[0040] Inject fluid into the specimen through the fluid inlet until the test ends to conduct a seepage test.

[0041] The test device provided by this application is equipped with an independent uniaxial pressure chamber and a confining pressure chamber, which are respectively used for uniaxial loading tests and triaxial loading tests, and can meet the mechanical property test requirements of specimens of different sizes. The confining pressure chamber can also conduct seepage tests simultaneously. It is equipped with a high-temperature loading system, which can heat the specimen to simulate the real state under high-temperature formation environment, and can conduct a variety of corresponding tests on the specimen according to specific experimental schemes, such as uniaxial gradient loading test, triaxial loading and unloading test, high-pressure seepage test, high-temperature triaxial test of rock, high-temperature triaxial seepage coupling test of coal and rock mass, etc. The data acquisition system set can accurately measure the axial compression deformation and circumferential expansion deformation of coal and rock mass, and can accurately measure the real deformation of coal and rock mass. Description of the Drawings

[0042] Figure 1 is the overall structural schematic diagram of a coal and rock mass rheological test device provided by a preferred embodiment of the present invention;

[0043] Figure 2 is the structural schematic diagram of a uniaxial loading test using a uniaxial pressure chamber provided by a preferred embodiment of the present invention;

[0044] Figure 3 is the structural schematic diagram of a triaxial loading test using a confining pressure chamber provided by a preferred embodiment of the present invention;

[0045] Figure 4 It is a schematic structural diagram of a confining pressure chamber provided by a preferred embodiment of the present invention.

[0046] Explanation of reference numerals:

[0047] Ⅰ - Axial loading device; Ⅱ - Uniaxial pressure chamber; Ⅲ - Confining pressure chamber;

[0048] 1 - Axial loading pressure cylinder; 2 Reaction beam; 3 - Axial pressure piston; 4 - Axial pressure sensor; 5 - Upper platen; 6 - Heat insulation plate; 7 - Specimen; 8 - Lining plate; 9 - First base; 10 - Foot pad; 11 - Lower platen; 12 - Cylinder cover; 13 - Through hole; 14 - Second base; 15 - Rotating handle; 16 - Oil outlet; 17 - Tile-shaped hoop; 18 - Fluid discharge port; 19 - Normal displacement sensor; 20 - Upper bearing plate; 21 - Protective cover; 22 - Axial displacement sensor; 23 - Power supply interface; 24 - First temperature sensor; 25 - Radial displacement sensor; 26 - Hole sieve lining plate; 27 - Acoustic emission device; 28 - Lower bearing plate; 29 - Rubber sealing ring; 30 - Heating jacket; 31 - Base plate; 32 - Electric hoist; 33 - Protective door; 34 - Oil receiving box; 35 - Support. Detailed implementation manners

[0049] The present invention will be further described below in conjunction with the drawings and embodiments.

[0050] The present invention provides a coal and rock mass rheological test device, as Figures 1 to 4 shown, which includes a rheological test main machine. The rheological test main machine includes a reaction frame, an axial loading device Ⅰ, and a data acquisition system. Among them, the reaction frame is mainly used to effectively support loading devices such as axial and confining pressure. The axial loading device Ⅰ is used to apply axial pressure to the specimen, that is, to provide formation environment pressure for the test specimen and simulate the normal stress conditions suffered by the specimen in the real environment.

[0051] The rheological test main machine provided by this application also includes a separately arranged uniaxial pressure chamber Ⅱ and a confining pressure chamber Ⅲ.

[0052] Among them, the uniaxial pressure chamber Ⅱ is used to place the specimen for uniaxial loading tests. In this application, the uniaxial pressure chamber is separately arranged, and uniaxial loading tests can be independently carried out, and there is enough space to place specimens of different sizes. Preferably, the uniaxial pressure chamber Ⅱ includes a first base 9 and a number of detachable lining plates 8 located on the first base 9. The specimen 7 is placed on the detachable lining plate 8, and the height of the lining plate can be adjusted according to the size of the specimen, so that the space meets the size of the specimen in the test, and thus it can be applicable to specimens of various shapes and sizes.

[0053] The confining pressure chamber Ⅲ includes a closable chamber body with an opening. The chamber body can be opened before the test for placing the specimen and is closed during the test. Inside the chamber body, there are an upper bearing plate 20 and a lower bearing plate 28. On the upper surface of the lower bearing plate, there is a perforated sieve backing plate 26 with multiple sieve holes for fluid passage. Between the upper bearing plate 20 and the perforated sieve backing plate 26 is for placing the specimen sealed on the side; the placed specimen is located in the central area of the chamber body, and the surrounding area forms an oil chamber for filling hydraulic oil; the oil chamber is provided with an oil inlet, which can be connected to an external oil pump device, and the oil chamber is filled with hydraulic oil through the oil pump to apply confining pressure to the specimen; on the lower bearing plate, there is a fluid inlet for injecting fluid into the interior of the specimen to conduct a seepage test. When injecting fluid, when the fluid flows from the bearing plate to the specimen, it first passes through the perforated sieve backing plate 26, increasing the contact area between the fluid and the bottom of the specimen and more accurately simulating the real underground seepage environment. The fluid can be liquids and gases such as water, CO2, and N2.

[0054] Preferably, the side of the specimen 7 is sealed with a low-friction fluororubber resistant to high temperature. On the one hand, it prevents the hydraulic oil from contacting the specimen and causing errors in the test results and the crushed slag of the fractured specimen from falling into the confining pressure chamber. On the other hand, it prevents fluid such as water from entering the hydraulic oil during the seepage process, resulting in contamination of the hydraulic oil.

[0055] The coal and rock mass rheological test does not require simulating extremely complex horizontal working conditions (such as different confining pressures in 4 horizontal directions). It only requires the confining pressure to be stable and uniform. Therefore, in this application, the specimen is surrounded by hydraulic oil to apply the confining pressure loading. The confining pressure is evenly and stably stressed, and the confining pressure device is simple, and the confining pressure maintaining method is simple (only one high-pressure oil pump is used for pressurization and pressure maintenance).

[0056] Preferably, at the top of the upper bearing plate 20, there is a lower pressing head 11 passing through the top of the chamber body. The lower pressing head 11 is used to receive the pressure of the axial loading device, so that the axial loading device Ⅰ can act on the specimen 7 through the lower pressing head 11 and the upper bearing plate 20.

[0057] Preferably, the confining pressure chamber of this application is also provided with a high-temperature loading system, which can heat the specimen 7 to conduct a high-temperature loading test.

[0058] The data acquisition system is used to collect and feedback various signals during the test process. In addition to the conventional normal displacement sensor 19 and axial pressure sensor 4, the data acquisition system of this application also includes high-temperature and high-pressure resistant axial displacement sensors 22 and radial displacement sensors 25 arranged around the specimen, which are respectively used to detect the axial displacement and radial displacement of the specimen under test conditions; the axial displacement sensor 22 and the radial displacement sensor 25 can measure the axial compression deformation and circumferential expansion deformation of the specimen, control the deformation loading, and feedback data.

[0059] During the test, when the uniaxial pressure chamber is placed below the axial loading device, a uniaxial loading test can be carried out. When the confining pressure chamber is placed below the axial loading device, a triaxial loading test, a high-temperature test, a seepage test, and a multi-field coupling test can be carried out.

[0060] Preferably, the rheological test host of the present application further includes a conversion device, which can convert the positions of the uniaxial pressure chamber and the confining pressure chamber, so that any one of them is located below the axial loading device, and the corresponding other one is located outside the axial loading device, enabling a quick conversion between the uniaxial loading test and the triaxial loading test.

[0061] The test device provided by the present application is provided with an independent uniaxial pressure chamber and a confining pressure chamber, which are respectively used for uniaxial loading tests and triaxial loading tests, and can meet the mechanical property test requirements of specimens of different sizes. The confining pressure chamber can also conduct a seepage test at the same time. It is equipped with a high-temperature loading system, which can heat the specimen to simulate the real state under the high-temperature environment of the formation, and can conduct a variety of corresponding tests on the specimen according to specific experimental schemes, such as uniaxial gradient loading tests, triaxial loading and unloading tests, high-pressure seepage tests, high-temperature triaxial tests of rocks, high-temperature triaxial seepage coupling tests of coal and rock masses, etc. The data acquisition system set can accurately measure the axial compression deformation and circumferential expansion deformation of coal and rock masses, and can accurately measure the real deformation of coal and rock masses.

[0062] Preferably, the axial loading device Ⅰ is used to apply axial pressure to the specimen. From top to bottom, it includes an axial loading pressure cylinder 1, an axial pressure piston 3, a heat insulation plate 6, and an upper pressure head 5 connected in sequence; the axial loading pressure cylinder 1 provides power for axial loading, drives the axial pressure piston 3 to move up and down, and then drives the upper pressure head 5 to move towards the specimen to apply axial pressure.

[0063] The normal displacement sensor 19 is located above the axial loading pressure cylinder 1 and is used to detect the displacement of axial loading; the axial pressure sensor 4 is located on the axial pressure piston 3 and is used to detect the magnitude of the axial loading pressure.

[0064] Setting the heat insulation plate 6 on the upper pressure head can prevent the temperature from being conducted to the axial pressure sensor 4 during the high-temperature test and causing damage to it.

[0065] Preferably, the chamber body is composed of a cylinder cover 12 and a bottom plate 31. The upper bearing plate 20, the specimen, and the lower bearing plate 28 are all arranged inside the cylinder cover 12. The cylinder cover and the bottom plate are separable and are used to place the specimen.

[0066] Further preferably, the upper bearing pressing plate 20 is T-shaped, including a horizontal section and a vertical section located in the central area of the horizontal section. The lower bearing pressing plate 28 is inverted T-shaped. The lengths of the horizontal sections of the upper and lower bearing pressing plates are slightly smaller than the inner diameter of the cylinder cover, so that the cylinder cover can cover the outer sides of the upper and lower bearing pressing plates. The pore sieve backing plate is arranged on the surface of the vertical section of the lower bearing pressing plate; the vertical sections of the upper bearing pressing plate 20 and the lower bearing pressing plate 28 are arranged oppositely, and the specimen is placed between the upper bearing pressing plate and the pore sieve backing plate. An oil cavity is formed between the side surfaces of the vertical sections of the upper bearing pressing plate 20 and the lower bearing pressing plate 28 and the inner side wall of the cylinder cover.

[0067] A tile-shaped tightening hoop 17 is provided between the lower side of the cylinder cover and the bottom plate for fixing the cylinder cover 12 to ensure the stability of the confining pressure chamber during the test.

[0068] The lower bearing pressing plate 28 is provided with a fluid inlet channel and an oil inlet channel. Specifically, the oil inlet channels are arranged through both sides of the horizontal section, and the channel outlet, i.e., the oil inlet, is aligned with the oil cavity for filling hydraulic oil into the oil cavity; the fluid inlet channels are arranged through the horizontal section and the vertical section, and the channel outlet, i.e., the fluid inlet, is aligned with the pore sieve backing plate for injecting fluid into the specimen. An oil outlet pipe port 16 communicating with the oil cavity is provided above the outer side of the cylinder cover.

[0069] The upper bearing pressing plate is provided with a fluid discharge channel. Specifically, the fluid discharge channel is arranged through the vertical section and the horizontal section, the channel inlet is aligned with the specimen, and the channel outlet, i.e., the fluid discharge port 18, is arranged on the side of the upper bearing pressing plate for discharging the fluid after the seepage is completed.

[0070] The bottom plate 31 is provided with a plurality of through holes 13. On the one hand, fluid inlet interfaces, oil inlet interfaces and fluid discharge interfaces can be arranged in the through holes. On the other hand, the data lines at the rear ends of the radial displacement sensor 25, the axial displacement sensor 22, the temperature sensor 24 and the acoustic emission device 27 can be connected to an external control system through the through holes 13, and the axial pressure, confining pressure, temperature and acoustic signals are recorded in real time by the servo control system and the man-machine operating system.

[0071] The inlet end of the fluid inlet interface can be connected to an external fluid source, i.e., the seepage loading system described later, through a high-pressure pipeline, and the outlet end is communicated with the inlet of the fluid inlet channel of the lower bearing pressing plate to inject fluid into the specimen (the fluid injection path is seepage loading system - fluid inlet interface - fluid inlet channel - specimen), providing a stable pore pressure for the seepage test; the fluid discharge port 18 of the upper bearing pressing plate is connected with a fluid discharge pipe, the fluid discharge pipe is connected with the inlet end of the fluid discharge interface, and the outlet end of the fluid discharge interface is connected with a storage container to discharge the fluid after the seepage is completed (the fluid discharge path is specimen - fluid discharge channel - fluid discharge port - fluid discharge pipe - fluid discharge interface - storage container).

[0072] The inlet end of the oil inlet interface is connected to an external oil source through an oil pipe, and the outlet end is connected to an oil inlet channel; when filling the oil chamber with oil, the oil pump is connected to the oil inlet interface and the oil outlet port through oil pipes respectively, and then the confining pressure chamber is filled with oil. When the confining pressure chamber is filled with hydraulic oil, the excess hydraulic oil flows into the oil pump through the oil outlet port. Finally, after the test is completed, the oil pump is connected to the oil inlet interface again to pump out the cooled hydraulic oil from the confining pressure chamber for recycling. Preferably, a sealing device is provided between the lower platen 28 and the bottom plate 31. The sealing device is preferably a double-layer rubber sealing ring 29, which plays a sealing role to prevent hydraulic oil from overflowing.

[0073] A second base 14 is provided below the bottom plate 31, and the second base is used to support the entire confining pressure chamber.

[0074] Preferably, there are two axial displacement sensors 22. The axial displacement sensors are arranged on both sides of the horizontal section of the lower platen around the left and right sides of the specimen. The radial displacement sensor 25 is annular and is sleeved around the circumference of the specimen.

[0075] The data acquisition system further includes an acoustic emission device 27 and a first temperature sensor 24; the acoustic emission device and the first temperature sensor are arranged on both sides of the horizontal section of the lower platen around the specimen. The first temperature sensor 24 can record the change of the specimen temperature in real time. The acoustic emission device collects the acoustic signals of the specimen during the test, converts the acoustic signals into electrical signals, and transmits them to the data acquisition and control equipment for processing.

[0076] Preferably, a protective cover 21 is provided between the inner side of the cylinder cover 12 and the upper platen 20 and the lower platen 28. The protective cover 21 is used to prevent the cylinder cover from colliding with the lines of each sensor when it falls during the test and damaging the sensors. As those skilled in the art can understand, through holes for pipelines (pipelines connecting the oil outlet port and the oil chamber) to pass through are provided on the protective cover.

[0077] Preferably, the high-temperature loading system includes a detachable flexible heating sleeve 30 and a heat insulation device; the detachable flexible heating sleeve 30 is sleeved on the outside of the chamber body (specifically the cylinder cover); a heating element is provided inside the detachable flexible heating sleeve 30, and a power interface 23 is reserved on the detachable flexible heating sleeve 30. By connecting the power supply, the heating element generates heat to provide the required temperature for the test; the heat insulation device is sleeved on the outside of the detachable flexible heating sleeve, and the heat insulation device adopts a nano-aerogel device. As those skilled in the art can understand, the high-temperature loading system further includes a second temperature sensor and a control system. The specimen is heated through the heating sleeve, insulated with nano-aerogel, the real-time temperature of the heating sleeve is collected by the second temperature sensor and fed back to the control system, and the control system controls the increase and decrease of the temperature according to the set temperature.

[0078] Preferably, the reaction force frame includes a support 35 and a reaction force beam 2 located on the support. The axial loading device is arranged on the reaction force beam. The reaction force beam is arranged in a side area rather than the central area of the support, so that the other side can accommodate a uniaxial pressure chamber or a confining pressure chamber that does not conduct tests.

[0079] A turntable is arranged on the support. The uniaxial pressure chamber and the confining pressure chamber are detachably installed on the turntable. By rotating the turntable, the position of the uniaxial pressure chamber or the confining pressure chamber can be adjusted so that the uniaxial pressure chamber or the confining pressure chamber is placed under the axial loading device on the reaction force beam. Preferably, a rotating handle 15 is arranged on the turntable, and it is convenient to rotate the turntable by rotating the rotating handle. A hoisting device such as an electric hoist 32 is arranged on the side of the reaction force beam aligned with the other side area of the support, for lifting the cylinder cover of the confining pressure chamber.

[0080] The stiffness of the reaction force frame should be able to meet the test requirements and have a strong ability to resist elastic deformation.

[0081] A protective door 33 is arranged on one side of the support (the side of the reaction force beam) to prevent the fragments from the specimen breaking under axial loading from popping out during the uniaxial loading test and injuring the test operators. Foot pads 10 are arranged under the support to keep the overall equipment stable.

[0082] After the test is completed, when using an oil pump to recover the hydraulic oil in the oil chamber, it cannot be guaranteed that all the liquid in the oil chamber can be pumped out, and some residual hydraulic oil will remain on the inner wall of the confining pressure chamber. Preferably, an oil receiving box 34 is also arranged on the support 35, for receiving the waste oil remaining after the oil pump extraction in the confining pressure chamber after the test, to prevent the waste oil from polluting the environment.

[0083] The coal and rock mass rheological test device provided by this application further includes a control cabinet, a servo power hydraulic station, a confining pressure loading system, a seepage loading system, a servo control system and a man-machine operating system.

[0084] The servo power hydraulic station is connected to the rheological test host through an oil delivery pipeline, and more specifically to the axial loading pressure cylinder, for providing axial loading power to the rheological test host.

[0085] The confining pressure loading system is connected to the rheological test host through an oil pipe, and more specifically to the oil inlet interface on the confining pressure chamber, for controlling the confining pressure loading of the specimen in the confining pressure chamber and simulating the horizontal stress borne by the specimen in the deep environment.

[0086] The seepage loading system is connected to the rheological test host, and more specifically to the fluid inlet interface and the fluid discharge interface on the confining pressure chamber. The high-pressure seepage pump in the seepage system conducts an injection seepage test on the specimen, for simulating the seepage effect of underground deep liquid or gas on the rock mass.

[0087] The servo control system and the man-machine operating system are integrated on a mainframe, and are connected to the rheological test mainframe, the confining pressure loading system, the seepage loading system, and the servo power hydraulic station through circuits, used to output control signals and input acquisition signals to the rheological test mainframe, the confining pressure loading system, the seepage loading system, and the servo power hydraulic station, and perform result processing, featuring high stability and high precision.

[0088] The control cabinet is connected to the rheological test mainframe, the servo power hydraulic station, the confining pressure loading system, the seepage loading system, the servo control system and the man-machine operating system through circuits, used to provide power to the rheological test mainframe, the servo power hydraulic station, the confining pressure loading system, the seepage loading system, the servo control and the man-machine operating system.

[0089] This application provides an operation process for uniaxial gradient loading test, which is as follows:

[0090] First, record and number the prepared specimens, then install the uniaxial pressure chamber and place the specimen to be tested at the center of the backing plate, and then debug the software program and check the wiring of the equipment and the installation of the sensors.

[0091] Perform preloading in the displacement loading mode to ensure good contact between the specimen and the indenter at all parts, enter the normal working state, and make the relationship between load and deformation tend to be stable.

[0092] Perform gradient loading in the force loading mode, apply load to the specimen until the specimen fractures, and at the same time, use the digital control system to record the time, the magnitude of the axial pressure, and the peak value of the pressure of the fractured specimen in real time. Record the failure mode of the specimen by taking pictures, and save and organize the data.

[0093] After the test is completed, perform subsequent operations such as pressure relief and cleaning.

[0094] This application provides an operation process for high-temperature triaxial rheological test, which is as follows:

[0095] First, saturate the prepared specimens, record and number the specimens, and then debug the test instruments and set the software program.

[0096] Wrap the saturated specimens with temperature-resistant low-friction fluororubber to isolate the oil, prevent hydraulic oil from entering the specimens and causing result errors, then place the specimens into the confining pressure chamber, install the hole sieve backing plate according to the test requirements, connect the axial displacement sensor, the radial displacement sensor, the acoustic emission device and the first temperature sensor, and install the tile tightening hoop outside the confining pressure chamber to fix the confining pressure chamber.

[0097] Connect the oil pump to the inlet interface and the outlet oil pipe. After filling the oil chamber of the confining pressure chamber with oil, disconnect the connection. Connect the confining pressure loading system to the inlet interface to provide confining pressure for the subsequent test. At the same time, connect the seepage loading system to the fluid inlet interface to provide osmotic pressure for the subsequent test. Then connect the fluid outlet to the storage container to hold the seeped fluid.

[0098] Install the high-temperature loading device and turn on the circuit. Set the test temperature, raise the temperature of the confining pressure chamber to the preset value and keep it for a period of time to ensure uniform heating of the test.

[0099] Adopt the displacement loading mode for pre-axial pressure loading and the constant pressure mode for pre-confining pressure loading to make it enter the normal working state, and the relationship between load and deformation tends to be stable.

[0100] Conduct confining pressure loading and axial pressure. After the confining pressure and axial pressure are loaded to the test values, gradually load the pore pressure. When seeped fluid appears at the fluid outlet, the porosity and permeability of the specimen can be calculated through the seepage flow rate.

[0101] When unloading the pressure, first unload the pore pressure, then unload the axial pressure, and finally unload the confining pressure in this order. Then remove the high-temperature loading device. After the hydraulic oil temperature in the confining pressure chamber drops to room temperature, connect the oil pump to the inlet interface, and the hydraulic oil in the confining pressure chamber can be pumped out through the inlet channel for recycling. Disassemble the confining pressure chamber and take out the specimen for preservation.

[0102] After the test is completed, carry out subsequent work such as data sorting and cleaning.

[0103] Example 1

[0104] This example provides an operation method for a uniaxial loading test, which is as follows:

[0105] 1. Prepare several specimens of different sizes and types, and record the dimensions of the specimens;

[0106] 2. According to the different sizes of the specimens, successively stack the cushion plates on the first base of the uniaxial pressure chamber to adjust the test space size. Finally, place the specimen at the center position of the cushion plate. If the uniaxial pressure chamber is not under the reaction beam, rotate the handle to turn the uniaxial pressure chamber under the axial loading device of the reaction beam and close the protective door.

[0107] 3. Open the axial loading pressure cylinder and the hydraulic servo pump, and apply axial pressure to the specimen through the axial loading pressure cylinder.

[0108] 4. Set the loading mode. First, perform preloading through displacement, and then use the force loading mode to conduct a loading test on the specimen until the specimen is fractured.

[0109] 5. Take pictures of the fractured specimens with a camera, record the time, pressure magnitude, and peak pressure of the fractured specimens through the data acquisition system, and export and organize the test data.

[0110] 6. Unload the axial pressure by means of displacement loading. After the pressure unloading is completed, open the protective door, save the broken specimens, and clean the uniaxial pressure chamber.

[0111] Example 2

[0112] In this example, water is used as the seepage fluid, and an operation method for a triaxial seepage test is provided as follows:

[0113] 1. Prepare several standard specimens with a diameter of φ50mm and a height of 100mm, label the specimens and record the initial state. Rotate the confining pressure chamber (the bottom plate, the second base, the rubber sealing ring, and the lower bearing plate of the confining pressure chamber are fixedly connected as a whole) to the lower part of the axial loading device on the reaction beam through the rotating handle;

[0114] 2. Place the pore sieve backing plate above the lower bearing plate to simulate the underground seepage environment. Place the prepared specimens on the pore sieve backing plate, and seal the periphery of the specimens with temperature-resistant low-friction fluororubber. On the one hand, it can prevent the hydraulic oil from contacting the specimens, resulting in result errors and the broken slag of the fractured specimens from falling into the confining pressure chamber. On the other hand, it can prevent water from entering the hydraulic oil during the seepage process, resulting in the pollution of the hydraulic oil. Place the upper bearing plate above the specimens.

[0115] 3. Set the radial displacement sensor at the height center of the temperature-resistant low-friction fluororubber-sealed specimens. Install two axial displacement sensors on the lower bearing plate of the confining pressure chamber around both sides of the specimen to be tested. Install the temperature sensor and the acoustic emission device on the lower bearing plate as well and close to the specimen to be tested. Connect the fluid discharge port on the upper bearing plate to the through hole of the bottom plate through the fluid discharge pipe, and lead the seeped water out of the confining pressure chamber through the through hole of the bottom plate. Connect the discharged liquid to the water storage container through the pipeline, calculate the permeability and porosity of the specimens through the seepage flow rate. Finally, connect the signal lines of the axial displacement sensor, the radial displacement sensor, the acoustic emission device, and the temperature sensor to the external control system through the through hole, and detect the axial deformation, radial deformation, acoustic signal, and temperature through the artificial control system.

[0116] 4. Then install the protective cover to protect the sensors in the confining pressure chamber and prevent damage to the sensors caused by human touch. Use a hoist to place the cylinder cover of the confining pressure chamber on the bottom plate to cover the entire confining pressure chamber. Install a tile tightening hoop outside the cylinder cover, which is used to fix the cylinder cover on the one hand to prevent it from sliding, and make the confining pressure chamber more airtight on the other hand.

[0117] 5. After the test piece is installed, connect the oil pump to the oil outlet pipe at the upper end of the cylinder cover and the oil inlet interface of the through hole in the bottom plate. Inject oil into the confining pressure chamber through the oil pump until the chamber is filled with oil. Then, turn off the oil pump and seal the confining pressure chamber. Connect the confining pressure loading system to the oil inlet interface and the seepage loading system to the fluid inlet interface. Program the man-machine control system to provide the pore water pressure and confining pressure required for the test for the test specimen to be tested.

[0118] 6. Turn on the servo hydraulic pump and activate the confining pressure loading system and the seepage loading system.

[0119] 7. Set a small initial pressure and perform axial preloading through the force loading mode. Program the test through the man-machine operating system, set the test axial pressure and confining pressure, and record the initial values of the axial deformation and circumferential deformation of the test specimen to be tested.

[0120] 8. Use the gradient loading method to load the axial pressure and confining pressure, and record the axial pressure, confining pressure, axial deformation, and circumferential deformation during the test.

[0121] 9. Conduct tests on the remaining test specimens according to steps 2 - 8 under different osmotic pressures, and record the seepage volume and seepage time.

[0122] 10. Export the test data and organize the test results.

[0123] Example 3

[0124] In this example, water is used as the seepage fluid to provide an operation method for high-temperature triaxial seepage tests, which is specifically as follows:

[0125] 1. Prepare several standard specimens with a diameter of φ50mm and a height of 100mm, label the specimens, and record their initial states. Rotate the confining pressure chamber (the bottom plate, the second base, the rubber sealing ring, and the lower bearing plate of the confining pressure chamber are fixedly connected as a whole) to the lower part of the axial loading device of the reaction beam through the rotating handle;

[0126] 2. Place the pore sieve backing plate above the lower bearing plate to simulate the underground seepage environment. Place the prepared specimens on the pore sieve backing plate, and seal the periphery of the specimens with heat-resistant low-friction fluororubber. On the one hand, this can prevent the contact between the hydraulic oil and the specimens from causing result errors and the broken slag of the fractured specimens from falling into the confining pressure chamber. On the other hand, it can prevent water from entering the hydraulic oil during the seepage process, resulting in the pollution of the hydraulic oil; place the upper bearing plate above the specimens.

[0127] 3. Set the radial displacement sensor at the height center of the low-temperature-resistant and low-friction fluororubber seal specimen. Install two axial displacement sensors on the lower bearing plate of the confining pressure chamber around both sides of the specimen to be tested. Also install the temperature sensor and the acoustic emission device on the lower bearing plate and close to the specimen to be tested. Connect the fluid discharge port on the upper bearing plate to the through hole on the bottom plate through a fluid discharge pipe, and lead the seeped water out of the confining pressure chamber through the through hole on the bottom plate. Connect the discharged liquid to the water storage container through a pipe. Calculate the permeability and the porosity of the specimen through the seepage flow rate. Finally, connect the signal lines of the axial displacement sensor, the radial displacement sensor, the acoustic emission device, and the temperature sensor to the external control system through the through holes, and detect the axial deformation, radial deformation, acoustic signal, and temperature through the manual control system.

[0128] 4. Then install the protective cover to protect the sensors in the confining pressure chamber and prevent damage to the sensors caused by human touch. Use a hoist to place the cylinder cover of the confining pressure chamber on the bottom plate to cover the entire confining pressure chamber. Install a tile tightening hoop on the outside of the cylinder cover, which is used to fix the cylinder cover to prevent it from sliding on the one hand, and make the confining pressure chamber more airtight on the other hand.

[0129] 5. After the specimen is installed, install the detachable flexible heating sleeve on the outside of the cylinder cover and connect the circuit. Connect the oil pump to the oil outlet on the upper end of the cylinder cover and the oil inlet interface of the through hole on the bottom plate. Inject oil into the confining pressure chamber through the oil pump until the cavity is full of oil, then turn off the oil pump and seal the confining pressure chamber. Connect the confining pressure loading system to the oil inlet interface and the seepage loading system to the fluid inlet interface. Provide the pore water pressure and confining pressure required for the test for the specimen to be tested through the man-machine control system programming.

[0130] 6. Open the servo hydraulic pump and turn on the confining pressure loading system and the seepage loading system.

[0131] 7. Set a small initial pressure and perform axial preloading through the force loading mode. Program the test through the man-machine operating system, set the axial pressure, confining pressure, and temperature of the test, and record the initial values of the axial deformation, circumferential deformation, and temperature of the specimen to be tested.

[0132] 8. Use the gradient loading method to load the axial pressure and confining pressure, and record the axial pressure, confining pressure, axial deformation, circumferential deformation, and temperature during the test.

[0133] 9. Conduct tests on the remaining specimens according to steps 2 - 8 under different osmotic pressures, and record the seepage volume and seepage time.

[0134] 10. Export the test data and organize the test results.

[0135] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art can make various changes and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A coal rock rheology test device, comprising a rheology test host, wherein the rheology test host comprises an axial loading device and a data acquisition system; characterized in that: The rheological test host also includes a uniaxial pressure chamber and a confining pressure chamber which are separately arranged; The uniaxial pressure chamber is used to place samples and perform uniaxial loading tests; the uniaxial pressure chamber includes a first base and a plurality of detachable pads located on the first base, and the height of the pads can be adjusted to accommodate samples of different sizes; The confining pressure chamber comprises an openable closed chamber body, wherein an upper pressure plate and a lower pressure plate are arranged in the chamber body, a perforated sieve pad is arranged on the upper surface of the lower pressure plate, a plurality of sieve holes for fluid to pass through are arranged on the perforated sieve pad, and a sample with side sealing is placed between the upper pressure plate and the perforated sieve pad; after being placed, the sample is located in the central area of ​​the chamber body, and an oil cavity for filling hydraulic oil is formed in the surrounding area of ​​the chamber body, and the oil cavity is provided with an oil inlet for filling hydraulic oil to apply confining pressure to the sample; a fluid inlet is arranged on the lower pressure plate for injecting fluid into the interior of the sample to perform a seepage test; the confining pressure chamber also comprises a high-temperature loading system; The data acquisition system includes an axial displacement sensor and a radial displacement sensor disposed around the sample, and used to detect the axial displacement and radial displacement of the sample under test conditions, respectively; The rheological test host also includes a conversion device, which can convert the positions of the uniaxial pressure chamber and the confining pressure chamber so that any one of them is located below the axial loading device and the corresponding other is located outside the axial loading device, thereby realizing rapid conversion between uniaxial loading tests and triaxial loading tests.

2. The coal rock rheology test device according to claim 1, characterized in that: The axial loading device is used to apply axial pressure to the sample, and comprises, from top to bottom, an axial loading pressure cylinder, an axial pressure piston, a temperature insulation plate and an upper pressure head connected in sequence; The data acquisition system also includes a normal displacement sensor and an axial pressure sensor; The normal displacement sensor is located above the axial loading pressure cylinder and is used to detect the displacement of the axial loading; The axial pressure sensor is located on the axial pressure piston and is used to detect the magnitude of the axial loading pressure; The top of the upper pressure plate is connected with a lower pressure head passing through the top of the chamber body, and the lower pressure head is used to bear the pressure of the axial loading device.

3. The coal rock rheology testing device according to claim 1, characterized in that: The coal rock mass rheology test device further comprises a reaction force frame, wherein the reaction force frame comprises a support and a reaction force beam located in a side area of ​​the support; The axial loading device is arranged on the reaction beam; A turntable is provided on the support, and the uniaxial pressure chamber and the confining pressure chamber are detachably mounted on the turntable. By rotating the turntable, the position of the uniaxial pressure chamber or the confining pressure chamber can be adjusted so that the uniaxial pressure chamber or the confining pressure chamber is placed below the axial loading device on the reaction beam.

4. The coal rock rheology testing device according to claim 1, characterized in that: The chamber body is composed of a cylinder cover and a bottom plate; a clamp is provided between the lower side of the cylinder cover and the bottom plate for fixing the cylinder cover; The upper pressure plate is T-shaped, including a horizontal section and a vertical section located in the center area of ​​the horizontal section; the lower pressure plate is in an inverted T-shape; the length of the horizontal section is slightly smaller than the cylinder cover, and the oil chamber is formed between the side of the vertical section and the side wall of the cylinder cover; the vertical sections of the upper pressure plate and the lower pressure plate are arranged opposite to each other, and the perforated screen pad is arranged on the upper surface of the vertical section of the lower pressure plate.

5. The coal rock rheology testing device according to claim 4, characterized in that: The lower pressure plate is provided with a fluid inlet channel and an oil inlet channel, and the upper pressure plate is provided with a fluid outlet channel; an oil outlet pipe port communicating with the oil chamber is provided on the upper outer side of the cylinder cover, and a fluid outlet port is provided on the side of the upper pressure plate; The bottom plate is provided with a plurality of through holes, and a fluid inlet interface, a fluid outlet interface and an oil inlet interface are arranged in the through holes; The inlet end of the fluid inlet interface is used to connect to an external fluid source, and the outlet end is communicated with the inlet of the fluid inlet channel, and the outlet of the fluid inlet channel, i.e., the fluid inlet, is aligned with the hole screen pad; The outlet of the fluid discharge channel is connected to a fluid discharge pipe, the fluid discharge pipe is connected to the inlet end of the fluid discharge interface, and the outlet end of the fluid discharge interface is connected to the outside, so as to discharge the fluid after the seepage test; The inlet end of the oil inlet interface is used to be connected to an external oil source, and the outlet end is connected to the oil inlet channel. The other end of the oil inlet channel, namely the oil inlet, is in communication with the oil cavity.

6. The coal rock rheology testing device according to claim 4, characterized in that: A sealing device is provided between the lower pressure plate and the bottom plate; A second base is provided below the bottom plate; A protective cover is provided between the inner side of the cylinder cover and the upper pressure bearing plate and the lower pressure bearing plate.

7. The coal rock rheology testing device according to claim 4, characterized in that: The axial displacement sensors include two, which are respectively arranged on both sides of the horizontal section of the lower pressure plate around the left and right sides of the sample, and the radial displacement sensor is annularly sleeved around the sample; The data acquisition system further includes an acoustic emission device and a first temperature sensor; the acoustic emission device and the first temperature sensor are located on both sides of the horizontal section of the lower pressure plate.

8. The coal rock rheology testing device according to claim 1, characterized in that: The high temperature loading system is used to heat the sample and perform a high temperature loading test; The high temperature loading system includes a detachable flexible heating jacket and a heat preservation device; The detachable flexible heating sleeve is arranged on the outer side of the chamber body; a heating element is arranged inside the detachable flexible heating sleeve; The heat preservation device is sleeved on the outer side of the detachable flexible heating sleeve, and the heat preservation device adopts a nano aerogel device.

9. A test method for the coal rock rheology test device according to any one of claims 1 to 8, characterized in that: The uniaxial pressure chamber is used to carry out a uniaxial loading test or the confining pressure chamber is used to carry out a triaxial loading and seepage test; The uniaxial loading test comprises the following steps: Putting a sample into the uniaxial pressure chamber, when the uniaxial pressure chamber is not below the axial loading device, adjusting the uniaxial pressure chamber to be below the axial loading device, applying a preload through the axial loading device, and then applying an axial load through the axial loading device until the test is completed; The triaxial loading and seepage test includes the following steps: Take a sample, seal the side, and then place the sample between the upper pressure plate and the hole screen pad in the chamber body, and install the axial displacement sensor and the radial displacement sensor around the sample; when the confining pressure chamber is not below the axial loading device, adjust the confining pressure chamber to be below the axial loading device; Fill the oil cavity with hydraulic oil through the oil inlet to apply pre-confining pressure to the sample; apply axial pre-pressure through the axial loading device; then apply axial load and confining pressure of preset target values ​​until the test is completed, and perform a triaxial loading test; The permeation test is performed by injecting fluid into the sample through the fluid inlet until the test is completed.

Images