A device for applying long-term stable confining pressure to a jointed rock model specimen and a method for using the device

Abstract

The present invention relates to a long-term stable confining pressure applying device for a jointed rock model specimen and a method for using the device, comprising a steel trough for placing the specimen, which has a hollow chamber inside, and a plurality of specimen axial pressure fixing devices are arranged in the chamber; an air inlet is opened on the chamber wall of the steel trough for placing the specimen, and an air inlet threaded pipe mouth is arranged on the air inlet for connecting with an air compressor; an air pressure threaded pipe mouth is also installed on the chamber wall of the steel trough for placing the specimen, for installing a barometer, and the sensing end of the barometer is embedded in the chamber; the specimen axial pressure fixing device is used to perform axial pressure simulation on the specimen, and when the confining pressure simulation is performed on the specimen, a steel cover plate is covered on the open end of the steel trough for placing the specimen, and the air compressor introduces gas into the steel trough for placing the specimen to perform confining pressure simulation on the specimen; the present invention has the characteristics of controllable confining pressure, convenient manufacturing, energy saving and economy, long-term stability, etc., and can apply long-term and stable confining pressure to the specimen to study the joint development, rock mechanics parameter changes and other issues under long-term confining pressure.

Description

Technical Field

[0001] The invention relates to a device for applying long-term stable confining pressure to a jointed rock model specimen and a use method thereof, and belongs to the field of rock and soil testing. Background Art

[0002] Irregular jointed rock masses, such as columnar jointed rock masses and serrated jointed rock masses, are prone to collapse, rock burst and other engineering accidents during tunnel excavation and other engineering construction due to the presence and abnormal development of internal joints and fissures. Therefore, the engineering mechanical properties of jointed rock masses, especially the mechanical properties under confining pressure conditions, need to be studied urgently. In-situ tests on irregular jointed rock masses are difficult to carry out due to the high cost of rock mass crushing, so similar materials with simple preparation, economical energy saving and easy control of joint parameters are often used for related experimental studies to analyze the engineering mechanical properties of irregular jointed rock masses.

[0003] Most of the current research on similar material models of jointed rock mass, when conducting mechanical tests, uses pressurized pretreatment to simulate the effect of initial confining pressure on the inherent joints and fissures in the specimens. However, the pretreatment time is often short due to the number of instruments and equipment, economic time cost, etc., and the closure and development of internal joints are difficult to simulate the actual occurrence of irregular jointed rock mass, thus affecting the accuracy and reliability of similar material model research. Despite this, considering the cost and operation time issues, most researchers still use preloading treatment to simulate the effect of initial confining pressure on the inherent joints and fissures in the specimens. Some researchers will use the method of stacking heavy objects on the specimens for long-term preloading treatment. This method has the advantages of being economical and easy to operate, but it cannot simulate the effect of radial confining pressure on the specimens, and still cannot truly simulate the long-term effect of confining pressure on jointed rock mass.

[0004] In summary, among the currently available test methods and devices, there is no confining pressure device and method that can conduct long-term, stable, efficient, economical, and controllable confining pressure tests on similar material samples of jointed rock masses. Summary of the invention

[0005] The present invention provides a long-term stable confining pressure applying device for jointed rock model specimens and a using method, which can simulate long-term axial and radial confining pressure on multiple groups of specimens, solving the problem of difficulty in simulating long-term and stable confining pressure after the existing specimens are prepared.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A device for applying long-term stable confining pressure to a jointed rock model specimen, comprising a specimen placement steel trough, the interior of which is a hollow chamber, and a plurality of specimen axial pressure fixing devices are arranged in the chamber;

[0008] An air inlet is opened on the wall of the chamber where the sample is placed in the steel tank, and an air inlet threaded pipe port is provided on the air inlet for connecting with the air compressor;

[0009] A pressure threaded pipe port is also installed on the chamber wall of the steel tank where the sample is placed, for installing a barometer, and the sensing end of the barometer is embedded in the chamber;

[0010] The sample axial pressure fixing device is used to simulate the axial pressure of the sample. When the sample is subjected to confining pressure simulation, a steel cover plate is placed on the open end of the steel trough where the sample is placed, and an air compressor introduces gas into the steel trough where the sample is placed to simulate the confining pressure of the sample.

[0011] As a further preferred embodiment of the present invention, the sample axial pressure fixing device comprises a load-bearing disc and a fixed disc, the load-bearing disc and the fixed disc are arranged in parallel, the two are fixed by a connecting column, and the sample is placed between the load-bearing disc and the fixed disc;

[0012] A spring is installed on the surface of the load-bearing disk, the force direction of the spring is perpendicular to the load-bearing disk, the bottom end of the spring is fixed on the surface of the load-bearing disk, and a force-applying device is installed on the top end of the spring;

[0013] As a further preferred embodiment of the present invention, the force-applying device includes a force-applying plate pressed on the top of the spring, and a plurality of knob devices are vertically arranged between the force-applying plate and the force-bearing disc, one end of the knob device is fixed to the force-applying plate, and the other end of the knob device is connected to the force-bearing disc through a force-bearing bolt, and the knob device is moved in a direction perpendicular to the force-bearing disc by rotating the force-bearing bolt;

[0014] As a further preferred embodiment of the present invention, a load-bearing groove is provided on the bottom surface of the load-bearing disc in contact with the sample, and a fixing groove is provided on the surface of the fixing disc in contact with the sample, and both ends of the sample are matched and embedded in the load-bearing groove and the fixing groove;

[0015] As a further preferred embodiment of the present invention, a load-bearing movable pad matching the sample is embedded in the load-bearing groove;

[0016] Portable handles are respectively provided on two symmetrical chamber walls of the specimen placement steel trough;

[0017] As a further preferred embodiment of the present invention, a plurality of axial pressure bolt holes are arranged on the fixing disk, and when the sample axial pressure fixing device is placed in the chamber, axial pressure bolts are inserted into the axial pressure bolt holes to fix the sample axial pressure fixing device to the bottom surface of the chamber;

[0018] As a further preferred embodiment of the present invention, the open end of the sample placement steel trough extends outward to form an edge, and through clamping bolt holes are respectively opened on the steel cover plate and the edge of the sample placement steel trough, and clamping bolts are inserted into the clamping bolt holes to connect the steel cover plate and the sample placement steel trough;

[0019] A U-shaped rubber ring is also provided on the edge of the steel trough for placing the specimen, and the steel cover plate is covered on the open end of the steel trough for placing the specimen, and the clamping bolts are tightened to seal;

[0020] As a further preferred embodiment of the present invention, when the steel cover plate is covered on the open end of the steel trough for placing the sample, a secondary sealing and fixing is performed by a plurality of fixing brackets;

[0021] The fixed bracket includes a bracket pressure column, a fixed bracket handle and a pressure pad. The fixed bracket handle is C-shaped, a threaded groove is provided at one end of the fixed bracket handle, and the internal thread is inserted to connect the bracket pressure column. The other end of the fixed bracket handle is equipped with a pressure pad. When the steel cover plate is covered on the open end of the sample placement steel groove, the pressure pad is against the edge of the sample placement steel groove, and the bottom end of the bracket pressure column is against the steel cover plate; the top end of the bracket pressure column is L-shaped, and the bottom end of the bracket pressure column is close to the pressure pad;

[0022] The distance between the bottom end of the support pressure column and the pressure pad can be adjusted by rotating the support pressure column;

[0023] A method for using the device for applying long-term stable confining pressure to a jointed rock model specimen specifically comprises the following steps:

[0024] Step S1: Calculate the axial confining pressure and radial confining pressure that the sample should withstand during the simulation test based on the similarity ratio of the material with similar rock mechanical parameters and strength as the sample and the real axial confining pressure and real radial confining pressure at the rock mass where the sample is located;

[0025] Step S2: Level the test site, and use the portable handle to lift the steel trough where the sample is placed to an open space or a workbench that is convenient for operation;

[0026] Step S3: Install a barometer in a preset air pressure threaded pipe opening, and screw the barometer to a position directly facing the operator's line of sight;

[0027] Step S4: a thin rubber pad is placed on the bottom of the sample and then placed on the surface of the fixed disc of the sample axial pressure fixing device, and the fixed disc is connected to the sample placement steel groove by inserting the axial pressure bolts into the axial pressure bolt holes;

[0028] Step S5: a thin rubber pad is also arranged on the top of the sample, a load-bearing disc is placed on the top of the sample, the load-bearing bolt is rotated, the knob device moves in a direction perpendicular to the load-bearing disc, and the force plate compresses the spring in the direction of the load-bearing disc. When the length of the knob device extending from the load-bearing disc reaches a preset value, the axial confining pressure applied by the spring to the top of the sample is close to the calculated axial confining pressure that should be borne during the simulation test;

[0029] Step S6: Place the U-shaped rubber ring at the open end of the sample placement steel trough, cover it with a steel cover plate, insert a clamping bolt into the clamping bolt hole, and connect the steel cover plate to the sample placement steel trough; at the same time, install fixed brackets at the four corners of the steel cover plate, rotate the bracket pressure column, and ensure that there is no gap between the edge of the sample placement steel trough, the U-shaped rubber ring, and the steel cover plate;

[0030] Step S7: Connect an air compressor through the air inlet threaded pipe provided on the air inlet, adjust the air compressor speed and observe the barometer until the air pressure displayed by the barometer reaches the calculated radial confining pressure that should be borne during the simulation test, and observe changes in the sample;

[0031] As a further preferred embodiment of the present invention, in step S1, the material similarity ratio is defined as C R , define the true axial confining pressure as σ L , define the true radial confining pressure as σ R , C R =R p / R m , where R p Represents the rock mechanics parameter strength of the real jointed rock mass material, R m The strength of geotechnical parameters representing similar material specimens;

[0032] The calculation shows that the axial confining pressure that the specimen should bear during the simulation test is σ l =σ L / C R , the radial confining pressure that the specimen should withstand during the simulation test is σ r =σ R / C R ;

[0033] In step S5, the length of the knob device extending out of the load-bearing disc is calculated by the formula l = σ l πr 2 / k, where l is the extension length of the lower part of the knob device, r is the radius of the top surface of the specimen, k is the elastic coefficient of the selected spring, σ l It is the axial confining pressure that the specimen should withstand during the simulation test.

[0034] Through the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The long-term stable confining pressure applying device for jointed rock model specimens provided by the present invention can simulate multiple groups of similar jointed rock specimens at the same time, with low economic cost;

[0036] 2. The long-term stable confining pressure applying device for jointed rock model specimen provided by the present invention can truly simulate the long-term effect of axial or radial or axial plus radial confining pressure on jointed rock;

[0037] 3. The long-term stable confining pressure application device for jointed rock model specimens provided by the present invention has low manufacturing cost, simple operation and strong application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0039] Figure 1 It is a schematic diagram of the overall structure of a preferred embodiment provided by the present invention;

[0040] Figure 2 is a schematic diagram of a top view of a preferred embodiment provided by the present invention;

[0041] Figure 3 is a front view structural schematic diagram of a preferred embodiment provided by the present invention;

[0042] Figure 4 is a schematic diagram of a test structure of a preferred embodiment provided by the present invention;

[0043] Figure 5 It is a front view of a sample axial pressure fixing device in a preferred embodiment provided by the present invention;

[0044] Figure 6 It is a top view of the specimen axial pressure fixing device in the preferred embodiment provided by the present invention;

[0045] Figure 7 It is a schematic diagram of the fixed bracket structure in the preferred embodiment provided by the present invention.

[0046] In the figure: 1 is a steel groove for placing the specimen, 2 is a U-shaped rubber ring, 3 is a steel cover plate, 4 is a specimen axial pressure fixing device, 5 is a fixed bracket, 6 is a barometer, 7 is an air inlet, 8 is a portable handle, 9 is an axial pressure bolt hole, 10 is a clamping bolt hole, 11 is a load-bearing disc, 12 is a fixed disc, 13 is an air inlet threaded pipe opening, 14 is an air pressure threaded pipe opening, 15 is a spring, 16 is a knob device, 17 is a load-bearing groove, 18 is a fixed groove, 19 is a load-bearing movable pad, 20 is a pressure pad, 21 is a fixed bracket handle, and 22 is a bracket pressure column. DETAILED DESCRIPTION

[0047] The present invention will now be described in further detail with reference to the accompanying drawings. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and "first", "second", etc. do not indicate the importance of the components, and therefore cannot be understood as a limitation on the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution by example, and do not limit the scope of protection of the present invention.

[0048] As explained in the background technology, what needs to be overcome in the current confining pressure simulation is how to perform long-term and stable axial and radial simulations after the sample preparation is completed. Based on this, the present application provides a long-term and stable confining pressure application device for a jointed rock model sample, which can achieve single and simultaneous simulation of axial or radial confining pressure of the sample under a preset pressure, which is also one of the biggest highlights of the present application.

[0049] Next, the device proposed in this application is specifically described. Figure 1-Figure 4 As shown, the whole comprises a sample placement steel trough 1, which has a hollow chamber inside, and a plurality of sample axial compression fixtures 4 are arranged in the chamber; placing a plurality of sample axial compression fixtures in the chamber can satisfy the simultaneous simulation of multiple groups of jointed rock mass samples of similar materials, and can satisfy the demand for axial compression simulation of samples in the test at a very low economic cost. An air inlet 7 is opened on the chamber wall of the steel trough for placing the sample, and an air inlet threaded pipe mouth 13 is arranged on the air inlet for connecting with the air compressor; an air pressure threaded pipe mouth 14 is also installed on the chamber wall of the steel trough for placing the sample, for installing a barometer 6, and the sensing end of the barometer is embedded in the chamber; when the sample is subjected to confining pressure simulation, a steel cover plate 3 is covered on the open end of the steel trough for placing the sample, and the air compressor passes gas into the steel trough for placing the sample through a hose to simulate the confining pressure of the sample. Here, the setting of the air compressor mainly realizes the simulation of the radial confining pressure of the sample, and the setting of the barometer can accurately know the internal situation of the air compressor when simulating the confining pressure of the steel trough for placing the sample. In order to ensure the air tightness of the barometer, when the barometer is installed on the air pressure threaded pipe mouth, raw tape is used to fill the gap to ensure the air tightness of the steel trough for placing the sample; this is also not involved in the test device in the prior art. Of course, the so-called radial confining pressure simulation also needs to meet certain restrictions to obtain the most accurate simulation results.

[0050] The sample axial pressure fixing device provided in this application is as follows Figure 5As shown, the sample axial pressure fixing device includes a load-bearing disc 11 and a fixed disc 12, which are arranged in parallel and fixed by a connecting column, and the sample is placed between the load-bearing disc and the fixed disc; a spring 15 is installed on the surface of the load-bearing disc, and the force direction of the spring is perpendicular to the load-bearing disc. The bottom end of the spring is fixed on the surface of the load-bearing disc, and a force-applying device is installed on the top of the spring. The force-applying device applies force to the spring, and the spring is compressed to apply axial force to the sample, so that the axial confining pressure can be simulated; here, the length of the spring is adjusted by the knob device 16 to control the application of axial pressure.

[0051] Here is a preferred embodiment of the force applying device, such as Figure 5 Combination Figure 6 As shown, the force-applying device includes a force-applying plate pressed on the top of the spring, and a plurality of knob devices are vertically arranged between the force-applying plate and the force-bearing disc. One end of the knob device is fixed on the force-applying plate, and the other end of the knob device is connected to the force-bearing disc through a force-bearing bolt. The knob device moves in a direction perpendicular to the force-bearing disc by rotating the force-bearing bolt.

[0052] Since the specimen needs to be stable when pressure is applied to it, a bearing groove 17 is provided on the bottom surface of the bearing disc in contact with the specimen, and a fixing groove 18 is provided on the surface of the fixing disc in contact with the specimen. The two ends of the specimen are matched and embedded in the bearing groove and the fixing groove. Similarly, the entire test axial pressure device also needs to be stable when placed in the specimen placement steel groove. Figure 5 As shown, the fixed disc is provided with a plurality of axial pressure bolt holes 9. When the sample axial pressure fixture is placed in the chamber, axial pressure bolts are inserted into the axial pressure bolt holes to fix the sample axial pressure fixture to the bottom surface of the chamber. In order to prevent the sample from being crushed by the axial force during simulation, a load-bearing movable pad 19 matching the sample is embedded in the load-bearing groove. In order to maintain the accuracy of the test, the size of the load-bearing movable pad needs to be smaller than the size of the top surface of the sample during actual operation.

[0053] When conducting simulation tests in this application, it is necessary to ensure the sealing of the steel trough where the sample is placed. This application adopts a double sealing structure to meet the long-term and stability of the simulation test. Figure 1 As shown, the open end of the sample placement steel trough extends outward to form an edge, and through-going clamping bolt holes 10 are respectively opened on the steel cover plate and the edge of the sample placement steel trough, and clamping bolts are inserted into the clamping bolt holes to connect the steel cover plate and the sample placement steel trough; a U-shaped rubber ring 2 is also provided on the edge of the sample placement steel trough, and the clamping bolts are tightened to seal when the steel cover plate is covered on the open end of the sample placement steel trough. The above is the first layer of sealing, and then, when the steel cover plate is covered on the open end of the sample placement steel trough, a secondary sealing and fixing is performed by a plurality of fixing brackets 5; specifically, the fixing bracket includes a bracket pressure column 22, a fixing bracket handle 21 and a pressure pad 20, Figure 7As shown, the fixed bracket handle is set in a C shape, a thread groove is set at one end of the fixed bracket handle, and the internal thread is inserted into the connecting bracket pressure column, and the other end of the fixed bracket handle is installed with a pressure pad. When the steel cover plate is covered on the open end of the sample placement steel groove, the pressure pad is against the edge of the sample placement steel groove, and the bottom end of the bracket pressure column is against the steel cover plate; the top end of the bracket pressure column is L-shaped, and the bottom end of the bracket pressure column is close to the pressure pad; in a preferred embodiment, the bracket pressure column is rotated clockwise (here from Figure 7 It can be seen that the top of the bracket pressure column has an extension part for easy rotation) to move the bracket pressure column downward toward the pressure pad to adjust the distance between the bottom end of the bracket pressure column and the pressure pad.

[0054] Figure 1-Figure 2 It can be seen that portable handles 8 are respectively arranged on two symmetrical chamber walls of the sample placement steel trough, and the position of the test device can be adjusted by lifting and carrying.

[0055] Finally, the present application also provides a method for using the device for applying long-term stable confining pressure to a jointed rock model specimen, which specifically comprises the following steps:

[0056] Step S1: Calculate the axial confining pressure and radial confining pressure that the sample should withstand during the simulation test based on the similarity ratio of the material with similar rock mechanical parameters and strength as the sample and the real axial confining pressure and real radial confining pressure at the rock mass where the sample is located;

[0057] Define the material similarity ratio as C R , define the true axial confining pressure as σ L , define the true radial confining pressure as σ R , C R =R p / R m , where R p Represents the rock mechanics parameter strength of the real jointed rock mass material, R m The strength of geotechnical parameters representing similar material specimens;

[0058] The calculation shows that the axial confining pressure that the specimen should bear during the simulation test is σ l =σ L / C R , the radial confining pressure that the specimen should withstand during the simulation test is σ r =σ R / C R ;

[0059] Step S2: Level the test site, and use the portable handle to lift the steel trough where the sample is placed to an open space or a workbench that is convenient for operation;

[0060] Step S3: Install a barometer in a preset air pressure threaded pipe opening, and screw the barometer to a position directly facing the operator's line of sight;

[0061] Step S4: a thin rubber pad is placed on the bottom of the sample and then placed on the surface of the fixed disc of the sample axial pressure fixing device, and the fixed disc is connected to the sample placement steel groove by inserting the axial pressure bolts into the axial pressure bolt holes;

[0062] Step S5: a thin rubber pad is also arranged on the top of the sample, a load-bearing disc is placed on the top of the sample, the load-bearing bolt is rotated, the knob device moves in a direction perpendicular to the load-bearing disc, and the force plate compresses the spring in the direction of the load-bearing disc. When the length of the knob device extending from the load-bearing disc reaches a preset value, the axial confining pressure applied by the spring to the top of the sample is close to the calculated axial confining pressure that should be borne during the simulation test;

[0063] Here, the length of the knob device extending out of the load-bearing disc directly affects the magnitude of the spring force, so the calculation formula for the length of the knob device extending out of the load-bearing disc is l = σ l πr 2 / k, where l is the extension length of the lower part of the knob device, r is the radius of the top surface of the specimen, k is the elastic coefficient of the selected spring, σ l is the axial confining pressure that the specimen should withstand during the simulation test;

[0064] Step S6: Place the U-shaped rubber ring at the open end of the sample placement steel trough, cover it with a steel cover plate, insert a clamping bolt into the clamping bolt hole, and connect the steel cover plate to the sample placement steel trough; at the same time, install fixed brackets at the four corners of the steel cover plate, rotate the bracket pressure column, and ensure that there is no gap between the edge of the sample placement steel trough, the U-shaped rubber ring, and the steel cover plate;

[0065] Step S7: Connect the air compressor through the air inlet threaded pipe provided on the air inlet, adjust the air compressor speed and observe the barometer until the air pressure displayed by the barometer reaches the calculated radial confining pressure that should be borne during the simulation test, and observe the changes of the sample.

[0066] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0067] The meaning of "and / or" described in this application means that the situations where each exists alone or both exist at the same time are included.

[0068] The term “connection” as used in this application may mean a direct connection between components or an indirect connection between components via other components.

[0069] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A device for applying long-term stable confining pressure to a jointed rock model specimen, characterized in that: It includes a steel trough for placing a specimen, which has a hollow chamber inside and a plurality of specimen axial pressure fixing devices arranged in the chamber; An air inlet is opened on the wall of the chamber where the sample is placed in the steel tank, and an air inlet threaded pipe port is provided on the air inlet for connecting with the air compressor; A pressure threaded pipe port is also installed on the chamber wall of the steel tank where the sample is placed, for installing a barometer, and the sensing end of the barometer is embedded in the chamber; The sample axial pressure fixing device is used to simulate the axial pressure of the sample. When the sample is subjected to confining pressure simulation, a steel cover plate is placed on the open end of the steel trough where the sample is placed, and an air compressor introduces gas into the steel trough where the sample is placed to simulate the confining pressure of the sample. The sample axial pressure fixing device comprises a load-bearing disc and a fixed disc, which are arranged in parallel and fixed by a connecting column, and the sample is placed between the load-bearing disc and the fixed disc; A spring is installed on the surface of the load-bearing disk, the force direction of the spring is perpendicular to the load-bearing disk, the bottom end of the spring is fixed on the surface of the load-bearing disk, and a force-applying device is installed on the top end of the spring; The force-applying device comprises a force-applying plate pressed on the top of the spring, and a plurality of knob devices are arranged vertically between the force-applying plate and the force-bearing disc, one end of the knob device is fixed on the force-applying plate, and the other end of the knob device is connected to the force-bearing disc through a force-bearing bolt, and the knob device is moved in a direction perpendicular to the force-bearing disc by rotating the force-bearing bolt; The open end of the sample placement steel trough extends outward to form an edge, and through clamping bolt holes are respectively opened on the steel cover plate and the edge of the sample placement steel trough, and clamping bolts are inserted into the clamping bolt holes to connect the steel cover plate and the sample placement steel trough; A U-shaped rubber ring is also provided on the edge of the steel trough for placing the specimen, and when the steel cover plate is covered on the open end of the steel trough for placing the specimen, the clamping bolts are tightened to seal it.

2. The device for applying long-term stable confining pressure to a jointed rock model specimen according to claim 1, characterized in that: A load-bearing groove is arranged on the bottom surface of the load-bearing disc in contact with the sample, and a fixing groove is arranged on the surface of the fixing disc in contact with the sample. Both ends of the sample are matched and embedded in the load-bearing groove and the fixing groove.

3. The device for applying long-term stable confining pressure to a jointed rock mass model specimen according to claim 2, characterized in that: A load-bearing movable pad matching the specimen is embedded in the load-bearing groove; Portable handles are respectively arranged on two symmetrical chamber walls of the sample placement steel trough.

4. The device for applying long-term stable confining pressure to a jointed rock mass model specimen according to claim 1, characterized in that: A plurality of axial pressure bolt holes are arranged on the fixing disc. When the sample axial pressure fixing device is placed in the chamber, axial pressure bolts are inserted into the axial pressure bolt holes to fix the sample axial pressure fixing device on the bottom surface of the chamber.

5. The device for applying long-term stable confining pressure to a jointed rock mass model specimen according to claim 1, characterized in that: When the steel cover is covered on the open end of the steel trough where the specimen is placed, it is fixed with secondary sealing by a number of fixing brackets; The fixed bracket includes a bracket pressure column, a fixed bracket handle and a pressure pad. The fixed bracket handle is C-shaped, a threaded groove is provided at one end of the fixed bracket handle, and the internal thread is inserted to connect the bracket pressure column. The other end of the fixed bracket handle is equipped with a pressure pad. When the steel cover plate is covered on the open end of the sample placement steel groove, the pressure pad is against the edge of the sample placement steel groove, and the bottom end of the bracket pressure column is against the steel cover plate; the top end of the bracket pressure column is L-shaped, and the bottom end of the bracket pressure column is close to the pressure pad; The distance between the bottom end of the support pressure column and the pressure pad can be adjusted by rotating the support pressure column.

6. A method for using the device for applying long-term stable confining pressure to a jointed rock model specimen according to any one of claims 1 to 5, characterized in that: The specific steps include: Step S1: Calculate the axial confining pressure and radial confining pressure that the sample should withstand during the simulation test based on the similarity ratio of the material with similar rock mechanical parameter strength as the sample and the real axial confining pressure and real radial confining pressure at the rock mass where the sample is located; Step S2: Level the test site, and use the portable handle to lift the steel trough where the sample is placed to an open space or a workbench that is convenient for operation; Step S3: Install a barometer in the preset air pressure threaded pipe opening, and screw the barometer to a position directly facing the operator's line of sight, so that the operator can observe the readings easily; Step S4: a thin rubber pad is placed on the bottom of the sample and then placed on the surface of the fixed disc of the sample axial pressure fixing device, and the fixed disc is connected to the sample placement steel groove by inserting the axial pressure bolts into the axial pressure bolt holes; Step S5: a thin rubber pad is also arranged on the top of the sample, a load-bearing disc is placed on the top of the sample, the load-bearing bolt is rotated, the knob device moves in a direction perpendicular to the load-bearing disc, and the force plate compresses the spring in the direction of the load-bearing disc. When the length of the knob device extending from the load-bearing disc reaches a preset value, the axial confining pressure applied by the spring to the top of the sample is close to the calculated axial confining pressure that should be borne during the simulation test; Step S6: Place the U-shaped rubber ring at the open end of the sample placement steel trough, cover it with a steel cover plate, insert a clamping bolt into the clamping bolt hole, and connect the steel cover plate to the sample placement steel trough; at the same time, install fixed brackets at the four corners of the steel cover plate, rotate the bracket pressure column, and ensure that there is no gap between the edge of the sample placement steel trough, the U-shaped rubber ring, and the steel cover plate; Step S7: Connect the air compressor through the air inlet threaded pipe provided on the air inlet, adjust the air compressor speed and observe the barometer until the air pressure displayed by the barometer reaches the calculated radial confining pressure that should be borne during the simulation test, and observe the changes of the sample.

7. The method for using the device for applying long-term stable confining pressure to a jointed rock model specimen according to claim 6, characterized in that: In step S1, the material similarity ratio is defined as , the true axial confining pressure is defined as , the true radial confining pressure is defined as , ,in, Represents the rock mechanics parameter strength of the real jointed rock mass material, The strength of geotechnical parameters representing similar material specimens; The calculation shows that the axial confining pressure that the specimen should withstand during the simulation test is The radial confining pressure that the specimen should withstand during the simulation test is ; In step S5, the formula for calculating the length of the knob device extending out of the load-bearing disc is: ,in, is the extension length of the lower part of the knob device, is the radius of the top surface of the specimen, is the elastic constant of the selected spring, It is the axial confining pressure that the specimen should withstand during the simulation test.

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