Method for measuring hardness of in-situ drilled rock through aqueous medium pressure head

Abstract

The invention discloses a method for measuring in-situ drilling rock hardness by using an aqueous medium pressure head. The method comprises the following steps: (1) connecting a hydraulic power system with a data acquisition system; (2) connecting a hydraulic power system with the test probe through a hydraulic pipeline; (3) connecting the front end of the push rod with the rear end of the test probe; (4) the push rod is controlled to push the test probe into the drill hole; s5, a hydraulic power system is started, power is transmitted to the probe assembly, a pressure head of the test probe extends in the radial direction of the drill hole to abut against the hole wall, and the compressive strength and the elastic modulus of the surrounding rock are tested through a data acquisition system. The device can measure the rock strength of different drill holes, different depths and different point positions so as to obtain the distribution condition of the roadway rock strength, the measurement result is closer to the field rock mass, a water medium is used for pressure transmission, the measurement process is simple, convenient, environment-friendly and safe, errors in the processes of sampling, processing and the like are avoided, the measurement efficiency is greatly improved, and the measurement cost is reduced. And the measurement cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of mining engineering, and in particular relates to a method for measuring the hardness of in-situ drilled rock using a water medium pressure head. Background Art

[0002] In-situ rock hardness testing has broad applications in mining, tunneling, geological disaster prevention, underground space development, water conservancy, and nuclear waste management. In mining, in-situ testing can inform tunnel support design, accurately assess the stability of roof and sidewalls, and prevent accidents like landslides. In tunneling, rapid acquisition of surrounding rock hardness information can optimize excavation techniques and support parameter configuration, ensuring construction safety and the long-term stability of tunnel structures. In geological disaster prevention, in-situ test data can be used to assess the risk of geological hazards such as landslides and collapses and formulate preventative measures. In underground space development, accurate understanding of rock strata mechanical properties aids in deep excavation design and the planning and construction of underground projects like energy storage facilities. In water conservancy and nuclear waste management, in-situ testing can effectively assess the stability of rock foundations and ensure the safe operation of large-scale engineering facilities. In-situ rock hardness testing provides realistic and reliable mechanical parameters for various geotechnical engineering projects, significantly improving the scientific nature of engineering design and construction safety, and possesses significant engineering application value and social significance.

[0003] In-situ rock hardness testing allows for the measurement of rock engineering mechanical properties without disturbing the rock formation on-site, thus avoiding the effects of stress release during sampling. Furthermore, the testing range is large and representative. Furthermore, the basic parameters obtained through in-situ testing are highly representative and reflect actual field conditions, such as rock compressive strength, tensile strength, and shear strength. This provides a basis for engineering design and helps predict rock mass stability and geological hazard risks, safeguarding public safety and sustainable development. Therefore, in-situ rock hardness testing technology is of great significance and can be applied across a wide range of areas.

[0004] Currently, the acquisition of rock hardness mainly relies on laboratory testing, that is, drilling cores, processing standard specimens, and performing compression, tension, or shear tests under laboratory conditions. However, this traditional testing method has the following problems: (1) The coring process may cause disturbances in the rock structure, causing the test results to deviate from the actual in-situ mechanical properties; (2) The core processing and testing cycle is long and the cost is high, making it difficult to achieve large-scale and rapid evaluation; (3) It is difficult to obtain complete cores in loose and broken formations, which seriously affects the representativeness of the data; (4) The data points obtained from the test are limited, which makes it difficult to fully reflect the spatial variation characteristics of the surrounding rock hardness.

[0005] In addition, existing in-situ testing methods, such as acoustic detection, drilling parameter method, impact rebound method, etc., are limited by testing accuracy, large environmental interference or narrow applicable aperture range of the device, and are difficult to meet the actual needs of rapid and accurate in-situ testing of rock hardness in coal mines and other complex geological environments. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for measuring the hardness of in-situ drilled rock using a water medium pressure head, which is suitable for small drilled holes, easy to operate, widely applicable to environments, and has high test data accuracy.

[0007] To solve the above technical problems, the present invention adopts the following technical solution: a method for measuring the hardness of in-situ drilled rock using a water medium pressure head, comprising the following steps: (1) Connect the hydraulic power system to the data acquisition system; (2) Connect the hydraulic power system to the test probe through the hydraulic pipeline; (3) Connect the front end of the push rod to the rear end of the test probe; (4) Operate the push rod to push the test probe into the borehole; (5) Fill the hydraulic pipeline and hydraulic power system with water, start the hydraulic power system, and transmit the hydraulic power to the test probe. The pressure head of the test probe extends along the radial direction of the borehole to press the hole wall. The data acquisition system collects the depth of the pressure head entering the borehole wall, the water pressure, and the water volume change in the hydraulic power system in real time. Finally, the critical (maximum) pressure Pm (critical load) of the rock wall is tested and converted into the compressive strength and elastic modulus of the surrounding rock through calculation.

[0008] The hydraulic power system includes a manual hydraulic plunger pump, which includes a horizontally arranged base plate, a bearing seat is provided on the left side of the base plate, and a rotating shaft arranged horizontally on the left and right is rotatably connected in the bearing seat through a pressure bearing and a ball bearing. A rotating handle is provided at the left end of the rotating shaft, and a fixed seat is provided on the right side of the base plate. A pump body is provided on the fixed seat, and a guide rod parallel to the rotating shaft is provided between the fixed seat and the bearing seat. A screw rod is coaxially provided at the right end of the rotating shaft, a nut is threadedly connected to the screw rod, and a rotation-limiting slider slidably connected to the guide rod is fixedly connected to the outer circle of the nut. A hollow rod is connected to the right end of the nut, and the screw rod coaxially extends into the hollow rod, and a plunger is coaxially provided on the right end of the hollow rod. The plunger extends into the pump body, and a sealing ring assembly is provided on the inner wall of the left side of the pump body that is slidably sealed with the outer circle of the plunger. A water injection hole is provided on the top of the pump body, and a sealing stud is provided in the water injection hole. A pressure measuring port is provided at the right end of the pump body, and a water outlet is provided at the bottom of the pump body, and the water outlet is connected to a reversing three-way valve.

[0009] The data acquisition system includes a data recorder, a displacement sensor and a pressure sensor. The displacement sensor is installed on the rotation limit slider, and the pressure sensor is installed on the pressure measuring port at the right end of the pump body. Both the displacement sensor and the pressure sensor are connected to the data recorder through a signal receiver.

[0010] The test probe includes a probe body, the front end of the probe body is a spherical guide head, the rear end face of the probe body is provided with a threaded joint, a high-pressure water inlet and a low-pressure water inlet, the front end of the push rod is connected to the probe body through a threaded joint, a blind hole is provided in the radial direction inside the probe body, a piston is provided at the bottom of the blind hole, a first sealing ring is provided between the outer circle of the piston and the inner circle of the blind hole, a guide cover is threadedly connected to the outer port of the blind hole, a second sealing ring is provided between the outer circle of the guide cover and the inner circle of the blind hole, a guide hole is opened in the center of the guide cover, a pressure rod extending into the guide hole is coaxially provided at the outer end of the piston, the pressure head is threadedly connected to the outer end of the pressure rod, a copper sleeve is provided between the inner circle of the guide hole and the outer circle of the pressure rod, the high-pressure water inlet is connected to the bottom of the blind hole through the high-pressure water channel, and the low-pressure water inlet is connected to the blind hole between the guide cover and the piston through the low-pressure water channel.

[0011] The hydraulic pipeline includes a high-pressure water pipe and a low-pressure water pipe. One end of the high-pressure water pipe is connected to the second interface of the reversing three-way valve, and the other end of the high-pressure water pipe is connected to the high-pressure water inlet. One end of the low-pressure water pipe is connected to the third interface of the reversing three-way valve, and the other end of the low-pressure water pipe is connected to the low-pressure water inlet.

[0012] The specific process of connecting the hydraulic power system with the data acquisition system in step (1) is as follows: install the displacement sensor on the rotation limit slider, install the pressure sensor on the pressure measuring port, and then use data cables to connect the displacement sensor and pressure sensor to the data recorder respectively.

[0013] Step (2) Connect the hydraulic power system to the test probe through the hydraulic pipeline. The specific process is: connect one end of the high-pressure water pipe to the second interface of the reversing three-way valve, then connect the other end of the high-pressure water pipe to the high-pressure water inlet, then connect one end of the low-pressure water pipe to the third interface of the reversing three-way valve, and finally connect the other end of the low-pressure water pipe to the low-pressure water inlet.

[0014] Step (3) Connecting the front end of the push rod to the rear end of the test probe: The specific process is that the threaded joint is welded to the rear end surface of the probe body, and the front end of the push rod is inserted into and threaded into the threaded joint.

[0015] The specific process of step (4) is: extend the test probe into the borehole, operate the push rod to push the test probe into the borehole, and the depth of the push rod into the borehole can be obtained by the length of the push rod.

[0016] The specific process of step (5) is as follows: first, fill the hydraulic pipeline and the pump body of the hydraulic power system with water in advance; then, hold the rotary handle and rotate it, the rotary shaft drives the screw to rotate, and the nut connected to the screw thread can only move to the right along the length direction of the screw under the limitation of the rotation limit slider, and the rotation limit slider also moves to the right with the limit block, and the nut drives the hollow rod and the plunger to move to the right, and the plunger drives the water in the pump body to pass through the reversing three-way valve and the high-pressure water pipe in turn. The high-pressure water inlet and high-pressure water channel are injected into the blind hole. The high-pressure water pushes the piston outward, which drives the pressure rod and pressure head outward along the guide cover. The pressure head presses against the borehole wall. The rotary handle is operated at a constant speed. The high-pressure water enters the blind hole at a constant speed, driving the pressure head to apply uniform pressure to the borehole wall until the rock wall breaks under the action of the pressure head. At this time, the pressure value monitored by the pressure sensor drops sharply. The peak pressure during this process is the critical load for rock failure. The reversing three-way valve is then operated to connect the first and third ports of the reversing three-way valve. At the same time, the high-pressure water pipe is separated from the second port of the reversing three-way valve. The rotary handle is continued to operate, pushing the plunger to pressurize the water in the pump body into the low-pressure water pipe. The water then enters the blind hole between the guide cover and the piston through the low-pressure water channel. The low-pressure water drives the piston back to the bottom of the blind hole. The water in the blind hole is pressed out of the high-pressure water pipe, and the pressure head retracts into the blind hole. The push rod is then rotated or moved to move the test probe to the next depth for the next rock hardness test.

[0017] By adopting the above technical solution, the present invention can conduct in-situ rapid testing of the surrounding rock of the roadway through some simple operations. By integrating the real-time monitoring data of the displacement sensor and pressure sensor, it can draw a real-time displacement-pressure curve during the acquisition process, and understand the rock strength testing process in more detail. It has the following advantages: (1) The testing equipment of the present invention is lightweight and can be taken directly to the site. No sampling is required during the testing process, which can avoid the influence of the sampling process on the properties of the rock. The in-situ testing method of the rock strength in the borehole is realized, and the original state of the rock is ensured.

[0018] (2) It is suitable for the needs of underground working environment. The density of measuring points can be adjusted according to the on-site conditions to test the strength of surrounding rock of a large area of tunnel, which can better reflect the actual situation on site.

[0019] (3) The test can be carried out continuously, and a large area of multiple holes can be tested.

[0020] (4) The testing method is fast and economical. It reduces the process and cost of drilling and taking cores downhole and then bringing them back to the laboratory for uniaxial compression testing, thus shortening the testing cycle.

[0021] (5) It can measure the surrounding rock strength under different lithology, different water content, different confining pressure and water pressure conditions. The probe body is equipped with a pad on the back of the blind hole to increase the diameter of the test probe to meet the needs of various sizes of drill holes, thereby increasing the applicability of the test device. The material is made of high-strength alloy, especially the pressure head, to ensure that it does not deform under high loads, thereby increasing the service life of the test equipment.

[0022] (6) It can test data at different depths and different points in a borehole; the test probe is miniaturized, and it can test boreholes of different sizes by adding a pad on the back, which has strong adaptability.

[0023] (7) The measured results include the drilling depth, the strength of the rock wall at that depth, and the ejection displacement of the ejector pin, which can be displayed in real time on the measuring instrument display screen. The measured data can also be stored, recorded, exported, replayed, and classified for management.

[0024] (8) The test process is simple and convenient, with low learning cost. A certain volume of pressure medium (water) is pressed into the blind hole of the test probe by a plunger hydraulic pump, and the displacement sensor measures the displacement of the plunger in the plunger hydraulic pump and converts it into the displacement of the pressure head.

[0025] (9) Water is used as the pressure medium. It is easy to add and drain water into the system before and after the test without polluting the on-site environment. Water can be taken from the on-site clean water pipeline and does not need to be carried or transported. It has the advantages of being green, environmentally friendly, pollution-free, not wasting resources, light to carry, and highly economical.

[0026] (10) The test probe and the plunger hydraulic pump are connected by two hydraulic pipes (high-pressure water pipe and low-pressure water pipe). The high-pressure water pipe and the low-pressure water pipe are connected to the pump body through a reversible three-way valve. The plunger hydraulic pump is equipped with a pressure sensor and a displacement sensor, which can collect data in real time during the loading process. The sensor and the data recorder are connected by a data connection line to ensure that the data collected by the sensor is transmitted to the recorder during the test. The data is simply processed by the built-in software to generate a measurement curve, making the test process visual and convenient. The data measured by the pressure sensor and displacement sensor are integrated and converted by the signal receiver and output to the data recorder. The real-time curve chart of the test process is generated by the special software and stored and played back.

[0027] In summary, the present invention utilizes the principle of the probing method to drill a hole in the rock mass that needs to be tested or directly utilizes a pressure-releasing or drilling engineering hole to insert the test probe deep into the borehole for testing. The present invention can conduct mechanical property tests on the roof rock layer in situ on-site in a coal mine. Compared with traditional laboratory experiments, the in-situ test takes into account factors such as the natural stress state, water content, temperature and geological structure of the rock, and can better reflect the in-situ rock strength. The present invention has strong durability and environmental adaptability, high test accuracy, adopts a new pin displacement measurement method, develops a supporting test software system, and forms a complete set of equipment for in-situ testing of rock strength in a borehole, realizing real-time in-situ acquisition of rock strength underground, which can adapt to the needs of the underground working environment. The test device has a simple structure and is easy to operate, and the test data can better reflect the in-situ rock strength. The system can measure rock strength at different boreholes, depths, and locations, thereby determining the distribution of rock strength in the tunnel. The results are close to those obtained on-site. Using water as a medium for pressure transmission, the measurement process is simple, convenient, environmentally friendly, and safe, avoiding errors in sampling and processing. This significantly improves measurement efficiency, reduces measurement costs, addresses the lag inherent in traditional methods, and promotes intelligent mining. It has excellent promotional value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the hydraulic power system, data acquisition system, hydraulic pipeline, test probe and push rod in the present invention; Figure 2 yes Figure 1 Axial cross-sectional view of the hydraulic power system; Figure 3 yes Figure 1 Axial cross-sectional view of the test probe; Figure 4 yes Figure 1 Exploded view of the test probe; Figure 5 It is the pressure-displacement curve of the in-situ test process; Figure 6 It is the relationship diagram between the compressive strength and elastic modulus Rc of the surrounding rock and the critical load Pm; Figure 7 It is the relationship diagram of the elastic modulus E of the surrounding rock and the displacement pressure slope k in the elastic deformation stage. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in further detail below with reference to the accompanying drawings and examples.

[0030] like Figures 1-4 As shown, a method for measuring the hardness of in-situ drilled rock using a water medium pressure head according to the present invention comprises the following steps: (1) Connect the hydraulic power system 3 to the data acquisition system; (2) Connect the hydraulic power system 3 to the test probe 2 through the hydraulic pipeline; (3) Connect the front end of the push rod 1 to the rear end of the test probe 2; (4) Operate the push rod 1 to push the test probe 2 into the borehole; (5) Fill the hydraulic pipeline and the hydraulic power system 3 with water, start the hydraulic power system 3, and transmit the hydraulic power to the test probe 2. The pressure head 41 of the test probe 2 extends along the radial direction of the borehole to press the hole wall. The data acquisition system collects the depth of the pressure head 41 entering the inner wall of the borehole, the water pressure, and the change of the water volume in the hydraulic power system 3 in real time. Finally, the critical (maximum) pressure Pm (critical load) of the rock wall is tested and converted into the compressive strength and elastic modulus of the surrounding rock through calculation.

[0031] The hydraulic power system 3 includes a manual hydraulic plunger pump, which includes a horizontally arranged base plate 4, a bearing seat 5 is provided on the left side of the base plate 4, and a rotating shaft 7 arranged horizontally on the left and right is rotatably connected in the bearing seat 5 through a pressure bearing 6 and a ball bearing 7. A rotating handle 8 is provided at the left end of the rotating shaft 7, a fixed seat 9 is provided on the right side of the base plate 4, a pump body 10 is provided on the fixed seat 9, a guide rod 11 parallel to the rotating shaft 7 is provided between the fixed seat 9 and the bearing seat 5, a screw rod 12 is coaxially provided on the right end of the rotating shaft 7, a nut 13 is threadedly connected to the screw rod 12, and the outer circle of the nut 13 is fixedly connected A rotation-limiting slider 14 is connected to the guide rod 11 in a sliding connection, a hollow rod 15 is connected to the right end of the nut 13, the screw 12 coaxially extends into the hollow rod 15, and a plunger 16 is coaxially provided at the right end of the hollow rod 15. The plunger 16 extends into the pump body 10, and a sealing ring assembly 17 is provided on the left inner wall of the pump body 10 and is slidingly and sealingly connected to the outer circle of the plunger 16. A water injection hole 18 is provided on the top of the pump body 10, and a sealing stud is provided in the water injection hole 18. A pressure measuring port 19 is provided at the right end of the pump body 10, and a water outlet 20 is provided at the bottom of the pump body 10. The water outlet 20 is connected to a reversing three-way valve 21.

[0032] The data acquisition system includes a data recorder 22, a displacement sensor 23 and a pressure sensor 24. The displacement sensor 23 is arranged on the rotation limit slider 14, and the pressure sensor 24 is installed on the pressure measuring port 19 at the right end of the pump body 10. The displacement sensor 23 and the pressure sensor 24 are both connected to the data recorder 22 through a signal receiver.

[0033] The test probe 2 includes a probe body 25, the front end of the probe body 25 is a spherical guide head 26, the rear end of the probe body 25 is provided with a threaded joint 27, a high-pressure water inlet 28 and a low-pressure water inlet 29, the front end of the push rod 1 is connected to the probe body 25 through the threaded joint 27, the inside of the probe body 25 is provided with a blind hole 30 along the radial direction, the bottom of the blind hole 30 is provided with a piston 31, the outer circle of the piston 31 is provided with a first sealing ring 32 between the inner circle of the blind hole 30, and the outer end of the blind hole 30 is threadedly connected to the guide cover 3 3. A second sealing ring 34 is provided between the outer circle of the guide cover 33 and the inner circle of the blind hole 30. A guide hole is opened in the center of the guide cover 33. A pressure rod 35 is coaxially provided at the outer end of the piston 31 and extends into the guide hole. The pressure head 41 is threadedly connected to the outer end of the pressure rod 35. A copper sleeve 36 is provided between the inner circle of the guide hole and the outer circle of the pressure rod 35. The high-pressure water inlet 28 is connected to the bottom of the blind hole 30 through the high-pressure water channel 39. The low-pressure water inlet 29 is connected to the blind hole 30 between the guide cover 33 and the piston 31 through the low-pressure water channel 40.

[0034] The hydraulic pipeline includes a high-pressure water pipe 37 and a low-pressure water pipe 38. One end of the high-pressure water pipe 37 is connected to the second interface of the reversing three-way valve 21, and the other end of the high-pressure water pipe 37 is connected to the high-pressure water inlet 28. One end of the low-pressure water pipe 38 is connected to the third interface of the reversing three-way valve 21, and the other end of the low-pressure water pipe 38 is connected to the low-pressure water inlet 29.

[0035] The specific process of connecting the hydraulic power system 3 with the data acquisition system in step (1) is as follows: installing the displacement sensor 23 on the rotation-limiting slider 14, installing the pressure sensor 24 on the pressure measuring port 19, and then using data cables to connect the displacement sensor 23 and the pressure sensor 24 to the data recorder 22 respectively.

[0036] Step (2) connects the hydraulic power system 3 to the test probe 2 through the hydraulic pipeline. The specific process is: connect one end of the high-pressure water pipe 37 to the second interface of the reversing three-way valve 21, then connect the other end of the high-pressure water pipe 37 to the high-pressure water inlet 28, then connect one end of the low-pressure water pipe 38 to the third interface of the reversing three-way valve 21, and finally connect the other end of the low-pressure water pipe 38 to the low-pressure water inlet 29.

[0037] Step (3) Connecting the front end of the push rod 1 to the rear end of the test probe 2. The specific process is as follows: the threaded joint 27 is welded to the rear end surface of the probe body 25, and the front end of the push rod 1 is inserted into and threadedly connected to the threaded joint 27.

[0038] The specific process of step (4) is as follows: extend the test probe 2 into the borehole, operate the push rod 1 to push the test probe 2 into the borehole, and the depth of the push rod 1 can be obtained by the length of the push rod 1.

[0039] The specific process of step (5) is as follows: first, fill the hydraulic pipeline and the pump body 10 of the hydraulic power system 3 with water in advance; then, hold the rotary handle 8 and rotate it, the rotating shaft 7 drives the screw rod 12 to rotate, and the nut 13 threadedly connected to the screw rod 12 can only move to the right along the length direction of the screw rod 12 under the limitation of the rotation-limiting slider 14. The rotation-limiting slider 14 also moves to the right along the limit block, and the nut 13 drives the hollow rod 15 and the plunger 16 to move to the right. The plunger 16 drives the water in the pump body 10 to pass through the reversing three-way valve 21 and the high-pressure water pipe 37 in sequence. The high-pressure water inlet 28 and the high-pressure water channel are injected into the blind hole 30. The high-pressure water pushes the piston 31 to move outward. The piston 31 drives the pressure rod 35 and the pressure head 41 to move outward along the guide cover 33. The pressure head 41 presses the wall of the drill hole. The rotary handle 8 is operated at a uniform speed. The high-pressure water enters the blind hole 30 at a uniform speed, driving the pressure head 41 to pressurize the wall of the drill hole at a uniform speed until the rock wall is broken under the action of the pressure head 41. At this time, the pressure value monitored by the pressure sensor 24 drops significantly. The peak pressure in this process is the critical load when the rock is broken. Then the reversing three-way valve 21 is operated to make the reversing The first interface of the three-way valve 21 is connected to the third interface, and the high-pressure water pipe 37 is separated from the second interface of the reversing three-way valve 21. The rotary handle 8 is continued to be operated to push the plunger 16 to press the water in the pump body 10 into the low-pressure water pipe 38, and then enters the blind hole 30 between the guide cover 33 and the piston 31 through the low-pressure water channel. The low-pressure water drives the piston 31 to return to the bottom of the blind hole 30, and the water in the blind hole 30 is pressed out of the high-pressure water pipe 37, and the pressure head 41 retracts into the blind hole 30; then the push rod 1 is rotated or moved to move the test probe 2 to the next depth for the next rock hardness test.

[0040] In summary, the working principle of the in-situ rock strength test of the present invention is summarized as follows: a hole is drilled in the rock mass to be tested, and the rock strength test device is used to pressurize the borehole wall for testing. The most important component of the rock strength test device is the test probe 2. After the pressure head is driven out by liquid pressure and contacts the hole wall, the screw plunger 16 continues to pump pressure at an appropriate speed, and the displacement of the pressure head and the amount of pressure applied are measured and displayed in real time, generating a pressure-displacement curve (such as Figure 5 When the borehole rock wall breaks under the action of the ejector, the pressure of the pressure sensor 24 will suddenly drop, and Figure 5 At the jump point X1 in the pump, the critical (maximum) pressure Pm (critical load) and the displacement of the ejector pin are recorded, and the volume of water in the pump is measured to obtain the rock strength data. Through laboratory testing of a large number of coal-bearing rocks, the relationship between Pm and the rock compressive strength or elastic modulus is obtained, thereby indirectly obtaining the rock compressive strength value tested in situ. Figure 6 is the relationship diagram between the compressive strength and elastic modulus Rc of the surrounding rock and the critical load Pm, Figure 7The figure shows the relationship between the elastic modulus E of the surrounding rock and the displacement-pressure slope k during the elastic deformation stage. After each test, the data recorder 22 records the critical water volume, the displacement value of the ejector pin, and the strength of the rock. Combined with the test position of the probe (depth within the borehole) read from the encoder, a set of data can be generated, namely the rock strength at a certain depth in the borehole and the pressure-displacement curve during the test. After completing the borehole test using this method, the rock strength in the borehole can be divided into several basic levels. At the same time, by measuring the critical pressure of the probe, the strength changes of the homogeneous rock section in the borehole can be identified. By increasing the density of measuring points, the distribution range of areas such as weakened sections, contact surfaces between rock layers, and fracture zones can be further clarified. This method is suitable for the geological conditions and engineering characteristics of coal mines, can perform in-situ measurements, is easy to use, and has a fast measurement speed. It is a very suitable method for rapid measurement of underground rock strength.

[0041] The above embodiments illustrate the basic principles and features of the present invention, but the above only illustrates preferred embodiments of the present invention and is not limited to the embodiments. Under the guidance of this patent, those skilled in the art can make many variations and improvements without departing from the scope of the present invention and the scope of protection of the claims, all of which fall within the scope of protection of the present invention. Therefore, the patent and protection scope of the present invention shall be based on the appended claims.

Claims

1. A method for measuring in-situ drilled rock hardness using a water medium pressure head, characterized by: The following steps are involved: (1) Connect the hydraulic power system to the data acquisition system; (2) Connect the hydraulic power system to the test probe through the hydraulic pipeline; (3) Connect the front end of the push rod to the rear end of the test probe; (4) Operate the push rod to push the test probe into the borehole; (5) Fill the hydraulic pipeline and hydraulic power system with water, start the hydraulic power system, and transmit the hydraulic power to the test probe. The pressure head of the test probe extends along the radial direction of the borehole to press the hole wall. The data acquisition system collects the depth of the pressure head entering the borehole wall, the water pressure, and the water volume change in the hydraulic power system in real time. Finally, the critical (maximum) pressure Pm (critical load) of the rock wall is tested and converted into the compressive strength and elastic modulus of the surrounding rock through calculation.

2. The method for measuring in-situ drilled rock hardness using an aqueous medium pressure head according to claim 1, characterized in that: The hydraulic power system includes a manual hydraulic plunger pump, which includes a horizontally arranged base plate, a bearing seat is provided on the left side of the base plate, and a rotating shaft arranged horizontally on the left and right is rotatably connected in the bearing seat through a pressure bearing and a ball bearing. A rotating handle is provided at the left end of the rotating shaft, and a fixed seat is provided on the right side of the base plate. A pump body is provided on the fixed seat, and a guide rod parallel to the rotating shaft is provided between the fixed seat and the bearing seat. A screw rod is coaxially provided at the right end of the rotating shaft, a nut is threadedly connected to the screw rod, and a rotation-limiting slider slidably connected to the guide rod is fixedly connected to the outer circle of the nut. A hollow rod is connected to the right end of the nut, and the screw rod coaxially extends into the hollow rod, and a plunger is coaxially provided on the right end of the hollow rod. The plunger extends into the pump body, and a sealing ring assembly is provided on the inner wall of the left side of the pump body that is slidably sealed with the outer circle of the plunger. A water injection hole is provided on the top of the pump body, and a sealing stud is provided in the water injection hole. A pressure measuring port is provided at the right end of the pump body, and a water outlet is provided at the bottom of the pump body, and the water outlet is connected to a reversing three-way valve.

3. The method for measuring in-situ drilled rock hardness using an aqueous medium pressure head according to claim 2, characterized in that: The data acquisition system includes a data recorder, a displacement sensor and a pressure sensor. The displacement sensor is installed on the rotation limit slider, and the pressure sensor is installed on the pressure measuring port at the right end of the pump body. Both the displacement sensor and the pressure sensor are connected to the data recorder through a signal receiver.

4. The method for measuring in-situ drilled rock hardness using an aqueous medium pressure head according to claim 3, characterized in that: The test probe includes a probe body, the front end of the probe body is a spherical guide head, the rear end face of the probe body is provided with a threaded joint, a high-pressure water inlet and a low-pressure water inlet, the front end of the push rod is connected to the probe body through a threaded joint, a blind hole is provided in the radial direction inside the probe body, a piston is provided at the bottom of the blind hole, a first sealing ring is provided between the outer circle of the piston and the inner circle of the blind hole, a guide cover is threadedly connected to the outer port of the blind hole, a second sealing ring is provided between the outer circle of the guide cover and the inner circle of the blind hole, a guide hole is opened in the center of the guide cover, a pressure rod extending into the guide hole is coaxially provided at the outer end of the piston, the pressure head is threadedly connected to the outer end of the pressure rod, a copper sleeve is provided between the inner circle of the guide hole and the outer circle of the pressure rod, the high-pressure water inlet is connected to the bottom of the blind hole through the high-pressure water channel, and the low-pressure water inlet is connected to the blind hole between the guide cover and the piston through the low-pressure water channel.

5. The method for measuring in-situ drilled rock hardness using an aqueous medium pressure head according to claim 4, characterized in that: The hydraulic pipeline includes a high-pressure water pipe and a low-pressure water pipe. One end of the high-pressure water pipe is connected to the second interface of the reversing three-way valve, and the other end of the high-pressure water pipe is connected to the high-pressure water inlet. One end of the low-pressure water pipe is connected to the third interface of the reversing three-way valve, and the other end of the low-pressure water pipe is connected to the low-pressure water inlet.

6. The method for measuring in-situ drilled rock hardness using water medium pressure head according to claim 5, characterized in that: The specific process of connecting the hydraulic power system with the data acquisition system in step (1) is as follows: install the displacement sensor on the rotation limit slider, install the pressure sensor on the pressure measuring port, and then use data cables to connect the displacement sensor and pressure sensor to the data recorder respectively.

7. The method for measuring in-situ drilled rock hardness using an aqueous medium pressure head according to claim 5, characterized in that: Step (2) Connect the hydraulic power system to the test probe through the hydraulic pipeline. The specific process is: connect one end of the high-pressure water pipe to the second interface of the reversing three-way valve, then connect the other end of the high-pressure water pipe to the high-pressure water inlet, then connect one end of the low-pressure water pipe to the third interface of the reversing three-way valve, and finally connect the other end of the low-pressure water pipe to the low-pressure water inlet.

8. The method for measuring in-situ drilled rock hardness using water medium pressure head according to claim 5, characterized in that: Step (3) Connecting the front end of the push rod to the rear end of the test probe: The specific process is that the threaded joint is welded to the rear end surface of the probe body, and the front end of the push rod is inserted into and threaded into the threaded joint.

9. The method for measuring in-situ drilled rock hardness using water medium pressure head according to claim 5, characterized in that: The specific process of step (4) is: extend the test probe into the borehole, operate the push rod to push the test probe into the borehole, and the depth of the push rod into the borehole can be obtained by the length of the push rod.

10. The method for measuring in-situ drilled rock hardness using water medium pressure head according to claim 5, characterized in that: The specific process of step (5) is: When the cam is in the hydraulic position, the water in the pump body of the hydraulic system is pumped in. First, fill the hydraulic pipeline and the pump body of the hydraulic power system with water in advance; then hold the rotary handle and rotate it, the rotating shaft drives the screw to rotate, and the nut connected to the screw thread can only move to the right along the length of the screw under the limitation of the rotation limit slider. The rotation limit slider also moves to the right following the limit block, and the nut drives the hollow rod and the plunger to move to the right. The plunger drives the water in the pump body to pass through the reversing three-way valve, the high-pressure water pipe, the high-pressure water inlet, and the high-pressure water channel into the blind hole in turn. The high-pressure water pushes the piston to move outward, and the piston drives the pressure rod and the pressure head to move outward along the guide cover. The pressure head presses the wall of the drilled hole, and the rotary handle is operated at a uniform speed. The high-pressure water enters the blind hole at a uniform speed, driving the pressure head to pressurize the wall of the drilled hole at a uniform speed until the cam is in the hydraulic position. Until the rock wall breaks under the action of the pressure head, the pressure value monitored by the pressure sensor drops significantly. The peak pressure in this process is the critical load when the rock is broken. Then operate the reversing three-way valve to connect the first interface and the third interface of the reversing three-way valve. At the same time, separate the high-pressure water pipe from the second interface of the reversing three-way valve. Continue to operate the rotating handle to push the plunger to press the water in the pump body into the low-pressure water pipe, and then enter the blind hole between the guide cover and the piston through the low-pressure water channel. The low-pressure water drives the piston to reset to the bottom of the blind hole, and the water in the blind hole is pressed out of the high-pressure water pipe, and the pressure head retracts into the blind hole. Then rotate the push rod or move the push rod to move the test probe to the next depth for the next rock hardness test.

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