Bonding centering device for rock direct tensile test and operation method

Abstract

The invention discloses a bonding centering device for a rock direct tensile test and an operation method, and the device comprises a clamping plate main body which comprises a clamping plate pressure head and a clamping plate base, and the clamping plate pressure head and the clamping plate base are connected through a connecting rod and are coaxially arranged; the centering clamper is mounted between the clamping plate pressure head and the clamping plate base and is used for clamping and centering a rock sample before bonding; wherein the centering clamping device comprises a limiting plate capable of rotating in the annular direction and a plurality of blades capable of swinging in the radial direction, and the limiting plate and the blades are arranged in a linkage mode, so that when the limiting plate rotates in the annular direction, all the blades are driven to synchronously and radially gather together so as to clamp the rock sample and enable the axis of the rock sample to be aligned with the axis of the clamping plate main body. According to the invention, the rock sample can be accurately aligned with the axis of the puller, and the test data is real and reliable.

Description

Technical Field

[0001] This invention relates to the field of geotechnical mechanics, and in particular to a bonding alignment device and operating method for direct tensile testing of rocks. Background Technology

[0002] In oil engineering projects such as hydraulic fracturing and wellbore stabilization, the accurate testing of rock tensile strength relies on direct tensile testing. The core challenge of this test is the bonding and alignment between the rock sample and the tensile head.

[0003] In existing technologies, manual bonding or simple clamping tools lack a unified coaxial reference, and the clamping components cannot move synchronously and collaboratively, causing the rock sample and the pull head axis to easily deviate. Improved cap-type devices also struggle to achieve active centering and are prone to generating additional bending moments. These problems directly cause deviations between the axial load and the sample axis, resulting in discrepancies between the measured tensile strength and the true value, thus affecting the reliability of the test data.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This specification provides an embodiment of a bonding and alignment device and operating method for direct tensile testing of rocks, in order to solve the problems of axial offset and distortion of measured tensile strength caused by the lack of a unified coaxial reference and the inability of the clamping components to move synchronously when bonding rock specimens and pull heads in direct tensile testing.

[0006] In a first aspect, embodiments of this specification provide an adhesive alignment device for direct tensile testing of rocks, comprising:

[0007] The clamp body includes a clamp head and a clamp base, wherein the clamp head and the clamp base are connected by a connecting rod and arranged coaxially;

[0008] A centering clamp is installed between the clamping head and the clamping base to clamp and center the rock sample before bonding.

[0009] The centering clamp includes a circumferentially rotatable limiting plate and multiple radially oscillating blades. The limiting plate and the blades are linked and configured so that when the limiting plate rotates circumferentially, all the blades are driven to converge radially synchronously to clamp and align the axis of the rock sample with the axis of the clamping plate body.

[0010] In some embodiments, the number of connecting rods is four, and the four connecting rods are evenly distributed along the circumference of the clamp body, respectively connecting the clamp head to the centering clamp and the centering clamp to the clamp base, so that the clamp head, the centering clamp, and the clamp base are coaxial.

[0011] In some embodiments, the centering clamp further includes a centering clamp base, and the groove portion of the centering clamp base is provided with a plurality of base blade fixing holes evenly distributed in a ring. One end of the blade is hinged to the base blade fixing hole by a rivet, so that the blade swings radially around the rivet, converging or diverging.

[0012] In some embodiments, the centering clamp further includes a centering clamp cover plate, which covers the limiting plate and is used to protect and axially limit the limiting plate, blades and rivets.

[0013] In some embodiments, the blade is an arc-shaped transmission component with a hinge hole and a mating hole at each end. The hinge hole is hinged to the blade fixing hole of the base by a rivet. All mating hole ends of the blades face the center of the device and are evenly distributed on the circumference.

[0014] In some embodiments, the limiting plate is provided with a guide groove corresponding to the number of blades. The guide groove is slidably engaged with the rivet at the mating hole end of the blade. By rotating the limiting plate circumferentially, the guide groove drives the rivet to drive the blades to synchronously converge or disperse radially.

[0015] In some embodiments, the device further includes a double-ended bolt for connecting the clamping head to the upper pull head of the tensile test, the lower pull head of the tensile test, and the clamping base, and the double-ended bolt is compatible with pull heads of various sizes and specifications.

[0016] In some embodiments, the device further includes a plate lifting adjustment device, which is connected to a centering clamp and is used to drive the centering clamp to move along the axial direction of the clamping plate body to adjust the clamping position of the centering clamp.

[0017] In some embodiments, the plate lifting adjustment device includes a plate lifting adjustment device base, a rotating handle, and a plate lifting adjustment device bolt. The rotating handle is convectively connected to the plate lifting adjustment device bolt, and the rotation of the rotating handle drives the plate lifting adjustment device bolt to move the centering clamp axially.

[0018] Secondly, embodiments of this specification provide a method for bonding alignment in direct tensile testing of rock, using the aforementioned apparatus, comprising the following steps:

[0019] The clamping head of the clamping plate body is connected to the clamping plate base through a connecting rod, so that the clamping head and the clamping plate base are arranged coaxially.

[0020] A centering clamp is installed between the clamping head and the clamping base. The centering clamp includes a limiting plate and multiple blades. The limiting plate and the blades are configured in a linkage manner.

[0021] Place the rock sample in the clamping area of ​​the central clamp, rotate the limiting plate circumferentially, drive all blades to converge radially synchronously, clamp the rock sample and align the axis of the rock sample with the axis of the clamp body.

[0022] The clamping head is connected and fixed to the upper pull head of the tensile test and the lower pull head of the tensile test is connected to the clamping base by double-ended bolts.

[0023] Apply adhesive to the corresponding bonding areas of the rock sample and the upper and lower pull heads, keep the centering clamp in the centered state, and continue until the adhesive cures to complete the coaxial bonding of the rock sample and the pull head.

[0024] This specification provides an embodiment of an adhesive alignment device for direct tensile testing of rock, comprising: a clamping plate body including a clamping plate indenter and a clamping plate base, the clamping plate indenter and the clamping plate base being connected by a connecting rod and arranged coaxially; and a centering clamp, installed between the clamping plate indenter and the clamping plate base, for clamping and centering the rock sample before bonding; wherein the centering clamp includes a circumferentially rotatable limiting plate and multiple radially oscillating blades, the limiting plate and the blades being linked, such that when the limiting plate rotates circumferentially, all the blades are driven to synchronously converge radially to clamp and align the axis of the rock sample with the axis of the clamping plate body. In this embodiment, the clamping plate indenter and the clamping plate base of the clamping plate body are connected by a connecting rod, and their axes are strictly calibrated during the connection process to ensure that the clamping plate indenter and the clamping plate base are arranged coaxially, thus completing the construction of the basic framework of the device. The centering clamp is installed in the area between the clamping head and the clamping base, ensuring proper assembly of the linkage structure between the limiting plate and multiple blades, enabling smooth power transmission. Through the linkage design of the limiting plate and blades, the blades are synchronously radially converged, forming a uniform circumferential clamping force. This forces the rock sample axis to align with the clamping body axis, completely eliminating the centering deviation caused by asynchronous movements and uneven force distribution in traditional clamping methods. It effectively avoids the generation of additional bending moments, ensuring that the axial load in the direct tensile test is consistent with the sample axis, providing a core guarantee for measuring the true tensile strength of the rock.

[0025] This specification also provides an embodiment of a bonding and centering method for direct tensile testing of rock, using the aforementioned device, comprising the following steps: First, connecting the clamping head of the clamping plate body to the clamping plate base via a connecting rod, so that the clamping head and the clamping plate base are arranged coaxially. Next, installing a centering clamp between the clamping head and the clamping plate base, the centering clamp including a limiting plate and multiple blades, the limiting plate and the blades being linked. Then, placing the rock sample in the clamping area of ​​the centering clamp, rotating the limiting plate circumferentially, driving all blades to synchronously converge radially, clamping the rock sample and aligning the axis of the rock sample with the axis of the clamping plate body. Next, connecting and fixing the clamping head to the upper pull head of the tensile test and the lower pull head of the tensile test to the clamping plate base using double-ended bolts. Finally, applying adhesive to the corresponding bonding areas of the rock sample with the upper and lower pull heads, maintaining the centered clamping state of the centering clamp until the adhesive cures, completing the coaxial bonding of the rock sample and the pull head. In the embodiments described in this specification, the logical flow of "baseline establishment - centering adjustment - fixed bonding" is strictly followed, fully translating the structural advantages of the device into practical operational results. This ensures that each step guarantees the final centering accuracy. Standardized operating procedures avoid the randomness and uncertainty of manual operation, ensuring consistent centering results for different operators and in different test scenarios, thus improving the repeatability and reliability of test results. Through the above operating method, precise coaxial bonding between the rock sample and the pull head is achieved, completely solving the problem of axial misalignment in traditional bonding methods. This ensures that direct tensile testing can be conducted under conditions of no eccentric loading, and the final measured rock tensile strength data accurately reflects the actual properties of the rock, providing precise data support for engineering operations. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0027] Figure 1 This is a three-dimensional schematic diagram of the bonding alignment device for direct rock tensile testing provided in the embodiments of this specification;

[0028] Figure 2 This is a three-dimensional cross-sectional view of a single blade in the centering clamp provided in the embodiments of this specification;

[0029] Figure 3 This is a three-dimensional schematic diagram of the centering clamp provided in the embodiments of this specification;

[0030] Figure 4This is a schematic diagram of a single blade in the centering clamp provided in the embodiments of this specification;

[0031] Figure 5 This is a schematic diagram of a single blade being inserted into a rivet in the centering clamp provided in the embodiments of this specification;

[0032] Figure 6 This is a three-dimensional top view of a single blade in the centering clamp provided in the embodiments of this specification, connected to the base of the centering clamp;

[0033] Figure 7 This is a three-dimensional top view of the centering clamp with the cover plate and limiting plate removed, as provided in the embodiments of this specification;

[0034] Figure 8 This is a three-dimensional top view of the centering clamp with the cover plate removed, as provided in the embodiments of this specification;

[0035] Figure 9 This is a three-dimensional cross-sectional view of the bonding alignment device for direct rock tensile testing provided in the embodiments of this specification;

[0036] Figure 10 This is a three-dimensional schematic diagram of the plate lifting and adjusting device provided in the embodiments of this specification;

[0037] Figure 11 This is a three-dimensional sectional view of the plate lifting and adjusting device provided in the embodiments of this specification;

[0038] Figure 12 This is a schematic flowchart of an adhesive alignment operation method for direct tensile testing of rock provided in the embodiments of this specification.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Clamping head; 2. Clamping base; 3. Upper pull head; 4. Centering clamp base; 5. Rock sample; 6. Plate lifting adjustment device base; 7. Lower pull head; 8. Double-ended bolt; 9. Centering clamp cover plate; 10. Limiting plate; 11. Blade; 12. Rivet; 13. Base blade fixing hole; 14. Rotating handle; 15. Plate lifting adjustment device bolt; 16. Connecting rod; 17. Limiting plate handle; 18. Guide groove; 19. Hinge hole; 20. Mating hole. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0042] As mentioned above, in actual operations such as hydraulic fracturing of reservoirs and wellbore stabilization in petroleum engineering, accurately testing the tensile strength of reservoir rocks is a core prerequisite for precisely determining the fracture initiation pressure, optimizing fracturing pump parameters, avoiding the risks of wellbore fracture initiation and collapse, ensuring wellbore operation safety, and improving reservoir stimulation efficiency. It directly determines the feasibility and implementation effect of the engineering plan.

[0043] Currently, most studies use the Brazilian splitting method to indirectly determine the tensile strength of rocks. However, the tensile strength obtained using this method is usually higher than the true tensile strength of the rock. The most accurate test method for the tensile modulus and tensile strength of rocks is the uniaxial tensile test, but this method is difficult to implement. The main reasons may include: (1) the diameter of the rock sample does not meet the standard of 50 mm, and the two ends of the rock sample are not completely parallel, and the thickness of the adhesive is different, which makes it difficult to ensure that the axis of the pull head is aligned with the axis of the rock sample when bonding the pull head; (2) the commonly used cap-type device, although using a spherical hinge, is not flexible enough to avoid the generation of bending moment and torque. The existing improved cap-type device is still unable to effectively avoid the influence of bending moment and torque due to its complex structure and being composed entirely of metal components.

[0044] The tensile strength measured by direct tensile test is more accurate. However, during the bonding process, uneven adhesive layer thickness or non-parallelism of the two ends of the sample can easily lead to deviation between the axial load and the sample axis, resulting in additional bending moment and making the measured strength lower than the true value.

[0045] To address the issue of deviation between axial load and rock sample axis during rock bonding, this specification provides a bonding alignment device and operating method for direct tensile testing of rocks. This device can significantly reduce the deviation caused by axial load and sample axis, and more accurately measure the true tensile strength of the rock.

[0046] See Figure 1 As shown in the embodiments of this specification, an adhesive alignment device for direct tensile testing of rock is provided, which may include:

[0047] The clamp body may include a clamp head 1 and a clamp base 2, wherein the clamp head 1 and the clamp base 2 are connected by a connecting rod 16 and arranged coaxially;

[0048] A centering clamp is installed between the clamping head 1 and the clamping base 2, and can be used to clamp and center the rock sample 5 before bonding.

[0049] The centering clamp may include a circumferentially rotatable limiting plate and a plurality of radially oscillating blades. The limiting plate and the blades are linked and configured such that when the limiting plate rotates circumferentially, all the blades are driven to converge radially synchronously to clamp and align the axis of the rock sample 5 with the axis of the clamping plate body.

[0050] Specifically, the clamp body can be composed of a clamp head 1 and a clamp base 2, which are rigidly connected by a connecting rod 16. During the connection process, it is strictly ensured that the axes of the clamp head 1 and the clamp base 2 are completely coincident, thereby forming a stable coaxial foundation frame. The centering clamp is installed in the area between the clamp head 1 and the clamp base 2.

[0051] See Figure 2 As shown, its core components may include a limiting plate 10 that can rotate circumferentially around the device axis, and multiple blades 11 that can swing radially along the device. The limiting plate 10 and the blades 11 can be linked, establishing a power transmission relationship through a specific mating structure. When the operator drives the limiting plate 10 to rotate circumferentially, the limiting plate 10 transmits power to the blades 11, causing all blades 11 to synchronously converge radially towards the center of the device. The rock sample 5 can be placed within the clamping area of ​​the centering clamp. When the blades 11 converge synchronously, they form a uniform circumferential clamping force on the rock sample 5. Under the action of the clamping force, the axis of the rock sample 5 can be forcibly adjusted to be completely aligned with the axis of the clamping plate body, thus laying the foundation for subsequent bonding operations.

[0052] The aforementioned device establishes a stable and unified coaxial reference frame, resolving the axial misalignment problem caused by the lack of a clear alignment reference in existing technologies, thus ensuring alignment accuracy from the outset. Through the linkage design of the limiting plate and blades, the blades are synchronously radially converged, forming a uniform circumferential clamping force. This forces the rock sample axis to align with the main axis of the clamping plate, completely eliminating alignment deviations caused by asynchronous movements and uneven force distribution in traditional clamping methods. It effectively avoids the generation of additional bending moments, ensuring that the axial load in the direct tensile test is consistent with the sample axis, providing a core guarantee for measuring the true tensile strength of the rock.

[0053] In some embodiments, the circumferential rotation of the limiting plate 10 can be reversed to drive the blades 11 to spread out radially in sync, thereby releasing the clamped rock sample 5.

[0054] In some embodiments, the number of the above-mentioned connecting rods can be four. The four connecting rods are evenly distributed along the circumference of the clamp body and respectively connect the clamp head 1 to the centering clamp (which may include the centering clamp base 4) and the centering clamp to the clamp base 2, so that the clamp head 1, the centering clamp, and the clamp base 2 are coaxial.

[0055] Specifically, the number of connecting rods 16 can be set to 4. The 4 connecting rods 16 are evenly distributed on the same circumferential surface around the central axis of the clamp body at the same angular interval (e.g., the included angle between adjacent connecting rods is 90°). One end of the connecting rod 16 can be fixedly connected to the clamp head 1, and the other end can pass through the corresponding mounting holes of the centering clamp in sequence and be fixedly connected to the clamp base 2. Through the rigid constraint of the connecting rod, the clamp head 1, the centering clamp, and the clamp base 2 form an integral structure, and strictly ensure that the axes of the three are completely coincident.

[0056] The stability of the coaxial reference is further enhanced by four circumferentially evenly distributed connecting rods, avoiding structural deformation or axial misalignment that might be caused by a single or non-uniformly distributed connecting rod, thus ensuring the overall coaxiality accuracy of the device. The integrated coaxial connection of the clamping head, centering clamp, and clamping base keeps the relative positions of each component stable during the centering process, providing reliable structural support for the precise centering of rock samples and improving the overall rigidity and centering stability of the device.

[0057] In some embodiments, the above-mentioned centering clamp may further include a centering clamp base 4. The groove portion of the centering clamp base 4 is provided with a plurality of base blade fixing holes 13 evenly distributed in a ring. One end of the blade 11 is hinged to the base blade fixing hole 13 by a rivet 12, so that the blade 11 can make radial swing around the rivet 12 to converge or disperse.

[0058] In some embodiments, the above-mentioned centering clamp may further include a centering clamp cover plate 9, which covers the limiting plate 10 and is used to protect and axially limit the limiting plate 10, the blade 11 and the rivet 12.

[0059] For details, please refer to Figure 2 and Figure 3As shown, the centering clamp can be composed of a centering clamp base 4, a centering clamp cover plate 9, a limiting plate 10, a limiting plate handle 17, blades 11, and rivets 12. The centering clamp base 4 has 12 evenly distributed annular base blade fixing holes 13 machined in its groove. These holes provide basic positioning fulcrums for the installation of the blades 11 and are the core support components for achieving the centering function of the entire device. Their evenly distributed annular layout ensures the symmetry and synchronization of the subsequent swinging of the blades 11. The rivets 12 are rotatably fitted with the blades 11 and the base blade fixing holes 13, allowing the blades 11 to perform radial swinging movements about the rivets 12 as the axis, either converging towards the center of the device or spreading outwards.

[0060] The working principle of the centering clamp is as follows: taking the annular positioning structure of the centering clamp base 4 as a reference, through the circumferential drive of the limiting plate 10 and with the help of the transmission action of the rivet 12, the rotational motion of the limiting plate 10 is converted into the synchronous radial gathering or dispersing action of the blades 11. By utilizing the synergistic clamping force of the 12 evenly distributed blades 11, the rock sample 5 is precisely aligned with the axis of the device, which can provide a reliable centering basis for subsequent bonding.

[0061] The articulated structure enables flexible radial oscillation of the blades and limits their movement trajectory, preventing blade deviation or jamming during movement. This ensures smooth blade convergence and divergence, further enhancing the reliability of centering operations.

[0062] The centering clamp cover 9 can be placed over the limiting plate 10, providing protection and axial restraint for internal components such as the limiting plate 10, blades 11, and rivets 12. This prevents axial movement of components during operation and ensures a stable relative position for each component. Simultaneously, the centering clamp cover 9 also provides effective protection, preventing external dust and impurities from entering the linkage mechanism, thus preventing component wear or jamming and extending the device's service life.

[0063] In some embodiments, the blade 11 can be an arc-shaped transmission component with a hinge hole 19 and a mating hole 20 at both ends. The hinge hole 19 is hinged to the base blade fixing hole 13 by a rivet 12. All the mating holes 20 ends of the blades 11 face the center of the device and are evenly distributed on the circumference.

[0064] For details, please refer to Figure 4 and Figure 5 As shown, the blade 11 can be an arc-shaped transmission component, with hinge holes 19 and mating holes 20 at both ends. Rivets 12 can be installed in the hinge holes 19 and mating holes 20. The hinge holes 19 and mating holes 20 are linked with the centering clamp base 4 and the limiting plate 10, respectively.

[0065] See Figure 6 and Figure 7 As shown, the blades 11 need to be hinged sequentially and in the same orientation along the circumference during installation: First, the hinge hole 19 of the first blade 11 can be hinged to the base blade fixing hole 13 through the rivet 12, allowing the blade to make radial swings around the rivet 12, "converging towards the center of the device and spreading outwards". Then, in the exact same orientation (ensuring that the swing direction and amplitude of all blades are synchronized), the hinge hole 19 of the second blade 11 is installed on the adjacent base blade fixing hole 13 through the rivet 12, and the second blade 11 is arranged in an orderly manner with the first blade 11 in the circumferential direction. The circumferential hinged installation of 12 blades 11 is completed in this way, so that the mating hole 20 end (linkage end) of all blades faces the center of the device and is evenly distributed on the circumference, forming an adjustable centering clamping structure. Among them, the rivet 12 plays a key role in connection and transmission. On the one hand, it hinges and fixes the blade 11 to the central clamp base 4. On the other hand, it serves as a transmission medium between the blade 11 and the limiting plate 10, transmitting the circumferential movement power of the limiting plate 10 to the blade 11.

[0066] The arc-shaped structure design increases the contact area between the blades and the rock sample, resulting in a more uniform clamping force. This prevents excessive local pressure from damaging the rock sample and improves clamping stability. The uniform distribution of the blade mating holes ensures that the power transmitted by the limiting plate is evenly applied to each blade, further guaranteeing the synchronicity and consistency of all blade movements and improving alignment accuracy.

[0067] In some embodiments, the limiting plate 10 is provided with a guide groove 18 corresponding to the number of blades. The guide groove 18 is slidably engaged with the rivet 12 at the mating hole 20 end of the blade 11. By rotating the limiting plate 10 in the circumferential direction, the guide groove 18 drives the rivet 12 to drive the blades 11 to synchronously converge or disperse radially.

[0068] For details, please refer to Figure 8As shown, the limiting plate 10 is provided with guide grooves 18 corresponding to the number of blades 11. The guide grooves 18 cooperate with the rivets 12 at the linkage end of the blades 11. The linkage between the centering clamp base 4 and the limiting plate 10 is achieved through the transmission bridge formed by the blades 11 and the rivets 12. That is, the centering clamp base 4 can provide a fixed hinge fulcrum for the blades 11, and the limiting plate 10 converts the circumferential motion into the radial power of the blades 11 through the guide grooves 18. The core function of this linkage design is to convert a single circumferential operation into the synchronous radial action of 12 blades 11, avoiding the centering deviation caused by multi-point operation. When the limit plate handle 17 is operated to rotate in the circumferential direction, the side wall of the guide groove 18 will generate a radial thrust (displacement) on the mating rivet 12. The rivet 12, as a key connection and transmission medium, on the one hand, hinges and fixes the blade 11 on the central clamp base 4, and on the other hand, accurately transmits the circumferential movement power of the limit plate 10 to the blade 11, causing the blade 11 to swing synchronously radially around the blade fixing hole 13 of the base.

[0069] The guide groove structure enables precise power conversion from circumferential rotation to radial oscillation, ensuring that the movement of the limiting plate is efficiently and accurately transmitted to the blades, thus improving the transmission efficiency of the linkage mechanism. The sliding engagement between the guide groove and the rivet allows for bidirectional movement of the blades, enabling simultaneous convergence and divergence. This not only facilitates the placement and removal of rock samples but also adapts to rock samples of different diameters, expanding the applicability of the device.

[0070] In some embodiments, the above-mentioned device may further include a double-ended bolt 8, which can be used to connect the clamping head 1 to the upper pull head 3 of the tensile test, the lower pull head 7 of the tensile test and the clamping base 2, and the double-ended bolt 8 is adapted to pull heads of various sizes and specifications.

[0071] For details, please refer to Figure 9 As shown, both ends of the double-ended bolt 8 can be threaded, with the thread specifications designed to accommodate tensile test pull heads of various common sizes. One end of the thread can be connected to the threaded hole of the clamping head 1, and the other end can be fixedly connected to the upper pull head 3 of the tensile test. Similarly, one end of the other set of double-ended bolts 8 can be connected to the threaded hole of the clamping base 2, and the other end can be fixedly connected to the lower pull head 7 of the tensile test, thereby enabling the entire centering device to form a stable and coaxial connection with the pull head system of the direct tensile test.

[0072] The use of double-ended bolts ensures a stable coaxial connection between the clamping plate and the tensile test head, guaranteeing that the coaxial reference of the device aligns with the axis of the head system, further guaranteeing the alignment accuracy between the rock specimen and the head. The adaptability of the double-ended bolts allows them to be used with head sizes and specifications, enhancing the versatility and practicality of the device in various testing scenarios and reducing the adaptation costs of the testing equipment.

[0073] In some embodiments, the above-described device may further include a plate lifting adjustment device, which is connected to a centering clamp and can be used to drive the centering clamp to move along the axial direction of the clamping plate body to adjust the clamping position of the centering clamp.

[0074] In some embodiments, the above-mentioned plate lifting adjustment device may include a plate lifting adjustment device base 6, a rotating handle 14, and a plate lifting adjustment device bolt 15. The rotating handle 14 is connected to the plate lifting adjustment device bolt 15 in a transmission manner. The rotation of the rotating handle 14 drives the plate lifting adjustment device bolt 15 to move the centering clamp axially.

[0075] For details, please refer to Figure 10 and Figure 11 As shown, the plate lifting adjustment device bolt 15 can be rotated or fixed by rotating the handle 14, causing the plate lifting adjustment device to push the centering clamp device upward or downward, thus realizing the flexible movement of the centering clamp. The plate lifting adjustment device is connected to the bottom or side of the centering clamp, and its power output end contacts the centering clamp, applying an axial driving force to it. By operating the control component of the plate lifting adjustment device, the centering clamp can be driven to move up and down along the axis of the clamp body, thereby adjusting the axial position of the centering clamp between the clamp head 1 and the clamp base 2.

[0076] The aforementioned plate lifting and adjusting device can adjust the centering clamp to the optimal clamping position according to the actual conditions such as the length of the rock sample and the requirements of the bonding area, ensuring that the clamping point falls on the optimal centering area of ​​the rock sample, further improving the centering accuracy. At the same time, it enhances the operational flexibility and adaptability of the device, enabling it to meet the centering requirements of rock samples of different specifications and expanding the application range of the device.

[0077] In some embodiments, the number of plate lifting adjustment devices can be four. The centering clamp can be moved by the four plate lifting adjustment devices to clamp the rock sample 5 in the optimal position so as to better adhere the rock sample 5.

[0078] The bonding and alignment device described above for direct tensile testing of rocks can achieve the following technical effects:

[0079] (1) The centering clamp, with the mechanical structure of “blade circumferential hinge + limit plate guide groove linkage”, can accurately achieve zero deviation centering between the rock specimen and the pull head axis, and completely eliminate the problem of eccentric force caused by traditional manual bonding.

[0080] (2) The clamping head not only compresses the rock sample, but also compacts it during the adhesive application stage, keeping the bonding surface flat and further avoiding eccentric stress caused by uneven bonding surface.

[0081] (3) The double-headed bolt connection can be adapted to various sizes of pull heads, which improves the universality of the device in different test scenarios.

[0082] (4) The plate lifting and adjusting device can flexibly control the axial position of the centering clamp, which is convenient to adjust to the best clamping position according to the rock size, bonding requirements, etc., enhancing the operational flexibility and adaptability of the device, and better centering the rock sample.

[0083] See Figure 12 As shown in the embodiments of this specification, a method for bonding alignment in direct tensile testing of rock is also provided. This method, using the above-described apparatus, may include the following steps:

[0084] S1201: Connect the clamping head of the clamping plate body to the clamping plate base through a connecting rod, so that the clamping head and the clamping plate base are arranged coaxially;

[0085] S1202: The centering clamp is installed between the clamping head and the clamping base. The centering clamp includes a limiting plate and multiple blades. The limiting plate and the blades are linked together.

[0086] S1203: Place the rock sample in the clamping area of ​​the centering clamp, rotate the limiting plate circumferentially, drive all blades to converge radially synchronously, clamp the rock sample and align the axis of the rock sample with the axis of the clamping plate body.

[0087] S1204: The clamping head is connected and fixed to the upper pull head of the tensile test and the lower pull head of the tensile test is connected to the clamping base by double-ended bolts;

[0088] S1205: Apply adhesive to the corresponding bonding areas of the rock sample and the upper and lower pull heads, keep the centering clamp in the centered state until the adhesive cures, and complete the coaxial bonding of the rock sample and the pull head.

[0089] In some embodiments, adhesive can be applied to the mating surfaces of the clamping plate body and the pull head, and the clamping head can be used to compact the bonding surfaces, maintaining the centered clamping state of the centered clamp until the adhesive is cured, thereby completing the coaxial bonding of the rock sample and the pull head.

[0090] Specifically, during the device assembly stage: the clamping head 1 of the clamping plate body and the clamping plate base 2 can be connected by the connecting rod 16. During the connection process, the axes of the two are strictly calibrated to ensure that the clamping head 1 and the clamping plate base 2 are arranged coaxially, thus completing the construction of the basic frame of the device.

[0091] Centering clamp installation stage: The centering clamp can be installed as a whole in the preset position between the clamping head 1 and the clamping base 2, ensuring that the linkage structure between the limiting plate 10 of the centering clamp and the multiple blades 11 is properly assembled, so as to achieve smooth power transmission.

[0092] Rock specimen alignment stage: The rock specimen 5 to be tested is placed stably in the clamping area of ​​the centering clamp. The operator manually or through the drive mechanism rotates the limiting plate 10 circumferentially. Under the action of the linkage structure, all blades 11 are driven to converge radially towards the center until the blades 11 are in close contact with the surface of the rock specimen 5. At this time, the axis of the rock specimen 11 is precisely aligned with the axis of the clamping plate body.

[0093] Pull head connection stage: The clamping head 1 is connected and fixed to the upper pull head 3 of the tensile test and the lower pull head 7 of the tensile test to the clamping base 2 by double-ended bolts 8. During the connection process, ensure that the connection is firm and that the axis of the pull head is consistent with the axis of the clamping body.

[0094] Bonding and curing stage: Apply a suitable adhesive evenly to the corresponding bonding parts of the rock sample 5 and the upper pull head 3 and lower pull head 7, as well as the mating surface of the clamp body and the pull head. Use the clamp head to compact the bonding surface. During the application process, keep the centering clamp on the rock sample 5 to prevent the rock sample 5 from shifting. Continue until the adhesive is completely cured, and the coaxial bonding between the rock sample 5 and the pull head is completed. Then, the direct tensile test can be performed.

[0095] The above method strictly follows the logical process of "benchmark establishment - centering adjustment - fixed bonding," fully translating the structural advantages of the device into practical operational results. This ensures that each step guarantees the final centering accuracy. Standardized operating procedures avoid the randomness and uncertainty of manual operation, ensuring consistent centering results for different operators and in different testing scenarios, thus improving the repeatability and reliability of test results. Simultaneously, it achieves precise coaxial bonding between the rock sample and the test head, completely solving the problem of axial misalignment in traditional bonding methods. This ensures that direct tensile tests can be conducted under eccentric loading conditions, and the final measured rock tensile strength data accurately reflects the actual properties of the rock, providing precise data support for engineering operations.

[0096] The present invention will be described in detail below with reference to embodiments, but is not limited thereto. It mainly includes the following steps:

[0097] (1) Establishment of overall connection and axial reference of the device

[0098] 1) The clamping head 1, clamping base 2 and centering clamp are connected by four connecting rods 16. The positioning effect of the connecting rods 16 ensures that the clamping head 1, clamping base 2 and centering clamp are arranged coaxially after assembly, providing a unified axial reference for the subsequent centering of rock or rock sample 5.

[0099] 2) Connect the clamping head 1 to the upper pull head 3 of the test equipment by means of double-headed bolts 8, and connect the clamping base 2 to the lower pull head 7 of the test equipment, so that the entire centering device and the pull head system of the direct tensile test form a stable and coaxial connection relationship.

[0100] (2) Assembly of the internal blades of the centering clamp

[0101] Install the internal blades 11 on the centering clamp to achieve subsequent radial clamping and centering of the rock sample 5:

[0102] 1) Take the first blade 11 and hinge its end with the hinge hole to the base blade fixing hole 13 in the groove of the centrally located clamp base 4 via a rivet 12. This ensures that the blade 11 can make radial swings around the rivet 12, "converging towards the center of the device and spreading outwards". This makes the radial swing of the blade around the rivet centered on the fixed hinge point, providing a "unified motion reference" for the coordinated movement of the 12 blades 11. After the subsequent 11 blades 11 are installed in the same orientation, the swing trajectories of all blades 11 are symmetrically distributed around the axis of the device.

[0103] 2) Following the same orientation as the first blade 11 (ensuring that the swing direction and amplitude of all blades 11 are synchronized), install the hinge holes of the remaining 11 blades 11 sequentially on the base blade fixing holes 13 adjacent to the central clamp base 4 through rivets 12, so that the 12 blades 11 are arranged in an orderly and symmetrical manner in the circumferential direction, and the "fitting hole end (linkage end)" of all blades 11 are facing the center of the device.

[0104] 3) Insert the guide grooves 18 on the limiting plate 10, which correspond to the number of blades 11, into the rivets 12 at the linkage end of the blades 11 one by one. Then cover the center clamp cover plate 9 to protect and axially limit the internal components such as the limiting plate 10 and blades 11, and ensure that the relative positions of each component are stable in subsequent operation.

[0105] (3) Adjust the axial position of the centering clamp (application of the plate lifting adjustment device)

[0106] The operating plate lifting and adjusting device is used to adjust the position of the centering clamp in the axial direction to adapt to the clamping requirements of the rock:

[0107] 1) Rotate the rotating handle 14 of the plate lifting adjustment device. Rotating the handle 14 drives the bolt 15 of the plate lifting adjustment device to rotate, so that the plate lifting adjustment device moves up or down along the axis, thereby pushing the centering clamp to move axially synchronously.

[0108] 2) Continue adjusting until the center clamp reaches the position where the rock sample 5 can be optimally clamped (this position must ensure that the axis of the rock sample 5 is most aligned with the axis of the clamp body and the upper and lower pull heads after installation).

[0109] (4) Centering operation of rock specimens

[0110] After placing the rock sample 5 to be tested in the center area of ​​the centering holder, centering is achieved through the linkage of the blades 11:

[0111] 1) Rotate the limit plate handle 17 to make the limit plate 10 rotate in the circumferential direction. Since the guide groove 18 of the limit plate 10 is tightly engaged with the rivet 12 at the linkage end of the blade 11, the circumferential displacement of the guide groove 18 will drive the rivet 12 to move synchronously.

[0112] 2) The displacement of rivet 12 further pulls blade 11 to make radial synchronous swing around its hinge point on the centering clamp base 4. As the rotation continues, the 12 blades 11 will gradually converge towards the center of the rock specimen, and finally clamp the rock specimen 5 precisely, so that the axis of the rock specimen 5 is completely aligned with the axis of the clamp body and the upper and lower pull heads, thus completing the centering.

[0113] (5) Bonding and fixing of rock samples

[0114] 1) Apply a suitable adhesive to the mating surfaces of the clamping head 1 and the upper pull head 3, and the mating surfaces of the clamping base 2 and the lower pull head 7. Utilize the structure of the clamping head 1 to compact the applied adhesive, ensuring that the adhesive is evenly and smoothly distributed in these mating surface areas, thus providing a smooth and sufficient bonding foundation for the subsequent bonding of the rock sample 5 to the pull head.

[0115] 2) Apply the same adhesive to the corresponding bonding areas of the rock sample 5 and the upper pull head 3 and lower pull head 7, and keep the centering clamp holding the rock sample 5 in a centered clamping state (ensure that the axis of the rock sample 5 is precisely aligned with the axis of the clamping plate body and the upper and lower pull heads). At the same time, with the clamping action of the clamping plate pressure head 1 on the overall structure, the adhesive is assisted to be evenly adhered between the rock sample 5 and the upper pull head 3 and lower pull head 7 until the adhesive is completely cured, so that the rock sample 5 is firmly connected to the upper pull head 3 and lower pull head 7 and the axis is aligned. At this time, the subsequent direct tensile test can be carried out.

[0116] The above-mentioned device and operating method can ensure that the tensioning head is completely aligned with the rock axis during the bonding process, thereby achieving a more accurate direct tensile test and thus measuring the true tensile strength of the rock.

[0117] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, system embodiments are basically similar to method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0118] The above description is merely an embodiment of the present specification and is not intended to limit the embodiments of the present specification. For those skilled in the art, various modifications and variations can be made to the embodiments of the present specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the embodiments of the present specification should be included within the scope of the claims of the embodiments of the present specification.

Claims

1. A bonding alignment device for direct tensile testing of rock, characterized in that, include: The clamp body includes a clamp head and a clamp base, wherein the clamp head and the clamp base are connected by a connecting rod and arranged coaxially; A centering clamp is installed between the clamping head and the clamping base to clamp and center the rock sample before bonding. The centering clamp includes a circumferentially rotatable limiting plate and multiple radially oscillating blades. The limiting plate and the blades are linked and configured so that when the limiting plate rotates circumferentially, all the blades are driven to converge radially synchronously to clamp and align the axis of the rock sample with the axis of the clamping plate body.

2. The apparatus according to claim 1, characterized in that, The number of connecting rods is 4. The 4 connecting rods are evenly distributed along the circumference of the clamp body and respectively connect the clamp head to the centering clamp and the centering clamp to the clamp base, so that the clamp head, the centering clamp and the clamp base are coaxial.

3. The apparatus according to claim 1, characterized in that, The centering clamp also includes a centering clamp base. The groove of the centering clamp base is provided with a plurality of base blade fixing holes evenly distributed in a ring. One end of the blade is hinged to the base blade fixing hole by a rivet, so that the blade can swing radially around the rivet, either converging or diverging.

4. The apparatus according to claim 1, characterized in that, The centering clamp also includes a centering clamp cover plate, which covers the limiting plate and is used to protect and axially limit the limiting plate, blades and rivets.

5. The apparatus according to claim 1, characterized in that, The blade is an arc-shaped transmission component with a hinge hole and a mating hole at each end. The hinge hole is hinged to the blade fixing hole of the base by a rivet. All mating holes of the blades face the center of the device and are evenly distributed on the circumference.

6. The apparatus according to claim 1, characterized in that, The limiting plate is provided with guide grooves corresponding to the number of blades. The guide grooves slide with the rivets at the mating holes of the blades. By rotating the limiting plate in the circumferential direction, the guide grooves drive the rivets to drive the blades to synchronously converge or disperse radially.

7. The apparatus according to claim 1, characterized in that, The device also includes a double-ended bolt, which is used to connect the clamping head to the upper pull head of the tensile test, the lower pull head of the tensile test, and the clamping base. The double-ended bolt is compatible with pull heads of various sizes and specifications.

8. The apparatus according to claim 1, characterized in that, The device also includes a plate lifting and adjusting device, which is connected to the centering clamp and is used to drive the centering clamp to move along the axis of the clamping plate body to adjust the clamping position of the centering clamp.

9. The apparatus according to claim 8, characterized in that, The plate lifting and adjusting device includes a plate lifting and adjusting device base, a rotating handle, and a plate lifting and adjusting device bolt. The rotating handle is connected to the plate lifting and adjusting device bolt in a transmission manner. The rotation of the rotating handle drives the plate lifting and adjusting device bolt to move the centering clamp axially.

10. A method for bonding alignment in direct tensile testing of rock, characterized in that, Using the apparatus as described in any one of claims 1-9 includes the following steps: The clamping head of the clamping plate body is connected to the clamping plate base through a connecting rod, so that the clamping head and the clamping plate base are arranged coaxially. A centering clamp is installed between the clamping head and the clamping base. The centering clamp includes a limiting plate and multiple blades. The limiting plate and the blades are configured in a linkage manner. Place the rock sample in the clamping area of ​​the central clamp, rotate the limiting plate circumferentially, drive all blades to converge radially synchronously, clamp the rock sample and align the axis of the rock sample with the axis of the clamp body. The clamping head is connected and fixed to the upper pull head of the tensile test and the lower pull head of the tensile test is connected to the clamping base by double-ended bolts. Apply adhesive to the corresponding bonding areas of the rock sample and the upper and lower pull heads, keep the centering clamp in the centered state, and continue until the adhesive cures to complete the coaxial bonding of the rock sample and the pull head.

Images