Tool structure and test method for anchoring fractured rock mass tension-shear-torsion sample

Abstract

The invention provides a tool structure and a test method for anchoring a fractured rock mass tension-shear-torsion sample, and belongs to the technical field of performance testing of new anchoring materials. The sample comprises a tension-torsion block, a shearing block and an anchor rod structure, the tension-torsion block is in a cuboid shape, a center shaft of the tension-torsion block is provided with a through drill hole, the hole wall is provided with a spiral groove, the shearing block is in a cuboid shape, the surface of the shearing block is provided with two grooves, and the depths and the widths of the grooves are equal. And the anchor rod structure is fixed on the tension-torsion block and the shearing block in an anchoring manner to form an anchored fractured rock mass tension-shear-torsion sample. A tool assembly matched with the structure of a sample is adopted, the sample is installed on a testing machine to be subjected to a tension-shear-torsion synchronous loading test, and key parameters such as a tensile load, a tensile displacement, a shear load, a shear displacement, a torsion load and a torsion angle can be recorded in real time. The test method ensures that the sample can simultaneously bear loads in all directions in the loading process, and interference and mutual influence between the loads are effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of performance testing of new anchoring materials, and particularly provides a tooling structure and a test method for a tensile-shear-torsion specimen of an anchored fractured rock mass. Background Art

[0002] As an important rock mass reinforcement method, the bolt technology has been widely applied in engineering practice. In the field of fractured rock mass anchoring, due to the complex structure and uneven mechanical properties of fractured rock masses, they often exhibit characteristics such as low strength, large deformation, and discontinuity, posing great challenges to engineering stability. Given that the initial displacement of rock blocks in fractured rock masses occurs along the joint fissure surface, the initial stress on bolts is mainly tensile and shear. Once the joint fissure opens, the frictional resistance on the fissure surface disappears, and in this case, the rock block may rotate around the bolt axis. Especially when the surrounding rock of the roadway (tunnel) is extremely loose, the possibility of rock block torsion is greater. Therefore, on the basis of tensile-shear loads, the rock block torsion adds a torsional load to the bolt, and the bolt will bear the combined loading conditions of tension, shear, and torsion, and torsional shear stress will also be generated at the anchoring interface.

[0003] Conducting tensile-shear-torsion performance testing on bolts anchored in fractured rock masses to evaluate the interaction and bearing performance between rock masses and anchoring components (such as bolts, cables, etc.) in rock mass engineering has important guiding significance for engineering design and construction in multiple fields such as tunnels, mine exploitation, and underground energy storage. Such testing can reveal the mechanical behavior of anchored fractured rock masses under stress conditions, especially the deformation and failure mechanisms under different degrees of tensile, shear, and torsional forces. Traditional pull-out tests and shear tests have conducted certain research on the evaluation of the interaction between bolts and surrounding rocks, but these tests are usually carried out under unidirectional stress, while rock masses and bolts in actual engineering often bear combined stress actions (tension, shear, torsion). Therefore, tensile-shear-torsion performance testing can more realistically simulate the behavior of anchored rock masses under complex stress conditions, reveal their contact, slip, deformation, and failure mechanisms under different stress states, and provide a more accurate basis for the research and development of new material bolts, performance evaluation, and anchoring design.

[0004] The synchronous application of tensile, shear, and torsional loads requires a triaxial loading device to simultaneously apply three different forces (tensile force, shear force, and torsional force) in the same test. This design requires the loading device to be able to independently control the forces in each direction and reduce the mutual interference between the forces. For example, servo loading systems in different directions are used to apply tensile force, shear force, and torsional force respectively to ensure the controllability and accuracy of the test. In the prior art, Chinese Patent (CN115711809A) provides a test system for the anchoring performance of full-scale rock bolts under combined loads. This test system consists of a tensile loading device, a shear loading device, and a torsional loading device to form a triaxial loading system, which can provide triaxial loads to the anchoring specimen. However, in the prior art, the structural form and tooling method of the anchoring rock mass tensile-shear-torsion specimen are not clearly proposed, nor can a clear operation process for the tensile-shear-torsion test method be provided. The main reason is that there is a certain contradiction and restrictive relationship between the tensile-shear-torsional loading method and the corresponding constraint conditions, and a unique design of the specimen's structural form is required to facilitate the application of various combined loads at the rock mass fracture site. Such tests have high requirements for the design of the anchoring fractured rock mass specimen, the loading function of the test device, and the assembly requirements. Each part needs to cooperate coordinately to ensure the accuracy of the test results. Therefore, the tooling design and test method of the anchoring fractured rock mass tensile-shear-torsion specimen should be further improved. Summary of the Invention

[0005] In order to test the anchoring performance of rock bolts in fractured rock masses under tensile-shear-torsional loading conditions, enable the rock bolts at the rock mass fracture surface to simultaneously bear the loads in each direction, and effectively avoid the interference and mutual influence between the loads, the present invention provides a tooling structure and test method for an anchoring fractured rock mass tensile-shear-torsion specimen, and the specific technical solutions are as follows.

[0006] A tooling structure for an anchoring fractured rock mass tensile-shear-torsion specimen includes a tensile-torsion block, a shear block, and an anchor bolt structure. The anchor bolt structure includes an anchor bolt, a tray, a nut, etc. The structural form of the tensile-torsion block is a cuboid plus a circular boss block. A through-hole is provided on the central axis of the tensile-torsion block, and a spiral groove is provided on the hole wall. The boss of the tensile-torsion block is frustum-shaped, and an annular groove is provided at the end edge; the shear block is a cuboid and is provided with two grooves, and the depth and width of the grooves are equal. The anchor bolt structure is anchored on the tensile-torsion block and the shear block.

[0007] Preferably, the length of the anchor bolt of the anchor bolt structure is greater than the sum of the lengths of the tensile-torsion block and the shear block. A tray and a nut are installed at the exposed end of the anchor bolt, and the tray is pressed on the tensile-torsion block.

[0008] Preferably, the cross-section of the main block is square, the length is greater than the side length of the cross-section, the cross-sectional area of the frustum block is smaller than that of the main block; the length of the shear block is equal to the length of the tensile-torsion block.

[0009] Preferably, the depth and width of the groove are less than the height of the shear block, and the length of the groove is equal to the side length of the cross-section of the shear block.

[0010] A manufacturing method of an anchoring fissured rock mass tensile-shear-torsion sample tooling structure, using the rock mass sample of the above-mentioned anchoring fissured rock mass tensile-shear-torsion sample tooling structure, the method steps include: after the materials are stirred evenly, pour them into the mold, insert the steel pipe wound with wool yarn into the tail of the prefabricated drill hole, manufacture the tensile-torsion block and the shear block, inject the anchoring agent into the prefabricated drill hole, and insert the anchor rod and then let it stand.

[0011] A test method for anchoring fissured rock mass tensile-shear-torsion, using the sample of the above-mentioned anchoring fissured rock mass tensile-shear-torsion sample tooling structure, the method steps include: put the rock sample into the interior of the testing machine and connect the rock sample with the testing machine; the testing machine loads the rock sample, and monitors and records the pull-out displacement, torsion angle, shear displacement, pull-out load, torsion load, and shear load.

[0012] Further preferably, the tooling components of the fissured rock mass anchoring sample and the testing machine include a rock sample pulling plate, a connecting plate, a pulling plate, a rock mass fixing plate, a specimen protection ring, an anti-wear sleeve group, a rock sample protection plate, a shear rock mass baffle, a bearing plate, a fixing plate, a rock mass pulling and connecting plate, and an anti-rotation plate. The rock sample pulling plate, the pulling plate, the connecting plate, the pulling plate, the rock mass fixing plate, the specimen protection ring, and the anti-wear sleeve group are installed on the tensile-torsion block. The rock sample pulling plate is arranged on both sides of the main block body, and both ends of the rock sample pulling plate are respectively connected with the rock mass pulling and connecting plate and the fixing plate; there are two rock sample pulling plates, and there are two pulling plates on the side surface of the rock sample pulling plate. There are two threaded holes at each end of the pulling plate, and the threaded holes at one end are arranged in the guide rail. The two pulling plates clamp and fix the rock sample pulling plate through a connecting plate; the specimen protection ring is installed on the round table of the tensile-torsion block. One end of the specimen protection ring is matched with the groove at the end of the round table, and the other end is provided with a circumferential groove; the inner side of the pulling plate is matched with the groove.

[0013] Further preferably, the anti-wear sleeve group has two shapes, circular and semi-circular. The circular anti-wear sleeve group is installed on the outside of the specimen protection ring, and the semi-circular anti-wear sleeve group is arranged between the specimen protection ring and the specimen bearing plate. The outer surface of the anti-wear sleeve group is provided with a plurality of rolling steel balls.

[0014] Further preferably, the rock sample protection plate and the shear rock mass baffle are installed on the shear block. One side of the rock sample protection plate is matched with the groove of the shear block, and the other side is connected with the anti-rotation plate; the two shear rock mass baffles are connected through the rock sample protection plates on both sides, and four rock sample protection plates are respectively arranged at the middle and rear ends of the rock mass sample and are connected end to end.

[0015] Further preferably, two rock mass pulling connection plates are provided. One end of each rock mass pulling connection plate is connected to the co-directional tension-torsion loading mechanism of the testing machine, and the other end is connected to the rock sample pulling plate. Two fixing plates are provided. One side of each fixing plate is fixed on the inner frame of the testing machine, and the other sides jointly fix the sample bearing plate. There is a U-shaped groove in the middle of the sample bearing plate. The bottom end of the U-shaped groove is semi-circular and has a diameter larger than that of the anti-wear sleeve group. A row of vertically arranged anti-wear rollers is provided on each side surface of the two sides of the U-shaped groove. There are threaded holes on the outside of the anti-wear rollers for installing anti-rotation plates, and drill holes are provided on the anti-rotation plates.

[0016] The beneficial effects of a rock mass sample and method for testing the tensile-shear-torsion anchoring performance of bolts in fractured rock masses provided by the present invention include:

[0017] (1) The structural form and tooling method of the anchored fractured rock mass sample are clarified, and three types of loads (tensile force, shear force, and torque) can be synchronously applied in the same test, so as to more realistically simulate the interaction between the rock mass and the anchoring component in actual engineering, especially the mechanical behavior of fractured rock masses under complex stress conditions.

[0018] (2) Different from the existing anchored rock mass samples, especially in the structure of the test piece, through the specially designed external assembly components of the sample and the assembly method of the components, the sample can evenly bear the loads in all directions during the stress process, effectively avoid the mutual influence between the loads, reduce the generation of interference loads, and at the same time make the test assembly, loading, and operation more convenient and reliable, providing technical support for subsequent related research and engineering applications.

[0019] (3) By improving the design of the assembly and manufacturing process of the anchored rock mass sample and optimizing the structure of the sample, the good cooperation between the sample and the experimental equipment is ensured, and the test accuracy is improved. The tooling optimization of the sample structure and the loading device makes the loading of the fractured rock mass anchoring sample more accurate, and can better monitor and record relevant test parameters, such as tensile displacement, shear displacement, torsion angle, etc. Description of the Drawings

[0020] Figure 1 is a schematic diagram of the tooling structure of the tensile-shear-torsion sample of the anchored fractured rock mass;

[0021] Figure 2 is a schematic diagram of the protective ring structure of the test piece;

[0022] Figure 3 is a cross-sectional view of the assembly of the protective ring and the rock sample;

[0023] Figure 4 is a schematic diagram of the loading structure of the rock mass sample;

[0024] Figure 5 is Figure 4 bottom view of

[0025] Figure 6 is Figure 5 The schematic diagram of the A-A cross-section in

[0026] Figure 7 is Figure 5 The schematic diagram of the B-B cross-section in

[0027] Figure 8 The schematic diagram of the pull-shear-torsion performance test system and specimen assembly

[0028] Figure 9 The schematic diagram of the pull-torsion block die

[0029] Figure 10 is Figure 9 The side sectional view of

[0030] Figure 11 The schematic diagram of the shear block die

[0031] Figure 12 is Figure 11 The side sectional view of

[0032] In the figure: 1 - pull-torsion type rock mass block; 2 - shear type rock mass block; 3 - anchor bolt; 4 - nut; 5 - tray; 6 - rock mass pulling connection plate; 7 - rock sample pulling plate; 8 - fixing plate; 9 - anti-rotation plate; 10 - shear rock mass baffle; 11 - rock sample protection plate; 12 - specimen bearing plate; 13 - pulling plate; 14 - wear-reducing sleeve set; 15 - connecting plate; 16 - pulling plate; 17 - anti-wear roller; 18 - sample protection ring; 19 - inner frame; 20 - shear plate. Specific implementation manners

[0033] Combined with Figures 1 to 12 shown, the specific implementation manners of a tooling structure and test method for an anchored fractured rock mass pull-shear-torsion specimen provided by the present invention are described.

[0034] A tooling structure for anchoring a tensile, shear and torsion specimen of a fractured rock mass comprises a tensile and torsion block, a shear block and an anchor structure. The anchor structure comprises an anchor, a tray and a nut. The tensile and torsion block comprises a main block and a truncated cone block. A through-drilling hole is arranged on the central axis of the tensile and torsion block and a spiral groove is arranged on the hole wall. The main block is a rectangular parallelepiped. The truncated cone block is truncated cone-shaped and an annular groove is arranged on the end edge. The shear block is a rectangular parallelepiped and is provided with two grooves. The depth and width of the grooves are equal. The anchor structure is anchored on the tensile and torsion block and the shear block. The anchor length of the anchor structure is greater than the sum of the lengths of the tensile and torsion block and the shear block. A tray and a nut are installed on the exposed end of the anchor. The tray is pressed on the tensile and torsion block. A drilling hole is arranged in the center of the tensile and torsion block that passes through the entire block in the height direction. A spiral groove is prefabricated on the wall of the drilling hole. The diameter and pitch of the groove are adjustable. The cross section of the main block is square, the length is greater than the side length of the cross section, and the height is slightly greater than the length and width. The cross-sectional area of ​​the truncated cone block is smaller than that of the main block. An annular groove is arranged on the end edge of the truncated cone. The length of the shear block is equal to the length of the tensile and torsion block. The depth and width of the groove are equal and much smaller than the height of the shear block, and the length of the groove is equal to the side length of the cross section of the shear block. The function of the shear block is to realize the application of shear load on the anchored rock mass. The shear block is a rectangular concrete block with two grooves, its cross section is a square, and its height is equal to the height of the tension and torsion block.

[0035] A method for making a tooling structure for anchoring a tensile, shear and torsion specimen of a fractured rock mass, using a rock mass specimen of the above-mentioned tooling structure for anchoring a tensile, shear and torsion specimen of a fractured rock mass, the method comprises the following steps: after the material is stirred evenly, pouring it into a mold, inserting a steel pipe with wool wrapped in a spiral into the tail of a prefabricated borehole, making a tensile and torsion block and a shear block, injecting an anchoring agent into the prefabricated borehole, inserting an anchor rod and letting it stand. Since the length of the anchor rod is greater than the sum of the lengths of the two rock mass blocks, the protruding end of the anchor rod is located outside the tensile and torsion rock mass block. A tray is installed at the protruding end of the anchor rod, the tray is in close contact with the tensile and torsion rock mass block, and is reinforced by a nut.

[0036] The improvement of the shape and structure of the rock specimens has made the anchored rock specimens perfectly combined with the corresponding three-way loading system, which can independently control the loads in each axis, reduce the mutual interference between loads in different directions, and ensure the controllability and accuracy of the test. In particular, the structure of the anchored fractured rock specimens makes the test assembly, loading and operation more convenient and reliable, providing technical support for subsequent related research and engineering applications.

[0037] The specific steps for making rock samples are as follows:

[0038] S1. Make rock-like blocks

[0039] The basic materials required for making the specimen are mixed in a certain ratio and stirred thoroughly. Then the stirred materials are poured into a mold of corresponding size and inserted into a steel pipe with a pre-drilled hole and external spirally wrapped with wool. After standing for a period of time, the steel pipe is taken out, the mold is disassembled, and the specimen is cured for a period of time.

[0040] S2. Fabricate the anchored rock mass

[0041] Arrange the taken-out shear-type rock mass blocks and pull-torsion type rock mass blocks vertically, with the pull-torsion type rock mass blocks on top and the shear-type rock mass blocks at the bottom. Align the drill holes and prefabricate fractures between the two rock masses. Inject anchoring agent (such as cement) into the drill holes at the top of the specimen and let it flow down along the drill holes. After filling, insert the anchor bolts and let it stand for more than seven days.

[0042] S3. Assemble the specimen

[0043] First, install the accessory part of the testing machine on the testing machine. Then, assemble the components of the pull-torsion block and shear block except for the rock mass blocks on the specimen. Finally, use a crane to place the specimen inside the testing machine and connect the specimen to the testing machine. At the same time, the middle part of the specimen contacts the components of the accessory part of the testing machine to bear the gravity of the specimen and avoid excessive friction at the connection between the testing machine and the specimen.

[0044] S4. Loading and recording

[0045] Through the servo control system supporting the testing machine, load the specimen according to the loading requirements, and at the same time monitor and record the test-related parameters, such as pull-out displacement, torsion angle, shear displacement, pull-out load, torsion load, shear load, etc. In addition, for convenient monitoring, pressure sensors and extensometers can also be connected to measure the local displacement and load.

[0046] A test method for tension, shear and torsion of anchored fractured rock mass, using the above-mentioned specimen of the tension, shear and torsion specimen fixture structure of anchored fractured rock mass, the method steps include: placing the rock specimen into the testing machine, connecting the rock specimen and the testing machine; the testing machine loads the rock specimen, monitors and records test parameters such as pull-out displacement, torsion angle, shear displacement, pull-out load, torsion load, shear load, etc. Among them, the testing machine includes a rock sample pull plate, a pull plate, a connecting plate, a pull plate, a rock mass fixing plate, a specimen protection ring, an anti-wear set, a rock sample protection plate, a shear rock mass baffle, a bearing plate, a fixing plate, a rock mass pull-out connecting plate and an anti-rotation plate. The rock sample pull plate, the pull plate, the connecting plate, the pull plate, the rock mass fixing plate, the specimen protection ring and the anti-wear set are installed on the pull-torsion block, the rock sample pull plate is arranged on both sides of the main block, and the two ends of the rock sample pull plate are respectively connected to the rock mass pull-out connecting plate and the fixing plate. There are two rock sample pull plates, and two pull plates are arranged on the side of the rock sample pull plate. The rock is fixed by the front and rear rock sample pull plates 7. However, since the size of the tension-torsion rock block 1 may not be completely consistent with the space between the rock sample pull plates 7 during production, the rock sample pull plates cannot completely fix the rock. Therefore, it is necessary to install a pull plate 13 on each side of the tension-torsion rock block 1 to limit the displacement of the rock block 1 parallel to the rock sample pull plate 7, so as to prevent the rock sample pull plate from loosening and causing the tension-torsion rock block 1 to slip out. The rock sample pull plate 7 is connected to the pull plate 16. When loading, the pull plate 16 transfers the axial tensile load of the testing machine to the tension-torsion block, and is the direct force-applying component of the specimen. There are two threaded holes at each end of the pull plate, and the threaded hole at one end is set in the guide rail. The two pull plates clamp and fix the rock sample pull plates through a connecting plate to ensure that the rock moves along the loading direction. The sample protection ring is installed on the truncated cone of the tension-torsion block. One end of the sample protection ring matches the groove at the end of the truncated cone, and the other end is provided with an annular groove. When loading, the secondary truncated cone of the tension-torsion rock mass block 1 and the rear main block are subjected to a relatively uniform force, which avoids the fracture of the junction between the secondary truncated cone and the main block due to stress concentration during loading. The inner side of the drawing plate matches the groove.

[0047] The specimen protection ring 18 is made of hard material, which can prevent the round balls on the surface of the anti-wear set 14 from being embedded in the rock specimen during the test and causing damage to the specimen. The anti-wear set has two shapes: circular and semi-circular. The circular anti-wear set is installed on the outside of the specimen protection ring, and the semi-circular anti-wear set is arranged between the specimen protection ring and the specimen bearing plate. The outer surface of the anti-wear set is provided with a plurality of rolling steel balls, which roll in any direction. The semi-circular anti-wear set can be directly placed on the specimen bearing plate 12, which is more convenient to use; when conducting tests involving torsion, a circular anti-wear set must be used, which has the advantage of protecting the specimen at all angles and is not limited by the torsion angle.

[0048] The rock sample protection plate and the shear rock baffle are installed on the shear block. One side of the rock sample protection plate cooperates with the groove of the shear block, and the other side is connected to the anti-rotation plate. The two shear rock baffles are connected through the rock sample protection plates on both sides, and four rock sample protection plates connected end to end are respectively arranged at the middle and rear end of the rock sample. The lower side of the shear block is suspended in the air, and a shear rock baffle 10 is respectively installed on both sides close to one end of the specimen bearing plate 12, which contacts the anti-rotation plates 9 on both sides to ensure that when a torsional load is applied to the left end of the testing machine, the tension and shear blocks cannot rotate together. The two shear rock baffles 10 are connected and fixed by the upper and lower rock sample protection plates 11. At the same time, four rock sample protection plates 11 are respectively installed in the middle and rear end of the shear rock block 2 to prevent local damage to the rock block and uneven force when the testing machine applies a load to the upper side of the shear block.

[0049] Two rock pull-out connecting plates are provided, one end of which is connected to the same-direction tension-torsion loading mechanism of the testing machine, and the other end is connected to the rock sample pulling plate. Two fixed plates are provided, one side of which is fixed to the inner frame of the testing machine, and the other side is used to fix the sample bearing plate. There is a U-shaped groove in the middle of the sample bearing plate, the bottom of which is semicircular and has a diameter slightly larger than the anti-wear set. A row of vertically arranged anti-wear rollers are provided on the sides of both sides of the U-shaped groove, and threaded holes are provided on the outer side of the anti-wear rollers for installing the anti-rotation plate. Drill holes are provided on the anti-rotation plate, and the drill holes are elliptical, which can cause a slight displacement in the horizontal direction.

[0050] The base of one end of the two rock pull-out connecting plates is connected to the same-direction tension-torsion loading mechanism of the testing machine, and the base of the other end is connected to the rock sample pull plate. One side of the two fixing plates is fixed to the inner frame of the testing machine, and the other side fixes the sample bearing plate together. There is a U-shaped groove in the middle of the sample bearing plate. The bottom of the U-shaped groove is semicircular, and its diameter is slightly larger than the anti-wear set. A row of vertically arranged anti-wear rollers are set on the sides of both sides of the U-shaped groove. There are threaded holes on the outside of the anti-wear rollers for installing anti-rotation plates. The drilled holes on the anti-rotation plates are elliptical, which can cause a slight displacement in the horizontal direction.

[0051] The base of the rock mass pulling connecting plate 6 is connected to the base of the rock mass pulling plate, which can transfer the tensile and torsional loads applied by the testing machine to the specimen and also play a role in fixing the relative position between the specimen and the testing machine. Two fixing plates 8 are installed on the front and rear sides of the inner frame of the testing machine, and the specimen bearing plate 12 is installed on the right side. Most of the weight of the specimen and the reaction force generated during the test are transferred to the inner frame of the testing machine through the above two components. There is a U-shaped groove in the middle of the specimen bearing plate, and a set of anti-wear rollers 17 are arranged on each side of the right side. The rollers are in contact with the left side of the shear rock mass baffle 10 to reduce the friction between the two components during shearing and avoid affecting the test results. The anti-rotation plate 9 is installed outside the anti-wear rollers 17 to limit the rotational movement of the shear block. To prevent the anti-rotation plate 9 from contacting the shear plate 20 of the vertical shear loading mechanism 200 of the testing machine and affecting the force on the shear block due to installation position deviation after the anti-rotation plate 9 is installed, the threaded holes on the anti-rotation plate 9 are designed as ellipses so that the anti-rotation plate can move slightly in the horizontal direction without affecting the test.

[0052] The specific test steps are as follows:

[0053] (I) Mold preparation

[0054] First, four steel plates with dimensions of 605×315×15 mm are spliced in sequence along the longest side. One of the longest sides of each steel plate has a groove to ensure the tightness of the splicing. A steel plate with dimensions of 315×315×15 mm is installed at the bottom of the four steel plates. There is a round hole with a diameter of about 40 mm in the center of the steel plate, and several screws are used to fix between every two adjacent steel plates. After splicing in the above order, a mold with a cavity of 300×300×605 mm is obtained inside. Since there are grooves on both sides of one end of the shear-type rock mass block, and the front half of the tension-torsion type rock mass block is set as a second-level frustum, corresponding-shaped steel blocks need to be added to the mold to obtain corresponding-shaped rock mass-like blocks. After the installation of the tension-torsion type rock mass block mold is completed, as shown in Figure 11 shown, after the installation of the shear-type rock mass block mold is completed, as shown in Figure 12 shown. After the above work is completed, a release agent is applied to the inner surface of the mold, and the mold preparation work ends.

[0055] (II) Production of rock mass-like blocks

[0056] Pour cement, stones, sand and water into a mixer in a ratio of 1:2:1:0.35 (or other ratios) for thorough mixing. At the same time, pour in a little water-reducing agent to increase the fluidity of the materials and facilitate the filling of the materials into the mold. Then, insert a hollow steel pipe with spiral wool yarn wound around the outside into the round hole at the bottom of the mold. The length of the hollow steel pipe is greater than the height of the mold. The purpose of this step is to prefabricate a drilled hole with threads on the surface in the center of the specimen. The diameter and pitch of the wound wool yarn can be changed to create different roughness of the drilled hole. Then, fill the mold with the mixed concrete material and use a concrete vibrator to remove the air in the material. Finally, place a cover plate with a matching size and a round hole in the middle above the mold. It needs to be left standing for 2 - 3 hours. After the specimen has basically solidified, remove the mold and the steel pipe, and cure for about 7 days. During the curing period, water the specimen twice a day to keep it moist and ensure the strength of the rock-like block. The main block size of the produced tensile-torsional rock-like block is 480×300×300mm, the height of the secondary frustum is 125mm, the diameter is 275mm, the depth of the circular groove at the edge of the frustum end is 10mm, and the width is 20mm. The size of the produced shear rock-like block is 605×300×300mm, and the groove sizes on both sides of the end are 300×10×10mm.

[0057] (III) Anchoring of Rock-Like Blocks

[0058] Install the specimen protection ring 18 on the secondary frustum of the tensile-torsional rock-like block 1. Then, arrange two rock-like blocks vertically. Among them, the shear rock-like block 2 is at the bottom and the tensile-torsional rock-like block 1 is at the top. When arranging, the secondary frustum of the shear rock-like block 2 is opposite to the grooved end of the tensile-torsional rock-like block 1, and the drilled holes and the four corners of the main blocks of the two rock-like blocks are aligned. Place a steel sheet with a size of 300×300×1mm and a 40mm diameter round hole in the middle between the two rock-like blocks. The purpose is to prevent the anchoring agent from oozing between the two rock-like blocks during anchoring, causing the two rock-like blocks to stick together and affecting the test results. The above steel sheet is composed of two half parts spliced together, so it can be separated and removed after anchoring. Then, place a funnel at the drilled hole at the upper end of the specimen and inject cement mortar into the funnel. After the drilled hole is filled, insert the anchor bolt, remove the excess mortar, and remove the steel sheet. Leave it standing for about 7 days. After the anchoring is completed, install a tray and a nut at the protruding end of the anchor bolt.

[0059] (IV) Assembling the Specimen

[0060] First, install the rock mass pulling connection 6 at the tensile loading end of the testing machine and the rock sample pulling plate 7 on the lower side, and install two fixing plates 8 at the corresponding positions of the inner frame. Install the specimen bearing plate 12 on the fixing plates, and finally install the anti-rotation plate 9. Then, install the shear rock mass baffles 10 on both sides of the groove end of the shear block, connect the two shear rock mass baffles 10 with two rock sample protection plates 11, and install 8 rock sample protection plates 11 in the middle and at the rear. Then, place the anti-wear sleeve group 14 into the U-shaped groove of the specimen bearing plate 10, and use a crane to lift the rock specimen into the testing machine. Among them, the main block part of the tensile-torsional rock mass block 1 is placed on the lower rock sample pulling plate 7, the specimen protection ring 18 on the secondary circular platform contacts the anti-wear sleeve group 10, and the tensile-torsional block is suspended. At this time, the crane is still under stress. Adjust the specimen to the horizontal position, and successively install the upper rock sample pulling plate 7, the front and rear pulling plates 13, and the connecting plate 15, and clamp the specimen. The specimen assembly is completed.

[0061] (V) Loading

[0062] Control the co-directional tensile-torsional loading mechanism 100 to apply a horizontally leftward load to the specimen through the servo control system. Stop loading when the load is greater than 1 kN. The purpose is to ensure that the specimen is in close contact with the specimen bearing plate 12. Then, move the vertical shear loading device of the testing machine to the tensile-torsional block, and stop moving when the front side of the shear plate 20 just does not contact the specimen bearing plate 12. At the same time, control the vertical shear loading mechanism 200 to apply a vertically downward shear force to the specimen through the servo control system. Stop loading when the load is greater than 1 kN. The purpose is to ensure that the specimen is in close contact with the shear plate 20. Then, control the co-directional tensile-torsional loading mechanism 100 to apply a torsional load to the specimen through the servo control system, and stop loading after the tensile-torsional block rotates a certain angle. Finally, control the two groups of loading mechanisms to load the specimen simultaneously at a certain displacement rate until the bolt breaks or the bolt slips relative to the rock mass block. Stop loading, save the data, take out the specimen with a crane, disassemble the components assembled on the rock mass block, and the test is completed.

[0063] The test can use the rotation angle as a variable to test the tensile-shear bearing capacity of the anchor rod at different torsion angles. The rotation angle can also be fixed, and the loading rate of the tensile load and the shear load can be used as a variable to test the bearing capacity of the anchor rod at different loading rates. The rotation angle can also be fixed, and different ratios of the loading rates of the tensile load and the shear load can be used as variables to simulate the situation in engineering practice when the angle between the rock crack and the anchor rod is not a right angle, and the anchor rod is subjected to shear force, and the bearing capacity of the anchor rod under this condition can be tested. This method improves the assembly and manufacturing process design of the anchored rock specimen and optimizes the structure of the specimen to ensure good coordination between the specimen and the experimental equipment, avoid excessive friction at the connection between the equipment and the specimen, and thus improve the accuracy of the test. The optimization of the loading system makes the loading of the specimen more accurate, and can better monitor and record relevant test parameters, such as pull-out displacement, torsion angle, shear displacement, etc.

[0064] This test method changes the loading mode of single-direction stress loading such as tension and shear, simulates the composite stress of tension, shear and torque borne by rock mass and anchor in actual engineering, and realizes the simultaneous application of three loads (tension, shear and torque) in the same test, so as to more realistically simulate the interaction between rock mass and anchoring components in actual engineering, especially the behavior of fractured rock mass under complex stress conditions; the improved rock mass specimen can ensure the synchronous action of the three loads of tension, shear and torsion, which is different from the existing rock specimens, especially in the specimen structure, through the specially designed tension and torsion blocks, shear blocks and anchor structures, so that the specimen can evenly bear the loads in all directions during the stress process, and effectively avoid interference and mutual influence between loads.

[0065] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A tooling structure for anchoring fractured rock mass tensile, shear and torsion specimens, comprising a tensile and torsion block, a shear block and an anchor rod structure, wherein the anchor rod structure comprises an anchor rod, a tray and a nut, and is characterized in that: The pulling and twisting block includes a main block and a truncated cone block. A through hole is arranged on the central axis of the pulling and twisting block and a spiral groove is arranged on the hole wall. The main block is a rectangular block. The truncated cone block is truncated cone-shaped and an annular groove is arranged on the end edge. The shearing block is a rectangular block and is provided with two grooves. The depth and width of the grooves are equal. The anchor rod structure is anchored on the pulling and twisting block and the shearing block.

2. The anchor fractured rock mass tension, shear and torsion test fixture structure according to claim 1, characterized in that: The anchor rod length of the anchor rod structure is greater than the sum of the lengths of the torsion block and the shear block. A tray and a nut are installed at the exposed end of the anchor rod, and the tray is pressed onto the torsion block.

3. The anchor fractured rock mass tension, shear and torsion test fixture structure according to claim 1, characterized in that: The cross section of the main block is a square, and its length is greater than the side length of the cross section. The cross-sectional area of ​​the truncated cone block is smaller than that of the main block. The length of the shear block is equal to that of the tension and torsion block.

4. The anchor fractured rock mass tension, shear and torsion test fixture structure according to claim 1, characterized in that: The depth and width of the groove are smaller than the height of the shear block, and the length of the groove is equal to the side length of the cross section of the shear block.

5. A method for manufacturing a fixture structure for anchoring a fractured rock mass tensile, shear and torsion specimen, using a rock mass specimen of the fixture structure for anchoring a fractured rock mass tensile, shear and torsion specimen according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: pouring the material into a mold after mixing it evenly, inserting a steel pipe with wool wrapped spirally into the tail of a prefabricated borehole, making a pulling and twisting block and a shearing block, injecting an anchoring agent into the prefabricated borehole, inserting an anchor rod and then letting it stand.

6. A test method for tension, shear and torsion of anchored fractured rock mass, using a specimen of the anchored fractured rock mass tension, shear and torsion specimen fixture structure according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: placing a rock sample into a testing machine and connecting the rock sample to the testing machine; the testing machine loads the rock sample, and monitors and records pull-out displacement, torsion angle, shear displacement, pull-out load, torsion load, and shear load.

7. A test method for tension, shear and torsion of anchored fractured rock mass according to claim 6, characterized in that: The testing machine includes a rock sample pulling plate, a pulling plate, a connecting plate, a pulling plate, a rock fixing plate, a specimen protection ring, an anti-wear set, a rock sample protection plate, a shear rock baffle, a load-bearing plate, a fixing plate, a rock pulling connecting plate and an anti-rotation plate. The rock sample pulling plate, the pulling plate, the connecting plate, the pulling plate, the rock fixing plate, the specimen protection ring and the anti-wear set are installed on the pulling and twisting block. The rock sample pulling plate is arranged on both sides of the main block, and the two ends of the rock sample pulling plate are respectively connected to the rock pulling connecting plate and the fixing plate; there are two rock sample pulling plates, and two pulling plates are arranged on the side of the rock sample pulling plate, and there are two threaded holes at both ends of the pulling plate, one of which is arranged in the guide rail, and the two pulling plates clamp and fix the rock sample pulling plate through a connecting plate; the specimen protection ring is installed on the truncated table of the pulling and twisting block, one end of the specimen protection ring cooperates with the groove at the end of the truncated table, and the other end is provided with an annular groove; the inner side of the pulling plate cooperates with the groove.

8. A test method for tension, shear and torsion of anchored fractured rock mass according to claim 7, characterized in that: The anti-wear sleeve has two shapes: circular and semicircular. The circular anti-wear sleeve is installed on the outside of the specimen protection ring, and the semicircular anti-wear sleeve is arranged between the specimen protection ring and the specimen bearing plate. The outer surface of the anti-wear sleeve is provided with multiple rolling steel balls.

9. A test method for tension, shear and torsion of anchored fractured rock mass according to claim 7, characterized in that: The rock sample protection plate and the shear rock baffle are installed on the shear block, one side of the rock sample protection plate cooperates with the groove of the shear block, and the other side is connected to the anti-rotation plate; the two shear rock baffles are connected by the rock sample protection plates on both sides, and four rock sample protection plates connected to each other are respectively arranged in the middle and rear end of the rock sample.

10. A test method for tension, shear and torsion of anchored fractured rock mass according to claim 7, characterized in that: Two rock pulling connecting plates are provided, one end of which is connected to the same-direction pulling and torsion loading mechanism of the testing machine, and the other end is connected to the rock sample pulling plate; two fixing plates are provided, one side of which is fixed on the inner frame of the testing machine, and the other side is used to fix the sample bearing plate; there is a U-shaped groove in the middle of the sample bearing plate, the bottom end of the U-shaped groove is semicircular, and the diameter is larger than the anti-wear set; a row of vertically arranged anti-wear rollers are provided on the side surfaces on both sides of the U-shaped groove, and threaded holes are provided on the outer side of the anti-wear rollers for installing the anti-rotation plate, and drill holes are provided on the anti-rotation plate.

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