Complex stress coupling rock torsion shear test system and method

Abstract

The application belongs to the technical field of rock testing, and particularly discloses a complex stress coupling rock torsional shear test system and method, which aims to simplify the device structure and enable the rock sample to be tested under the test condition of only axial force and simultaneously subjected to axial pressure and torsional shear force. The rock torsional shear test system can convert the axial pressure into torsional shear force through the transmission mechanism of the power conversion assembly on one hand, and can apply axial pressure to the rock sample fixed between the two sample fixing heads through the pressure shaft of the axial pressure mechanism on the other hand. Therefore, the rock sample can be tested under the test condition of only axial force and simultaneously subjected to axial pressure and torsional shear force, without the need to set a special power mechanism to provide torsional shear force. Compared with the existing rock torsional shear test device structure, the rock torsional shear test system is simpler in structure, lower in manufacturing cost, and beneficial to reducing the laboratory space occupied.

Description

Technical Field

[0001] This invention belongs to the field of rock testing technology, specifically relating to a complex stress-coupled rock torsion-shear test system and method. Background Technology

[0002] In underground rock mass engineering construction, rock masses are often subjected to multiple complex stresses. For example, rock masses may experience shear stress while under axial compression. Therefore, knowing the shear strength parameters of rock under axial compression is one of the guarantees for the safety and reliability of rock mass engineering construction. Currently, the main methods for testing the shear strength parameters of rock in relevant testing specifications are as follows: direct shear test, variable angle plate shear test, and triaxial compression test. Each method has its own advantages and disadvantages. For the direct shear test, not only is a specific bidirectional loading testing machine with shear-specific capabilities required, but the direction of the shear load is also determined, resulting in failure only along the predetermined load direction, and the result may not be failure along the direction of minimum shear stress. For the variable angle plate shear test, although all material compression testing machines can be used, it not only has the same problems as the direct shear test, but also requires correction for the friction coefficient of the variable angle plate. For the triaxial compression test, not only is a dedicated triaxial compression testing machine required, but the stress state of the rock and the testing and analysis process are also complex. Although all of the above different types of shear tests can ultimately obtain the shear strength parameters when the rock fails, the rock is subjected to a complex stress state during the test, and the pure shear stress on the rock cannot be obtained.

[0003] In fact, pure shear stress is of great value for studying rock mass engineering failure. Laboratories in engineering construction or scientific research units typically possess Material Testing Systems (MTS) capable of providing axial pressure, such as material compression testing machines. To address the issue of whether all material compression testing machines can perform pure shear tests on rocks, Chinese invention patent application CN104297027A provides a rock specimen and a method for pure shear testing; however, this method cannot achieve the required shear angle under pure shear.

[0004] For rock pure shear testing, existing rock torsion shear testing devices are all specially designed and manufactured to provide torsion shear force. However, existing rock torsion shear testing devices for pure shear testing have at least one of the following drawbacks: (1) They can only perform pure shear, and the testing function is too simple; (2) The shaft for applying torque during torsion shear is fixed, which causes the lever arm to change and cannot apply linear torsion load; (3) They need to be specially designed and manufactured, which not only requires a lot of money, but also requires a lot of laboratory space; (4) They cannot be tested directly on existing testing machines; (5) If complex coupling conditions are considered, supporting peripheral facilities are required, such as triaxial loading, seepage, heating and other coupling conditions; (6) It is inconvenient to use strain method or acoustic emission positioning and other techniques to test the state of torsion shear change; (7) The axial load cannot be constant or change in a controllable manner.

[0005] For example, Chinese invention patent application CN108152147A discloses a rock sample torsional fracture test device, which includes a main frame. A main hydraulic cylinder assembly and a double-rod hydraulic cylinder assembly are respectively mounted on the upper and lower crossbeams of the main frame for applying pressure to the rock sample. A load sensor is installed at the end of the main piston rod of the main hydraulic cylinder assembly that passes through the upper crossbeam. An anti-rotation mechanism is provided on the lower surface of the upper crossbeam directly opposite the main piston rod to limit the rotation of the load sensor and the main piston rod. The anti-rotation mechanism is provided with a sample pressure block having a groove that mates with the rock sample. The auxiliary piston rod of the double-rod hydraulic cylinder assembly... One end of the piston rod passes through the lower crossbeam and a sample pressing block is installed on it. The sample pressing block has a groove that matches the groove on the sample pressing block for clamping the rock sample. The other end of the auxiliary piston rod passes through the auxiliary cylinder and a bearing is installed on it. A power output mechanism for applying torque to the rock sample is set on one side of the lower crossbeam. The power output mechanism is connected to the connecting shaft through a transmission mechanism. A torque sensor is installed on the connecting shaft. The other end of the torque sensor is fixedly connected to the end of the auxiliary piston rod with the bearing. The torque sensor, load sensor, main hydraulic cylinder group, double-rod hydraulic cylinder group and power output mechanism are all connected to the control module.

[0006] Although the aforementioned rock sample torsional fracture test apparatus, by setting up a main hydraulic cylinder group and a double-rod hydraulic cylinder group, can be used to apply axial pressure to the rock sample, and by setting up a power output mechanism and then connecting the power output mechanism to the connecting shaft, it can be used to apply torque to the rock sample, realizing the study of deformation and failure of rocks under the simultaneous action of axial pressure and torsional shear force, this undoubtedly increases the complexity and size of the apparatus. Moreover, it cannot convert axial pressure into torsional shear force, so it cannot be used in conjunction with equipment that can provide axial pressure. It is necessary to design and manufacture a separate main hydraulic cylinder group and a double-rod hydraulic cylinder group to provide axial pressure, as well as a power output mechanism to provide torsional shear force, which also increases the equipment cost and occupies more laboratory space. Summary of the Invention

[0007] This invention provides a complex stress-coupled rock torsion-shear testing system, which aims to simplify the device structure and enable it to test rock samples under test conditions with only axial force, simultaneously subjected to axial pressure and torsion-shear force.

[0008] The technical solution adopted by the present invention to solve its technical problem is: a complex stress-coupled rock torsion-shear test system, including a main body of the device and a sample fixing mechanism;

[0009] The main body of the device is provided with a working cavity;

[0010] The sample fixing mechanism includes two sample fixing heads arranged opposite each other in the working chamber, and each of the two sample fixing heads is provided with a sample fixing part at the corresponding part of each other.

[0011] The parts on the main body of the device corresponding to the two sample fixing heads are the first mounting position and the second mounting position, respectively.

[0012] A power conversion component is provided at the first mounting position and / or the second mounting position of the main body of the device. The power conversion component includes a torque output component, a power input component, a transmission mechanism, and a shaft pressure mechanism.

[0013] The torque output component is rotatably mounted on the main body of the device and is fixedly connected to the corresponding sample fixing head, and can drive the connected sample fixing head to rotate relative to another sample fixing head.

[0014] The power input component is movably configured and can move along a straight line;

[0015] The transmission mechanism is connected to the torque output component and the power input component respectively, and can convert the linear motion of the power input component into the rotational motion of the torque output component.

[0016] The axial pressure mechanism includes a pressure shaft that is slidably disposed in the power input component. The inner end of the pressure shaft passes through the inner end of the power input component, the torque output component, and the sample fixing head connected to the torque output component in sequence and extends to the sample fixing part. The outer end of the pressure shaft is provided with a sliding groove.

[0017] The axial pressure mechanism further includes a piston that is slidably disposed in a groove of the pressure shaft and forms a pressure chamber with the groove, wherein a pressurizing medium is provided in the pressure chamber; the pressure generated by the pressurizing medium is such that the outer end face of the piston is flush with the outer end face of the power input component.

[0018] Furthermore, the main body of the device includes a device base, a support rod disposed on the device base, and a device cover disposed at the top of the support rod;

[0019] The working chamber is the space between the device base and the device cover.

[0020] Furthermore, the support rod is a telescopic support rod with adjustable length, and there are at least three of them, arranged in a circular array.

[0021] Furthermore, the axial pressure mechanism also includes a pressurized medium inlet pipe and a pressurized medium outlet pipe that are respectively connected to the pressure chamber, as well as a locking mechanism disposed in the slide groove of the pressure shaft for limiting the piston.

[0022] Furthermore, the rock torsion shear testing system also includes a pressure shaft pressurization module;

[0023] The pressurizing medium outlet of the pressure shaft pressurizing module is connected to the pressurizing medium inlet pipe, and its pressurizing medium inlet is connected to the pressurizing medium outlet pipe.

[0024] Furthermore, the two sample fixing heads are an upper sample fixing head and a lower sample fixing head, which are set at the top and bottom respectively;

[0025] The first mounting position of the main body of the device corresponds to the fixed head on the sample, and the power conversion component is only set at the first mounting position;

[0026] The sample lower fixing head is fixedly connected to the device base;

[0027] The torque output component is ring-shaped;

[0028] The power input component and the torque output component are coaxially arranged;

[0029] The transmission mechanism includes a gear ring disposed on the top surface of the torque output component and surrounding the power input component, a rack disposed on the power input component and distributed along its motion trajectory centerline, and shaft gears rotatably disposed on the main body of the device and meshing with the gear ring and rack respectively.

[0030] Furthermore, the power input component has a power input end located on the outside of the main body of the device, and the surface of the power input end is the outer end face of the power input component;

[0031] A reset plate is provided on the power input component. The reset plate is located on the upper side of the device cover, and a reset spring is provided between the reset plate and the device cover.

[0032] Furthermore, there are at least three reset springs, which are evenly distributed around the power input component.

[0033] Furthermore, the power input component is rectangular in shape, and racks are provided on all four sides.

[0034] There are four shaft gears, which mesh with racks on the four sides of the power input component.

[0035] Furthermore, the rock torsion shear testing system also includes a test bench;

[0036] The main body of the device is fixedly mounted on the test bench.

[0037] This invention also provides a method for conducting complex stress-coupled rock torsion-shear tests. This method employs a rock torsion-shear testing system, which is the aforementioned complex stress-coupled rock torsion-shear testing system. The method includes the following steps:

[0038] Step 1: Prepare a rock sample and fix it between the two sample fixing heads of the rock torsion shear test system;

[0039] Step 2: Install the rock torsion shear test system with the rock sample fixed on it onto the device that can provide axial pressure, and connect the pressure chamber and the pressure shaft pressurization module in a loop; then, make the pressure rod of the device that provides axial pressure just contact the outer end face of the piston, and control the amount of pressurizing medium injected into the pressure chamber to pre-apply a constant axial pressure to the rock sample.

[0040] Step 3: The device providing axial pressure drives the power input component and piston to move linearly. The transmission mechanism converts the linear motion of the power input component into the rotational motion of the torque output component. The torque output component then drives the fixed sample head to rotate relative to another fixed sample head, applying a torsional torque to the rock sample. Simultaneously, the piston and power input component move axially in sync. The amount of pressurizing medium injected into the pressure chamber is controlled by the pressure shaft pressurization module to apply a constant axial pressure to the rock sample, or to ensure that the axial pressure applied to the rock sample meets the expected axial pressure variation of the test.

[0041] Step four: Measure the deformation and damage of the rock sample during the test, and collect information for data analysis.

[0042] The beneficial effects of this invention are:

[0043] 1) The rock torsion shear test system sets up a power conversion component at the first and / or second mounting positions of the main body of the device. Since the power input component of the power conversion component can move in a linear direction, it can axially cooperate with the pressure rod of the device that can provide axial pressure, so as to use the axial pressure provided by the device as power. Then, the linear motion of the power input component can be converted into the rotational motion of the torque output component through the transmission mechanism of the power conversion component, and the torque output component can drive the specimen fixing head fixedly connected to it to rotate relative to another specimen fixing head, so as to apply a torsional torque to the rock specimen installed and fixed between the two specimen fixing heads for testing.

[0044] Meanwhile, because the pressure shaft of the axial pressure mechanism is slidably installed inside the power input component, the inner end of the pressure shaft extends to the sample fixing part, and a piston is slidably installed in the groove at the outer end of the pressure shaft. The pressure chamber formed by the piston and the groove contains a pressurizing medium that makes the outer end face of the piston flush with the outer end face of the power input component. Thus, the pressure rod of the device that provides axial pressure can act on the outer end face of the piston and the outer end face of the power input component at the same time. That is, the pressure rod can simultaneously drive the piston of the power input component and the axial pressure mechanism to move. The piston movement will inevitably drive the pressurizing medium to push the pressure shaft, so that the rock sample installed and fixed between the two sample fixing heads can be tested by applying axial pressure through the pressure shaft of the axial pressure mechanism.

[0045] It is evident that this rock torsion shear test system can convert axial pressure into torsion shear force and can apply axial pressure to the rock sample through the pressure axis. Therefore, it can perform tests on rock samples under test conditions with only axial force, where the rock sample is subjected to both axial pressure and torsion shear force simultaneously. There is no need to set up a dedicated power mechanism to provide torsion shear force. Compared with existing rock torsion shear test devices with the same function, it has a simpler structure, lower manufacturing cost, and helps to reduce the laboratory space occupied.

[0046] 2) Since the rock torsion shear test system can be used with equipment that can provide axial pressure, the entire rock torsion shear test system can be regarded as the test specimen and tested on the existing testing machine, thus expanding the testing function of the existing testing machine.

[0047] 3) This rock torsion shear test system uses a transmission mechanism in which the shaft gear simultaneously meshes with the gear ring and the rack to convert the linear motion of the power input component into the rotational motion of the torque output component. This allows the power to be input and output at both ends within a shorter transmission distance, making the overall structure of the device simple and compact, which is conducive to reducing the size and eliminating the need to produce new testing machines, thus saving a lot of costs and space.

[0048] 4) The rock torsion shear test system uses a transmission mechanism that simultaneously meshes the gear ring and rack, which ensures that the lever arm remains constant during the torsion shear process and that the torsional load can be applied linearly.

[0049] 5) Multiple openings can be formed on the side of the working chamber, which not only facilitates the operator to disassemble and assemble rock samples, but also facilitates speckle testing.

[0050] 6) This rock torsion shear test system also facilitates simultaneous strain method and acoustic emission testing of rock samples during the test process.

[0051] 7) The multiple openings formed on the side of the working chamber also facilitate the application of radial loads to the rock sample in order to conduct torsional shear tests under radial loads.

[0052] 8) This rock torsion shear test system can directly utilize the peripheral facilities of existing testing machines to conduct other coupled tests, such as temperature field module, confining pressure field module, seepage field module, etc., without the need for redesign and production, which helps to further reduce costs.

[0053] 9) By controlling the amount of pressurized medium in the pressure chamber to achieve constant or regular pressure changes, the axial pressure applied to the rock sample can be kept constant or controlled to conduct torsion shear tests under constant pressure or torsion shear tests under variable pressure. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the implementation structure of the rock torsion shear test system in this invention;

[0055] Figure 2 It is along Figure 1 Sectional view of line AA in the middle;

[0056] Figure 3 yes Figure 1 A three-dimensional structural diagram of the implementation method;

[0057] Figure 4 This is a three-dimensional structural diagram of the power input component;

[0058] Figure 5 This is a schematic diagram of the implementation structure of the ring clamp;

[0059] Figure 6 This is a schematic diagram of the installation structure of the torque sensor;

[0060] Figure 7 This is a schematic diagram of the installation structure of the angle sensor;

[0061] Figure 8 It is a rock sample with a solid cylindrical structure;

[0062] Figure 9 It is a rock sample with a hollow cylindrical structure;

[0063] Figure 10 It is a rock sample with a solid square columnar structure;

[0064] Figure 11 It is a rock sample with a hollow square column structure;

[0065] The components in the diagram are labeled as follows: device body 100, working chamber 110, device base 120, support rod 130, telescopic cylinder 131, telescopic rod body 132, annular clamp 136, second locking element 137, elastic inner ring 138, device top cover 140, sample fixing mechanism 200, upper sample fixing head 210, lower sample fixing head 220, power conversion assembly 300, torque output component 310, power input component 320, power input end 321, reset plate 322, reset spring 323, and transmission mechanism 3. 30. Gear ring 331, rack 332, shaft gear 333, shaft pressure mechanism 340, pressure shaft 341, piston 342, pressure chamber 343, pressurized medium inlet pipe 344, pressurized medium outlet pipe 345, clamping platform 346, test bench 400, rock sample 500, torque sensor mounting base 810, torque sensor 820, angle sensor mounting base 830, angle sensor 840, angle sensor body 841, upper pointer of angle sensor 842, lower pointer of angle sensor 843. Detailed Implementation

[0066] The invention will now be further described with reference to the accompanying drawings.

[0067] In the description of this invention, it should be noted that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for ease of description, not indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention; when "many" indicates a quantity, it usually refers to a quantity of three or more, for example, "multiple" usually refers to three or more; the expression "mainly composed of or constituted by" can be interpreted as also including structural components not mentioned in the sentence; "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist, for example: A and / or B, which can indicate: A alone, A and B simultaneously, and B alone. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0068] Combination Figure 1 , Figure 2 and Figure 3 As shown, a complex stress-coupled rock torsion-shear test system includes a main body 100 and a sample fixing mechanism 200.

[0069] The main body 100 is the main component of the rock torsion shear test system, and it has a working chamber 110 inside; the working chamber 110 is the space for placing the rock sample 500 and conducting the test.

[0070] The sample fixing mechanism 200 is mainly used to install and fix the rock sample 500 to be tested for testing; the rock sample 500 to be tested can be of various types, such as: Figure 8 Rock specimen 500, shown as a solid cylindrical structure Figure 9 Rock sample 500, shown as having a hollow cylindrical structure. Figure 10 The solid square column structure rock sample 500 shown Figure 11 The hollow square column structure of the rock sample 500 shown is an example. The sample fixing mechanism 200 includes two sample fixing heads arranged opposite each other in the working chamber 110, and each of the two sample fixing heads has a sample fixing part at a corresponding position. The sample fixing part can have various structures, as long as it is convenient to fix the end of the rock sample 500. Preferably, it is a sample fixing groove with a regular polygonal cross-section. Usually, a fixing joint that matches the sample fixing groove is glued to the end of the rock sample 500, or the end of the rock sample 500 is processed into a structure that matches the sample fixing groove for fixing. For example: Figure 3 The sample fixing part shown in the embodiment is a regular hexagonal sample fixing groove, which is usually fixed by a hexagonal connector glued to the end of the rock sample 500; for example: Figure 10 The sample fixing part shown in the embodiment is a regular quadrilateral sample fixing groove, which can directly engage and fix the end of a solid square column-shaped rock sample 500; for hollow rock samples 500, a protrusion can usually be provided in the sample fixing groove or the connecting groove of the fixing joint to engage with the end of the inner cavity of the rock sample 500 to increase the adhesive area; for example: Figure 9 The connecting groove of the fixed joint shown in the embodiment is provided with a protrusion; for example: Figure 11 The sample fixing part shown in the embodiment is a square sample fixing groove with a protrusion in the center.

[0071] The parts on the main body 100 corresponding to the two sample fixing heads are the first mounting position and the second mounting position, respectively; a power conversion component 300 is provided at the first mounting position and / or the second mounting position of the main body 100, the power conversion component 300 includes a torque output component 310, a power input component 320, a transmission mechanism 330 and an axial pressure mechanism 340.

[0072] The torque output component 310 is rotatably mounted on the device body 100 and fixedly connected to the corresponding sample fixing head, and can drive the connected sample fixing head to rotate relative to another sample fixing head; the torque output component 310 is mainly used to apply torsional torque to the rock sample 500 to be tested; there are various ways in which the torque output component 310 can be rotatably mounted on the device body 100, for example: through a rotating shaft to rotate with the device body 100, or through a thrust ball bearing to support the torque output component 310 on the device body 100 so that it can rotate, or through an annular groove provided on the device body 100, in which the torque output component 310 with a circular outer circumference is rotatably mounted;

[0073] When only one sample fixing head is connected to the torque output component 310, the other sample fixing head is usually fixedly connected to a component that is stationary relative to the torque output component 310, preferably fixedly connected to the device body 100. When the two sample fixing heads are connected to the two torque output components 310 respectively, it is only necessary to make the two torque output components 310 have a rotation difference to make the two sample fixing heads rotate relative to each other. For example, when power conversion components 300 are provided at the first and second mounting positions of the device body 100, and the center lines of the motion trajectories of the power input components 320 of the two power conversion components 300 are parallel to each other, the transmission ratios of the transmission mechanisms 330 of the two power conversion components 300 are different, so that the two torque output components 310 have a rotation difference.

[0074] The power input component 320 is movably mounted and can move linearly. The power input component 320 is mainly used to axially engage with the pressure rod of a device that provides axial pressure, utilizing the axial pressure provided by the device as power. The power input component 320 is movably mounted on its mounting bracket or the main body 100 of the device, and its mounting bracket or the main body 100 of the device typically has a structure to limit the movement of the power input component 320, ensuring that it can move linearly. The power input component 320 is usually arranged vertically in the center, and its circumferential profile dimension is smaller than the size of the central opening of the top cover or base of the main body 100, the torque output component 310, etc., so that while engaging or threaded transmission through the transmission mechanism 330, the power input component 320 can move freely and stably up and down.

[0075] The transmission mechanism 330 is connected to the torque output component 310 and the power input component 320 respectively, and can convert the linear motion of the power input component 320 into the rotational motion of the torque output component 310. The transmission mechanism 330 can be of various types, such as: gear and rack mechanism, ball screw mechanism, cam mechanism, crank and connecting rod mechanism, lever mechanism, etc.

[0076] The axial compression mechanism 340 is mainly used to apply axial pressure to the rock sample 500, which is installed and fixed between two sample fixing heads. The axial compression mechanism 340 includes a pressure shaft 341 slidably disposed in the power input component 320. The inner end of the pressure shaft 341 passes through the inner end of the power input component 320, the torque output component 310, and the sample fixing head connected to the torque output component 310 and extends to the sample fixing part. The outer end of the pressure shaft 341 is provided with a sliding groove. Usually, a guide groove is opened in the power input component 320 along its movement trajectory to allow the pressure shaft 341 to slide. The pressure shaft 341 is slidably disposed in the guide groove. The inner end of the pressure shaft 341 is mainly used to abut against the end of the rock sample 500. The purpose of opening the sliding groove at the outer end of the pressure shaft 341 is to reserve space for adjusting the stroke of the pressure shaft 341, so as to avoid the axial compression mechanism 340 and the power input component 320 not being able to use the same axial force as power when there is a stroke difference between the pressure shaft 341 and the power input component 320.

[0077] The axial compression mechanism 340 also includes a piston 342 slidably disposed in a groove of the pressure shaft 341 and forming a pressure chamber 343 with the groove. The pressure chamber 343 contains a pressurizing medium. The pressure generated by the pressurizing medium allows the outer end face of the piston 342 to be flush with the outer end face of the power input component 320. During the process of simultaneously applying axial pressure and torsional shear force to the rock sample 500 in this rock torsion shear test system, the stroke of the pressure shaft 341 is often less than the stroke of the power input component 320. By providing a pressurizing medium in the pressure chamber 343, the axial pressure on the piston 342 can be transmitted to the pressure shaft 341 through the pressure of the pressurizing medium, so that the pressure on the piston 342 can be transmitted to the pressure shaft 341. 41. An axial pressure is applied to the rock sample 500, which is fixed between two sample fixing heads. On the other hand, the stroke difference between the pressure shaft 341 and the power input component 320 can be eliminated by discharging or compressing the pressurizing medium. Specifically, when the stroke of the piston 342 is the same as that of the power input component 320, and the stroke of the pressure shaft 341 is smaller, the pressurizing medium is squeezed by the pressure shaft 341 and the piston 342, so that part of the pressurizing medium is discharged or compressed into a smaller volume to eliminate the stroke. Furthermore, the operator can also control the amount of pressurizing medium in the pressure chamber 343 to control the magnitude of the axial pressure applied by the pressure shaft 341 to the rock sample 500.

[0078] The aforementioned complex stress-coupled rock torsion shear test system can be used to conduct pure torsion shear tests, torsion shear tests under constant pressure, and torsion shear tests under varying pressure.

[0079] Specifically, and then combined Figure 1 , Figure 2 and Figure 3As shown, one embodiment of the device body 100 includes a device base 120, a support rod 130 mounted on the device base 120, and a device cover 140 mounted on the top of the support rod 130; the working chamber 110 is the space between the device base 120 and the device cover 140. This device body 100 has a simple structure and is easy to manufacture; the support rod 130 supports the device cover 140, allowing multiple openings to be formed on the side of the working chamber 110, facilitating the installation and removal of the rock sample 500 by the operator. Typically, only one operator is needed to conduct the experiment.

[0080] To improve the overall structural strength of the main body 100 of the device and the stability of the support rod 130 supporting the upper cover 140 of the device, for example... Figure 3 As shown, another embodiment of the device body 100 is as follows: based on the above, the support rods 130 are at least three in number and arranged in a ring array.

[0081] The two sample fixing heads can be arranged in various directions within the working chamber 110. To facilitate the fixing of the rock sample 500 and improve the accuracy of the test, it is preferable to arrange the two sample fixing heads in a vertical or horizontal direction, so that the two sample fixing heads are coaxial and their axial direction is vertical or horizontal. For example: Figures 1-3 In the embodiment shown, the two sample fixing heads are arranged in a vertical direction.

[0082] To facilitate testing of rock samples 500 of various lengths and dimensions, for example... Figure 1 , Figure 2 and Figure 3 As shown, the support rod 130 is preferably an adjustable telescopic support rod; and the two sample fixing heads are preferably an upper sample fixing head 210 and a lower sample fixing head 220, which are respectively set vertically. The relative distance between the first mounting position and the second mounting position of the device body 100 can be adjusted by adjusting the length of the support rod 130. Since the power conversion component 300 is provided at the first mounting position and / or the second mounting position, and the torque output component 310 of the power conversion component 300 is fixedly connected to the corresponding upper sample fixing head 210 or lower sample fixing head 220, the relative distance between the upper sample fixing head 210 and the lower sample fixing head 220 can be adjusted. This allows rock samples 500 of different lengths to be installed between the upper sample fixing head 210 and the lower sample fixing head 220 for testing, which is very convenient.

[0083] The telescopic support rod 130 typically includes a telescopic cylinder 131 and a telescopic rod body 132 nested together. Its telescopic movement can be achieved in various ways, such as: telescopic movement via a helical mechanism, but in this type of support rod 130, at least one end needs to be rotatably connected; telescopic movement via a pneumatic or hydraulic system; telescopic movement via a linear motor; or telescopic movement via manual operation.

[0084] To facilitate adjusting the length of the support rod 130 and locking it in place, and then combining... Figure 1 , Figure 2 and Figure 3 As shown, one embodiment of the support rod 130 includes a telescopic cylinder 131 disposed on the device base 120, and a telescopic rod body 132 nested with the telescopic cylinder 131 and movable along its axial direction; the telescopic cylinder 131 and / or the telescopic rod body 132 are provided with a locking structure to restrict the movement of the telescopic rod body 132; the top end of the telescopic rod body 132 is the top end of the support rod 130.

[0085] The aforementioned locking structure is used to lock and fix the support rod 130 after its length has been adjusted, so that it remains at that length, thereby facilitating the testing of rock samples 500 of the corresponding length. The locking structure can achieve locking in various ways, such as locking by twisting the thread, locking axially by using a snap ring, locking by using a pin or screw, etc.

[0086] Combined Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, a preferred embodiment of the locking structure includes a notch at the upper end of the telescopic rod 131, an annular clamp 136 sleeved on the upper end of the telescopic rod 131, and second locking members 137 respectively connected to both ends of the annular clamp 136. This locking structure has the following advantages: It has strong stability. When locking, the second locking part 137 can be screwed on to make the ring clamp 136 more secure, tightening the upper end of the telescopic cylinder 131 and the telescopic rod body 132, making it less likely to loosen or fall off. It is highly convenient, not only can it be installed and disassembled very easily, but it can also be adjusted within a continuous length range, making it more flexible and easy to use, and it can test rock samples of more sizes up to 500. With good reliability, it can be basically ensured that the support rod 130 will not break or deform during use, thus ensuring safety.

[0087] For example Figure 2As shown, in a preferred embodiment of the present invention, the axial pressure mechanism 340 further includes a pressurized medium inlet pipe 344 and a pressurized medium outlet pipe 345, which are respectively connected to the pressure chamber 343, and a retaining plate 346 disposed in the groove of the pressure shaft 341 for limiting the piston 342. The pressurized medium inlet pipe 344 and the pressurized medium outlet pipe 345 are respectively used for injecting and discharging the pressurized medium in the pressure chamber 343 to control the pressure in the pressure chamber 343, thereby facilitating the operator to control the magnitude of the axial pressure applied by the pressure shaft 341 to the rock sample 500; the retaining plate 346 is mainly used to limit and support the piston 342, preventing the piston 342 from entering the groove too deeply when not in operation.

[0088] As another preferred embodiment of the present invention, the rock torsion shear test system further includes a pressure shaft pressurization module; the pressurization medium outlet of the pressure shaft pressurization module is connected to the pressurization medium inlet pipe 344, and its pressurization medium inlet is connected to the pressurization medium outlet pipe 345.

[0089] The aforementioned pressure shaft pressurization module mainly consists of a container filled with pressurizing medium, a pressurizing pump, a flow meter, and control valves. It can inject and / or discharge pressurizing medium into the pressure chamber 343 to control the magnitude of the axial pressure applied by the pressure shaft 341 to the rock sample 500. This facilitates the study of the mechanical behavior of the rock sample 500 under axial pressure-torsional shear coupling, obtaining the mechanical parameters of the rock, and providing experimental basis and data support for rock engineering exploration and design. The pressurizing medium can be various, such as gas, water, hydraulic oil, etc.

[0090] Based on the aforementioned pressure axis pressurization module, the process and principle of conducting a constant axial pressure torsional shear test on this rock torsional shear test system are as follows: After the rock sample is prepared and installed, the test bench 400 is first adjusted so that the pressure rod of the pressure testing machine is in contact with the outer end face of the piston 342, and the axial pressure sensor of the pressure testing machine displays a data greater than zero; then, hydraulic oil is injected into the pressure chamber 343 through the pressurization medium inlet pipe 344, so that its pressure reaches the expected axial pressure magnitude experienced by the rock sample 500; subsequently, the hydraulic oil will transmit pressure to the surroundings, the piston 342 will tend to slide outwards, and transmit the pressure to the pressure rod; the pressure shaft 341 will tend to move inwards, and... The axial pressure is directly transmitted to the end of the rock sample 500; at this point, the operation of pre-applying a constant axial pressure to the rock sample 500 is completed; during the subsequent torsion shear operation, the oil discharge of the pressurized medium discharge pipe 345 is controlled by the overflow valve. During the axial movement of the pressure rod of the pressure testing machine to apply pressure, the piston 342 and the power input component 320 move axially synchronously. When the pressure generated by the hydraulic oil is greater than the preset axial pressure, it will reach the oil discharge threshold of the pressurized medium discharge pipe 345. The hydraulic oil is discharged into the oil tank through the pressurized medium discharge pipe 345 so that the pressure transmitted by the hydraulic oil to the surroundings remains constant, thereby keeping the axial pressure applied by the pressure shaft 341 to the rock sample 500 constant.

[0091] As a preferred embodiment of the present invention, combined with Figure 1 , Figure 2 and Figure 3As shown, the first mounting position of the device body 100 corresponds to the upper fixing head 210 of the sample, and the power conversion component 300 is only provided at the first mounting position; the lower fixing head 220 of the sample is fixedly connected to the device base 120; the torque output component 310 is annular; the power input component 320 is coaxially arranged with the torque output component 310; the transmission mechanism 330 includes a gear ring 331 disposed on the top surface of the torque output component 310 and surrounding the power input component 320, a rack 332 disposed on the power input component 320 and distributed along its motion trajectory centerline, and a shaft gear 333 rotatably disposed on the device body 100 and meshing with the gear ring 331 and the rack 332 respectively. The shaft gear 333 is generally rotatably connected to the device body 100 through bearings, bushings, or shaft hole fittings. This rock torsion shear test system has a simple and relatively symmetrical structure, is not only easy to process and manufacture, but also has good stability. When the power input component 320 moves downward under axial pressure, its rack 332 drives the shaft gear 333 to rotate, which in turn drives the torque output component 310 to rotate, thereby applying a torsional torque to the rock sample 500. The lower end of the power input component 320 can pass through the inner hole of the torque output component 310, and to facilitate the downward movement of the power input component 320, a clearance space corresponding to the power input component 320 is usually provided on the upper part of the fixed head 210 on the sample. Figure 2 As shown.

[0092] Furthermore, the aforementioned transmission mechanism 330 uses a shaft gear 333 meshing with a gear ring 331 and a rack 332 respectively for transmission, which has the following advantages: The transmission ratio is flexible; by designing the tooth ratio of shaft gear 333, gear ring 331 and rack 332, different speed ratio transmissions can be achieved; this makes the transmission speed ratio easier to adjust and optimize. High transmission accuracy; the continuous tooth surface contact between shaft gear 333, gear ring 331, and rack 332 can effectively reduce runout and vibration during movement, achieve smooth motion transmission, and ensure accuracy. It has a strong load-bearing capacity; the shaft gear 333 has multiple tooth surfaces in contact with the gear ring 331 and the rack 332, which can effectively distribute the load, increase the load-bearing area, and have a high load-bearing capacity; this structure can transmit a large amount of power and torque, and is further conducive to being used with equipment that provides axial pressure. Easy to process and assemble; the tooth surface machining technology is mature and readily available, and the assembly is relatively simple and straightforward, which reduces the manufacturing difficulty and cost of parts. The structure is compact; the shaft gear 333 meshes with the gear ring 331 and the rack 332 at the same time, which allows power to be input and output at both ends in a shorter transmission distance, and has the characteristics of simple and compact structure.

[0093] To facilitate the use of the power input component 320 with equipment that can provide axial pressure, for example... Figure 1 , Figure 2 and Figure 4 As shown, the power input component 320 has a power input end 321 located outside the main body 100 of the device. The power input end 321 is mainly used to abut or engage with the end of the pressure rod of the device that can provide axial pressure. The surface of the power input end 321 is the outer end face of the power input component 320.

[0094] The best, then combined Figure 1 and Figure 2 As shown, a preferred embodiment of the power conversion assembly 300 is as follows: a reset plate 322 is provided on the power input component 320, the reset plate 322 is located on the upper side of the device cover 140, and a reset spring 323 is provided between the reset plate 322 and the device cover 140. By providing the reset plate 322 and the reset spring 323, after the axial pressure is removed, the power input component 320 of the power conversion assembly 300 can automatically reset to the initial position under the elastic force of the reset spring 323, so as to facilitate the replacement of a new rock sample 500 for the next set of tests.

[0095] To ensure accurate resetting of the power conversion assembly 300 and improve its stability and the service life of the resetting mechanism, for example... Figure 1 As shown, another preferred embodiment of the power conversion component 300 is as follows: based on the above, at least three reset springs 323 are provided and are evenly distributed around the power input component 320.

[0096] To further improve the stability and load-bearing capacity of this rock torsion shear test system, combined with Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, another preferred embodiment of the power conversion assembly 300 is as follows: the power input component 320 is rectangular, with racks 332 on each of its four sides; simultaneously, four shaft gears 333 are provided, each meshing with one of the racks 332 on the four sides of the power input component 320. This power conversion assembly 300 has good structural symmetry and further increases the contact surfaces of the transmission mechanism, greatly improving the load-bearing capacity and transmission accuracy of the rock torsion-shear test system.

[0097] To facilitate the installation and setup of this rock torsion-shear testing system in the working position, for example... Figure 1 , Figure 2 and Figure 3As shown, it also includes a test bench 400; the main body 100 of the device is fixedly mounted on the test bench 400. Generally, the device base 120 of the main body 100 of the device is fixedly connected to the test bench 400 by multiple base bolts.

[0098] This invention also provides a method for testing rock under complex stress-coupled torsional shear forces. This method employs a rock torsional shear testing system, which is the aforementioned complex stress-coupled rock torsional shear testing system. The process of testing a rock sample 500 under simultaneous axial pressure and torsional shear force is as follows:

[0099] Preparation before the test: Before the test begins, the rock sample is prepared and installed. The diameter and length of the rock sample 500 to be tested have specified standard test dimensions, which need to be made to meet the standards during rock processing. Then, a fixing joint, such as a hexagonal joint, is glued to the end of the rock sample 500. A through hole for the pressure shaft 341 to pass through can be reserved on the fixing joint at the end of the rock sample 500 where axial pressure is to be applied, or it can be left unreserved. Finally, the rock sample 500 with fixing joints glued to both ends is fixed between the two sample fixing heads of the rock torsion shear test system, so that the fixing joints and the sample fixing parts are positioned and fitted. At this point, the rock sample 500 is fixed.

[0100] Device Debugging: Install the rock torsion-shear testing system with the rock sample 500 fixed on a laboratory device capable of providing axial pressure (e.g., MTS), and connect and fix the device base 120 to the test bench 400; circulate the pressure chamber 343 with the pressure shaft pressurization module; then, ensure that the pressure rod of the device providing axial pressure is in contact with the outer end face of the piston 342, and the axial pressure sensor displays a data greater than zero; next, control the amount of pressurizing medium injected into the pressure chamber 343 to achieve the expected axial pressure on the rock sample 500; then, the pressurizing medium will transmit pressure to all sides, the piston 342 will tend to slide outwards, and transmit the pressure to the pressure rod; the pressure shaft 341 will tend to move inwards, and directly transmit the axial pressure to the end of the rock sample 500; at this point, the operation of pre-applying a constant axial pressure to the rock sample 500 is complete.

[0101] Test begins: The axial pressure of the pressure rod serves as the power input for the linear motion of the power input component 320 and the piston 342. This linear motion is then converted into rotational motion of the torque output component 310 via the transmission mechanism 330. The torque output component 310 drives the fixed sample head to rotate relative to another fixed sample head, thus applying a torsional torque to the rock sample 500 mounted between the two fixed sample heads. During this process, the piston 342 moves axially synchronously with the power input component 320. When the pressure generated by the pressurizing medium exceeds the preset axial pressure, a threshold for discharging the pressurizing medium is reached. The pressurizing medium is then discharged to maintain a constant pressure, ensuring a constant axial pressure on the rock sample 500. Alternatively, the pressurizing medium can be injected and / or discharged to ensure the axial pressure on the rock sample 500 follows the expected pattern of change. Finally, the deformation and damage of the rock sample 500 during the test are measured, and data such as stress-strain, axial pressure, torsion angle, and torsional torque are collected for data analysis.

[0102] In the above tests, the instruments for collecting parameters such as stress and strain, axial pressure, torsion angle and / or torque are all arranged in the existing technology. Typically, the instruments for collecting stress and strain or torsion angle can be installed between the specimen fixing head and the rock specimen 500. In order to facilitate the detection of the torque of the test load, a torque sensor 820 corresponding to the torque output component 310 or the specimen fixing head connected to the torque output component 310 can be set for detection.

[0103] For example Figure 6 As shown, a preferred arrangement of the torque sensor 820 is as follows: a torque sensor mounting base 810 with an annular structure coaxial with the torque output component 310 or the sample fixing head connected to the torque output component 310 is provided, and the torque sensor 820 is placed on the torque sensor mounting base 810, with the probe of the torque sensor 820 abutting against the torque output component 310 or the sample fixing head; in order to improve the accuracy of torque detection, it is preferable to provide multiple uniformly distributed torque sensors 820 on the torque sensor mounting base 810.

[0104] For example Figure 7 As shown, a preferred arrangement of the angle sensor 840 is as follows: an angle sensor mounting base 830 is provided inside the hollow rock sample 500, and the angle sensor 840 is provided on the angle sensor mounting base 830; the angle sensor 840 generally includes an angle sensor body 841 vertically arranged in the center of the angle sensor mounting base 830, an upper angle sensor pointer 842 arranged on the upper end of the angle sensor body 841, and a lower angle sensor pointer 843 arranged below the upper angle sensor pointer 842.

Claims

1. A complex stress-coupled rock torsion-shear test system, comprising a main body of the device (100) and a specimen fixing mechanism (200). The device body (100) is provided with a working cavity (110). The sample fixing mechanism (200) includes two sample fixing heads arranged opposite each other in the working chamber (110), and each of the two sample fixing heads has a sample fixing part at the corresponding part of each other. Its features are: It also includes a pressure shaft pressurization module; The parts on the main body (100) of the device that correspond to the two sample fixing heads are the first mounting position and the second mounting position, respectively. A power conversion assembly (300) is provided at the first mounting position and / or the second mounting position of the main body (100) of the device. The power conversion assembly (300) includes a torque output component (310), a power input component (320), a transmission mechanism (330), and a shaft pressure mechanism (340). The torque output component (310) is rotatably mounted on the main body (100) of the device and is fixedly connected to the corresponding sample fixing head, and can drive the sample fixing head connected to it to rotate relative to another sample fixing head. The power input component (320) is movably configured and can move in a straight line; The transmission mechanism (330) is connected to the torque output component (310) and the power input component (320) respectively, and can convert the linear motion of the power input component (320) into the rotational motion of the torque output component (310); The axial pressure mechanism (340) includes a pressure shaft (341) slidably disposed in the power input component (320). The inner end of the pressure shaft (341) passes through the inner end of the power input component (320), the torque output component (310), and the sample fixing head connected to the torque output component (310) in sequence and extends to the sample fixing part. The outer end of the pressure shaft (341) is provided with a sliding groove. The axial pressure mechanism (340) further includes a piston (342) slidably disposed in a groove of the pressure shaft (341) and forming a pressure chamber (343) with the groove. The pressure chamber (343) is provided with a pressurizing medium. The pressure generated by the pressurizing medium can make the outer end face of the piston (342) flush with the outer end face of the power input component (320). The axial pressure mechanism (340) also includes a pressurized medium inlet pipe (344) and a pressurized medium outlet pipe (345) respectively connected to the pressure chamber (343), and a clamping table (346) provided in the groove of the pressure shaft (341) for limiting the piston (342). The pressurizing medium outlet of the pressure shaft pressurizing module is connected to the pressurizing medium inlet pipe (344), and its pressurizing medium inlet is connected to the pressurizing medium outlet pipe (345).

2. The complex stress-coupled rock torsion-shear test system according to claim 1, characterized in that: The main body of the device (100) includes a device base (120), a support rod (130) disposed on the device base (120), and a device cover (140) disposed on the top of the support rod (130). The working chamber (110) is the space between the device base (120) and the device top cover (140); The support rod (130) is a telescopic support rod with adjustable length, and there are at least three of them, which are arranged in a ring array.

3. The complex stress-coupled rock torsion-shear test system according to claim 2, characterized in that: The two sample fixing heads are an upper sample fixing head (210) and a lower sample fixing head (220) set at the top and bottom respectively. The first mounting position of the main body (100) of the device corresponds to the fixed head (210) on the sample, and the power conversion component (300) is only provided at the first mounting position. The sample lower fixing head (220) is fixedly connected to the device base (120); The torque output component (310) is annular; The power input component (320) and the torque output component (310) are coaxially arranged; The transmission mechanism (330) includes a gear ring (331) disposed on the top surface of the torque output member (310) and surrounding the power input member (320), a rack (332) disposed on the power input member (320) and distributed along its motion trajectory centerline, and a shaft gear (333) rotatably disposed on the device body (100) and meshing with the gear ring (331) and the rack (332) respectively.

4. The complex stress-coupled rock torsion-shear test system according to claim 3, characterized in that: The power input component (320) has a power input end (321) located outside the main body (100) of the device, and the surface of the power input end (321) is the outer end face of the power input component (320); The power input component (320) is provided with a reset plate (322), which is located on the upper side of the device cover (140), and a reset spring (323) is provided between the reset plate (322) and the device cover (140).

5. The complex stress-coupled rock torsion-shear test system according to claim 4, characterized in that: The reset springs (323) are at least three in number and are evenly distributed around the power input element (320).

6. The complex stress-coupled rock torsion-shear testing system according to any one of claims 3 to 5, characterized in that: The power input component (320) is rectangular in shape, and racks (332) are provided on all four sides. There are four shaft gears (333), which mesh with the racks (332) on the four sides of the power input component (320).

7. The complex stress-coupled rock torsion-shear test system according to claim 6, characterized in that: It also includes a test bench (400); The main body (100) of the device is fixedly mounted on the test bench (400).

8. A method for testing complex stress-coupled rock torsion-shear, wherein the method employs a rock torsion-shear testing system for rock testing, characterized in that: The rock torsion shear testing system is the complex stress-coupled rock torsion shear testing system as described in any one of claims 1 to 7; the method includes the following steps: Step 1: Prepare a rock specimen (500) and fix the rock specimen (500) between the two specimen fixing heads of the rock torsion shear test system; Step 2: Install the rock torsion shear test system with the rock sample (500) fixed on it onto a device that can provide axial pressure, and circulate the pressure chamber (343) with the pressure shaft pressurization module; then, make the pressure rod of the device that provides axial pressure just contact the outer end face of the piston (342), and then control the amount of pressurizing medium injected into the pressure chamber (343) to pre-apply a constant axial pressure to the rock sample (500); Step 3: The device that provides axial pressure drives the power input component (320) and piston (342) to make linear motion. The transmission mechanism (330) converts the linear motion of the power input component (320) into the rotational motion of the torque output component (310). The torque output component (310) then drives the sample fixing head fixedly connected to it to rotate relative to another sample fixing head, applying a torsional torque to the rock sample (500). At the same time, the piston (342) moves axially synchronously with the power input component (320). The amount of pressurizing medium injected into the pressure chamber (343) is controlled by the pressure shaft pressurization module to apply a constant axial pressure to the rock sample (500), or to make the axial pressure applied to the rock sample (500) meet the expected axial pressure change of the test. Step 4: Measure the deformation and damage of the rock sample (500) during the test and collect information for data analysis.

Images