Fractured rock mass anchor rod anchoring performance impact tensile test system and test method

Abstract

The invention discloses a fractured rock mass anchor rod anchoring performance impact tensile test system and test method, and relates to the technical field of mechanical property testing. A high-strength spring energy storage mechanism, a double-drop-hammer impact mechanism and a fixed cross beam of the system are respectively mounted on a guide supporting polished rod, and the double-drop-hammer impact mechanism and an impact plate are fixedly connected or not fixed and are respectively used for an impact test of a momentum transfer method and an impact test of a drop-hammer free falling body method. The technical problem that existing test equipment cannot be compatible with two test methods is solved. The test system can be used for carrying out a tensile impact test on the axial anchoring performance of an anchor rod at a rock mass joint surface, switching and integration of an impact test of a momentum transfer method and an impact test of a drop hammer and free falling body method are realized, a tester can provide larger impact energy at a small height, and the test efficiency is improved. Meanwhile, the synchronism of drop hammer impact can be guaranteed, and the impact test system can be suitable for tensile impact performance tests of anchor rods in concrete filled steel tubes and large-size rock masses.

Description

Technical Field

[0001] This invention relates to the field of anchor bolt anchoring performance testing technology, and in particular provides an impact tensile testing system and method for anchor bolt anchoring performance in fractured rock masses. Background Technology

[0002] Rock bolts, as important rock mass support and reinforcement materials, are widely used in slope rock mass disaster prevention and control, underground engineering excavation support, and mine roadway support. Anchoring the bolts to the rock mass with anchoring agents can effectively prevent rock strata sliding or rock mass collapse. Rock bolts are subjected to various mechanical forces in complex rock mass geological environments, including static and dynamic impact loads. Therefore, the strength, stiffness, impact resistance, and energy absorption properties of rock bolt materials must be thoroughly tested and verified.

[0003] While traditional static load testing can assess the strength and stability of anchor bolts, it cannot accurately reflect their behavior under actual dynamic impact loads. The development of dynamic impact testing systems and the innovation of testing methods for anchor bolts aim to evaluate their performance under impact forces by simulating impact loads in actual engineering projects, ensuring their ability to withstand sudden dynamic loads and guaranteeing the safety of the support structure. Laboratory impact testing systems often use free-falling hammers or pendulums to simulate impact loads, observing the stress and deformation of the support system during the impact process by impacting the anchor bolt. With the expansion of anchor bolt applications and a deeper understanding of the impact of impact loads on anchor bolt structures, the engineering community has placed higher demands on the testing of anchor bolt impact performance. The commonly used impact testing method is the falling hammer free fall method, which is used to simulate the working condition when the anchor bolt is suddenly subjected to an impact load while it is at rest. However, in actual engineering projects such as mining and underground engineering construction, the impact loads on the rock mass, such as earthquakes, rock bursts (rockbursts), and blasting, not only have the characteristics of high strain rate, but are also often accompanied by complex momentum transfer processes. Therefore, researchers have proposed another impact testing method, namely the falling hammer-anchor bolt free fall method, also known as the momentum transfer method. This method can simulate the working condition of the anchor bolt being suddenly buffered and rapidly decelerated during its movement.

[0004] Existing drop hammer impact testing systems either only support the single drop hammer free-fall method, with relatively limited impact energy and velocity, failing to meet the requirements for testing the high-energy impact performance of materials; or they only employ the momentum transfer method, which suffers from problems such as complex equipment, high cost, and difficult maintenance, and lacks a comprehensive testing system that can simultaneously support both testing methods. Therefore, developing a system capable of simultaneously implementing the drop hammer direct impact method and the momentum impact testing method is of great significance for studying the mechanical behavior of rock masses under these complex loads. Summary of the Invention

[0005] To better control the impact energy adjustment in impact tests, realize impact test simulation under different working conditions, and improve the efficiency of impact mechanical property testing of anchor bolt support materials in roadways prone to rock bursts, this invention provides an impact tensile testing system and method for the anchoring performance of anchor bolts in fractured rock masses. The specific technical solution is as follows:

[0006] An impact tensile test system for anchorage performance in fractured rock mass includes a guide support bar, a high-strength spring energy storage mechanism, a double-falling hammer impact mechanism, a fixed crossbeam, and an impact plate. The high-strength spring energy storage mechanism, the double-falling hammer impact mechanism, and the fixed crossbeam are respectively mounted on the guide support bar. The high-strength spring energy storage mechanism increases the impact load of the test by compressing the spring. The double-falling hammer impact mechanism is fixedly connected to the impact plate, and the anchorage specimen is connected to the double-falling hammer impact mechanism through the impact plate and falls synchronously. Alternatively, the fixed crossbeam is fixedly connected to the impact plate, the fixed crossbeam and the impact plate fix the anchorage specimen, and the falling hammer directly impacts the impact plate to transfer the impact load to the anchor.

[0007] Preferably, multiple guide support rods are distributed between the upper and lower support plates. The guide support rods include positioning rods, guide rods, and load-bearing rods. Positioning cutting rings are provided on the positioning rods and guide rods. A fixed pulley group is installed above the upper support plate to lift the double drop hammer impact mechanism. An impact plate guide rod, a spring damping pad, a nitrogen damping rod, and a sample shearing impact pad block are installed on the lower support plate.

[0008] Preferably, the high-strength spring energy storage mechanism is mounted on the positioning light bar. The high-strength spring energy storage mechanism includes a spring retaining ring, a high-strength spring, and a spring protective sleeve. The inner diameter of the spring retaining ring is the same as the inner diameter of the cutting ring of the positioning light bar. The impact energy is increased by adjusting the compression of the high-strength spring.

[0009] Preferably, the double-falling hammer impact mechanism includes two symmetrically connected hammer body mechanisms and hammer body lifting mechanisms. The hammer body mechanism is a box structure formed by connecting an upper bearing plate, a lower bearing plate, and a side baffle. Spring compression plates connected to both ends of the lower bearing plate are installed between the positioning light rod and the guide light rod. The spring compression plates at symmetrical positions below the two sets of hammer body mechanisms are fixedly connected by rigid connecting plates. A hammer body hanging shaft bracket is installed above the upper bearing plate of the hammer body. A set of parallel tension bosses of the hammer body hanging shaft bracket are provided with symmetrical through holes. The middle through hole is used to fix the hanging pin, and the through holes at both ends can be used to fit parallel double-axis hanging seats.

[0010] Preferably, the hammer lifting mechanism includes an inner perforated plate, an outer perforated plate, a lifting device guide seat, a lifting hook, a hook shaft, a lifting and detaching cylinder, and a lifting pulley assembly; the lifting device guide seat, lifting hook, hook shaft, lifting and detaching cylinder, and lifting pulley assembly are installed between the inner perforated plate and the outer perforated plate; the end of the lifting hook is connected to the lifting and detaching cylinder, and when the lifting hook falls, the lower end is connected to the fixed hook, connecting the hammer lifting mechanism and the hammer mechanism.

[0011] Preferably, the fixed crossbeam is mounted on the bearing light bar, and four locking piston assemblies are respectively installed on the front and rear of the fixed crossbeam for locking and fixing the fixed crossbeam. The fixed crossbeam is connected to two three-stage hydraulic cylinders, and the height of the fixed crossbeam is adjusted by the three-stage hydraulic cylinders. The bottom end of the three-stage hydraulic cylinder is fixed to the lower bearing plate, and the through hole in the center of the fixed crossbeam is used to fix the sample.

[0012] Preferably, the impact plate is a porous tensile structure, with screw through holes provided on the impact platforms at both ends of the impact plate. The impact platforms are fixedly connected to the lower bearing plate of the drop hammer mechanism by screws, or to the impact pad plate by screws. Three through holes are distributed on the horizontal bearing plate in the middle of the impact plate, and screw through holes are also provided adjacent to the middle through hole for fixing and anchoring the sample. The diameter of the positioning through holes on both sides is larger than the diameter of the impact plate guide rod. Before the test, the impact plate is positioned and installed by the impact plate guide rod and the positioning holes.

[0013] The high-energy direct impact test method for anchoring fractured rock mass utilizes the aforementioned impact tensile testing system for anchoring performance of fractured rock mass anchors. The specific steps include:

[0014] S1. Prepare steel pipe concrete anchored fractured rock mass specimens, wherein the steel pipe without impact boss and with hanger connecting nut installed at the end is the upper segment steel pipe, and the steel pipe with impact boss installed at the end is the lower segment steel pipe, and the free section of the anchor is located below the impact boss of the lower segment steel pipe.

[0015] S2. Fix the anchoring specimen between the impact plate and the fixed crossbeam. Pass the anchoring specimen through the through hole in the middle of the impact plate so that the impact plate is installed above the impact boss of the lower segment steel pipe. After the upper segment steel pipe passes through the through hole in the middle of the fixed crossbeam, fix the hanger at the end of the upper segment steel pipe so that the impact plate and the anchoring specimen are suspended below the fixed crossbeam by the hanger. At the same time, install the pressure sensor, pallet pressure plate, pallet, nut and other accessories.

[0016] S3. Determine the mass Δm of the added weight and the spring compression δ based on the estimated impact energy required. The relationship between the impact energy W and the total mass of the hammer (after adding weight) m, the spring stiffness k, the initial spring compression δ, and the hammer lifting height h is expressed as follows:

[0017] W = 2kδ 2+mgh

[0018] S4. Control the oil pressure of the lifting and dropping cylinder so that the lower end of the lifting hook hooks onto the fixed pin. Then, pass the two hanging shafts of the parallel double-axis bracket through the through holes of the outer punch plate and the through holes at both ends of the hammer hanging shaft bracket and fix them to the inner punch plate. The falling hammer mechanism and the falling hammer lifting mechanism are connected together through a two-stage connecting device.

[0019] S5. The dropping hammer mechanism and the dropping hammer lifting mechanism are lifted to a height h by the lifting pulley group on the hammer lifting mechanism;

[0020] S6. Install a movable drop cylinder between the outer perforated plate of the drop hammer lifting mechanism and the baffle of the parallel double-axis bracket. By controlling the oil pressure, pull out the parallel double-axis bracket so that the drop hammer mechanism and the drop hammer lifting mechanism are connected only by the lifting hook and the fixed pin.

[0021] S7. Simultaneously control the lifting and detaching cylinders on both sides of the test system to raise the lifting hook, disengage the drop hammer mechanism from the drop hammer lifting mechanism, and drop the hammer mechanism. After contacting the impact plate, the impact load is transferred to the anchored rock mass, and the pressure change during the impact process is recorded by the pressure sensor.

[0022] The high-energy momentum impact test method for anchoring fractured rock mass utilizes the aforementioned impact tensile testing system for anchoring performance of fractured rock mass anchors. The specific steps include:

[0023] S1. Prepare steel pipe concrete anchored fractured rock mass specimens, wherein the steel pipe without impact boss and with hanger connecting nut installed at the end is the upper segment steel pipe, and the steel pipe with impact boss installed at the end is the lower segment steel pipe, and the free section of the anchor is located below the impact boss of the lower segment steel pipe.

[0024] S2. Connect the drop hammer mechanism and the drop hammer lifting mechanism, control the oil pressure of the lifting and dropping cylinder, so that the lower end of the lifting hook hooks onto the fixed pin, and pass the hanging shaft of the parallel double shaft bracket through the through hole of the outer punch plate of the drop hammer lifting mechanism, the through hole of the hammer body hanging shaft bracket and the inner punch plate in sequence to fix and connect them. The drop hammer mechanism and the drop hammer lifting mechanism are connected by a two-stage connecting device.

[0025] S3. Connect and fix the impact platforms at both ends of the impact plate to the lower pressure plate of the drop hammer mechanism with screws;

[0026] S4. Pass the prepared steel pipe concrete anchored fractured rock mass specimen through the through hole between the impact plate and the fixed crossbeam. Fix the impact boss of the lower steel pipe below the impact plate, so that the anchored specimen is fixed together with the drop hammer mechanism through the impact plate. Place the sensor plate, pressure sensor, and sensor plate in sequence above the fixed crossbeam through the upper steel pipe. Finally, fix the hanger rod to the hanger rod connecting nut. Place the sensor plate, pressure sensor, sensor plate, and tray in sequence from top to bottom on the free section of the anchor rod below the impact boss of the lower steel pipe. Finally, fix it with the nut.

[0027] S5. Determine the mass Δm of the added weight and the spring compression δ based on the estimated impact energy required. The relationship between the impact energy W and the total mass m of the falling hammer, the mass m1 of the impact plate, the mass m2 of the anchor specimen and installation accessories, the spring stiffness k, the initial spring compression δ, and the hammer lifting height h is expressed as follows:

[0028] W = 2kδ 2 +(m+m1+m2)gh

[0029] S6. The dropping hammer mechanism and the dropping hammer lifting mechanism are lifted to a height h by the lifting pulley group on the hammer lifting mechanism;

[0030] S7. Install a movable drop cylinder between the outer perforated plate of the drop hammer lifting mechanism and the baffle of the parallel double-axis bracket. By controlling the oil pressure, pull out the parallel double-axis bracket so that the drop hammer mechanism and the drop hammer lifting mechanism are connected only by the lifting hook and the fixed pin.

[0031] S8. Control the lifting and detaching cylinder of the test system to raise the lifting hook, disengage the drop hammer mechanism from the drop hammer lifting mechanism, and lower the anchored specimen together with the drop hammer mechanism. When the boom contacts the sensor pressure plate, it suddenly decelerates. The momentum of the drop hammer mechanism and the anchored specimen is transferred to the anchor rod and the fixed crossbeam through the boom. The pressure sensor above the fixed crossbeam can record the change curves of the impact force and displacement transmitted to the fixed crossbeam during the impact process. The pressure sensor below the impact boss can record the change curves of the impact force and displacement transmitted to the tray during the impact process.

[0032] The beneficial effects of the impact tensile testing system and method for anchoring performance of anchor bolts in fractured rock masses provided by this invention are:

[0033] (1) Through the coordinated assembly of various mechanisms, the test system can simultaneously realize the simulation test of the direct impact method of anchor bolt drop hammer and the momentum impact method at the rock joint surface. The test of different impact test methods can be completed in the same test system, which can ensure the consistency of basic conditions such as test environment and equipment parameters, and make the material impact performance data obtained under different test methods more comparable.

[0034] (2) This test system can be used to test the axial impact performance of steel pipe concrete anchored jointed rock mass and large-size anchored jointed rock mass anchor rods. The test specimen and the test system work together and are easy to install. It is also applicable to the tensile impact performance test of rod-shaped components such as metal materials, non-metal materials and composite materials, which greatly expands the scope of application of the test and is of great significance for studying the impact mechanical behavior of rock mass anchor rods.

[0035] (3) The high-strength spring energy storage mechanism and the double-falling hammer impact mechanism in this test system can effectively provide greater impact energy at a smaller height by compressing the spring, ensuring the synchronicity of the falling hammer impact and improving the test efficiency of impact performance testing. At the same time, when using this system for impact testing, it still has the testing function of directly impacting anchored rock specimens in a general impact testing system. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of an impact tensile test system for anchoring performance of anchor bolts in fractured rock masses.

[0037] Figure 2 This is an isometric schematic diagram of an impact tensile test system for anchoring performance of anchor bolts in fractured rock masses;

[0038] Figure 3 This is a schematic diagram of the drop hammer mechanism;

[0039] Figure 4 This is a cross-sectional schematic diagram of the drop hammer mechanism and the drop hammer lifting mechanism;

[0040] Figure 5 This is a top view of the impact plate;

[0041] Figure 6 This is the overall assembly diagram of the high-energy direct impact test for anchoring fractured rock mass;

[0042] Figure 7 yes Figure 6 Enlarged cross-sectional view of position A in the middle;

[0043] Figure 8 yes Figure 6 Enlarged cross-sectional view of position B in the middle;

[0044] Figure 9 This is a schematic diagram of the overall structure of the high-energy momentum impact test for anchoring fractured rock mass;

[0045] Figure 10 This is a schematic diagram illustrating the principle of the drop hammer anchoring free-fall impact method;

[0046] Figure 11 This is a schematic diagram illustrating the principle of the drop hammer free-fall impact method;

[0047] In the diagram: 1-Upper bearing plate; 2-Lower bearing plate; 3-Positioning light bar; 4-Guide light bar; 5-Bearing light bar; 6-Fixed pulley block; 7-Impact plate guide rod; 8-Nitrogen damping rod; 9-Spring damping pad; 10-Sample shearing impact pad; 11-Spring retaining ring; 12-High-strength spring; 13-Spring protective sleeve; 14-Upper bearing plate; 15-Lower bearing plate; 16-Side baffle; 17-Spring compression plate; 18-Hammer body hanging shaft bracket; 19-Fixed hanging pin; 20-Parallel double-axis hanging seat; 21-Inner punched plate; 22-Outer punched plate; 23-Lifting device guide seat; 24-Lifting hook; 25-Lifting hook; 26-Lifting and dropping cylinder; 27-Lifting pulley block; 28- Locking piston assembly; 29-Three-stage hydraulic cylinder; 30-Impact pad; 31-Impact boss; 32-Hanging rod connecting nut; 33-Upper segment steel pipe; 34-Lower segment steel pipe; 35-1 pressure sensor, 35-2 pressure sensor, 35-3 pressure sensor; 37-1 sensor pressure plate, 37-2 sensor pressure plate, 37-3 sensor pressure plate, 37-4 sensor pressure plate; 38-Hanging rod; 39-Panel; 40-Nut; 41-Moving drop cylinder; 42-Anchor rod; 43-Anchoring base; 44-Drop stop; 45-Impact hammer; 100-High-strength spring energy storage mechanism; 200-Double drop hammer impact mechanism; 300-Fixed crossbeam; 400-Impact plate. Detailed Implementation

[0048] Combination Figures 1 to 11 As shown, the specific implementation of the impact tensile test system and test method for anchoring performance of fractured rock mass anchors provided by the present invention is described.

[0049] The impact tensile test system for anchoring performance of fractured rock mass anchor bolts includes guide support rods, a high-strength spring energy storage mechanism 100, a double-falling hammer impact mechanism 200, a fixed crossbeam 300, and an impact plate 400. The high-strength spring energy storage mechanism 100, the double-falling hammer impact mechanism 200, and the sample fixing mechanism 300 are independently installed on 12 guide support rods. Through coordinated assembly, they can simulate various impact conditions and impact tests on different samples. The high-strength spring energy storage mechanism 100 increases the impact load of the test by compressing springs.

[0050] The guide support rods consist of 12 rods distributed between the upper bearing plate 1 and the lower bearing plate 2, which can be divided into positioning rods 3, guide rods 4, and bearing rods 5. Positioning cutting rings are located at certain intervals on the positioning rods 3 and guide rods 4. Two sets of fixed pulley groups 6 are installed above the upper bearing plate 1 to lift the double drop hammer impact mechanism. The lower bearing plate 2 is equipped with an impact plate guide rod 7, a nitrogen shock absorber rod 8, a spring shock absorber pad 9, and a sample shearing impact pad block 10. The impact plate guide rod 7 is used to position and install the sample. The nitrogen shock absorber rod 8 and the spring shock absorber pad 9 play a shock absorption role during the test to prevent damage to the test platform.

[0051] The high-strength spring energy storage mechanism 100 is installed on the positioning light bar 3 and includes a spring retaining ring 11, a high-strength spring 12 and a spring protective sleeve 13. The spring retaining ring 11 and the high-strength spring 12 are inside the spring protective sleeve. The inner diameter of the spring retaining ring 11 is the same as the inner diameter of the cutting ring of the positioning light bar 3. The compression amount of the high-strength spring 12 can be adjusted by the spring retaining ring 11 to increase different impact energies.

[0052] The double-falling hammer impact mechanism 200 includes two symmetrically connected hammer mechanisms and hammer lifting mechanisms. The hammer mechanism is formed by connecting an upper pressure plate 14, a lower pressure plate 15, and a side baffle 16 to form a box structure. Spring compression plates 17 connected to both ends of the lower pressure plate 15 are installed between the positioning light bar 3 and the guide light bar 4. The spring compression plates 17 at symmetrical positions below the two sets of hammer mechanisms are fixedly connected by rigid connecting plates to ensure the synchronicity of the falling hammer impact. A hammer shaft bracket 18 is installed above the upper pressure plate 14 of the hammer. There are three sets of symmetrical through holes on a set of parallel tension bosses of the hammer shaft bracket 18. A fixing pin 19 is installed in the middle through hole, and parallel double-axis brackets 20 can be installed in the through holes at both ends. The fixing pin 19 and the parallel double-axis brackets 20 form a two-stage connection device between the hammer mechanism and the hammer lifting mechanism.

[0053] The hammer lifting mechanism includes an inner perforated plate 21, an outer perforated plate 22, a lifting device guide seat 23, a lifting hook 24, a hook shaft 25, a lifting and dropping cylinder 26, and a lifting pulley block 27. The lifting device guide seat 23, lifting hook 24, hook shaft 25, lifting and dropping cylinder 26, and lifting pulley block 27 are installed between the inner perforated plate 21 and the outer perforated plate 22. The horizontal end of the lifting hook 24 is connected to the lifting and dropping cylinder 26. When the lifting hook 24 falls, its lower end just hooks the fixing pin 19, connecting the hammer lifting mechanism and the hammer mechanism.

[0054] The fixed crossbeam 300 is mounted on the bearing light bar 5. Four locking piston groups 28 are respectively installed on the front and back of the fixed crossbeam 100 for locking and fixing the fixed crossbeam 100. The fixed crossbeam 100 is connected to two three-stage hydraulic cylinders 29, which can adjust the height of the fixed crossbeam 100. The bottom end of the three-stage hydraulic cylinder 29 is fixed on the lower bearing plate 2. The through hole in the center of the fixed crossbeam 100 is used to fix the sample.

[0055] The impact plate 400 is a relatively complex porous tensile structure. There is a row of screw through holes on the impact platform at both ends of the impact plate 400. It can be connected to the lower bearing plate 15 of the drop hammer mechanism by screws, or the impact pad 30 can be installed to prevent the impact plate 400 from being damaged during the impact of the drop hammer. There are three through holes distributed on the horizontal bearing plate in the middle of the impact plate 400. There is also a row of screw through holes around the middle through hole, which can be used to fix and anchor the sample. The diameter of the positioning holes on both sides is slightly larger than the diameter of the impact plate guide rod 7. Before the test, the impact plate 400 is positioned and installed by the impact plate guide rod 7 and the positioning holes.

[0056] This system can perform two types of anchor bolt impact tests on the same testing machine: the drop hammer-anchor bolt free-fall impact test and the drop hammer free-fall impact method, as well as the impact pull-out test. Typically, anchor bolt impact testing methods in fractured rock masses mainly include the drop hammer-anchor bolt free-fall impact method and the drop hammer free-fall impact method. Both methods use anchorage specimens containing discontinuities, applying axial tensile loads to the anchor bolt by opening these discontinuities. Figure 10 The drop hammer-anchor free-fall impact method shown is a momentum transfer method. In this method, the anchor rock mass moves together with the drop hammer. Before the test begins, the anchor rock mass is fixed between the drop hammer and the crossbeam. At the start of the test, the external constraints are released, allowing the anchor rock mass, crossbeam, and drop hammer to fall freely simultaneously. When the system descends to a certain height, the crossbeam contacts the stop mechanism, and momentum is transferred to the anchor rod and crossbeam, resulting in significant stress on the anchor rod and anchorage interface. Figure 11 The drop hammer free-fall impact test is similar to the impact pull-out test, i.e., the direct impact method. In this method, the anchor bolt is stationary in the rock mass, and the drop hammer maintains a certain height difference with the anchored rock mass. During the test, the drop hammer falls freely, and when it contacts the impact plate, its kinetic energy is transferred through a series of processes to ultimately reach the anchor bolt. In the drop hammer-anchor bolt free-fall impact test, the drop hammer and the anchoring base together represent the surrounding rock around the anchor bolt. The entire system maintains a constant relative position during the impact, and there is no energy transfer within the system. Therefore, this test simulates the mechanical response generated when the energy released from the deep rock mass force source is transferred to the anchored rock mass before a rockburst or rock burst occurs. However, in the drop hammer free-fall impact test, the drop hammer is in direct contact with the rock mass near the anchor bolt, simulating the mechanical behavior of the anchored rock mass and anchor bolt when dynamic impact failure occurs in the shallow surrounding rock.

[0057] Using an impact tensile testing system for anchoring performance of fractured rock mass anchors, during impact testing of anchored fractured rock mass, the double-falling hammer impact mechanism 200 is not fixedly connected to the impact plate 400. The fixed crossbeam 300 and the impact plate 400 fix the anchored specimen. The impact load is transferred to the anchor rod by the direct impact of the falling hammer on the impact plate 400, which can realize the impact test of the falling hammer free fall method. When the double-falling hammer impact mechanism 200 is fixedly connected to the impact plate 400, the anchored specimen is connected to the double-falling hammer impact mechanism 200 through the impact plate 400 and falls synchronously. When the anchored specimen contacts the fixed crossbeam 300, it is suddenly buffered and decelerated sharply, which can realize the impact test of the momentum transfer method.

[0058] The high-energy direct impact test method for anchored fractured rock mass, utilizing the aforementioned high-energy direct impact and momentum impact test system for anchored fractured rock mass, includes the following steps:

[0059] S1. Prepare steel pipe concrete anchored fractured rock mass specimens. The steel pipe without the impact boss 31 and with the hanger connecting nut 32 at the end is the upper segment steel pipe 33, and the steel pipe with the impact boss 31 at the end is the lower segment steel pipe 34. The free section of the anchor is located below the impact boss 31 of the lower segment steel pipe 34.

[0060] S2. For example Figure 6 The anchoring specimen is fixed between the fixed crossbeam 300 and the impact plate 400. Pressure sensor 35-1 and pallet plate 36 are placed sequentially on the impact boss of the lower segment steel pipe 34, followed by the placement of the impact plate 28 on top. Impact pads 30 are placed on the impact platforms at both ends of the impact plate. The upper segment steel pipe 33 is passed through the central through hole of the fixed crossbeam 27. Sensor plate 37-1, pressure sensor 35-2, and sensor plate 37-2 are then placed sequentially above the fixed crossbeam 300. Finally, the hanger 38 is fixed to the hanger connecting nut, suspending the impact plate 400 and the anchoring specimen below the fixed crossbeam 300 via the hanger 38. Sensor plate 37-3, pressure sensor 35-3, sensor plate 37-4, and pallet 39 are placed sequentially from top to bottom on the free section of the anchor rod below the impact boss of the lower segment steel pipe 34, and finally secured with nuts 40.

[0061] S3. Calculate the impact energy according to the expression, and calculate the mass Δm of the added weight and the spring compression δ. The relationship between the impact energy W and the total mass of the falling hammer (after adding weight) m, the spring stiffness k, the initial spring compression δ, and the lifting height h of the hammer is expressed as follows:

[0062] W = 2kδ 2 +mgh

[0063] S4. Connect the drop hammer mechanism and the drop hammer lifting mechanism. Control the oil pressure of the lifting and dropping cylinder 26 so that the lower end of the lifting hook 24 hooks onto the fixed pin 19. The parallel double-axis bracket 20 passes through the through hole of the outer perforated plate 22 of the drop hammer lifting mechanism, the through hole of the hammer body hanging shaft bracket 18, and is fixedly connected to the inner perforated plate 21. The drop hammer mechanism and the drop hammer lifting mechanism are connected together through a two-stage connecting device.

[0064] S5. The falling hammer mechanism and the falling hammer lifting mechanism are lifted to a height h by the lifting pulley group 27 on the hammer lifting mechanism.

[0065] S6. Install a movable drop cylinder 41 between the outer perforated plate 22 of the drop hammer lifting mechanism and the baffle of the parallel double-axis bracket 20. By controlling the oil pressure, pull out the parallel double-axis bracket 20 so that the drop hammer mechanism and the drop hammer lifting mechanism are connected only by the lifting hook 24 and the fixed pin 19.

[0066] S7. Control the lifting and dropping cylinder 26 of the test system to raise the lifting hook 24, disengage the drop hammer mechanism from the drop hammer lifting mechanism, and drop the hammer mechanism. After contacting the impact plate 400, the impact load is transferred to the anchored rock mass. Pressure sensor 35-1 can record the change curve of the impact force and displacement of the lower segment steel pipe during the impact process. Pressure sensor 35-2 can record the change curve of the impact force and displacement of the upper segment steel pipe 33 during the impact process. Pressure sensor 35-3 can record the change curve of the impact force and displacement transmitted to the tray during the impact process.

[0067] High-energy momentum impact test method for anchoring fractured rock mass, such as Figure 9 As shown, when conducting a high-energy momentum impact test on anchored fractured rock mass, the anchored specimen needs to be fixed on the impact plate. The impact plate is fixedly connected to the lower bearing plate of the drop hammer mechanism, so that the anchored specimen and the drop hammer mechanism fall together from a fixed height. The specific steps are as follows:

[0068] S1. Prepare steel-concrete composite anchored fractured rock mass specimens. Among them, the steel pipe with the end of the hanger connecting nut 32 is the upper segment steel pipe 33, the steel pipe with the end of the impact boss 31 is the lower segment steel pipe 34, and the free section of the anchor is located below the impact boss 31.

[0069] S2. Connect the drop hammer mechanism and the drop hammer lifting mechanism. Control the oil pressure of the lifting and dropping cylinder 26 so that the lower end of the lifting hook 24 hooks onto the fixed pin 19. The hanging shaft of the parallel double-axis bracket 20 passes through the through hole of the outer punch plate 22 of the drop hammer lifting mechanism, the through hole of the hammer body hanging shaft bracket 18, and is fixedly connected to the inner punch plate 21. The drop hammer mechanism and the drop hammer lifting mechanism are connected together through a two-stage connecting device.

[0070] S3. Connect and fix the impact platforms at both ends of the impact plate 400 to the lower bearing plate 15 of the drop hammer mechanism with screws.

[0071] S4. Pass the prepared steel pipe concrete anchored fractured rock mass specimen through the through hole between the upper segment steel pipe 33 and the impact plate 400 and the fixed crossbeam 300. Fix the impact boss 31 of the lower segment steel pipe 34 to the bottom of the impact plate 400 with screws, so that the anchored specimen is fixed together with the drop hammer mechanism through the impact plate 400. Place the sensor pressure plate 37-1, pressure sensor 35-2 and sensor pressure plate 37-2 in sequence above the fixed crossbeam 27 through the upper segment steel pipe 33. Finally, fix the hanger 38 to the hanger connecting nut. Place the sensor pressure plate 37-3, pressure sensor 35-3, sensor pressure plate 37-4 and tray 39 in sequence from top to bottom on the free section of the anchor rod below the impact boss 31 of the lower segment steel pipe 34. Finally, fix it with nut 40.

[0072] S5. Calculate the mass Δm of the added weight and the spring compression δ according to the formula. At this point, the relationship between the impact energy W and the total mass of the falling hammer (after adding weight) m, the mass of the impact plate m1, the mass of the anchoring specimen and installation accessories m2, the spring stiffness k, the initial spring compression δ, and the hammer lifting height h is expressed as follows:

[0073] W = 2kδ 2 +(m+m1+m2)gh

[0074] S6. The falling hammer mechanism and the falling hammer lifting mechanism are lifted to a height h by the lifting pulley group 27 on the hammer lifting mechanism.

[0075] S7. Install a movable drop cylinder 41 between the outer perforated plate 22 of the drop hammer lifting mechanism and the baffle of the parallel double-axis bracket 20. By controlling the oil pressure, pull out the parallel double-axis bracket 20 so that the drop hammer mechanism and the drop hammer lifting mechanism are connected only by the lifting hook 24 and the fixed pin 19.

[0076] S8. Control the lifting and dropping cylinder 26 of the test system to raise the lifting hook 24, disengage the drop hammer mechanism from the drop hammer lifting mechanism, and lower the anchored specimen together with the drop hammer mechanism. When the boom contacts the sensor pressure plate 37-2, it suddenly decelerates. The momentum of the drop hammer mechanism and the anchored specimen is transferred to the anchor rod and the fixed crossbeam through the boom. The pressure sensor 35-2 can record the change curves of the impact force and displacement transmitted to the fixed crossbeam during the impact process, and the pressure sensor 35-3 can record the change curves of the impact force and displacement transmitted to the tray during the impact process.

[0077] Based on the steps of the two test methods described above, this system is not only applicable to high-energy direct impact and momentum impact testing of anchored fractured rock masses, but also to the tensile impact mechanical property testing of large-sized anchored rock masses through the coordinated assembly of the test system's components. It is also suitable for testing the tensile impact properties of rod-shaped components made of any metallic, non-metallic, or composite materials. This multi-functional drop hammer impact testing system for fractured rock mass anchors can simultaneously implement both direct drop hammer impact and momentum impact testing methods, which is of great significance for studying the mechanical behavior of rock masses under these complex loads.

[0078] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An impact tensile test system for anchoring performance of anchor bolts in fractured rock masses, characterized in that, The device includes a guide support bar, a high-strength spring energy storage mechanism, a double-falling hammer impact mechanism, a fixed crossbeam, and an impact plate. The high-strength spring energy storage mechanism, the double-falling hammer impact mechanism, and the fixed crossbeam are respectively installed on the guide support bar. The high-strength spring energy storage mechanism increases the impact load of the test by compressing the spring. The double-falling hammer impact mechanism is fixedly connected to the impact plate, and the anchored specimen is connected to the double-falling hammer impact mechanism through the impact plate and falls synchronously. Alternatively, the fixed crossbeam is fixedly connected to the impact plate, and the fixed crossbeam and the impact plate fix the anchored specimen. The falling hammer directly impacts the impact plate to transfer the impact load to the anchor rod.

2. The impact tensile test system for anchoring performance of fractured rock mass anchors according to claim 1, characterized in that, Multiple guide support rods are distributed between the upper and lower support plates. The guide support rods include positioning rods, guide rods, and load-bearing rods. Positioning cutting rings are provided on the positioning rods and guide rods. A fixed pulley group is installed above the upper support plate to lift the double drop hammer impact mechanism. An impact plate guide rod, a spring damping pad, a nitrogen damping rod, and a sample shearing impact pad block are installed on the lower support plate.

3. The impact tensile test system for anchoring performance of fractured rock mass anchors according to claim 2, characterized in that, The high-strength spring energy storage mechanism is installed on the positioning light bar. The high-strength spring energy storage mechanism includes a spring retaining ring, a high-strength spring, and a spring protective sleeve. The inner diameter of the spring retaining ring is the same as the inner diameter of the cutting ring of the positioning light bar. The impact energy is increased by adjusting the compression of the high-strength spring.

4. The impact tensile test system for anchoring performance of fractured rock mass anchor bolts according to claim 3, characterized in that, The dual-falling hammer impact mechanism includes two symmetrically connected hammer bodies and a hammer lifting mechanism. Each hammer body is a box structure formed by connecting an upper pressure plate, a lower pressure plate, and a side baffle. Spring compression plates connected to both ends of the lower pressure plate are installed between the positioning light bar and the guide light bar. The spring compression plates at symmetrical positions below the two sets of hammer bodies are fixedly connected by rigid connecting plates. A hammer body hanger is installed above the upper pressure plate of the hammer body. A set of parallel tension bosses of the hammer body hanger are provided with symmetrical through holes. The middle through hole is used to fix a hanging pin, and the through holes at both ends can be used to fit parallel double-axis hangers.

5. The impact tensile test system for anchoring performance of fractured rock mass anchor bolts according to claim 4, characterized in that, The hammer lifting mechanism includes an inner perforated plate, an outer perforated plate, a lifting device guide seat, a lifting hook, a hook shaft, a lifting and dropping cylinder, and a lifting pulley assembly. The lifting device guide seat, lifting hook, hook shaft, lifting and dropping cylinder, and lifting pulley assembly are installed between the inner perforated plate and the outer perforated plate. The end of the lifting hook is connected to the lifting and dropping cylinder, and when the lifting hook falls, the lower end is connected to the fixed hook, connecting the hammer lifting mechanism and the hammer mechanism.

6. The impact tensile test system for anchoring performance of fractured rock mass anchor bolts according to claim 5, characterized in that, The fixed crossbeam is mounted on the bearing light bar. Four locking piston assemblies are installed on the front and back of the fixed crossbeam respectively for locking and fixing the fixed crossbeam. The fixed crossbeam is connected to two three-stage hydraulic cylinders, and the height of the fixed crossbeam is adjusted by the three-stage hydraulic cylinders. The bottom end of the three-stage hydraulic cylinder is fixed to the lower bearing plate. The through hole in the center of the fixed crossbeam is used to fix the sample.

7. The impact tensile test system for anchoring performance of fractured rock mass anchor bolts according to claim 6, characterized in that, The impact plate is a porous tensile structure. Screw through holes are provided on the impact platforms at both ends of the impact plate. The impact platforms are fixedly connected to the lower bearing plate of the drop hammer mechanism by screws, or to the impact pad plate by screws. Three through holes are distributed on the horizontal bearing plate in the middle of the impact plate. Screw through holes are also provided at the positions adjacent to the middle through hole for fixing and anchoring the sample. The diameter of the positioning through holes on both sides is larger than the diameter of the impact plate guide rod. Before the test, the impact plate is positioned and installed by the impact plate guide rod and positioning holes.

8. A high-energy direct impact test method for anchoring fractured rock mass, wherein the test is conducted using the impact tensile testing system for anchoring performance of fractured rock mass anchors as described in any one of claims 1 to 7, characterized in that... The specific steps include: S1. Prepare steel pipe concrete anchored fractured rock mass specimens, wherein the steel pipe without impact boss and with hanger connecting nut installed at the end is the upper segment steel pipe, and the steel pipe with impact boss installed at the end is the lower segment steel pipe, and the free section of the anchor is located below the impact boss of the lower segment steel pipe. S2. Fix the anchoring specimen between the impact plate and the fixed crossbeam. Pass the anchoring specimen through the through hole in the middle of the impact plate so that the impact plate is installed above the impact boss of the lower segment steel pipe. After the upper segment steel pipe passes through the through hole in the middle of the fixed crossbeam, fix the hanger at the end of the upper segment steel pipe so that the impact plate and the anchoring specimen are suspended below the fixed crossbeam by the hanger. At the same time, install the pressure sensor, pallet pressure plate, pallet, nut and other accessories. S3. Determine the mass Δm of the added weight and the spring compression δ based on the estimated impact energy required. The relationship between the impact energy W and the total mass of the hammer (after adding weight) m, the spring stiffness k, the initial spring compression δ, and the hammer lifting height h is expressed as follows: W=2kδ 2 +mgh S4. Control the oil pressure of the lifting and dropping cylinder so that the lower end of the lifting hook hooks onto the fixed pin. Then, pass the two hanging shafts of the parallel double-axis bracket through the through holes of the outer punch plate and the through holes at both ends of the hammer hanging shaft bracket and fix them to the inner punch plate. The falling hammer mechanism and the falling hammer lifting mechanism are connected together through a two-stage connecting device. S5. The dropping hammer mechanism and the dropping hammer lifting mechanism are lifted to a height h by the lifting pulley group on the hammer lifting mechanism; S6. Install a movable drop cylinder between the outer perforated plate of the drop hammer lifting mechanism and the baffle of the parallel double-axis bracket. By controlling the oil pressure, pull out the parallel double-axis bracket so that the drop hammer mechanism and the drop hammer lifting mechanism are connected only by the lifting hook and the fixed pin. S7. Simultaneously control the lifting and detaching cylinders on both sides of the test system to raise the lifting hook, disengage the drop hammer mechanism from the drop hammer lifting mechanism, and drop the hammer mechanism. After contacting the impact plate, the impact load is transferred to the anchored rock mass, and the pressure change during the impact process is recorded by the pressure sensor.

9. A method for high-energy momentum impact testing of anchored fractured rock mass, comprising testing using the impact tensile testing system for anchoring performance of anchor bolts in fractured rock mass as described in any one of claims 1-7, characterized in that, The specific steps include: S1. Prepare steel pipe concrete anchored fractured rock mass specimens, wherein the steel pipe without impact boss and with hanger connecting nut installed at the end is the upper segment steel pipe, and the steel pipe with impact boss installed at the end is the lower segment steel pipe, and the free section of the anchor is located below the impact boss of the lower segment steel pipe. S2. Connect the drop hammer mechanism and the drop hammer lifting mechanism, control the oil pressure of the lifting and dropping cylinder, so that the lower end of the lifting hook hooks onto the fixed pin, and pass the hanging shaft of the parallel double shaft bracket through the through hole of the outer punch plate of the drop hammer lifting mechanism, the through hole of the hammer body hanging shaft bracket and the inner punch plate in sequence to fix and connect them. The drop hammer mechanism and the drop hammer lifting mechanism are connected by a two-stage connecting device. S3. Connect and fix the impact platforms at both ends of the impact plate to the lower pressure plate of the drop hammer mechanism with screws; S4. Pass the prepared steel pipe concrete anchored fractured rock mass specimen through the through hole between the impact plate and the fixed crossbeam. Fix the impact boss of the lower steel pipe below the impact plate, so that the anchored specimen is fixed together with the drop hammer mechanism through the impact plate. Place the sensor plate, pressure sensor, and sensor plate in sequence above the fixed crossbeam through the upper steel pipe. Finally, fix the hanger rod to the hanger rod connecting nut. Place the sensor plate, pressure sensor, sensor plate, and tray in sequence from top to bottom on the free section of the anchor rod below the impact boss of the lower steel pipe. Finally, fix it with the nut. S5. Determine the mass Δm of the added weight and the spring compression δ based on the estimated impact energy required. The relationship between the impact energy W and the total mass m of the falling hammer, the mass m1 of the impact plate, the mass m2 of the anchor specimen and installation accessories, the spring stiffness k, the initial spring compression δ, and the hammer lifting height h is expressed as follows: W=2kδ 2 +(m+m1+m2)gh S6. The dropping hammer mechanism and the dropping hammer lifting mechanism are lifted to a height h by the lifting pulley group on the hammer lifting mechanism; S7. Install a movable drop cylinder between the outer perforated plate of the drop hammer lifting mechanism and the baffle of the parallel double-axis bracket. By controlling the oil pressure, pull out the parallel double-axis bracket so that the drop hammer mechanism and the drop hammer lifting mechanism are connected only by the lifting hook and the fixed pin. S8. Control the lifting and detaching cylinder of the test system to raise the lifting hook, disengage the drop hammer mechanism from the drop hammer lifting mechanism, and lower the anchored specimen together with the drop hammer mechanism. When the boom contacts the sensor pressure plate, it suddenly decelerates. The momentum of the drop hammer mechanism and the anchored specimen is transferred to the anchor rod and the fixed crossbeam through the boom. The pressure sensor above the fixed crossbeam can record the change curves of the impact force and displacement transmitted to the fixed crossbeam during the impact process. The pressure sensor below the impact boss can record the change curves of the impact force and displacement transmitted to the tray during the impact process.

Images