In-situ environmental device for simulating rock brazilian split and testing method thereof

Abstract

The application discloses an in-situ environment device for simulating rock Brazilian splitting and a testing method thereof, and belongs to the field of rock mechanics testing. The device comprises an in-situ loading device and a testing clamp. A motor, a two-stage worm gear transmission unit, a pressure sensor and a tension rod are arranged in the loading device shell, so that 5KN-precision loading can be realized and can be expanded. The clamp comprises a support cylinder base, a middle support cylinder, a light-transmitting cylinder window made of X-ray penetrating material, a splitting upper cover, an upper and lower clamp and adjusting bolts. The upper clamp is fixed to the splitting upper cover through the adjusting bolts, and the lower clamp is rigidly connected with the tension rod. During testing, the splitting load is applied from bottom to top, and a CT device penetrates the light-transmitting cylinder window to realize real-time scanning, so that the step loading and three-dimensional reconstruction are realized in cooperation with closed-loop control. The application solves the problems of separation of traditional equipment loading and observation, poor precision and easy deviation of load, and realizes in-situ, visual and fine testing of the rock splitting process.

Description

Technical Field

[0001] This invention relates to the field of rock mechanical property testing technology, and more specifically, to an in-situ environment device and testing method for simulating the Brazilian splitting test of rocks. Background Technology

[0002] In rock engineering fields such as underground engineering, mining, and geothermal development, rock splitting and tensile failure is one of the main causes of surrounding rock instability and engineering collapse. Therefore, accurately exploring the damage evolution law of rocks under splitting conditions is of fundamental significance for rock mass stability research and engineering disaster prevention and control. The Brazilian splitting method, as a standard rock tensile property testing method certified by the International Society for Rock Mechanics (ISRM), has been widely used in engineering practice due to its simple sample preparation and clear testing principle.

[0003] However, traditional Brazilian rock splitting test equipment and methods have the following significant technical drawbacks:

[0004] (1) Traditional splitting equipment lacks special matching tooling fixtures, making it difficult to build a standardized in-situ Brazilian splitting test scenario. It is impossible to achieve uniform and centered accurate force transfer to cylindrical rock samples through the upper and lower symmetrical structure, which easily leads to problems such as uneven load on the sample and uneven stress distribution, resulting in large test data errors and poor repeatability.

[0005] (2) Traditional equipment is mostly offline destructive testing. The loading process is separated from the internal structure observation process. It can only obtain macroscopic damage parameters and cannot capture the evolution characteristics of microscopic cracks inside the rock during the entire loading process.

[0006] (3) Conventional equipment has limited loading accuracy and a narrow load adaptability range. It is difficult to stably achieve precise gradient loading of small tonnage (such as 5KN level) and cannot adapt to the splitting test requirements of a larger load range. The load adjustment accuracy and working condition adaptability are poor.

[0007] (4) Traditional equipment cannot be synchronously coupled with CT scanning equipment, and cannot obtain the internal structure, microcrack initiation and propagation evolution characteristics of rock samples under different pressure conditions in real time under continuous stress loading. It cannot complete the three-dimensional reconstruction of the internal damage structure and is difficult to accurately reveal the micromechanical mechanism of rock splitting failure.

[0008] To address the aforementioned technical deficiencies, there is an urgent need to develop an in-situ Brazilian splitting test device and method that can achieve precise force loading, uniform force alignment, and compatibility with CT scanning equipment. Summary of the Invention

[0009] This invention aims to solve the technical problems existing in the current Brazilian rock splitting test technology, such as separation of loading and observation, poor controllability of loading accuracy, easy force imbalance, and inability to be used in real time with CT scanning equipment. It provides a rock splitting test device and method that can achieve accurate, uniform, in-situ, and visualized testing.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0011] An in-situ environmental apparatus for simulating Brazilian splitting of rock includes an in-situ loading device and a test fixture.

[0012] The in-situ loading device includes a housing, a power unit, a transmission unit, a pressure sensor, and a tension rod installed within the housing. The power unit drives the transmission unit, which is connected to the pressure sensor. The pressure sensor is connected to the tension rod to output a controllable linear loading force. The upper end of the tension rod extends from the top of the housing and is used to connect to a clamp and transmit the loading force.

[0013] The test fixture includes a support cylinder base, a middle support cylinder, a light-transmitting window, a splitting top cover, an upper clamp, a lower clamp, and a positioning element. The support cylinder base is fixed to the upper end of the housing. The middle support cylinder is fixed to the support cylinder base. The light-transmitting window is connected above the middle support cylinder, and its side wall has a sample placement opening for placing and removing rock samples. The splitting top cover is located at the top of the light-transmitting window. The upper clamp is connected to the lower part of the splitting top cover via the positioning element. The lower clamp is rigidly connected to the upper end of the tension rod and is directly driven by the tension rod. The rock sample is placed inside the light-transmitting window and positioned between the upper clamp and the lower clamp. During operation, the tension rod can drive the lower clamp to apply a splitting load to the rock sample from bottom to top.

[0014] As a preferred technical solution, the transmission unit includes a first worm, a first worm wheel, a transmission shaft, a second worm, a second worm wheel, a lifting screw, a guide rod, and a crossbeam. The power unit is a motor. The output end of the motor is connected to the first worm. The transmission shaft is horizontally rotatably connected to the housing via bearings. The first worm wheel is mounted on the transmission shaft, and the first worm meshes with the first worm wheel. A second worm is also mounted on the transmission shaft. The lifting screw is vertically rotatably connected to the housing via bearings. The lower end of the lifting screw is fixedly connected to the second worm wheel, and the second worm meshes with the second worm wheel. The guide rod is vertically fixed inside the housing and parallel to the lifting screw. One end of the crossbeam is threadedly connected to the lifting screw, and the other end is slidably connected to the guide rod. The pressure sensor is connected to the middle of the top surface of the crossbeam. Through the above two-stage worm gear transmission, a large reduction ratio and large torque output can be achieved, and the self-locking characteristics of the worm gear can be used to ensure stable loading.

[0015] Furthermore, the transmission unit also includes two baffles and two limit switches; the two baffles are fixed to the upper and lower sides of one end of the crossbeam, and the two limit switches are respectively fixed to the top and bottom walls inside the housing, with each baffle and corresponding limit switch arranged vertically opposite each other. When the crossbeam moves to its limit position, the baffle triggers the limit switch, thereby cutting off the power or triggering reverse control, thus providing mechanical limit protection.

[0016] As a preferred technical solution, the positioning component is an adjusting bolt, the lower end of which passes through the split upper cover and is threadedly connected to the upper clamp. By turning the adjusting bolt, the height and level of the upper clamp can be finely adjusted to ensure that it is parallel and aligned with the lower clamp.

[0017] As a preferred technical solution, the light-transmitting window is made of an X-ray-transmitting material, such as carbon fiber composite material or polyetheretherketone (PEEK). These materials have the characteristics of high strength, low density, and high X-ray transmittance, which can minimize the impact on the quality of CT scan imaging.

[0018] As a preferred technical solution, the in-situ loading device further includes a controller. The signal output terminal of the pressure sensor is connected to the controller, and the control terminal of the controller is connected to the power unit. The controller, based on the real-time feedback signal from the pressure sensor, performs closed-loop control of the power unit's output to achieve precise loading of a preset force value.

[0019] Furthermore, the present invention also provides an in-situ testing method for Brazilian splitting of rocks based on the above-mentioned device, comprising the following steps:

[0020] S1. Installation steps: Place the rock sample through the sample placement opening of the light-transmitting tube window and place it on the lower clamp.

[0021] S2. Calibration Steps: Using an external tool (such as a long-handled parallel clamp), insert it through the sample placement opening and clamp the upper and lower clamps together. Once the upper and lower clamps are observed to be parallel, tighten the adjusting bolt to fix the upper clamp, ensuring that the lower surface of the upper clamp is parallel and centered with the upper surface of the rock sample. Then, remove the tool. This calibration method is simple and intuitive, and effectively ensures the alignment of the load.

[0022] S3. Loading and Synchronous Scanning Steps: Start the in-situ loading device, and the tension rod drives the lower clamp to apply a splitting load to the rock sample from bottom to top; at the same time, start the CT scanning equipment, so that X-rays penetrate the light-transmitting tube window to scan the rock sample under continuous loading in real time and obtain its internal structure image.

[0023] Furthermore, the loading and synchronous scanning steps also include a closed-loop control step: the pressure sensor collects load data in real time and feeds it back to the controller; the controller compares the load data with the preset target load value, and adjusts the output of the power unit in real time according to the comparison result, so as to perform closed-loop precise control of the loading force and realize graded loading or constant pressure loading.

[0024] Furthermore, the graded loading includes multiple load levels. Under each load level, the loading force is kept constant and maintained for a preset time (such as 30 seconds, 60 seconds, or 180 seconds) so that the CT scanning equipment can complete the high-quality image acquisition under that load level.

[0025] Furthermore, after the loading and synchronous scanning steps, the test method also includes a three-dimensional reconstruction step: based on the images of the internal structure of the rock sample obtained by the CT scanning equipment at different loading stages, the three-dimensional reconstruction software is used to perform image processing and analysis to generate a three-dimensional visualization model of the initiation, propagation and penetration of internal microcracks in the rock sample during the splitting process.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) This invention adopts a transmission structure of a motor-driven two-stage worm gear and lifting screw. Utilizing the large reduction ratio and self-locking characteristics of the worm gear, it can output large torque and achieve smooth, self-locking power transmission. Combined with real-time load feedback and closed-loop control from a high-precision pressure sensor, it can achieve precise control of the loading force. It can stably complete fine gradient loading of small loads and can also be extended to adapt to larger load conditions, effectively solving the problems of poor loading accuracy and insufficient stability of traditional equipment.

[0028] (2) This invention adopts a symmetrical splitting structure of "fixed upper clamp and dynamic loading lower clamp", and the upper clamp is horizontally fixed by adjusting bolts, so that the upper and lower clamps and the sample are aligned. In particular, in the calibration step, the method of using external tools to clamp the upper and lower clamps simultaneously for parallel calibration is simple to operate and has high calibration accuracy. It ensures perfect alignment and parallel contact between the upper and lower clamps and the cylindrical rock sample, so that the sample is subjected to uniform force during loading, effectively avoiding the problems of off-center loading and stress concentration.

[0029] (3) The fixture is equipped with a light-transmitting tube window made of X-ray penetrating material (such as carbon fiber and PEEK) to ensure the smooth penetration of X-rays and realize the synchronous coupling of the splitting loading process and CT non-destructive scanning. This enables researchers to capture the entire process of initiation, propagation and penetration of microcracks inside the rock at different loading stages in real time under continuous stress on the sample, and to complete the three-dimensional reconstruction of internal damage, thus realizing the "visualized" characterization of the rock splitting damage mechanism.

[0030] (4) The baffle and limit switch installed in the transmission unit constitute a mechanical limit protection system. When the crossbeam moves beyond the allowable range, the baffle triggers the limit switch, which can cut off the power in time, effectively preventing the equipment from being damaged due to overtravel and improving the safety and reliability of the equipment.

[0031] (5) The device has a high degree of integration, the fixture and the main body of the in-situ loading device are firmly assembled, and the structure is compact. The unique calibration tool usage method simplifies the calibration process, eliminates the need for repeated sample disassembly and assembly, and improves testing efficiency and reliability. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the present invention;

[0033] Figure 2 This is a schematic diagram of the in-situ loading device;

[0034] Figure 3 for Figure 2 A diagram showing the other direction;

[0035] Figure 4 This is a cross-sectional view of the present invention;

[0036] Figure 5 A flowchart of the test method;

[0037] In the figure: 1-In-situ loading device, 101-House, 102-Pressure sensor, 103-Tension rod, 104-First worm gear, 105-First worm wheel, 106-Drive shaft, 107-Second worm gear, 108-Second worm wheel, 109-Lifting screw, 110-Guide rod, 111-Crossbeam, 112-Motor, 113-Baffle, 114-Limit switch, 2-Test fixture, 201-Support cylinder base, 202-Intermediate support cylinder, 203-Light-transmitting cylinder window, 204-Split top cover, 205-Upper fixture, 206-Lower fixture, 207-Adjusting bolt, 3-Rock sample. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] Please see Figures 1 to 4As shown, this embodiment provides an in-situ environment device for simulating Brazilian splitting of rock. This device is specifically designed to work in conjunction with X-ray non-destructive testing equipment such as industrial CT scanners.

[0041] The device mainly consists of two modules: in-situ loading device 1 and test fixture 2.

[0042] The in-situ loading device 1 is the power and control core of the entire system. It includes a robust housing 101, inside which a motor 112, a transmission unit, a pressure sensor 102, and a tension rod 103 are installed.

[0043] The transmission unit adopts a two-stage worm gear reduction structure. Specifically, it includes a first worm 104, a first worm wheel 105, a transmission shaft 106, a second worm 107, a second worm wheel 108, a lifting screw 109, a guide rod 110, and a crossbeam 111.

[0044] The output shaft of motor 112 (preferably a servo motor) is coaxially connected to the first worm gear 104 via a coupling. Drive shaft 106 is horizontally rotatably mounted within housing 101 via bearings, and a first worm wheel 105 and a second worm gear 107 are fixedly mounted on it. The first worm gear 104 meshes with the first worm wheel 105, forming a first-stage reduction. The second worm gear 107 on drive shaft 106 meshes with a second worm wheel 108 mounted at the lower end of lifting screw 109, forming a second-stage reduction.

[0045] The lifting screw 109 is vertically rotatably mounted inside the housing 101 via bearings. The guide rod 110 is also vertically fixed inside the housing 101, parallel to the lifting screw 109. One end of the crossbeam 111 has an internal threaded hole for threaded connection with the lifting screw 109; the other end of the crossbeam 111 has a sliding sleeve for sliding engagement with the guide rod 110, serving as a guide and preventing rotation.

[0046] The pressure sensor 102 is fixedly installed at the center of the top surface of the crossbeam 111. The lower end of the tension rod 103 is connected to the sensing surface of the pressure sensor 102, and the upper end of the tension rod 103 extends through the guide hole at the top of the housing 101.

[0047] The core functional requirements of this device are that the sensor can accurately measure a 5KN loading force and achieve closed-loop control, be compact in size for easy integration into the in-situ loading device housing 101, have bidirectional tensile and compressive load-bearing capacity, and be suitable for CT scanning environments with non-magnetic compatibility. Considering these requirements, this embodiment preferably uses an S-type bidirectional tensile and compressive resistance strain gauge force sensor.

[0048] In addition, the transmission unit is equipped with a mechanical limit protection mechanism. A baffle 113 is fixed to the upper and lower surfaces of the sliding end of the crossbeam 111 (i.e., the end connected to the guide rod 110). A limit switch 114 is fixed to the top and bottom walls inside the housing 101, corresponding to the baffle 113. The two baffles 113 and the two limit switches 114 are located on the same vertical line. When the crossbeam 111 moves upward to its upper limit position, the upper baffle 113 will touch the upper limit switch 114; when the crossbeam 111 moves downward to its lower limit position, the lower baffle 113 will touch the lower limit switch 114. Once the limit switch 114 is triggered, it sends a signal to the controller, which then cuts off the power to the motor 112 or issues a reverse movement command, thereby achieving limit protection.

[0049] The test fixture 2 includes, from bottom to top: a support cylinder base 201, an intermediate support cylinder 202, a light-transmitting cylinder window 203, and a split top cover 204.

[0050] The support cylinder base 201 is fixed to the top of the housing 101 by bolts and flanges. The lower end of the intermediate support cylinder 202 is fixedly connected to the support cylinder base 201, and its upper end is fixedly connected to the lower end of the light-transmitting cylinder window 203.

[0051] The light-transmitting window 203 is a cylindrical structure with two placement openings larger than the rock sample in the center of its side wall. These openings are positioned opposite each other for easy access to the rock sample 3. To allow X-rays to penetrate with almost no attenuation, the light-transmitting window 203 is integrally made of carbon fiber composite material or polyetheretherketone (PEEK) material, ensuring both strength and excellent X-ray transmission performance. The intermediate support cylinder 202 and the support cylinder base 201 can be made of metal materials (such as aluminum alloy) to ensure structural support strength.

[0052] The split cover 204 is a cover with a central through hole, which is detachably installed on top of the light-transmitting cylindrical window 203 via threads. An adjusting bolt 207 is installed inside the central through hole of the split cover 204, and the lower end of the adjusting bolt is connected to an upper clamp 205. Tightening the adjusting bolt 207 connects it to the upper clamp 205, thereby securing the upper clamp 205.

[0053] The upper end of the tension rod 103 passes through the central hole of the support cylinder base 201 and the intermediate support cylinder 202, extends into the interior of the light-transmitting window 203, and is rigidly connected to a lower clamp 206. The lower end face of the lower clamp 206 is fixed to the tension rod 103, and its upper end face is machined with an arc-shaped contact surface that matches the radius of curvature of the rock sample 3. Correspondingly, the lower surface of the upper clamp 205 is also machined with the same arc-shaped contact surface to ensure the line contact loading method with the cylindrical rock sample 3, which conforms to the mechanical standards of the Brazilian splitting test.

[0054] The rock sample 3 is placed inside the light-transmitting window 203 and positioned between the upper clamp 205 and the lower clamp 206. During operation, the tension rod 103 can drive the lower clamp 206 to apply a splitting load to the rock sample 3 from bottom to top.

[0055] The device also includes a controller (not shown in the figure). The signal output terminal of the pressure sensor 102 is connected to the controller, and the control terminal of the controller is connected to the motor 112. The controller can be a PLC, a microcontroller, or an industrial computer, and it stores preset loading programs (such as constant speed loading, constant force holding, and graded loading). The controller receives the real-time load signal from the pressure sensor 102 and, through control algorithms such as PID, adjusts the speed and direction of the motor 112 in real time to achieve closed-loop precise control of the output load.

[0056] Example 2

[0057] This embodiment provides a method for in-situ testing of Brazilian splitting of rocks using the above-described device, including the following steps:

[0058] Step S1: Sample installation.

[0059] Select a standard cylindrical rock sample 3 (e.g., 50 mm in diameter and 50 mm in height). Open the door of the CT scanning room and place the entire device on the CT scanner turntable. Ensure that the tension rod 103 is reliably connected to the lower clamp 206. Then, through the placement opening on the side of the light-transmitting window 203, place the rock sample 3 horizontally, ensuring it falls precisely onto the arc-shaped contact surface of the lower clamp 206.

[0060] Step S2: Centering and Calibration.

[0061] Install the light-transmitting cylindrical window 203 and the splitting top cover 204 assembly. The operator uses a long-handled parallel clamp (external tool) to reach into the sample placement port and clamp both the upper clamp 205 and the lower clamp 206 simultaneously, bringing them together. At this point, visually inspect to ensure that the arc-shaped contact surfaces of the upper clamp 205 and the lower clamp 206 are parallel to each other.

[0062] While keeping the clamps in a clamped state, tighten the adjusting bolt 207 to connect it to the upper clamp 205 and stabilize the upper clamp 205. Clamp the rock sample 3 using the upper clamp 205 and the lower clamp 206. Then, release the clamps and pull the sample out of the placement port. At this point, calibration is complete; the lower surface of the upper clamp 205 is now parallel and in centered contact with the upper surface of the rock sample 3.

[0063] Step S3: Load and synchronize scan.

[0064] The continuous scanning mode of the CT scanner is activated. Simultaneously, motor 112 is started via the controller. Loading is performed according to a preset loading program (e.g., a displacement rate of 0.5 mm / min or a load rate of 0.5 KN / s).

[0065] The power from motor 112 is transmitted to lifting screw 109 via first worm 104, first worm wheel 105, drive shaft 106, second worm 107, and second worm wheel 108. Lifting screw 109 rotates, driving crossbeam 111 to move upwards. Crossbeam 111 drives pressure sensor 102 and tension rod 103 to move upwards. Tension rod 103 drives lower clamp 206 to apply a splitting load to rock sample 3 from bottom to top.

[0066] Simultaneously, the X-ray beam emitted by the CT scanning equipment penetrates vertically or obliquely through the light-transmitting window 203 made of carbon fiber, performing continuous or step-by-step scanning on the rock sample 3 being loaded. Since the light-transmitting window 203 provides almost no obstruction to the X-rays, high-resolution tomographic images of the sample's interior can be obtained.

[0067] Step S4: Closed-loop precision control.

[0068] Throughout the loading process, pressure sensor 102 acquires load values ​​in real time at millisecond-level frequency and feeds them back to the controller. The controller compares the actual load with the preset target load value and uses a PID algorithm to dynamically adjust the speed and torque of motor 112, thereby achieving high-precision closed-loop force control.

[0069] For example, when a constant load of 5 kN needs to be maintained during scanning, the controller will automatically fine-tune the output of motor 112 to resist pressure fluctuations and ensure load stability. In this way, graded loading or constant pressure loading can be achieved.

[0070] Step S5: Graded loading and multi-stage imaging.

[0071] To study the crack evolution process, a graded loading strategy can be adopted. For example, the target load can be set by the controller to be 10%, 30%, 50%, 70%, and 90% of the failure load. The graded loading includes multiple load levels. Under each load level, the loading force is kept constant for a preset time (e.g., 180 seconds) to allow the CT scanning equipment to complete high-quality image acquisition under that load level and record the various stages of microcrack propagation from initiation to stable expansion and accelerated propagation.

[0072] Step S6: 3D reconstruction and data analysis.

[0073] After the experiment, a series of two-dimensional tomographic images acquired by CT scans under different loading stages were imported into three-dimensional reconstruction software (such as Avizo and VGStudio MAX). Through image processing (such as filtering, thresholding, and noise reduction), voxel information of the rock matrix, pores, and cracks was extracted, ultimately generating a three-dimensional spatial distribution and evolution model of internal cracks in rock sample 3 throughout the splitting process (i.e., a three-dimensional visualization model). Combined with the synchronously recorded load-displacement curves, the Brazilian splitting failure mechanism of the rock can be systematically and accurately revealed from both the macroscopic mechanical response and the microscopic structural evolution levels.

[0074] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0075] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An in-situ environmental device for simulating Brazilian splitting of rock, characterized in that, include: The in-situ loading device (1) includes a housing (101), a power unit, a transmission unit, a pressure sensor (102), and a tension rod (103) installed in the housing (101); the power unit drives the transmission unit, the transmission unit is connected to the pressure sensor (102), the pressure sensor (102) is connected to the tension rod (103) to output a controllable linear loading force, and the upper end of the tension rod (103) protrudes from the top of the housing (101); The test fixture (2) includes a support cylinder base (201), an intermediate support cylinder (202), a light-transmitting cylinder window (203), a split upper cover (204), an upper clamp (205), a lower clamp (206), and a positioning component; the support cylinder base (201) is fixed to the upper end of the housing (101); the intermediate support cylinder (202) is fixed to the support cylinder base (201); the light-transmitting cylinder window (203) is connected above the intermediate support cylinder (202), and its side wall has a sample placement opening; the split upper cover (204) is disposed on the top of the light-transmitting cylinder window (203); the upper clamp (205) is connected to the lower part of the split upper cover (204) through the positioning component; the lower clamp (206) is rigidly connected to the upper end of the tension rod (103); The rock sample (3) is placed inside the light-transmitting tube window (203) and located between the upper clamp (205) and the lower clamp (206); The tension rod (103) can drive the lower clamp (206) to apply a splitting load to the rock sample (3) from bottom to top.

2. The in-situ environmental device for simulating Brazilian splitting of rock according to claim 1, characterized in that, The transmission unit includes a first worm (104), a first worm wheel (105), a transmission shaft (106), a second worm (107), a second worm wheel (108), a lifting screw (109), a guide rod (110), and a crossbeam (111). The power unit is a motor (112); the output end of the motor (112) is connected to the first worm (104), the transmission shaft (106) is horizontally rotatably connected to the housing (101) through bearings, the first worm wheel (105) is mounted on the transmission shaft (106), the first worm (104) meshes with the first worm wheel (105), a second worm (107) is also mounted on the transmission shaft (106), and the lifting screw (109) is vertically rotatably connected to the housing through bearings. Inside the body (101), the lower end of the lifting screw (109) is fixedly connected to a second worm gear (108), the second worm (107) meshes with the second worm gear (108), the guide rod (110) is vertically fixed inside the housing (101) and parallel to the lifting screw (109), one end of the crossbeam (111) is threadedly connected to the lifting screw (109), and the other end is slidably connected to the guide rod (110); the pressure sensor (5) is connected to the middle of the top surface of the crossbeam (111).

3. The in-situ environmental device for simulating Brazilian splitting of rock according to claim 2, characterized in that, The transmission unit also includes two baffles (113) and two limit switches (114); the two baffles (113) are fixed to the upper and lower sides of one end of the crossbeam (111), and the two limit switches (114) are respectively fixed to the top and bottom walls inside the housing (101), and each baffle (113) and the corresponding limit switch (114) are arranged vertically opposite to each other.

4. The in-situ environmental device for simulating Brazilian splitting of rock according to claim 3, characterized in that, The positioning element is an adjusting bolt (207), the lower end of which is threadedly connected to the upper clamp (205) after passing through the split upper cover (204).

5. The in-situ environmental device for simulating Brazilian splitting of rock according to claim 4, characterized in that, The light-transmitting cylindrical window (203) is made of an X-ray penetrating material, which is either a carbon fiber composite material or a polyether ether ketone material.

6. The in-situ environmental device for simulating Brazilian splitting of rock according to claim 5, characterized in that, The in-situ loading device (1) also includes a controller. The signal output terminal of the pressure sensor (102) is connected to the controller, and the control terminal of the controller is connected to the power unit. The controller controls the output of the power unit in a closed loop according to the real-time feedback signal of the pressure sensor (102) to achieve accurate loading of the preset force value.

7. A method for in-situ testing of Brazilian splitting of rock based on the device described in claim 6, characterized in that, Includes the following steps: S1. Installation steps: Place the rock sample through the sample placement opening of the light-transmitting tube window and place it on the lower clamp. S2. Calibration steps: Using an external tool, insert it through the sample placement opening and clamp the upper and lower clamps together. After observing that the upper and lower clamps are parallel, tighten the adjusting bolt to fix the upper clamp, so that the lower surface of the upper clamp is parallel to and in centered contact with the upper surface of the rock sample, and then pull the tool out. S3. Loading and Synchronous Scanning Steps: Start the in-situ loading device, and the tension rod drives the lower clamp to apply a splitting load to the rock sample from bottom to top; at the same time, start the CT scanning equipment, so that X-rays penetrate the light-transmitting tube window to scan the rock sample under continuous loading in real time and obtain its internal structure image.

8. The in-situ testing method for Brazilian splitting of rock according to claim 7, characterized in that, The loading and synchronous scanning steps further include: The pressure sensor collects load data in real time and feeds it back to the controller; The controller compares the load data with the preset target load value and adjusts the output of the power unit in real time according to the comparison result to perform closed-loop precise control of the loading force and realize graded loading or constant pressure loading.

9. The in-situ testing method for Brazilian splitting of rock according to claim 8, characterized in that, The graded loading includes multiple load levels. Under each load level, the loading force is kept constant for a preset time so that the CT scanning equipment can complete the image acquisition under that load level.

10. The in-situ testing method for Brazilian splitting of rock according to claim 9, characterized in that, Following the loading and synchronous scanning steps, the method further includes: Three-dimensional reconstruction steps: Based on the images of the internal structure of the rock sample obtained by the CT scanning equipment at different loading stages, three-dimensional reconstruction is performed to generate a three-dimensional visualization model of the initiation, propagation and penetration of internal microcracks in the rock sample during the splitting process.

Images