Pen type rock mass friction tester and method based on biaxial decoupling sensing core

Abstract

The invention discloses a pen type rock mass friction tester and method based on a double-shaft decoupling sensing core, and relates to the technical field of geotechnical engineering in-situ tests.The tester comprises a shell, a holding part is arranged at the middle section of the shell, a communication channel is formed in the holding part, the upper end of the communication channel is communicated with a first cavity formed in the upper portion of the shell, and the lower end of the communication channel is communicated with a second cavity formed in the lower portion of the shell; a control unit is arranged in the first cavity; the lower end of the communication channel communicates with a second cavity formed in the lower portion of the shell, a sensing unit is arranged in the second cavity, the lower portion of the sensing unit is arranged on a clamping head, and a clamping unit is arranged in the clamping head. According to the pen type rock mass friction tester and method based on the double-shaft decoupling sensing core, the single, solid and motion-gap-free elastic element cross beam is adopted as a sensing unit, the mechanical abrasion and jamming risks are fundamentally eliminated through the design, the equipment size can be reduced to be the size of a marking pen, and the cost is reduced. The carrying and the use are more convenient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of in-situ testing of geotechnical engineering, in particular to a pen-type rock mass friction tester and method based on a biaxial decoupling sensing core. BACKGROUND

[0002] The shear strength of rock structure surface is a decisive parameter for evaluating the stability of various rock engineering (such as slope, dam, tunnel, and mine). The accurate determination of the basic friction angle, as a key input parameter of the shear dilation model such as the Barton-Bandis model, is crucial.

[0003] The prior art is as follows: The laboratory tilt test method recommended by the International Society for Rock Mechanics (ISRM) is currently recognized as the gold standard for determining the basic friction angle of rock surface. It places a pair of rock samples with flat contact surfaces on a variable-angle platform, gradually increases the shear stress using the gravity component, and until the upper rock sample starts to slide, the platform inclination at this time is the basic friction angle. The principle of this method is reliable, but it has inherent and significant limitations: Non-in-situ: Must be sampled from the engineering site, which destroys the in-situ environment of the rock mass (such as humidity, microcosmic water film, gas adsorption, etc.), and the test results may not fully reflect the real working conditions.

[0004] Time-consuming and labor-intensive: From sampling, sample preparation (cutting, flattening) to testing, the entire process cycle is long, and cannot meet the needs of rapid reconnaissance and real-time decision-making on the engineering site.

[0005] Device-dependent: Requires a dedicated laboratory and large tilt test table, and cannot be flexibly applied on site.

[0006] In addition to the above method, a utility model patent with publication number CN223361971U and the name of a handheld rock sample friction test device is disclosed in the art. The device is provided with two mutually perpendicular movable seats and two independent force sensors for measuring normal force and shear force, respectively. Although this design realizes the concept of handheld measurement, its mechanical structure has the following fundamental defects: Structurally bulky and low integration: Its essence is the combination of two macro sliding mechanisms, resulting in a large volume and heavy weight, not truly "portable", and difficult to operate in a small or irregular work surface.

[0007] Susceptible to torque interference: When handheld, the operator's force is difficult to be completely eccentric and twisted. This eccentricity and torsional moment can easily cause the sliding mechanism to jam or be unevenly stressed, thereby seriously interfering with the measurement accuracy of the shear force and causing the results to be distorted.

[0008] The test material distortion: usually use fixed metal or hard alloy probe, test is the friction between the probe material and rock, not the engineering more concerned about the "rock and rock between" friction characteristics.

[0009] In summary, the field needs a tester that can overcome the above-mentioned defects. SUMMARY

[0010] The purpose of the present application is to provide a pen-type rock mass friction tester and method based on a dual-axis decoupling sensing core, which solves the problems raised in the background art.

[0011] To achieve the above-mentioned purpose, the present application provides a pen-type rock mass friction tester based on a dual-axis decoupling sensing core, comprising a shell, a holding part is arranged at the middle segment of the shell, a communication channel is opened in the holding part, the upper end of the communication channel is communicated with a first cavity opened in the upper part of the shell, and a control unit is arranged in the first cavity; The lower end of the communication channel is communicated with a second cavity opened in the lower part of the shell, a sensing unit is arranged in the second cavity, and a clamping head is arranged below the sensing unit, and a clamping unit is arranged in the inside of the clamping head.

[0012] Preferably, the clamping head comprises an end plate, a connecting sleeve is arranged at the upper end of the end plate, an external thread is opened in the outer wall of the connecting sleeve, the connecting sleeve is connected with the shell, and an internal thread is correspondingly opened in the shell; A receiving sleeve is arranged at the lower end of the end plate, and a bottom plate is arranged at the lower end of the receiving sleeve.

[0013] Preferably, the clamping unit comprises a support frame arranged on the bottom plate, an electric push rod is arranged above the support frame, the output end of the electric push rod is connected with a linkage disc, the linkage disc is arranged below the support frame, three groups of clamping jaws are arranged below the linkage disc, each group of clamping jaws comprises a connecting rod fixedly connected below the linkage disc, the lower end of the connecting rod is connected with a connecting block through a guide sleeve arranged on the bottom plate, the connecting block is hingedly connected with one end of a rotating rod, the other end of the rotating rod is hingedly connected with one end of a clamping arm, and two rotating rods are arranged in each group of clamping jaws; The upper part of the clamping arm is also hingedly connected with one end of a fixed rod, the other end of the fixed rod is fixedly connected with the lower end of the bottom plate, and two fixed rods are arranged in each group of clamping jaws; The other end of the clamping arm is provided with a backing plate.

[0014] Preferably, the sensing unit comprises a strain gauge and an elastic element, the elastic element is inserted into a fixed frame, the fixed frame is fixedly arranged on the end plate, and the fixed frame and the elastic element are both inserted through the insert and fixed by the fixing member.

[0015] Preferably, the elastic element comprises a cross beam, the cross beam comprises a first radial arm and a second radial arm symmetrically arranged along a y-axis, and a first axial arm and a second axial arm symmetrically arranged along an x-axis, roots of the first axial arm, the second axial arm, the first radial arm and the second radial arm are intersected, and are an integral structure.

[0016] Preferably, the strain gauge is provided with a plurality of strain gauges, including a first strain gauge and a second strain gauge arranged on the front and back of the first axial arm, a third strain gauge and a fourth strain gauge arranged on the front and back of the second axial arm, a fifth strain gauge and a sixth strain gauge arranged on the upper surface and the lower surface of the first radial arm, and a seventh strain gauge and an eighth strain gauge arranged on the upper surface and the lower surface of the second radial arm.

[0017] Preferably, the first strain gauge, the second strain gauge, the third strain gauge and the fourth strain gauge are connected by a connecting wire to form a normal force measurement bridge. The fifth strain gauge, the sixth strain gauge, the seventh strain gauge and the eighth strain gauge are connected by a connecting wire to form a shear force measurement bridge. The strain gauge is also electrically connected to the control unit.

[0018] Preferably, the control unit comprises a battery pack and a main control circuit board, the main control circuit board is integrated with a microcontroller and a signal conditioning sub-module, the battery pack and the main control circuit board are electrically connected, and the main control circuit board and the battery pack are both fixed in the first cavity by a supporting element.

[0019] Preferably, the upper part of the shell is also embedded with a display screen, a plurality of keys are arranged below the display screen, and the keys and the display screen are electrically connected to the control unit.

[0020] A method of a pen-type rock mass friction tester based on a dual-axis decoupling sensing core, comprising the following steps: Step S1, clamping the rock sample by the clamping unit inside the clamping head; Step S2, holding the clamping head, and pressing the rock sample below the clamping head against the surface of the rock mass structure to be tested, keeping the tester axis perpendicular to the contact surface to ensure the accuracy of the normal force direction; Step S3, slowly press the tester to the rock mass surface, apply the normal force through the holding part, at this time the first axial arm and the second axial arm of the cross beam are compressed, the normal force measurement bridge outputs a voltage signal proportional to the pressure, which is transmitted to the microcontroller through the signal conditioning submodule; Keep the normal force stable, slide the tester horizontally along the contact surface, the rock sample generates friction with the structural plane, the shear force makes the first radial arm and the second radial arm of the cross beam bend, the shear force measurement bridge outputs a voltage signal proportional to the friction force, which is also transmitted to the microcontroller after the signal conditioning submodule; Step S4, the microcontroller converts the received analog signal into a digital signal, calculates the real-time normal force, shear force, calculates the friction coefficient and the basic friction angle, and displays the calculation results in real time on the display screen; Step S5, press the confirmation recording key, the current measured friction coefficient, basic friction angle and corresponding normal force, shear force data are stored to the controller; Step S6, release the pressing and sliding action, stop applying force; Step S7, repeat the above steps to obtain multiple normal force-shear force data points, further linearly fit the shear force-normal force data points, and take the slope of the fitted straight line as the final basic friction angle; Step S8, start the electric push rod to release the clamping jaw, take down the rock sample, turn off the power of the equipment, clean the tester, and complete the test.

[0021] Therefore, the pen-type rock mass friction tester and method based on the dual-axis decoupling sensing core have the following beneficial effects: (1) The cross beam, a single, solid and motion gap-free elastic element, is used as a sensing unit in the present application. This "static design" fundamentally eliminates mechanical wear and jamming risks, so that the size of the device can be reduced to the size of a pen, making it more convenient to carry and use.

[0022] (2) The three sets of clamping jaws in the clamping unit are symmetrically distributed, and through the coordinated action of the connecting rod, rotating rod and linkage disc, the sample can be clamped synchronously from multiple directions, avoiding the sample displacement and loosening problems caused by uneven force of traditional single or double clamping jaws.

[0023] The technical solutions of the present application will be further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a structural schematic diagram of an embodiment of the pen-type rock mass friction tester and method based on the dual-axis decoupling sensing core of the present application; Figure 2 FIG. 2 is a partial internal structure schematic diagram of the pen-type rock mass friction tester and method based on the dual-axis decoupling sensing core of the present application; Figure 3 A structure schematic view of a sensing unit of a pen-type rock mass friction tester and method based on a biaxial decoupling sensing core according to the present application; Figure 4 A structure schematic view of a clamping unit of a pen-type rock mass friction tester and method based on a biaxial decoupling sensing core according to the present application; The reference signs: 1, shell; 11, holding part; 12, second cavity; 2, control unit; 21, display screen; 22, button; 3, sensing unit; 31, cross beam; 32, first radial arm; 33, second radial arm; 34, first axial arm; 35, second axial arm; 36, first strain gauge; 37, second strain gauge; 38, third strain gauge; 39, fourth strain gauge; 310, fifth strain gauge; 311, sixth strain gauge; 312, seventh strain gauge; 313, eighth strain gauge; 314, fixed frame; 315, plug-in; 316, fixing part; 4, clamping head; 41, end plate; 42, connecting sleeve; 43, external thread; 44, receiving sleeve; 45, bottom plate; 5, clamping unit; 51, support frame; 52, electric push rod; 53, linkage disc; 54, connecting rod; 55, guide sleeve; 56, connecting block; 57, rotating rod; 58, clamping arm; 59, fixed rod; 510, pad plate. DETAILED DESCRIPTION

[0025] The technical solutions of the present application are further described below by means of the accompanying drawings and examples.

[0026] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the usual meaning as understood by a person with ordinary skill in the art to which the present application belongs. The terms "first", "second" and similar words used in the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar words mean that the elements or objects before the words cover the elements or objects listed after the words and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "up", "down", "left", "right" and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships may also change accordingly.

[0027] EXAMPLE Please refer to Figures 1-4The application provides a pen type rock mass friction tester based on a double-axis decoupling sensing core, which comprises a shell 1, the shell 1 is made of high-strength lightweight material (such as aviation aluminum alloy), is ergonomic, and is convenient for single-handed holding, force applying and operation. A holding part 11 is arranged at the middle position of the shell 1, a communication channel is formed in the holding part 11, the upper end of the communication channel is communicated with a first cavity formed in the upper part of the shell 1, and a control unit 2 is arranged in the first cavity. The lower end of the communication channel is communicated with a second cavity 12 formed in the lower part of the shell 1, a sensing unit 3 is arranged in the second cavity 12, and the sensing unit 3 is arranged on a clamping head 4 below. The inside of the clamping head 4 is provided with a clamping unit 5 for clamping a sample.

[0028] The clamping head 4 comprises an end plate 41, the upper end of the end plate 41 is provided with a connecting sleeve 42, an outer thread 43 is formed in the outer wall of the connecting sleeve 42, the connecting sleeve 42 is connected with the shell 1, and an inner thread is formed in the shell 1 in correspondence. The lower end of the end plate 41 is provided with a receiving sleeve 44, and the lower end of the receiving sleeve 44 is provided with a bottom plate 45.

[0029] The clamping unit 5 comprises a support frame 51 arranged on the bottom plate 45, an electric push rod 52 arranged above the support frame 51, an output end of the electric push rod 52 connected to a linkage disc 53 arranged below the support frame 51, three groups of clamping jaws arranged below the linkage disc 53, each group of clamping jaws comprising a connecting rod 54 fixedly connected below the linkage disc 53, the lower end of the connecting rod 54 connected with a connecting block 56 through a guide sleeve 55 arranged on the bottom plate 45, the connecting block 56 hingedly connected with one end of a rotating rod 57, the other end of the rotating rod 57 hingedly connected with one end of a clamping arm 58, and two rotating rods 57 arranged in each group of clamping jaws. The upper part of the clamping arm 58 is also hingedly connected with one end of a fixed rod 59, the other end of the fixed rod 59 is fixedly connected with the lower end of the bottom plate 45, and two fixed rods 59 are arranged in each group of clamping jaws. The other end of the clamping arm 58 is provided with a pad 510, the pad 510 is made of anti-skid material, the friction force with the rock sample is increased, and relative sliding between the sample and the clamping jaw during the test is prevented, and in the embodiment, the pad 510 is made of rubber material.

[0030] The sensing unit 3 comprises a strain gauge and an elastic element, the elastic element is inserted into a fixed frame 314, the fixed frame 314 is fixedly arranged on the end plate 41, and the fixed frame 314 and the elastic element are penetrated by an insert 315 and fixed by a fixing piece 316.

[0031] The elastic element comprises a cross beam 31, which is made of tool steel or titanium alloy with high elastic limit. Figure 3As shown, the cross beam 31 includes a first radial arm 32 and a second radial arm 33 symmetrically arranged along the y-axis, and a first axial arm 34 and a second axial arm 35 symmetrically arranged along the x-axis, the roots of the first axial arm 34, the second axial arm 35, the first radial arm 32 and the second radial arm 33 intersect and are of an integral structure.

[0032] The strain gauges are provided in multiple, including a first strain gauge 36 and a second strain gauge 37 provided on the front and back of the first axial arm 34, a third strain gauge 38 and a fourth strain gauge 39 provided on the front and back of the second axial arm 35, a fifth strain gauge 310 and a sixth strain gauge 311 provided on the upper surface and the lower surface of the first radial arm 32, and a seventh strain gauge 312 and an eighth strain gauge 313 provided on the upper surface and the lower surface of the second radial arm 33.

[0033] The first strain gauge 36, the second strain gauge 37, the third strain gauge 38 and the fourth strain gauge 39 are connected by a connecting wire 1 to form a normal force measurement bridge. The specific connection relationship is as follows: One end of the first strain gauge 36 is connected to one end of the third strain gauge 38 as the "power positive terminal" of the bridge (connected to power supply); the other end of the first strain gauge 36 is connected to one end of the second strain gauge 37 to form the "first node" of the bridge; the other end of the third strain gauge 38 is connected to one end of the fourth strain gauge 39 to form the "second node" of the bridge; the other end of the second strain gauge 37 is connected to the other end of the fourth strain gauge 39 as the "power negative terminal" of the bridge (ground GND). The first node and the second node are the "signal output terminal" of the bridge, used to output the differential voltage signal related to the normal force, denoted as U n +、U n -.

[0034] When the axial arm is compressed / stretched by the normal force, the resistance change directions of the first strain gauge 36 and the third strain gauge 38 are consistent (same increase or same decrease), and the resistance change directions of the second strain gauge 37 and the fourth strain gauge 39 are consistent and opposite to those of the first strain gauge 36 / third strain gauge 38.

[0035] The fifth strain gauge 310, the sixth strain gauge 311, the seventh strain gauge 312 and the eighth strain gauge 313 are connected by a connecting wire 2 to form a shear force measurement bridge. The specific connection relationship is as follows: One end of the fifth strain gauge 310 is connected with one end of the seventh strain gauge 312 as the "power positive terminal" (supply power) of the bridge. The other end of the fifth strain gauge 310 is connected with one end of the sixth strain gauge 311 to form the "third node" of the bridge. The other end of the seventh strain gauge 312 is connected with one end of the eighth strain gauge 313 to form the "fourth node" of the bridge. The other end of the sixth strain gauge 311 is connected with the other end of the eighth strain gauge 313 as the "power negative terminal" (ground GND) of the bridge. The third node and the fourth node are the "signal output terminals" of the bridge, used to output the differential voltage signal related to the shear force, denoted as U s + and U s -.

[0036] When the radial arm is bent by the shear force, the fifth strain gauge 310 and the eighth strain gauge 313 are stretched (resistance increases), and the sixth strain gauge 311 and the seventh strain gauge 312 are compressed (resistance decreases). The full-bridge circuit amplifies the difference between the increase and the decrease as a voltage signal, improving the measurement sensitivity.

[0037] The strain gauges are also electrically connected with the control unit 2. Specifically, the output signals of the two groups of bridges are transmitted to the signal conditioning submodule through wires, and then processed by the microcontroller. In this embodiment, two groups of four-core shielded wires (each group corresponds to one bridge) are used. Each group of wires includes: 2 signal lines (transmitting U n + and U n - or U s + and U s -); 2 power supply lines (transmitting 5V power supply and GND to power the bridge); the outer layer of the signal line and the power supply line is wrapped with a metal shielding layer to reduce electromagnetic interference. One end of the wire is welded to the lead terminal of the strain gauge, and the other end is connected to the main control circuit board through the communication channel inside the shell 1.

[0038] The specific connection relationship is as follows: The normal force bridge signal: U n + and U n - are respectively connected to the normal signal input terminals of the signal conditioning submodule, and then output to the microcontroller after amplification and filtering.

[0039] The shear force bridge signal: U s + and U s - are respectively connected to the shear signal input terminals of the signal conditioning submodule, and then output to the microcontroller after amplification and filtering.

[0040] The power supply terminals of the bridge are connected with the "voltage stabilizing output terminals" of the signal conditioning submodule, and the GND terminals are connected with the common ground of the main control circuit board, to ensure stable power supply.

[0041] The principle of the sensing unit 3 is that the cross beam 31 converts the normal force and shear force into the resistance change of the strain gauge through the deformation of the axial arm and the radial arm, and outputs the electric signal through two groups of bridge circuits, and the control unit 2 presents the friction coefficient and the basic friction angle on the display screen 21 through signal processing and calculation, so as to realize the rapid and portable measurement of the friction characteristics of the rock mass.

[0042] The control unit 2 includes a battery pack and a main control circuit board, the main control circuit board is integrated with a microcontroller, a signal conditioning sub-module and a micro digital acceleration sensor (in this embodiment, the micro digital acceleration sensor with the model ADI ADXL367 is selected), the micro digital acceleration sensor is connected with the microcontroller through an electric wire, and is used for obtaining the normal force and the shear force in the moment when the acceleration is greater than 0, the micro digital acceleration sensor adopted in this embodiment is the mature prior art in the field, and the model has been given, and the circuit connection and principle will not be described in detail here. The battery pack and the main control circuit board are electrically connected, and the battery pack supplies power for the main control circuit board and the electric push rod 52. The main control circuit board and the battery pack are both fixed in the first cavity through a supporting element, and the supporting element can adopt a supporting plate, a bolt and a nut or the like.

[0043] The upper portion of the shell 1 is also embedded with the display screen 21, and a plurality of keys 22 are arranged below the display screen 21, and the keys 22 and the display screen 21 are electrically connected with the control unit 2. The keys 22 include a power-on key / power-off key, an electric push rod 52 control key and a confirmation recording key.

[0044] A method of a pen-type rock mass friction tester based on a dual-axis decoupling sensing core, wherein the dual-axis decoupling means that the sensing core of the tester is subjected to forces in two directions at the same time, but the internal circuit design of the tester is like a precise filter, which perfectly separates the signals of the two forces, and realizes independent and accurate reading of the values of the normal force and the shear force at the same moment without interference. Specifically, the method comprises the following steps: Step S1, press the electric push rod 52 control key once downward, the output end of the electric push rod 52 moves downward, drives the linkage disc 53 to move downward, drives the connecting rod 54 and the rotating rod 57 to link, so that the clamping arms 58 of the three groups of clamping jaws rotate around the fixed rods 59 and are in an open state; at this time, the rock sample is placed in the center of the clamping opening, and the electric push rod 52 control key is pressed twice downward, the output end of the electric push rod 52 moves upward, the clamping arms 58 are closed, and the sample is clamped through the pad 510; Step S2, hold the holding part 11, and press the rock sample below the clamping head 4 against the surface of the rock mass structure surface to be tested, keep the axis of the tester perpendicular to the contact surface, and ensure the accuracy of the normal force direction; Step S31, slowly press the tester to the rock surface, apply the normal force through the holding part 11, at this time the first axial arm 34 and the second axial arm 35 of the cross beam 31 are compressed, the normal force measurement bridge outputs a voltage signal proportional to the pressure, which is transmitted to the microcontroller through the signal conditioning submodule; Step S32, keep the normal force stable, slide the tester along the contact surface, the rock sample generates friction with the structural surface, the shear force makes the first radial arm 32 and the second radial arm 33 of the cross beam 31 bend, the shear force measurement bridge outputs a voltage signal proportional to the friction force, which is also transmitted to the microcontroller through the signal conditioning submodule; Step S4, the microcontroller converts the received analog signal into a digital signal, calculates the real-time normal force, shear force, calculates the friction coefficient and the basic friction angle, and the calculation results are displayed in real time on the display screen 21; Wherein, the process of calculating the real-time normal force, shear force, calculating the friction coefficient and the basic friction angle is as follows: First, the axial arm receives the normal force compression / stretching, generating axial strain The axial strain is directly measured by the strain gauge; The radial arm is bent by the shear force, generating bending strain The bending strain is directly measured by the strain gauge; The strain is converted into force by the following two formulas: Normal force calculation formula: ; Shear force calculation formula: ; Wherein, , are the calibrated normal and tangential coefficients obtained through indoor experiments; , are the normal and tangential strain values measured by the strain gauge.

[0045] The calculation formula of the friction coefficient is as follows: ; The calculation formula of the basic friction angle is as follows: .

[0046] The above calculation process is calculated by the data processing module in the microcontroller, wherein the calculation formula and fixed parameters are preset in the data processing module, during measurement, the strain signal output by the strain gauge through the wire, the data processing module calculates the final result, and outputs to the display screen 21 through the transmission circuit for display.

[0047] Step S5, press the confirm record key, the current measured friction coefficient, basic friction angle and corresponding normal force, shear force data are stored to the controller; Step S6, release the press and slide action, stop applying force; Step S7, repeat the above steps, get a plurality of normal force-shear force data points, further linear fitting is performed on the shear force-normal force data points, and the slope of the fitting straight line is As the final basic friction angle; Step S8, press the electric push rod 52 control key once, start the electric push rod 52 to release the clamping jaw, take down the rock sample, turn off the power of the device, clean the tester, and complete the test.

[0048] Therefore, the application adopts the above-mentioned pen-type rock mass friction tester and method based on a dual-axis decoupling sensing core, adopts a single, solid, and motion gap-free elastic element cross beam as a sensing unit. This design fundamentally eliminates the risk of mechanical wear and jamming, so that the size of the device can be reduced to the size of a pen, making it more convenient to carry and use.

[0049] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A pen-type rock mass friction tester based on a dual-axis decoupled sensing core, characterized in that: The device includes a housing, a gripping part is provided in the middle section of the housing, a connecting channel is provided in the gripping part, the upper end of the connecting channel is connected to a first cavity opened in the upper part of the housing, and a control unit is provided in the first cavity; The lower end of the communication channel is connected to a second cavity opened in the lower part of the housing. A sensing unit is provided in the second cavity, and a clamping head is arranged below the sensing unit. A clamping unit is provided inside the clamping head.

2. The pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 1, characterized in that: The clamping head includes an end plate, and a connecting sleeve is provided at the upper end of the end plate. The outer wall of the connecting sleeve is provided with external threads. The connecting sleeve is connected to the housing, and the housing is provided with corresponding internal threads. The lower end of the end plate is provided with a receiving sleeve, and the lower end of the receiving sleeve is provided with a base plate.

3. The pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 2, characterized in that: The clamping unit includes a support frame mounted on the base plate. An electric push rod is mounted above the support frame. The output end of the electric push rod is connected to a linkage plate. The linkage plate is mounted below the support frame. Three sets of grippers are mounted below the linkage plate. Each set of grippers includes a connecting rod fixedly connected to the lower part of the linkage plate. The lower end of the connecting rod passes through a guide sleeve mounted on the base plate and is connected to a connecting block. The connecting block is hinged to one end of a rotating rod. The other end of the rotating rod is hinged to one end of a clamping arm. Two rotating rods are mounted in each set of grippers. The upper part of the clamping arm is also hinged to one end of the fixing rod, and the other end of the fixing rod is fixedly connected to the lower end of the base plate. Each set of clamping claws is provided with two fixing rods. A pad is provided at the other end of the clamping arm.

4. A pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 3, characterized in that: The sensing unit includes a strain gauge and an elastic element. The elastic element is inserted into a fixed frame, which is fixedly mounted on the end plate. Both the fixed frame and the elastic element are inserted through the fixed element and fixed by fasteners.

5. A pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 4, characterized in that: The elastic element includes a cross beam, which includes a first radial arm and a second radial arm symmetrically arranged along the y-axis, and a first axial arm and a second axial arm symmetrically arranged along the x-axis. The roots of the first axial arm, the second axial arm, the first radial arm, and the second radial arm intersect and are integral structures.

6. A pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 5, characterized in that: The strain gauges are provided in multiple ways, including a first strain gauge and a second strain gauge provided on the front and back sides of the first axial arm, a third strain gauge and a fourth strain gauge provided on the front and back sides of the second axial arm, a fifth strain gauge and a sixth strain gauge provided on the upper and lower surfaces of the first radial arm, and a seventh strain gauge and an eighth strain gauge provided on the upper and lower surfaces of the second radial arm.

7. A pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 6, characterized in that: The first strain gauge, the second strain gauge, the third strain gauge, and the fourth strain gauge are connected by a connecting wire to form a normal force measurement bridge. The fifth strain gauge, the sixth strain gauge, the seventh strain gauge, and the eighth strain gauge are connected by a second connecting wire to form a shear force measurement bridge; The strain gauge is also electrically connected to the control unit.

8. A pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 7, characterized in that: The control unit includes a battery pack and a main control circuit board. The main control circuit board integrates a microcontroller and a signal conditioning submodule. The battery pack and the main control circuit board are electrically connected, and both the main control circuit board and the battery pack are fixed in the first cavity by support elements.

9. A pen-type rock friction tester based on a dual-axis decoupled sensing core according to claim 8, characterized in that: A display screen is also fitted into the upper part of the housing, and multiple buttons are provided below the display screen. Both the buttons and the display screen are electrically connected to the control unit.

10. A method for a pen-type rock mass friction tester based on a biaxial decoupled sensing core according to any one of claims 1-9, characterized in that, Includes the following steps: Step S1: Clamp the rock sample using the clamping unit inside the clamping head; Step S2: Hold the gripping part and place the rock sample below the clamping head against the surface of the rock mass structure to be tested, keeping the axis of the tester perpendicular to the contact surface to ensure the accurate direction of the normal force; Step S3: Slowly press the tester onto the rock surface and apply normal force through the grip. At this time, the first axial arm and the second axial arm of the cross beam are compressed. The normal force measuring bridge outputs a voltage signal that is proportional to the pressure and is transmitted to the microcontroller through the signal conditioning submodule. Maintaining the normal force is stable, the tester slides horizontally along the contact surface. The rock sample rubs against the structural surface. The shear force causes the first and second radial arms of the cross beam to bend. The shear force measuring bridge outputs a voltage signal that is proportional to the friction force. It is also transmitted to the microcontroller after passing through the signal conditioning submodule. Step S4: The microcontroller converts the received analog signal into a digital signal, calculates the real-time normal force, shear force, friction coefficient and basic friction angle, and displays the calculation results on the display screen in real time. Step S5: Press the confirmation and record button. The currently measured friction coefficient, basic friction angle, and corresponding normal force and shear force data are stored in the controller. Step S6: Release the pressing and sliding motion, and stop applying force; Step S7: Repeat the above steps to obtain multiple sets of normal force-shear force data points. Further perform linear fitting on the shear force-normal force data points, and use the slope of the fitted line as the final basic friction angle. Step S8: Start the electric push rod to release the gripper, remove the rock sample, turn off the power to the equipment, clean the tester, and complete the test.

Images