CN105547871B - A kind of static pressure rock impact funnel breaking test device and method - Google Patents

Abstract

A static pressure rock impact funnel failure experiment device and method, through the static pressure loading device and the dynamic pressure loading device to conduct experiments on rock specimens, and the dynamic pressure loading experiment can be carried out under the static pressure loading condition, which solves the problem of the prior art There are technical problems such as low safety performance, incomplete experimental scope, and inability to simulate the real situation well. Through the above-mentioned structure and method, the present invention can safely and accurately conduct rock impact funnel damage experiments, and the experiment has good repeatability, which is more in line with actual deep mining engineering conditions in mines.

Description

A static pressure rock impact funnel failure experimental device and method

technical field

The invention belongs to the field of rock mechanics, and in particular relates to a static pressure rock impact funnel destruction experiment device and method.

Background technique

With the increase of people's demand for resources, the intensity of mining is gradually increasing, and the shallow resources are decreasing day by day. The mines at home and abroad have entered the state of deep resource mining one after another. During the mining process of deep mines, the rock mass is destroyed under the joint action of in-situ stress and impact loads such as explosions, and in-situ stress will affect the efficiency of ore mining or roadway excavation. Therefore, it is necessary to study the problem of rock impact failure under initial stress.

At present, the loading methods used in the study of rock impact dynamics mainly include explosives and Hopkinson rod devices. Among them, explosives can be used in field deep rock mass blasting experiments and laboratory model blasting experiments under initial stress. The field blasting experiment environment is complicated, the experiment period is long, the cost is high, the geological conditions of different sites are different, the initial stress changes greatly, and the repeatability is poor; the laboratory model experiments mostly use similar materials to make corresponding block models, and drill holes on the models. Embedding explosives, stuffing, and detonating explosives to load after applying a static load. However, there are certain safety problems in using explosives as impact loads, and explosives are not easy to obtain, which increases the difficulty of implementing field experiments and laboratory model blasting experiments. The Hopkinson rod device is mainly used for testing dynamic mechanical properties such as dynamic compressive strength and dynamic tensile strength of materials. At present, researchers have made corresponding modifications to the Hopkinson rod device considering the stress state of deep rock mass. For example, Publication No.: CN 1731133A Publication Date: 2006.2.8 The title of the invention is "Experimental Method and Device for Dynamic and Static Combined Loading Rock Mechanics". It is worth noting that this device is mainly used for testing rock dynamic mechanical parameters under dynamic and static combined loading conditions. In the design process of deep mine mining, the influence of in-situ stress on rock impact damage range and damage form should also be considered.

Contents of the invention

In order to solve the above-mentioned technical problems, the present invention provides a static pressure rock impact funnel destruction experiment device and method, through the static pressure loading device and the dynamic pressure loading device to carry out experiments on the rock specimens respectively, and can carry out the dynamic pressure loading experiment At the same time, static pressure loading is carried out on the rock test piece, which solves the technical problems of low safety performance, incomplete test range and inability to simulate the real situation well in the prior art.

In order to achieve the above object, the technical solution adopted in the present invention is: a method of static pressure rock impact funnel destruction experimental device, the steps of which are:

1) Adjust the air pressure of the dynamic pressure loading device and the position of the percussion rod in the barrel to ensure the impact velocity required for the experiment;

2) Use a press to calibrate the hydraulic jack and hydraulic pump, and match the reading on the pressure gauge with the load on the press to determine the exact output load of the hydraulic jack;

3) Assemble the static pressure loading device, and place the rock specimen on the lower force transmission plate;

4) Adjust the relative position of the dynamic pressure loading device and the static pressure loading device, so that the variable-section punch in the dynamic pressure loading device is inserted into the bottom of the prefabricated round hole of the rock specimen;

5) Using the dynamic pressure loading device and the static pressure loading device, the dynamic pressure loading experiment under static pressure is carried out on the rock specimen.

The specific experimental method in step 5) is as follows:

5a), when performing the test of the one-way static pressure loading device: start the lower side hydraulic pump, and apply the specified static load to the rock specimen;

5b), when conducting the experiment of the bidirectional static pressure loading device: start the lower side hydraulic pump and the right hydraulic pump, and apply a specified static load to the rock specimen;

5c), start the dynamic pressure loading device, apply force to the incident rod through the impact rod, so as to perform impact loading on the rock specimen, and use the data acquisition and processing system to collect the stress waveform of the strain gauge.

The static pressure loading device is used for static pressure loading, and the static pressure loading device includes a rigid frame; the upper side force transmission plate, the left side force transmission plate, the lower side force transmission plate and the right side force transmission plate surround the frame shape structure, in which the upper force transmission plate and the left force transmission plate are connected to the rigid frame through positioning pins, the right force transmission plate and the right hydraulic jack connected to the outside of the right force transmission plate are set on the jack support, and the lower side force transmission plate The force plate is arranged on the lower side hydraulic jack; the right side hydraulic pump is connected to the right side hydraulic jack through the oil delivery pipe, and the lower side hydraulic pump is connected to the lower side hydraulic jack through the oil delivery pipe, and a pressure gauge is also arranged on the right side hydraulic pump and the lower side hydraulic pump.

In the static pressure loading device, the rigid frame is placed on the support platform, and height adjustment bolts are also arranged on the lower surface of the support platform.

The jack support is fixed on the rigid frame through positioning pins, and the lower side hydraulic jack is arranged on the rigid frame.

The rigid frame is composed of a lower frame structure, two left and right frame structures in the middle and an upper frame structure connected by fastening bolts.

A dynamic pressure loading device is used for dynamic pressure loading. The dynamic pressure loading device includes an injection rod, a strain gauge is attached to the injection rod, and a variable-section punch is arranged at the front end of the injection rod, and a rubber ring is set on the variable-section punch. .

The variable cross-section punch is composed of two connected cylinders, the diameter of the front cylinder is smaller than the diameter of the rear cylinder, the rear cylinder is connected with the incident rod, and the front cylinder is inserted into the prefabricated circular hole on the rock test piece Inside.

The contact between the front end of the variable cross-section punch and the rock specimen is covered with a braking steel plate, and the diameter of the round hole in the middle of the braking steel plate is adapted to the cross-sectional diameter of the front end of the variable cross-section punch.

The beneficial effect of the present invention is: the present invention is provided with static pressure loading device and dynamic pressure loading device through above-mentioned structure and method, carries out experiment to rock sample, and beneficial effect is as follows:

1. The present invention can carry out one-way static pressure loading and two-way static pressure loading, the loading conditions are optional, and the load can be adjusted in a large range.

2. The present invention adopts the mechanical loading mode Hopkinson rod to provide the impact load. Compared with the explosive chemical explosion loading mode, the test conditions are easy to realize, and the test load is stable, safe and repeatable.

3. Compared with the prior art, the present invention considers the influence of the initial stress on the impact damage range of the rock, and is more in line with the reality of deep mining engineering in mines.

Description of drawings

Figure 1: Schematic diagram of the structure of the static pressure loading device in the present invention.

Figure 2: Schematic diagram of the structure of the dynamic pressure loading device in the present invention.

Fig. 3: is the front view of the rock test piece in the present invention.

Fig. 4: is the top view of the rock test piece in the present invention.

Figure 5: Experimental effect diagram of the rock specimen when the speed of the impacting rod is 5m/s and the static load is 15Mpa.

Figure 6: Experimental effect diagram of the rock specimen when the speed of the impacting rod is 5m/s and the static load is 0Mpa.

Detailed ways

A static pressure rock impact funnel destruction experimental device method, the steps are:

1) Adjust the air pressure of the dynamic pressure loading device 25 and the position of the impact rod 18 in the barrel to ensure the impact velocity required for the experiment;

2) Use a press to calibrate the hydraulic jack and hydraulic pump, match the reading on the pressure gauge 12 with the load on the press, and determine the accurate output load of the hydraulic jack;

3) Assemble the static pressure loading device 26, and place the rock test piece 17 on the lower force transmission plate 4;

4) Adjust the relative position of the dynamic pressure loading device 25 and the static pressure loading device 26, so that the variable cross-section punch 21 in the dynamic pressure loading device 25 is inserted into the bottom of the prefabricated round hole of the rock test piece 17;

5) Using the dynamic pressure loading device 25 and the static pressure loading device 26, the rock specimen 17 is subjected to a dynamic pressure loading experiment under static pressure:

5a), when performing a one-way static pressure loading device test: start the lower side hydraulic pump 13, and apply a static load of a specified size to the rock test piece 17;

5b), when carrying out the test of the two-way static pressure loading device: start the lower side hydraulic pump 13 and the right hydraulic pump 14, and apply a static load of a specified size to the rock test piece 17;

5c), start the dynamic pressure loading device, apply force to the incident rod 19 through the impact rod 18, so as to perform impact loading on the rock specimen 17, and use the data acquisition and processing system 24 to collect the strain waveform of the strain gauge 20 at the same time, through the existing The formula thus calculates the impact velocity experienced by the actual incident rod 19 .

Adopt static pressure loading device 26 to carry out static pressure loading, include rigid frame 1 in the described static pressure loading device 26; The force plate 7 surrounds and forms a frame structure, wherein the upper side force plate 4 and the left force plate 5 are connected to the rigid frame 1 through the positioning pin 3, the right force plate 7 and the right side connected to the outside of the right force plate 7 The side hydraulic jack 8 is set on the jack support 10, and the lower side force transmission plate 6 is set on the lower side hydraulic jack 9; the right hydraulic pump 14 is connected to the right hydraulic jack 8 through the oil delivery pipe 11, and the lower side hydraulic pump 13 is connected through the oil delivery pipe 11. The lower side hydraulic jack 9 is also provided with a pressure gauge 12 on the right side hydraulic pump 14 and the lower side hydraulic pump 13 . The rigid frame 1 in the static pressure loading device 26 is placed on the supporting platform 15 , and a height adjusting bolt 16 is also arranged on the lower surface of the supporting platform 15 . The jack support 10 is fixed on the rigid frame 1 through the positioning pin 3, and the lower side hydraulic jack 9 is arranged on the rigid frame 1. The rigid frame 1 is composed of a lower frame structure, two left and right frame structures in the middle and an upper frame structure connected by fastening bolts 2 .

Adopt dynamic pressure loading device 25 to carry out dynamic pressure loading, described dynamic pressure loading device 25 includes incident rod 19, is pasted strain gage 20 on the incident rod 19, and the front end of incident rod 19 is provided with variable-section punch 21, variable cross-section The punch 21 is covered with a rubber ring 22 . The variable cross-section punch 21 is composed of two connected cylinders, the diameter of the front cylinder is smaller than the diameter of the rear cylinder, the rear cylinder is connected with the incident rod 19, and the front cylinder is inserted into the rock test piece 17. In the prefabricated round hole. The front end of the variable cross-section punch 21 is covered with a brake steel plate 23 at the contact point with the rock test piece 17, and the diameter of the round hole in the middle of the brake steel plate 23 is adapted to the cross-sectional diameter of the front end of the variable cross-section punch.

Example 1:

The experimental system includes a static pressure loading device 26 and a dynamic pressure loading device 25 . The rigid frame 1 of the static pressure loading device 26 is connected by fastening bolts 2, the rigid frame 1 is provided with pin holes, the upper side force transmission plate 4 and the left side force transmission plate 5 are connected with the rigid frame 1 through the positioning pin 3, and the jack The support 10 is connected with the rigid frame 1 through the positioning pin 3, the right hydraulic jack 8 and the right force transmission plate 7 are placed on the jack support 10, the right hydraulic jack 8 is in close contact with the rigid frame 1, and the lower hydraulic jack 9 Placed on the rigid frame 1, the lower side force transmission plate 6 is placed on the lower side hydraulic jack 9. The hydraulic pump is connected with the hydraulic jack through the oil delivery pipe 11. Pressure gauges 12 are arranged on the right hydraulic pump 14 and the lower hydraulic pump 13 .

The rock test piece 17 is a square test piece with a central round hole. The length of the test piece is 100 mm, the width is 100 mm, and the thickness is 50 mm. A round hole is prefabricated in the center of the test piece. Be arranged on the hydraulic jack 9 on the lower side.

The dynamic pressure loading device includes a striking rod 18, an incident rod 19, and a variable-section punch 21. A strain gauge 20 is attached to the incident rod, and a rubber ring 22 is set on the variable-section punch. The rubber ring 22 is an energy-absorbing rubber ring here. . Both sections of the variable section punch 21 are circular, the diameter of the larger section is the same as that of the incident rod 19, and the diameter of the smaller section is adapted to the prefabricated circular hole on the rock test piece 17. A circular hole is prefabricated in the middle of the brake steel plate 23, and the aperture is adapted to the smaller section diameter of the variable-section punch 21.

Experimental steps:

Step 1. Adjust the air pressure of the Hopkinson rod device and the position of the percussion rod 18 in the gun barrel to achieve the required impact velocity for the experiment.

Step 2. Use the press to check the hydraulic jack and the hydraulic pump, and match the reading on the pressure gauge 12 with the load on the press to determine the exact output load of the hydraulic jack.

Step 3. Place the support platform 15 behind the incident rod 19, assemble the rigid frame 1 by fastening the bolts 2, and place the rigid frame 1 on the support platform 15. The upper side force transmission plate 4 and the left side force transmission plate 5 are fixed on the rigid frame 1 with positioning pins 3 .

Step 4. Place the lower hydraulic jack 9 on the rigid frame 1, place the lower force transmission plate 6 on the lower hydraulic jack 9, and place the right hydraulic jack 8 and the right force transmission plate 7 on the jack and force transmission plate support 10. Place the rock test piece 17 on the lower force transmission plate 4 to ensure that the upper force transmission plate 4, the lower force transmission plate 6, the rock test piece 17, and the lower hydraulic jack 9 are aligned in the vertical direction.

Step 5. Measure the height from the center of the incident rod 19 to the ground. The lower side hydraulic pump 13 is started, and a small load is applied to the rock test piece 17, so that the rock test piece 17 is in close contact with the upper side force transmission plate 4 and the lower side force transmission plate 6. Adjust the height adjustment bolt 16 to make the height of the center of the rock test piece 17 consistent with the space height of the center of the incident rod 19. If two-way static pressure loading is required, the right force transmission plate 7 and the right hydraulic jack 8 need to be adjusted so that the left force transmission plate 5, the right force transmission plate 7, the rock specimen 17 and the right hydraulic jack 8 are in the Align horizontally.

Step 6. Fix the brake steel plate 23 on the ground with expansion screws, put the rubber ring 22 on the variable-section punch 21, and insert the smaller cross-section end of the variable-section punch 21 into the rock specimen 17 through the brake steel plate 23 At the bottom of the hole of the prefabricated round hole, the other end of the variable section punch 21 is aligned with the incident rod 19 and is close to it.

Step 7. When carrying out single static pressure loading, it is only necessary to start the lower side hydraulic pump 13 to apply a static load of a specified size to the rock specimen 17; when carrying out two-way loading, it is necessary to start two hydraulic pumps at the same time. Start the air valve of the Hopkinson rod device to perform impact loading on the rock specimen 17.

In this example, sandstone is selected as the rock test piece, and its size is 100mm×100mm×50mm. A round hole is prefabricated in the middle of the test piece, with a diameter of 8mm and a hole depth of 45mm; the hydraulic jack model is ultra-thin FPY-50, with a maximum loading force of 50t; The model of the pressure gauge is YB-150B, the precision is 0.25 grade, and the range is 0~60Mpa. The hydraulic pump model is CP-700, the maximum output pressure is 70MPa. The diameter of the impact rod 18 and the incident rod 19 is 37mm; the diameter of the larger section end of the variable section punch 21 is 37mm, the length of the larger section end is 25mm, the diameter of the smaller section end is 7.9mm, and the length is 116mm; the thickness of the rubber ring is 25mm, and the inner diameter φ10mm, outer diameter φ45mm.

When implementing it:

Step 1. In this embodiment, the impact speed of the impact rod 18 is 5 m/s. Adjust the air pressure of the Hopkinson rod device and the position of the percussion rod 18 in the gun barrel to achieve the required impact velocity for the experiment.

Step 2. Use the press to check the lower hydraulic jack 9 and the lower hydraulic pump 13 three times, calculate the average value of the output data of the press, and obtain the corresponding relationship between the reading on the pressure gauge 12 and the output load of the press. Table 1. In this embodiment, a static load of 15 MPa in the vertical direction is applied to the rock test piece 17, and the lateral area of the rock is 5000 mm ² , so a load of 75 kN is required. When using the lower side hydraulic pump 13 to load the rock test piece 17, the reading on the pressure gauge corresponds approximately to 11.75Mpa.

Table 1 Jack calibration results

The calibration results are fitted into a linear relationship: y=6.3738x, y is the output pressure of the press (kN), and it is also the output pressure of the jack (kN); x is the reading of the pressure gauge (MPa).

Step 3. Place the support platform 15 behind the incident rod 19 of the Hopkinson rod device, assemble the rigid frame 1 by fastening the bolts 2, and place the rigid frame 1 on the support platform 15. The upper force transmission plate 4 is fixed on the rigid frame 1 with the positioning pin 3 .

Step 4. Place the lower jack 9 on the rigid frame 1 , and place the lower force transmission plate 6 on the lower jack 9 . Place the rock test piece 17 on the lower force transmission plate 4 to ensure that the upper force transmission plate 4, the lower force transmission plate 6, the rock test piece 17, and the lower hydraulic jack 9 are aligned in the vertical direction.

Step 5. Measure the height from the center of the incident rod 19 to the ground. The lower side hydraulic pump 13 is started, and a small load is applied to the rock test piece 17, so that the rock test piece 17 is in close contact with the upper side force transmission plate 4 and the lower side force transmission plate 6. Adjust the height adjustment bolt 16 to make the height of the center of the rock test piece 17 consistent with the height of the center of the incident rod 19.

Step 6. Fix the brake steel plate 23 on the ground with expansion screws, put the rubber ring 22 on the variable-section punch 21, and insert the variable-section punch 21 into the prefabricated round hole of the rock test piece 17 through the brake steel plate 23. Hole bottom.

Step 7. Use the lower hydraulic pump 13 to apply a static load to the rock test piece 17, and stop loading when the pressure gauge reads 11.75 MPa. At this time, the static load applied to the rock test piece is 15 MPa. Start the air valve of the Hopkinson rod device to perform impact loading on the rock specimen 17. The experimental results are shown in Figure 5.

Step 8. In order to facilitate the comparison of results, this embodiment also carried out an experiment with an impact velocity of 5m/s and a static load of 0Mpa. It is only necessary to apply a small load to the rock test piece with a hydraulic pump, so that the rock test piece is closely connected to the upper and lower force transmission plates. At this time, it is considered that the applied static load is 0Mpa, and the experimental results are shown in Figure 6.

It can be seen from the experimental results that the failure area of the rock specimen is similar to the funnel shape. Under the same impact velocity conditions, when the static load is 0Mpa, the funnel mouth is approximately circular, and when the static load is 15Mpa, the shape of the funnel mouth is approximately elliptical.

Claims (8)

1. a kind of static pressure rock impact funnel breaking test method, its step are：

1）, adjustment dynamic pressure loading device（25）Air pressure and trip rod（18）Position in gun tube, it is ensured that impact speed needed for experiment Degree；

2）, using forcing press hydraulic jack and hydraulic pump are proofreaded, by pressure gauge（12）On reading and forcing press on Load it is corresponding, determine the accurate output loads of hydraulic jack；

3）, assembling static pressure loading device（26）, by rock sample（17）It is placed on downside force transmitting board（6）On；

4）, adjustment dynamic pressure loading device（25）With static pressure loading device（26）Relative position, make dynamic pressure loading device（25）In Variable cross-section drift（21）Insert rock sample（17）The bottom hole of prefabricated circular hole；

5）, utilize dynamic pressure loading device（25）With static pressure loading device（26）, to rock sample（17）Carry out the dynamic pressure under static pressure Loading experiment；

Described static pressure loading device（26）For carrying out static pressure loading, which includes rigid frame（1）；Upside force transmitting board （4）, left side force transmitting board（5）, downside force transmitting board（6）With right side force transmitting board（7）Around composition frame-type structure, wherein upside force transmitting board （4）With left side force transmitting board（5）Pass through alignment pin（3）Connect rigid frame（1）, right side force transmitting board（7）And it is connected to right side power transmission Plate（7）The right side hydraulic jack in outside（8）It is arranged on jacking bracket（10）On, downside force transmitting board（6）It is arranged on downside liquid Press jack（9）On；Right side hydraulic pump（14）Pass through petroleum pipeline（11）Connection right side hydraulic jack（8）, lower hydraulic pump （13）Pass through petroleum pipeline（11）Connect lower hydraulic jack（9）, in right side hydraulic pump（14）With lower hydraulic pump（13）It is upper to go back It is provided with pressure gauge（12）.

A kind of 2. static pressure rock impact funnel breaking test method according to claim 1, it is characterised in that：Step 5）In Specific experiment method is as follows：

5a）, when carrying out the experiment of unidirectional static pressure loading device：Start lower hydraulic pump（13）, to rock sample（17）Application refers to Determine size dead load；

5b）, when carry out Bidirectional static loading device experiment when：Start lower hydraulic pump（13）With right side hydraulic pump（14）, to rock Stone test specimen（17）Apply and specify size dead load；

5c）, start dynamic pressure loading device, pass through trip rod（18）To incident bar（19）Force shock is carried out, so as to try rock Part（17）Carry out Impulsive load, while Usage data collection processing system（24）Gather foil gauge（20）Stress wave.

A kind of 3. static pressure rock impact funnel breaking test method according to claim 1, it is characterised in that：Described is quiet Press loading device（26）Middle rigid frame（1）It is placed on support platform（15）On, in support platform（15）Lower surface on also set It is equipped with height adjustment bolt（16）.

A kind of 4. static pressure rock impact funnel breaking test method according to claim 1, it is characterised in that：Described thousand Jin topmast seat（10）Pass through alignment pin（3）It is fixed on rigid frame（1）On, lower hydraulic jack（9）It is arranged on rigid frame （1）On.

A kind of 5. static pressure rock impact funnel breaking test method according to claim 1, it is characterised in that：Described is firm Property framework（1）Pass through fastening bolt by two frame structures of lower frame construction, middle part or so and frame superstructure（2）Connection Composition.

A kind of 6. static pressure rock impact funnel breaking test method according to claim 1, it is characterised in that：Using dynamic pressure Loading device（25）Carry out dynamic pressure loading, described dynamic pressure loading device（25）Include incident bar（19）, incident bar（19）On Post foil gauge（20）, incident bar（19）Front end be provided with variable cross-section drift（21）, variable cross-section drift（21）On be cased with rubber Circle（22）.

A kind of 7. static pressure rock impact funnel breaking test method according to claim 6, it is characterised in that：Described change Section drift（21）It is made up of two cylinders to link together, front end cylinder diameter is less than back end cylindrical body diameter, after Hold cylinder and incident bar（19）Connection, front end cylinder insertion rock sample（17）On prefabricated circular hole in.

A kind of 8. static pressure rock impact funnel breaking test method according to claim 6, it is characterised in that：Described change Section drift（21）Front end and rock sample（17）Contact position is cased with braking steel plate（23）, brake steel plate（23）Middle circular hole Aperture is adapted to variable cross-section punch head diameter of section.