A periodic hammer impact rock vibration destruction testing machine and testing method

Abstract

The present invention discloses a periodic hammer impact rock vibration destruction testing machine and testing method, which belongs to the field of rock mechanical property testing. The testing machine includes: a periodic vibration impact testing system, which is used to subject the rock sample to be tested to confining pressure and axial pre-static load, and then subject the rock sample to be tested to axial dynamic impact according to a set vibration impact frequency; a data acquisition system, which is used to record the damage behavior characteristics of the rock sample to be tested during the vibration impact process; a frequency control system, which is used to provide the vibration impact frequency and vibration impact mode for the periodic vibration impact testing system, and the frequency control system is connected to the computer and the periodic vibration impact device. The present invention applies periodic longitudinal impact to the test sample under the condition of applying confining pressure and axial pre-static load to the test sample, thereby simulating the vibration destruction process caused by dynamic disturbance of the rock mass under the conditions of blasting, ore mining, ground stress changes, etc.

Description

Technical Field

[0001] The invention belongs to the field of rock mechanical property testing, and in particular relates to a periodic hammer impact rock vibration destruction testing machine and a testing method. Background Art

[0002] With the improvement of economic level and people's quality of life, people have an increasingly strong demand for the development and utilization of deep underground resources. In the process of breaking the rock mass, dynamic disturbance will inevitably occur to the rock mass around the working face, causing vibration damage to the surrounding rock mass, reduced mechanical properties, and reduced ability to withstand external loads. Existing studies have shown that the deformation and crushing effect of the rock mass is closely related to its mechanical properties and crushing energy consumption. In particular, in the actual rock breaking process, the load form on the rock mass is often not a single one, but a cyclic and repeated one. The periodic vibration impact continues to accumulate damage to the rock mass. The rock instability induced by this repeated disturbance seriously threatens the safety of the project.

[0003] Some existing test devices focus on the impact damage caused by a single vibration on the rock mass. Often, in the simulation of multiple repeated damage tests, repeated single tests are roughly used; at the same time, the control of the vibration impact rate is not fine enough, and the rate attenuation phenomenon during the vibration impact process cannot be well simulated. Therefore, it is urgent to develop a test system for rock under periodic vibration impact loads. Summary of the invention

[0004] In order to achieve the above objectives, the present invention proposes a periodic hammer impact rock vibration destruction testing machine and test method, which can effectively simulate the periodic vibration destruction phenomenon caused by the disturbance of the rock mass during the rock breaking process, and solve the problems of single function of the vibration impact test device in the prior art, easy failure of the test device and complicated operation. When simulating the blasting vibration destruction of deep rock mass, the rock mass is usually in a state of confining pressure. The propagation and destruction mode of the shock wave of the rock mass under this condition is significantly different from that of the state without confining pressure. Therefore, the present invention applies periodic longitudinal impact to the test sample under the condition of applying confining pressure to it, thereby simulating the vibration destruction process caused by dynamic disturbance of the rock mass under the conditions of blasting, ore mining, ground stress change, etc.

[0005] The technical solution of the present invention is achieved in this way:

[0006] According to a first aspect of the technical solution of the present invention, there is provided a periodic hammer impact rock vibration failure testing machine, comprising:

[0007] The periodic vibration impact test system is used to subject the rock sample to be tested to confining pressure and axial pre-static load, and then subject the rock sample to be tested to axial dynamic impact according to the set vibration impact frequency, comprising a bench, a triaxial pressurizing device and a periodic vibration impact device, wherein the triaxial pressurizing device is installed above the bench, and the periodic vibration impact device is installed below the bench;

[0008] A data acquisition system, used to record the damage behavior characteristics of the rock sample to be tested during the vibration impact process, comprising a computer, a strain gauge, a pressure sensor 1, a pressure sensor 2 and an extensometer, wherein the pressure sensor 1 and the pressure sensor 2 are installed on the triaxial pressurizing device, the pressure sensor 1, the pressure sensor 2 and the extensometer are connected to the strain gauge, and the strain gauge is connected to the computer;

[0009] A frequency control system is used to provide a vibration impact frequency and a vibration impact mode for the periodic vibration impact test system, and the frequency control system is connected to the computer and the periodic vibration impact device.

[0010] Furthermore, the table top of the test stand is equipped with a bearing platform for placing the rock sample to be tested, a triaxial pressurizing device base is provided on the bearing platform, an impact pad for bearing impact load is provided above the base, the impact pad passes through the bearing platform and the triaxial pressurizing device base, and is embedded in the triaxial pressurizing device base, and the impact pad and the triaxial pressurizing device base are connected by a sealing ring.

[0011] Furthermore, the triaxial pressurizing device comprises a triaxial pressurizing closed outer cover, a pressurizing oil pipe, an oil return pipe and a pressurizing pump.

[0012] Furthermore, the three-axis pressurized closed outer cover is connected to the pressurized oil pipe and the return oil pipe, and a lifting device is provided on the upper part and fixed to the upper part of the test bench; the pressurized pump is connected to the other end of the pressurized oil pipe and the return oil pipe, and a built-in oil tank is provided inside the pressurized pump; a sealing strip is attached to the lower edge of the three-axis pressurized closed outer cover, and the three-axis pressurized closed outer cover forms a sealed space with the base of the three-axis pressurizing device under the action of the lifting device, so that the rock sample to be tested is subjected to confining pressure after pressurization.

[0013] Furthermore, a pressurizing valve is provided on the pressurized oil pipe, and a pressure reducing valve is provided on the oil return pipe.

[0014] Furthermore, the periodic vibration impact device includes a vibration striker, a hammer head and a power transmission device.

[0015] Furthermore, a vibrating striker is provided at the lower end of the bearing platform, the lower end of the striker is connected to a hammer head, and the hammer head is connected to a power transmission device.

[0016] Furthermore, the power transmission device includes a hammer handle, a first power transmission shaft, a seven-shaped transmission leg, a transmission rod, a second power transmission shaft, a power transmission turntable, and a power motor.

[0017] Furthermore, the hammer head is connected to the hammer handle, the hammer handle is fixed on the seven-shaped transmission leg, and the other end of the seven-shaped transmission leg is connected to the transmission rod; the seven-shaped transmission leg is fixed on the power transmission shaft 2, and the power transmission shaft 2 is fixed on the baffles on both sides of the test bench; the power transmission turntable is fixed on the power transmission shaft 1, the power transmission shaft 1 is connected to the power motor, and is fixed on the baffles on both sides of the test bench together with the power motor; the power motor is connected to the frequency control system; the radius of the power transmission turntable increases continuously along the circumferential direction, and the part with the largest radius and the part with the smallest radius on the circumferential surface of the power transmission turntable are connected in a cliff-like manner.

[0018] Furthermore, the pressure sensor 1 is installed on the inner wall of the triaxial pressurized closed outer cover, the pressure sensor 2 is installed on the inner top plate of the triaxial pressurized closed outer cover, and the extensometer is installed on the base of the triaxial pressurization device.

[0019] Furthermore, in the frequency control system, the required frequency is input by a computer, and the frequency controller controls the power motor to reach a corresponding rotation speed, thereby achieving the required vibration impact frequency.

[0020] According to a second aspect of the technical solution of the present invention, a periodic hammer impact rock vibration failure test method is provided, wherein the periodic hammer impact rock vibration failure test machine according to any of the above aspects is used, comprising the following steps:

[0021] (1) Place the rock sample to be tested on the impact pad, control the lifting device to slowly lower the triaxial pressurization closed cover, so that the triaxial pressurization closed cover is tightly fitted and sealed with the triaxial pressurization device base, apply axial preload static load, and measure the value through pressure sensor 2;

[0022] (2) Start the booster pump. When the value of the pressure sensor stabilizes at the specified confining pressure value, the actual rock mass confining pressure state simulated by the test is reached;

[0023] (3) setting the vibration impact frequency and the vibration impact mode, starting the periodic vibration impact device, transmitting the vibration impact energy to the rock sample to be tested, and determining the damage state of the rock sample to be tested through the second pressure sensor;

[0024] (4) When the rock sample to be tested is damaged, the periodic vibration impact device and the data acquisition system are turned off, the triaxial pressurized closed cover is slowly raised, and the rock sample to be tested is taken out.

[0025] Beneficial effects of the present invention:

[0026] The technical solution of the present invention applies axial static load and confining pressure to the rock sample through a triaxial pressurizing device, and then controls the periodic vibration impact device through a frequency control system to apply a periodic vibration impact load of a preset frequency to the rock sample, so that the rock sample is in a three-dimensional dynamic stress state. In the simulation of multiple repeated destruction tests, instead of a rough repeated single vibration impact destruction test, the frequency control system can finely control the impact frequency, and can well simulate the rate attenuation phenomenon in the vibration impact process. Therefore, it can well simulate the actual rock breaking process in which the rock mass is subjected to cyclic and repeated periodic vibration impacts, providing a theoretical basis for actual on-site construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 It is a schematic front view of the structure of a periodic hammer impact rock vibration destruction testing machine according to an embodiment of the present invention;

[0029] Figure 2 It is intended to supplement the structure of the periodic hammer impact rock vibration destruction testing machine according to an embodiment of the present invention;

[0030] Figure 3 Partial details of the vibration impact system according to an embodiment of the present invention Figure 1 ;

[0031] Figure 4 Partial details of the vibration impact system according to an embodiment of the present invention Figure 2 ;

[0032] Figure 5 A cross-sectional view of a triaxial pressurized closed housing according to an embodiment of the present invention;

[0033] Figure 6 A top view of the structure of a periodic hammer impact rock vibration destruction testing machine according to an embodiment of the present invention;

[0034] Figure 7 A schematic diagram of the force on a sample according to an embodiment of the present invention;

[0035] Figure 8 1 is a time history curve of periodic impact vibration stress according to an embodiment of the present invention.

[0036] In the figure: 1—computer; 2—bench; 3—return oil pipe; 4—vertical positioning bolt; 5—vertical lifter of three-axis pressurized outer cover; 6—pressurized oil pipe; 7—bench bearing platform 1; 8—three-axis pressurized closed outer cover; 9—impact pad; 10—three-axis pressurized device base; 11—bench bearing platform 2; 12—personnel protection frame; 13—power transmission shaft 1; 14—power transmission shaft 2; 15—hammer support frame; 16—bench bearing platform 3; 17—frequency controller; 18—hammer head; 19—vibration striker; 20—power Motor; 21—confining pressure boosting pump; 22—horizontal positioning bolts and nuts; 23—personnel protection transparent partition; 24—boosting pump control switch; 25—gantry lift control button; 26—hammer start switch; 27—power transmission turntable; 28—transmission rod; 29—seven-shaped transmission leg; 30—vertical positioning nut; 31—hammer handle; 32—connecting circular groove mouth one; 33—transmission shaft; 34—connecting circular groove mouth two; 36—pressure sensor one; 35—pressure sensor two; 37-pressurization valve; 38-pressure reducing valve.

[0037] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] Here, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are only examples of devices and methods consistent with some aspects of the present disclosure.

[0039] The terms "first", "second", etc. in the specification of the present disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein, for example.

[0040] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or apparatus.

[0041] Multiple includes two or more.

[0042] It should be understood that the term "and / or" used in this disclosure is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone.

[0043] The technical solution of the present invention relates to a periodic hammer impact rock vibration damage testing machine and test method. The rock sample under confining pressure and axial pre-loaded static load is placed in an axial vibration impact state by controlling the vibration impact system, and then the frequency control system is used to change the impact damage form, and the rock sample is further subjected to axial vibration impact at a specific frequency to study the impact damage process of the axial vibration load generated under axial vibration impact of different periods on the rock sample, and then the mechanical behavior of rock impact damage caused by periodic vibration load is studied.

[0044] The rock periodic vibration impact load test system consists of three systems: a periodic vibration impact test system, a data acquisition system and a frequency control system. The periodic vibration impact test system subjects the rock sample to confining pressure and axial pre-static load, and then performs axial dynamic impact on the rock sample according to the set vibration impact frequency. The data acquisition system can record the damage behavior characteristics of the rock sample during the vibration impact process, and the frequency control system provides a stable vibration frequency and vibration impact mode for the periodic vibration impact test system.

[0045] Here, it should be noted that, compared with the transverse impact (such as the Hopkinson pressure bar), the present invention adopts the condition of applying confining pressure to the test sample and then applying periodic longitudinal impact to it. The advantages of selecting the longitudinal impact mainly include:

[0046] (1) Stress distribution: Longitudinal impact can better simulate the stress distribution under actual geological conditions and is suitable for studying the longitudinal failure characteristics of rock masses.

[0047] (2) Failure mode: The crack propagation mode usually caused by longitudinal impact is more consistent with the actual situation of underground rock mass and helps to predict the failure behavior more accurately.

[0048] (3) Equipment simplification: The longitudinal impact test equipment has a relatively simple structure and is easy to implement and control.

[0049] (4) Data acquisition: Longitudinal impact tests can more conveniently obtain the mechanical parameters and responses of rock mass under actual working conditions, providing more reliable data support for subsequent design.

[0050] The periodic vibration shock test system controls the periodic vibration shock test bench, which consists of a test bench, a triaxial pressurizing device, and a periodic vibration shock device. The table of the test bench is equipped with a load-bearing platform for placing the test sample, and a triaxial pressurizing device base is provided on the load-bearing platform. An impact pad for bearing the impact load of the sample is provided above the base. The pad passes through the load-bearing platform and the triaxial pressurizing device base, and is embedded in the base. The pad and the triaxial oiling device base are connected by a sealing ring.

[0051] The triaxial pressurization device includes a triaxial pressurization closed outer cover, a pressurized oil pipe, an oil return pipe, and a pressurization pump. The triaxial pressurization closed outer cover is connected to the pressurized oil pipe and the oil return pipe, and a lifting device is provided on the upper part and fixed to the upper part of the test bench, so that the rock sample can be subjected to axial pre-static load. The pressurized oil pump is connected to the other end of the pressurized oil pipe and the oil return pipe, and a built-in oil tank is provided inside the pressurized oil pump. A sealing strip is attached to the lower edge of the triaxial pressurization closed outer cover. The triaxial pressurization closed outer cover forms a sealed space with the pressurization device base under the pressure of the lifter, and the rock sample can be subjected to confining pressure after pressurization.

[0052] A vibrating striker is provided at the lower end of the bearing platform, and the lower end of the striker is connected to the hammer head, and the hammer head is connected to the hammer handle and the power transmission device. The power transmission device includes a hammer handle, a power transmission shaft 1, a seven-shaped transmission leg, a transmission rod, a power transmission shaft 2, a power transmission turntable, and a power motor. The hammer handle is fixed on the seven-shaped transmission leg, and the other end of the seven-shaped transmission leg is connected to the transmission rod. The seven-shaped transmission leg is fixed on the power transmission shaft 2, and the power transmission shaft 2 is fixed on the baffles on both sides of the platform. The power transmission turntable is fixed on the power transmission shaft 1, and the transmission shaft 1 is connected to the power motor, and is fixed on the baffles on both sides of the platform together with the power motor. The power motor is connected to the frequency controller on the bottom plate of the platform. The radius of the power transmission turntable increases continuously along the circumferential direction, and the part with the largest radius and the part with the smallest radius on the circumferential surface of the power transmission turntable are connected in a cliff-like manner; through this design, the hammer head can periodically hit the vibrating striker.

[0053] Here, the vibrating striker acts as an axial vibration impact on the sample, causing local stress concentration in the sample and forming an initial stress field. In the stress concentration area, the microcracks inside the sample begin to activate and expand, forming new cracks. When the vibration impact reaches a certain critical value, the expanded cracks aggregate and trigger macroscopic damage, resulting in the overall instability of the rock sample. At this time, the presence of confining pressure may cause the failure mode to present more brittle or complex characteristics.

[0054] The data acquisition system includes a computer, a strain gauge, a stress sensor 1, a stress sensor 2, an extensometer and a transmission line. The pressure sensor 1 is installed on the inner wall of the triaxial pressurized closed housing, the stress sensor 2 is installed on the inner top plate of the triaxial pressurized closed housing, the extensometer is installed on the base of the triaxial pressurized device, the pressure sensor and the extensometer are connected to the strain gauge through the transmission line, and the strain gauge is connected to the computer through the transmission line.

[0055] The frequency control system is connected to the computer through a transmission line, and is also connected to the power motor through a transmission line. The required frequency is input by the computer, and the power motor is controlled to reach a corresponding speed through the frequency control system, thereby achieving the required vibration impact frequency.

[0056] Specifically, the technical solution of the present invention first provides a periodic hammer impact rock vibration destruction testing machine, including: a vibration impact system, a frequency control system and a data acquisition system. The vibration impact system puts the rock sample in a vibration impact state, and performs axial vibration impact on the rock sample through a hammer. The frequency control system is the vibration frequency of the vibration impact system through different impact modes, and the data acquisition system can record the mechanical change characteristics of the rock sample under each impact.

[0057] In a preferred embodiment, the vibration impact system includes a test stand, a hammer head, a hammer handle, a hammer support frame, a power transmission shaft 1, a seven-shaped transmission leg, a transmission rod, a power transmission shaft 2, a power transmission turntable, a power motor, a vertical positioning bolt, a vertical positioning nut, a horizontal positioning bolt, a horizontal positioning nut, a vibration striker, a three-axis pressurizing device base, an impact pad, a test pad 2, a sealing ring, a three-axis pressurizing closed outer cover, a pressurized oil pipe, a return oil pipe, a confining pressure pump, a three-axis pressurizing outer cover vertical lift, a test stand bearing platform 1, a test stand bearing platform 2, a test stand bearing platform 3, a test stand lift control button, a pressurizing pump control switch, a pressurizing valve, a pressure reducing valve, and a hammer start switch. The confining pressure boosting pump is fixed to the rig bearing platform one by horizontal positioning bolts, and a small oil tank is arranged in the boosting pump; the three-axis pressurized outer cover vertical lifter is fixed to the rig bearing platform one by vertical positioning bolts and nuts, the moving part of the lifter fixes the three-axis pressurized outer cover by vertical positioning bolts and nuts, and the lifter controls the up and down movement of the three-axis pressurized closed outer cover through the guide rail; the pressurized oil pipe and the return oil pipe are respectively connected to the two sides of the three-axis pressurized outer cover, the pressurized oil pipe is located at the upper end of the three-axis pressurized outer cover, and the return oil pipe is located at the lower part of the three-axis pressurized outer cover, the other ends of the pressurized oil pipe and the return oil pipe are connected to the confining pressure boosting pump, and the pressurized oil pipe and the return oil pipe are connected together during the up and down movement of the three-axis pressurized outer cover connected to the lifter; a pressurizing valve is provided on the pressurized oil pipe, and a pressure reducing valve is provided on the return oil pipe.

[0058] In a preferred embodiment, the hammer support frame is fixed on the support platform three of the platform, and the hammer support frame is used to place the hammer head; the hammer head is fixed on the hammer handle, the hammer handle is connected and fixed to the seven-shaped transmission leg, the middle part of the seven-shaped transmission leg passes through the power transmission shaft two and is fixed, the power transmission shaft two is divided into three parts: the left and right ends are fixed to the connecting circular groove openings on the two sides of the platform and the middle rotatable transmission shaft, the middle transmission shaft is stuck in the bearings in the left and right circular grooves, and the other end of the seven-shaped transmission leg is connected to the transmission rod; the power transmission turntable is fixed on the platform through the power transmission shaft one, the power transmission shaft one has the same structure as the power transmission shaft two, the power motor is fixed on the groove at one end of the transmission shaft one, and the transmission power of the power motor is transmitted to the middle rotatable transmission shaft of the transmission shaft one, the power transmission turntable drives the transmission turntable to rotate through the rotation of the power motor, and transmits the rotational power to the transmission rod; the radius of the power transmission turntable increases continuously along the circumferential direction, and the part with the largest radius and the part with the smallest radius on the circumferential surface of the power transmission turntable are connected in a cliff-like manner.

[0059] In a preferred embodiment, the base of the three-axis pressurizing device is fixed on the second support platform of the test bench; there is a vibrating striker above the radial trajectory direction of the hammer head, the top of the striker is connected to the impact pad, the impact pad is stuck on the base of the three-axis pressurizing device, and there is a sealing ring between the impact pad and the base of the three-axis pressurizing device, the sealing ring can ensure that the pressurized oil will not leak out during the transmission of the vibration load between the striker and the impact pad; the hammer head strikes the striker in the radial trajectory direction through the force transmission structure, and the striker transfers the vibration impact load to the rock sample above the impact pad, thereby performing an axial dynamic impact on the rock sample.

[0060] In a preferred embodiment, the frequency control system includes a computer, a frequency controller, vertical positioning bolts, vertical positioning nuts, a power motor and a transmission line. The frequency controller is fixed on the third test stand supporting platform through vertical positioning bolts and nuts. The computer is connected to the frequency controller through a transmission line, and the frequency controller is connected to the power motor through a transmission line.

[0061] In a preferred embodiment, the data acquisition system includes a computer, an extensometer, a strain gauge, a pressure sensor 1, a pressure sensor 2 and a transmission line. The pressure sensor 1 is installed on the inner wall of the triaxial pressurized closed outer cover, the pressure sensor 2 is installed on the inner top plate of the triaxial pressurized closed outer cover, the extensometer is installed on the base of the triaxial pressurizing device, the extensometer, the pressure sensor 1 and the pressure sensor 2 are connected to the strain gauge through the transmission line, and the strain gauge is connected to the computer through the transmission line.

[0062] The technical solution of the present invention also provides a periodic hammer impact rock vibration failure test method, using the periodic hammer impact rock vibration failure test machine as above, comprising the following steps:

[0063] 1) With the pressure valve and pressure relief valve closed, place a standard cylindrical rock sample of φ50mm×100mm on the impact pad, place the sample pad 2 on top of the sample, press the control button of the console stand lift, slowly lower the triaxial pressurization closed cover, and make the triaxial pressurization closed cover fit tightly and seal with the base of the triaxial pressurization device. This process applies an axial preload static load to the sample, and its value can be measured by pressure sensor 2; then open the pressure valve, start the pressure pump control switch and observe the value of pressure sensor 1 on the computer. When the value of pressure sensor 1 stabilizes at the specified confining pressure value, the actual rock mass confining pressure state simulated by the test is reached, and the set maximum confining pressure shall not exceed 40MPa; then set the hammer vibration impact frequency and vibration impact mode on the computer, turn on the pressure sensor 2, and then turn on the pressure sensor 1. The power motor starts to run at the specified frequency and transmits power to the power transmission turntable. The power transmission turntable converts the rotational power into vibration impact energy to control the hammer head to hit the striker. The vibration impact energy is transmitted to the rock sample through the striker. The real-time display of the pressure sensor 2 on the computer is observed. The pressure sensor 2 can express the damage state of the rock sample. When the value of the pressure sensor 2 is stable within a certain value range at a certain frequency, it indicates that the rock sample has not been broken. At the same time, in this process, the extensometer transmits the information of the sample to the strain gauge, and the data of the strain gauge is displayed in real time on the computer. When the displayed pressure suddenly decreases continuously, the rock sample is damaged. At this time, the strain data on the computer tends to be stable and no longer changes significantly.

[0064] 2) When the rock sample is damaged, turn off the hammer start switch, turn off the strain gauge, close the pressurizing valve, open the pressure reducing valve, and recover the pressurized oil in the three-axis closed barrel to the oil tank in the pressure recovery mode of the pressure pump until the oil recovery is completed and close the pressure reducing valve and the pressure pump control switch;

[0065] 3) Press the control button of the console stand lift to slowly raise the triaxial pressurized closed cover until it reaches a safe height for easy removal of the sample, and then the sample can be taken out.

[0066] Example

[0067] like Figure 1-6 As shown, a periodic hammer impact rock vibration destruction testing machine and test method include a periodic vibration impact testing system, a data acquisition system and a frequency control system. The periodic vibration impact testing system will control the hammer head 18 to perform axial dynamic impact on the rock sample according to the vibration impact frequency set by the computer 1. The data acquisition system can record the damage behavior characteristics of the rock sample during the vibration impact process. The frequency control system provides a stable vibration frequency and vibration impact mode for the periodic vibration impact testing system. Figure 7 A schematic diagram of the force on the specimen is shown.

[0068] The periodic vibration impact test system relies on the test bench 2 to combine the components together, and the triaxial pressurizing device applies confining pressure and axial pre-static load to the test sample, and the periodic vibration impact device applies radial vibration impact to the test sample. The test bench 2 is divided into three layers, namely the test bench bearing platform 1 7, the test bench bearing platform 2 11 and the test bench bearing platform 3 16; the three-axis pressurized outer cover vertical lift 5 and the confining pressure boosting pump 21 are installed on the test bench bearing platform 1 7; the three-axis pressurized outer cover vertical lift 5 is fixed on the test bench bearing platform 1 7 by vertical positioning bolts 4 and nuts; the confining pressure boosting pump 21 is fixed on the test bench bearing platform 1 7 by horizontal positioning bolts and nuts 22, and the confining pressure boosting pump 21 is respectively connected to the pressurized oil pipe 6 and the return oil pipe 3, and the other ends of the pressurized oil pipe 6 and the return oil pipe 3 are respectively connected to the two sides of the three-axis pressurized closed outer cover 8, wherein the pressurized oil pipe 6 is located at the upper end of the three-axis pressurized closed outer cover 8, and the return oil pipe 3 is located at the lower end of the three-axis pressurized closed outer cover 8; the lifting end of the three-axis pressurized outer cover vertical lift 5 is connected to the upper end of the three-axis pressurized closed outer cover 8.

[0069] A triaxial pressurizing device base 10 is installed on the bench bearing platform 11, and an impact pad 9 is provided on the triaxial pressurizing device base 10. The impact pad 9 and the triaxial pressurizing device base 10 are connected by a sealing ring. The sealing ring has a certain ductility, which can avoid the impact pad 9 and the triaxial pressurizing device base 10 from generating a gap during the impact vibration process; a circular hole with the same diameter as the vibration striker 19 is left between the triaxial pressurizing device base 10 and the bench bearing platform 11; the triaxial pressurizing outer cover vertical lift 5 can control the triaxial pressurizing closed outer cover 8 to descend, so that it is in close contact with the triaxial pressurizing device base 10, and at the same time, an axial pre-static load is applied to the test sample; a closed space is formed inside the triaxial pressurizing closed outer cover 8, and the high-pressure oil generated by the confining pressure pump 21 enters the above-mentioned closed space through the pressurized oil pipe 6, and applies confining pressure to the test sample in the closed space.

[0070] A hammer support frame 15 and a frequency controller 17 are installed on the bench bearing platform 3 16; the frequency controller 17 is fixed to the bench bearing platform 3 16 by vertical positioning bolts 4 and nuts; a hammer head 18 is placed on the hammer support frame 15, and the hammer head 18 is fixed on the hammer handle 31, and the hammer handle 31 is fixedly connected to the seven-shaped transmission leg 29, and the seven-shaped transmission leg 29 passes through the power transmission shaft 2 14 in the middle and is fixed on the transmission shaft 33; the two ends of the transmission shaft 33 are respectively inserted into the connecting circular groove mouth 1 32 and the connecting circular groove mouth 2 34, and are connected by bearings to realize the independent rotation of the transmission shaft 33, and the connecting circular groove mouth 1 32 and the connecting circular groove mouth 2 34 are respectively fixed on the protective plates on both sides of the bench 2; the other end of the seven-shaped transmission leg 29 is fixedly connected to the transmission rod 28; the power transmission turntable 27 passes through the power transmission shaft 13 in the middle and is fixed on the transmission shaft 33, and the two ends of the transmission shaft 33 are respectively inserted into the connecting circular groove mouth 1 32 and the connecting circular groove mouth 2 34, and are connected by bearings. The transmission shaft 33 is connected to realize the independent rotation of the power transmission turntable 27 driven by the transmission shaft 33, and the connecting circular groove mouth 1 32 and the connecting circular groove mouth 2 34 are respectively fixed on the protective plates on both sides of the stand 2; a power motor 20 is provided on the power transmission shaft 13, and the power motor 20 is fixed on the connecting circular groove mouth 1 32, and the rotating part of the power motor 20 is fixed on the transmission shaft 33; a vibration striker 19 is provided on the movement trajectory of the hammer head 18, and the vibration striker 19 passes through the three-axis pressurizing device base 10 and the stand bearing platform 2 11, and is fixedly connected to the impact pad 9; since the radius of the power transmission turntable 27 increases continuously along the circumferential direction, and the part with the largest radius and the part with the smallest radius on the circumferential surface of the power transmission turntable are connected in a cliff-like manner, so during the rotation of the power transmission turntable 27, the distance between the free end of the transmission rod 28 and the center of the power transmission turntable 27 will show a periodic cliff-like change, and the hammer head 18 will hit the vibration striker 19 once every rotation of the power transmission turntable 27.

[0071] The data acquisition system includes a computer 1, a strain gauge, a pressure sensor 1 36, a pressure sensor 2 35, an extensometer and a transmission line. The pressure sensor 1 36 is mounted on the inner wall of the triaxial pressurized closed housing, the pressure sensor 2 35 is mounted on the inner top plate of the triaxial pressurized closed housing, the extensometer is mounted on the base of the triaxial pressurized device, the extensometer, the pressure sensor 1 and the pressure sensor 2 are connected to the strain gauge through the transmission line, and the strain gauge is connected to the computer through the transmission line.

[0072] The frequency control system may include a computer 1, a frequency controller 17, vertical positioning bolts, vertical positioning nuts, a power motor 20 and a transmission line. The frequency controller is fixed on the gantry support platform three by vertical positioning bolts and nuts. The computer 1 is connected to the frequency controller 17 by a transmission line, and the frequency controller 17 is connected to the power motor 20 by a transmission line.

[0073] A hammer impact rock vibration failure test method implemented by a periodic hammer impact rock vibration failure test machine comprises the following steps:

[0074] 1) Under the premise that the pressure valve 37 and the pressure relief valve 38 are closed, place a standard cylindrical rock sample of φ50mm×100mm on the impact pad 9, place the sample pad 2 on the sample, adjust the platform lift control button 25 of the triaxial pressure cover vertical lift 5, and slowly lower the triaxial pressure closed cover 8 so that the triaxial pressure closed cover 8 is tightly attached and sealed to the triaxial pressure device base 10;

[0075] 2) Then open the pressure valve 37, start the pressure pump control switch 24, and the confining pressure pressure pump 21 injects the oil in the oil tank into the inside of the three-axis closed device along the pressure oil pipe 6. Observe the value of the pressure sensor 36 on the computer 1. When the value of the pressure sensor 36 stabilizes at the specified confining pressure value, the actual rock mass confining pressure state simulated by the test is reached. The set maximum confining pressure shall not exceed 40MPa. During the experiment, the confining pressure pressure pump 21 will automatically adjust to keep the confining pressure at the set value; then set the hammer vibration impact frequency and vibration impact mode on the computer 1, turn on the strain gauge, turn on the hammer start switch 26, and the power motor 20 starts to operate at the specified frequency and transmits it to the power transmission turntable 27. The power transmission The turntable 27 converts the rotational power into vibration impact energy for controlling the hammer head 18 to strike the vibration striker 19, and transmits the vibration impact energy to the rock sample through the vibration striker 19. The real-time display of the pressure sensor 2 35 on the computer is observed. The pressure sensor 2 35 can express the damage state of the rock sample. When the value of the pressure sensor 2 35 is stable within a certain value range at a certain frequency, it indicates that the rock sample has not been broken. At the same time, in this process, the extensometer transmits the information of the sample to the strain gauge, and the data of the strain gauge is displayed in real time on the computer 1; when the displayed pressure suddenly decreases continuously, the rock sample is damaged, and at this time, the strain data on the computer tends to be stable and no longer changes significantly;

[0076] 3) When the rock sample is damaged or the test needs to be stopped, the hammer start switch 26 is turned off, the strain gauge is turned off, the pressurizing valve 37 is closed, the pressure reducing valve 38 is opened, and the pressurized oil in the three-axis sealing device is recovered into the oil tank in the pressure recovery mode of the confining pressure boosting pump 21 until the oil recovery is completed, and the pressure reducing valve 38 and the boosting pump control switch 24 are closed;

[0077] 4) Press the control button 25 of the console stand lift to slowly raise the triaxial pressurized closed outer cover 8 until the triaxial pressurized closed outer cover 8 is raised to a safe height for conveniently taking out the sample, and then the sample can be taken out.

[0078] Experimental verification

[0079] (1) Damage variables defined based on elastic modulus

[0080] The most common method in the study of rock material damage mechanics is to define the damage variable using the elastic modulus. The elastic modulus under the damaged condition measured by the testing machine of the present invention is Define the damage variable.

[0081]

[0082] Where:

[0083] —Elastic modulus of the material under non-destructive conditions;

[0084] - Elastic modulus under damaged conditions measured by the testing machine of the present invention.

[0085] (2) Damage factors

[0086] There are many factors that affect the damage process of rock samples under periodic impact, such as the mechanical properties of the rock sample itself, static stress, stress amplitude, and loading frequency of periodic impact. The damage process of the rock sample directly affects the number of cycles of periodic impact vibration. The damage factor is usually used to quantitatively evaluate the degree of damage to the rock sample during the periodic impact process. The test machine of the present invention can obtain parameters such as the number of periodic impact cycles, the ratio of the axial preload static load to the peak strength of the rock under static load, and the peak impact load. Figure 8 As shown. From this, the damage factor can be calculated:

[0087]

[0088] Where:

[0089] - the number of cyclic impact cycles measured by the testing machine of this invention;

[0090] —Rock damage factor under cyclic impact;

[0091] —Ratio of axial preload static load to rock peak strength under static load;

[0092] —Dynamic enhancement factor;

[0093] —The effect of the impact frequency parameter on the periodic impact damage factor;

[0094] —Peak value of cyclic impact load.

[0095] (3) Cyclic impact damage cumulative evolution equation

[0096] It is usually considered that the damage variable It is strain The function of With the strain As long as the testing machine invented by this invention measures the strain of the rock sample during the cyclic impact process, the evolution law of the damage variable of the rock under the cyclic impact can be obtained.

[0097]

[0098] Where:

[0099] —The testing machine invented thereby measures the peak point of the stress-strain curve of the rock sample;

[0100] —elastic modulus of rock sample;

[0101] —viscosity coefficient, which can be obtained through creep tests;

[0102] —Strain rate of the rock specimen during the impact process.

[0103] The damage caused by each impact to the rock is based on the damage caused by the previous impacts. Therefore, the damage caused by each impact to the rock cannot be simply a linear superposition of the damage caused by the previous impacts. The damage caused by periodic impact to the rock is a cumulative process. The cracks inside the rock gradually expand and penetrate with the increase in the number of impacts. Therefore, the final damage degree of the rock shows a superposition effect.

[0104]

[0105] Where:

[0106] —Calculated damage value of the rock sample after the nth impact cycle;

[0107] —The accumulated damage value of the rock sample after the nth impact.

[0108] Therefore, by conducting periodic impact vibration failure experiments and analyzing rock samples in the present invention, the energy transfer change law of deep rock mass during the cyclic impact process can be revealed. By analyzing the failure mode of rock, the failure instability mechanism and failure mode of different types of rock under different stress states can be obtained, and the conclusion can be used as a theoretical basis for actual on-site construction.

[0109] In summary, the present invention controls the rock sample subjected to confining pressure and axial pre-static load to be in an axial vibration impact state through the control of the vibration impact system, and then uses the frequency control system to change the impact damage form, and further performs axial vibration impact at a specific frequency on the rock sample to study the impact damage process of the axial vibration load generated under axial vibration impacts of different periods on the rock sample, and then studies the mechanical behavior of rock impact damage caused by periodic vibration loads.

[0110] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0111] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0112] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), including a number of instructions for a terminal (which can be a mobile phone, computer, server, air conditioner, or network equipment, etc.) to execute the methods described in each embodiment of the present invention.

[0113] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the purpose and protection scope of the present invention, which all fall within the protection of the present invention.

Claims

1. A periodic hammer impact rock vibration failure testing machine, characterized in that: include: The periodic vibration impact test system is used to subject the rock sample to be tested to confining pressure and axial pre-static load, and then subject the rock sample to be tested to axial dynamic impact according to the set vibration impact frequency, comprising a bench, a triaxial pressurizing device and a periodic vibration impact device, wherein the triaxial pressurizing device is installed above the bench, and the periodic vibration impact device is installed below the bench; The periodic vibration impact device includes a vibration striker, a hammer head and a power transmission device; the power transmission device includes a hammer handle, a first power transmission shaft, a seven-shaped transmission leg, a transmission rod, a second power transmission shaft, a power transmission turntable and a power motor; Wherein, the hammer head is connected to the hammer handle, the hammer handle is fixed on the seven-shaped transmission leg, and the other end of the seven-shaped transmission leg is connected to the transmission rod; the seven-shaped transmission leg is fixed on the power transmission shaft 2, and the power transmission shaft 2 is fixed on the baffles on both sides of the platform; the power transmission turntable is fixed on the power transmission shaft 1, the power transmission shaft 1 is connected to the power motor, and is fixed on the baffles on both sides of the platform together with the power motor; the power motor is connected to the frequency control system; the radius of the power transmission turntable increases continuously along the circumferential direction, and the part with the largest radius and the part with the smallest radius on the circumferential surface of the power transmission turntable are connected in a cliff-like manner; wherein, during the rotation of the power transmission turntable, the distance between the free end of the transmission rod and the center of the power transmission turntable will change periodically in a cliff-like manner, and the hammer head will hit the vibrating striker once every rotation of the power transmission turntable; A data acquisition system, used to record the damage behavior characteristics of the rock sample to be tested during the vibration impact process, comprising a computer, a strain gauge, a pressure sensor 1, a pressure sensor 2 and an extensometer, wherein the pressure sensor 1 and the pressure sensor 2 are installed on the triaxial pressurizing device, the pressure sensor 1, the pressure sensor 2 and the extensometer are connected to the strain gauge, and the strain gauge is connected to the computer; A frequency control system is used to provide a vibration impact frequency and a vibration impact mode for the periodic vibration impact test system, to perform fine control on the vibration impact frequency, and to simulate the rate attenuation phenomenon during the vibration impact process; the frequency control system is connected to the computer and the periodic vibration impact device.

2. The periodic hammer impact rock vibration failure testing machine according to claim 1, characterized in that: The table top of the test stand is equipped with a bearing platform for placing the rock sample to be tested, a triaxial pressurizing device base is arranged on the bearing platform, an impact pad for bearing impact load is arranged above the base, the impact pad passes through the bearing platform and the triaxial pressurizing device base, and is embedded in the triaxial pressurizing device base, and the impact pad and the triaxial pressurizing device base are connected by a sealing ring.

3. The periodic hammer impact rock vibration failure testing machine according to claim 2, characterized in that: The three-axis pressurizing device comprises a three-axis pressurizing closed outer cover, a pressurizing oil pipe, an oil return pipe and a pressurizing pump.

4. The periodic hammer impact rock vibration failure testing machine according to claim 3 is characterized in that: The three-axis pressurized closed outer cover is connected with the pressurized oil pipe and the return oil pipe, and a lifting device is provided on the upper part and fixed on the upper part of the bench; the pressurized pump is connected with the other end of the pressurized oil pipe and the return oil pipe, and a built-in oil tank is provided inside the pressurized pump; a sealing strip is attached to the lower edge of the three-axis pressurized closed outer cover, and the three-axis pressurized closed outer cover forms a sealed space with the base of the three-axis pressurized device under the action of the lifting device, so that the rock sample to be tested is subjected to confining pressure and axial preload static load after pressurization. Wherein, a pressurizing valve is arranged on the pressurizing oil pipe, and a pressure reducing valve is arranged on the return pressure oil pipe.

5. The periodic hammer impact rock vibration failure testing machine according to claim 4, characterized in that: The vibrating striker is arranged at the lower end of the bearing platform, the lower end of the vibrating striker is connected to the hammer head, and the hammer head is connected to the power transmission device.

6. The periodic hammer impact rock vibration failure testing machine according to claim 5, characterized in that: The pressure sensor 1 is installed on the inner wall of the triaxial pressurized closed outer cover, the pressure sensor 2 is installed on the inner top plate of the triaxial pressurized closed outer cover, and the extensometer is installed on the base of the triaxial pressurizing device.

7. The periodic hammer impact rock vibration failure testing machine according to claim 6, characterized in that: In the frequency control system, the required frequency is input by a computer, and the power motor is controlled by the frequency control system to reach a corresponding rotation speed, thereby achieving the required vibration impact frequency.

8. A periodic hammer impact rock vibration failure test method, characterized in that: The method is operated by using a periodic hammer impact rock vibration failure testing machine according to any one of claims 4 to 7, and comprises the following steps: (1) Place the rock sample to be tested on the impact pad, control the lifting device to slowly lower the triaxial pressurization closed cover, so that the triaxial pressurization closed cover is tightly fitted and sealed with the triaxial pressurization device base, apply axial preload static load, and measure the value through pressure sensor 2; (2) Start the booster pump. When the value of the pressure sensor stabilizes at the specified confining pressure value, the actual rock mass confining pressure state simulated by the test is reached; (3) setting the vibration impact frequency and the vibration impact mode, starting the periodic vibration impact device, transmitting the vibration impact energy to the rock sample to be tested, and determining the damage state of the rock sample to be tested through the second pressure sensor; (4) When the rock sample to be tested is damaged, the periodic vibration impact device and the data acquisition system are turned off, the triaxial pressurized closed cover is slowly raised, and the rock sample to be tested is taken out.

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