CN107422039B - Single-shaft loading coal body ultrasonic velocity testing system device and experimental method - Google Patents
Single-shaft loading coal body ultrasonic velocity testing system device and experimental method Download PDFInfo
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- CN107422039B CN107422039B CN201710785390.1A CN201710785390A CN107422039B CN 107422039 B CN107422039 B CN 107422039B CN 201710785390 A CN201710785390 A CN 201710785390A CN 107422039 B CN107422039 B CN 107422039B
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Abstract
The invention relates to a single-shaft loading coal body ultrasonic velocity testing device which comprises a bearing upright post, a cross beam, a base, a workbench, a lifting driving mechanism, an upper detection body, a lower detection body, a sound wave transducer, a resistance strain gauge and a control circuit, wherein two ends of the bearing upright post are respectively and mutually and vertically connected with the cross beam and the base to form a rectangular frame structure; the method comprises three steps of coal sample collection, coal sample detection, detection data summarization operation and the like. The invention effectively improves the working efficiency and precision of the coal mechanical property detection operation on one hand, and effectively improves the general type of the detection equipment while improving the detection operation efficiency on the other hand.
Description
Technical Field
The invention relates to a single-shaft loading coal body ultrasonic velocity testing system device and an experimental method, and belongs to the technical field of geological survey.
Background
The coal-based stratum structure and physical property characteristics have great practical significance for underground safe and efficient green mining of coal and development of coal bed gas. Currently, the main method for obtaining coal-based stratum structure and physical property information is mainly exploration, wherein in the process of geological exploration operation, an ultrasonic operation exploration medium is mainly used, and it is found in the process of ultrasonic geological exploration operation at present, on one hand, the currently used ultrasonic exploration equipment often has a relatively complex structure, poor use flexibility and great operation difficulty, and on the other hand, the currently used ultrasonic detection equipment often can only perform exploration detection operation in a specific direction in the exploration process, so that the defects of poor mechanical detection performance of the current geological exploration operation on the detection operation surface, insufficient general type of the detection equipment and the like can not be effectively and comprehensively obtained, and therefore, a brand new ultrasonic detection device and detection method for geological exploration are urgently needed to be developed to meet the needs of actual use.
Disclosure of Invention
The invention aims to overcome the defects and provides a uniaxial loading coal body ultrasonic velocity testing system device and an experimental method.
In order to realize the purpose, the invention is realized by the following technical scheme:
a single-shaft loading coal body ultrasonic speed testing device comprises two bearing upright columns, a cross beam, a base, two working tables, a lifting driving mechanism, an upper detection body, a lower detection body, an acoustic wave transducer, a resistance strain gauge and a control circuit, wherein the two bearing upright columns are symmetrically distributed on the center line of the base, the two ends of each bearing upright column are respectively and vertically connected with the cross beam and the base to form a rectangular frame structure, the two working tables are respectively arranged on the upper surface of the base and the lower surface of the cross beam through the lifting driving mechanism and are mutually and coaxially distributed, the upper detection body and the lower detection body are respectively arranged on the working tables on the base and the cross beam and are coaxially distributed with the working tables, each of the upper detection body and the lower detection body comprises a bearing column, a hard positioning sleeve, an elastic positioning sleeve and a pressure bearing end, the bearing column is in a cylindrical hollow tubular structure, and the positions of the two ends are respectively a detection end and a wire end, the detection end and the wire end are connected with the pressure-bearing end, wherein the detection end is connected with the workbench through the pressure-bearing end, the pressure-bearing end is abutted against the surface of the coal briquette to be detected, the pressure-bearing end of the detection end is provided with a detection port which is coaxially distributed with the bearing column, the hard positioning sleeve and the elastic positioning sleeve are tubular structures which are coaxially distributed with the bearing column, the lower end surface of the hard positioning sleeve and the lower end surface of the elastic positioning sleeve are distributed in parallel and level with the lower end surface of the bearing column, the upper end surface is lower than the upper end surface of the bearing column by 1-10 cm, the hard positioning sleeve and the inner surface of the bearing column are mutually connected in a sliding way through a sliding rail and are coated outside the elastic positioning sleeve, the acoustic transducer is embedded in the elastic positioning sleeve and is coaxially distributed with the bearing column, the lower end surface of the acoustic transducer is embedded in the detection port and is distributed in parallel and level with the lower end surface of the detection port, the lateral surface of the bearing column of the wire end is provided with a wire hole, the wire of sound wave transducer passes through wire guide and control circuit electrical connection, resistance strain gauge two altogether and paste and wait to detect the coal cinder side surface, and two resistance strain gauges all are located and wait to detect the same side surface position of coal cinder, two resistance strain gauge axis mutually perpendicular distribute, mutual parallel and all with control circuit electrical connection between the resistance strain gauge, it is the cylinder structure with last detection body, the coaxial distribution of lower detection body to wait to detect the coal cinder, and wait to detect the coal cinder diameter and go up detection body, the diameter of lower detection body is the same, control circuit installs on the base and respectively with lift actuating mechanism, sound wave transducer, resistance strain gauge electrical connection.
Furthermore, the lifting driving mechanism is any one of a pneumatic cylinder, a hydraulic cylinder and a screw rod mechanism.
Furthermore, the lower surface of the workbench is respectively connected with the cross beam and the base in a sliding mode through a travelling mechanism.
Furthermore, the upper detection body, the lower detection body and the coal briquette to be detected are mutually connected through insulating sealing sleeves, and the insulating sealing sleeves are coated on the outer surfaces of the upper detection body, the lower detection body and the coal briquette to be detected.
Furthermore, the height of the coal briquette to be detected is 70-100 mm.
Furthermore, the two resistance strain gauges on the side surfaces of the coal briquette to be detected are symmetrical by using the center line of the coal briquette to be detected, and the distance between the two resistance strain gauges is 3-5 mm.
Furthermore, coupling agents are arranged at two ends of the coal briquette to be detected and abut against the end faces of the upper detection body and the lower detection body through the coupling agents.
An experimental method of a single-shaft loading coal body ultrasonic velocity testing device comprises the following steps:
firstly, collecting a coal sample, namely observing to find out a bedding surface, determining the type (original/structural coal) of the coal, roughly observing coal and rock components, determining the directions of end cutting and surface cutting according to the bedding surface, measuring the length, width and height of the coal block, taking a coal pillar with the diameter of 50mm of a rock core according to the requirement, drilling the coal pillars in the same coal block as much as possible, if the coal block is larger, reasonably dividing the coal pillar as much as possible, and taking out the coal cores in three directions, wherein the size of the coal sample is phi 50mm multiplied by 100mm;
the method according to the first step requirement, wherein the three directional coal cores are respectively defined as X, Y, Z direction, and the X direction is parallel to the surface cleat direction or perpendicular to the end cleat direction; the Y direction is perpendicular to the face cleat or parallel to the end cleat direction; the Z direction refers to the direction perpendicular to the bedding;
setting an original point position on a coal body to be detected, establishing a three-axis coordinate system by taking the original point as a reference point, sampling by sampling equipment along the X-axis, Y-axis and Z-axis directions of the three-axis coordinate system to obtain three detected coal samples with the same diameter and length, and labeling and storing the coal samples for later use respectively;
secondly, coal sample detection, after the first operation is finished, sequentially detecting three coal samples obtained from the same coal body to be detected according to the sequence of an X axis, a Y axis and a Z axis, when the detection operation is carried out, firstly, an upper detection body and a lower detection body are respectively installed on a base and a worktable on a cross beam, then a lifting driving mechanism adjusts the distance between the base and the worktable on the cross beam, so that the distance between the upper detection body and the lower detection body is at least 0.5-1 cm greater than the height of the coal sample, then, the tail end of the coal sample is connected with the detection end of the lower detection body, then, the distance between the base and the worktable on the cross beam is adjusted through the lifting driving mechanism, so that the detection end of the upper detection body is connected with the upper end surface of the coal sample, axial pressure of 0-10 MPa is applied to the coal sample, pressure is maintained for 10-20 min after certain numerical pressure is required by loading axial pressure according to a scheme, after the axial pressure is stable, firstly, independently starting an acoustic transducer in an upper detection body to perform ultrasonic oscillation on a coal sample for 1-5 minutes, then standing for 5-30 seconds, independently starting an acoustic transducer in a lower detection body again to perform ultrasonic oscillation on the coal sample for 1-5 minutes, then standing for 5-30 seconds, simultaneously starting the acoustic transducers in the upper detection body and the lower detection body to perform ultrasonic oscillation on the coal sample until 30-60 seconds before pressure maintaining operation is stopped, respectively acquiring longitudinal and transverse strain values generated by the coal sample during each group of ultrasonic oscillation operation through a resistance strain gauge during oscillation operation, then transmitting the acquired parameters to a control circuit, and after the detection of three coal sample parameters of an X axis, a Y axis and a Z axis is completed, classifying and summarizing the detected data;
and thirdly, detecting data summarizing operation, performing data operation by the control circuit after the second operation is completed, and performing data operation on the collected coal samples in the X-axis direction, the Y-axis direction and the Z-axis direction respectively during the data operation, and then performing summarizing operation on the data of the coal samples in the X-axis direction, the Y-axis direction and the Z-axis direction so as to obtain longitudinal and transverse wave speeds and strain parameters of the coal body to be detected.
Furthermore, in the second step, the operation frequency of the acoustic wave transducer is 0.3-2 MHz.
Further, in the third step, the data operation function is:
longitudinal and transverse wave velocity calculation function: vp = L/tp-t0 Vs = L/ts-t0;
wherein: vp-longitudinal wave velocity (m/s);
vs — transverse wave velocity (m/s);
l is the distance (m) between the centers of the upper and lower plug transducers;
tp is the time(s) taken by the longitudinal wave in the sample;
ts is the time(s) the shear wave takes in the sample;
t 0-zero delay(s) of the instrument system;
poisson ratio calculation function:
wherein: v-poisson's ratio;
ε d -transverse strain of the coal sample;
ε 1 -axial strain of the coal sample;
young's modulus calculation function:
wherein: E-Young's modulus;
σ -represents the forward stress (force F/S received per unit area);
ε -represents the forward strain (relative deformation Δ L/L under external force); bulk modulus calculation function:
wherein: k-bulk modulus;
v0-volume of coal sample under the action of axial pressure;
dP is the difference between the pressure of the final state and the pressure of the initial state;
dV is the difference value between the volume of the final state coal sample and the volume of the initial state coal sample;
volume strain calculation function: θ = Δ V/V;
wherein the method comprises the following steps: theta is the volume strain value;
v is the volume of the coal sample;
delta V is the variation of the volume of the coal sample under the action of axial pressure;
comprehensive strain calculation function of coal sample, epsilon v ＝ε 1 +2ε 3
Wherein: epsilon v Is the volume strain of the coal sample;
ε 1 is the axial strain;
ε 2 is the transverse strain.
Further, the product modulus K and the elastic modulus (or young) E, poisson ratio μ are a relation function:
the device has the advantages of simple structure, flexible and convenient use and high detection operation efficiency and detection precision, effectively improves the working efficiency and precision of the coal mechanical property detection operation on one hand, and can simultaneously obtain elastic parameters such as Young modulus, volume modulus, poisson ratio, longitudinal wave velocity, transverse wave velocity and the like through one-time detection, thereby improving the detection operation efficiency and effectively improving the general type and application range of the detection device.
Drawings
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a schematic structural view of a bearing guide frame.
Detailed Description
As shown in fig. 1 and 2, as shown in fig. 1, a single-shaft loading coal body ultrasonic velocity testing device comprises a bearing upright column 1, a cross beam 2, a base 3, two working tables 4, a lifting driving mechanism 5, an upper detection body 6, a lower detection body 7, an acoustic wave transducer 8, a resistance strain gauge 9 and a control circuit 10, wherein the bearing upright column 1 is symmetrically distributed on the center line of the base 3, two ends of the bearing upright column 1 are respectively and vertically connected with the cross beam 2 and the base 3 to form a rectangular frame structure, the working tables 4 are respectively and coaxially distributed on the upper surface of the base 3 and the lower surface of the cross beam 2 through the lifting driving mechanism 5, the two working tables 4 are respectively and coaxially distributed, the upper detection body 6 and the lower detection body 7 are respectively arranged on the base 3 and the working table 4 on the cross beam 2 and are coaxially distributed with the working tables 4, the upper detection body 6 and the lower detection body 7 respectively comprise a bearing column 101, a hard positioning sleeve 102, an elastic positioning sleeve 103 and a pressure-bearing end 104, the bearing column 101 is a cylindrical hollow tubular structure, the two ends of the bearing column are respectively provided with a detection end 105 and a lead end 106, the detection end 105 and the lead end 106 are both connected with a pressure-bearing end 104, wherein the detection end 105 is connected with the workbench 4 through the pressure-bearing end 104, the pressure-bearing end 104 is abutted against the surface of the coal briquette 11 to be detected, the pressure-bearing end 104 of the detection end 105 is provided with a detection port 12, the detection port 12 and the bearing column 1 are coaxially distributed, the hard positioning sleeve 102 and the elastic positioning sleeve 103 are tubular structures coaxially distributed with the bearing column 101, the lower end surfaces of the hard positioning sleeve 102 and the elastic positioning sleeve 103 are distributed in parallel and level with the lower end surface of the bearing column 101, the upper end surface is 1-10 cm lower than the upper end surface of the bearing column 101, wherein the hard positioning sleeve 102 and the inner surface of the bearing column 101 are mutually connected in a sliding manner through a sliding rail 13 and are coated outside the elastic positioning sleeve 103, the acoustic wave transducer 8 is embedded in the elastic positioning sleeve 103 and coaxially distributed with the bearing column 101, the lower end face of the acoustic wave transducer 8 is embedded in the detection port 12 and is flush with the lower end face of the detection port 12, the side surface of the bearing column 101 of the lead end 106 is provided with a lead hole 14, the lead of the acoustic wave transducer 8 is electrically connected with the control circuit 10 through the lead hole 14, two resistance strain gauges 9 are attached to the side surface of the coal briquette 11 to be detected, the two resistance strain gauges 9 are both positioned on the same side surface position of the coal briquette 11 to be detected, the axes of the two resistance strain gauges 9 are mutually and vertically distributed, the resistance strain gauges 9 are mutually parallel and are electrically connected with the control circuit 10, the coal briquette 11 to be detected is of a cylindrical structure coaxially distributed with the upper detection body 6 and the lower detection body 7, the diameter of the coal briquette 11 to be detected is the same as that of the upper detection body 6 and the lower detection body 7, and the control circuit 10 is installed on the base 3 and is respectively electrically connected with the lifting driving mechanism 5, the acoustic wave transducer 8 and the resistance strain gauges 9.
In this embodiment, the lifting driving mechanism 5 is any one of a pneumatic cylinder, a hydraulic cylinder and a screw mechanism.
In this embodiment, the lower surface of the worktable 4 is slidably connected with the beam 2 and the base 3 through the traveling mechanism 15.
In this embodiment, the upper detecting body 6, the lower detecting body 7 and the coal briquette 11 to be detected are connected with each other through the insulating sealing sleeve 16, and the insulating sealing sleeve 16 covers the outer surfaces of the upper detecting body 6, the lower detecting body 7 and the coal briquette 11 to be detected.
In this embodiment, the height of the coal briquette 11 to be detected is 70-100 mm.
In this embodiment, the two resistance strain gauges 9 on the side surface of the coal briquette to be detected 11 are symmetrical with the centerline of the coal briquette to be detected 11, and the distance between the two resistance strain gauges 9 is 3-5 mm.
In this embodiment, the couplants 17 are disposed at two ends of the coal briquette 11 to be detected, and abut against the end surfaces of the upper detection body 6 and the lower detection body 7 through the couplants 17.
As shown in fig. 2, an experimental method of a uniaxial loading coal body ultrasonic velocity testing device comprises the following steps:
firstly, collecting a coal sample, namely observing to find out a bedding surface, determining the type (primary/structural coal) of the coal, roughly observing coal rock components, determining the directions of end cleft and face cleft according to the bedding surface, measuring the length, width and height of the coal block, taking coal pillars with the diameter of 50mm of a rock core according to needs, drilling the coal pillars in the same coal block as much as possible, and if the coal block is larger, reasonably dividing the coal block as much as possible, taking out the coal cores in three directions, wherein the size of the coal sample is phi 50mm multiplied by 100mm;
the method according to the first step requirement, wherein the three directional coal cores are respectively defined as X, Y, Z direction. The X direction is parallel to the face cleat or perpendicular to the end cleat direction; the Y direction is perpendicular to the face cleat or parallel to the end cleat direction; the Z direction refers to the direction perpendicular to the bedding;
setting an original point position on a coal body to be detected, establishing a three-axis coordinate system by taking the original point as a reference point, sampling by sampling equipment along the X-axis, Y-axis and Z-axis directions of the three-axis coordinate system to obtain three detected coal samples with the same diameter and length, and labeling and storing the coal samples for later use respectively;
secondly, coal sample detection, after the first operation is finished, sequentially detecting three coal samples obtained from the same coal body to be detected according to the sequence of an X axis, a Y axis and a Z axis, when the detection operation is carried out, firstly, an upper detection body and a lower detection body are respectively installed on a base and a worktable on a cross beam, then a lifting driving mechanism adjusts the distance between the base and the worktable on the cross beam, so that the distance between the upper detection body and the lower detection body is at least 0.5-1 cm greater than the height of the coal sample, then, the tail end of the coal sample is connected with the detection end of the lower detection body, then, the distance between the base and the worktable on the cross beam is adjusted through the lifting driving mechanism, so that the detection end of the upper detection body is connected with the upper end surface of the coal sample, axial pressure of 0-10 MPa is applied to the coal sample, pressure is maintained for 10-20 min after certain numerical pressure is required by loading axial pressure according to a scheme, after the axial pressure is stable, firstly, independently starting an acoustic transducer in an upper detection body to perform ultrasonic oscillation on a coal sample for 1-5 minutes, then standing for 5-30 seconds, independently starting an acoustic transducer in a lower detection body to perform ultrasonic oscillation on the coal sample for 1-5 minutes, then standing for 5-30 seconds, simultaneously starting the acoustic transducers in the upper detection body and the lower detection body to perform ultrasonic oscillation on the coal sample until 30-60 seconds before pressure maintaining operation is stopped, respectively acquiring strain pressure values generated by the coal sample during each group of ultrasonic oscillation operation through a resistance strain gauge during oscillation operation, then transmitting the acquired parameters to a control circuit, and after the parameter detection of three coal samples of an X axis, a Y axis and a Z axis is completed, performing classification and summarization operation on the detected data;
and thirdly, detecting data summarizing operation, performing data operation by the control circuit after the second operation is completed, and performing data operation on the collected coal samples in the X-axis direction, the Y-axis direction and the Z-axis direction respectively during the data operation, and then performing summarizing operation on the data of the coal samples in the X-axis direction, the Y-axis direction and the Z-axis direction so as to obtain longitudinal and transverse wave speeds and strain parameters of the coal body to be detected.
In this embodiment, in the second step, the operating frequency of the acoustic wave transducer is 0.3-2 MHz.
In this embodiment, in the third step, the data operation function is:
longitudinal and transverse wave velocity calculation function: vp = L/tp-t0 Vs = L/ts-t0;
wherein: vp-longitudinal wave velocity (m/s);
vs — transverse wave velocity (m/s);
l is the distance (m) between the centers of the upper and lower plug transducers;
tp is the time(s) taken by the longitudinal wave in the sample;
ts is the time(s) the shear wave takes in the sample;
t 0-zero delay(s) of the instrument system;
poisson ratio calculation function:
wherein: v-poisson's ratio;
ε d -transverse strain of the coal sample;
ε 1 -axial strain of the coal sample;
young's modulus calculation function:
wherein: E-Young's modulus;
σ -represents the forward stress (force F/S received per unit area);
ε -represents the forward strain (relative deformation Δ L/L under external force); bulk modulus calculation function:
wherein: k-bulk modulus;
v0-volume of coal sample under the action of axial pressure;
dP is the difference between the pressure of the final state and the pressure of the initial state;
dV is the difference value between the volume of the final state coal sample and the volume of the initial state coal sample;
volume strain calculation function: θ = Δ V/V;
wherein: theta is the volume strain value;
v is the volume of the coal sample;
delta V is the variation of the volume of the coal sample under the action of axial pressure;
comprehensive strain calculation function of coal sample, epsilon v ＝ε 1 +2ε 3
Wherein: epsilon v Is the volume strain of the coal sample;
ε 1 is the axial strain;
ε 2 is the transverse strain.
In this embodiment, the relationship function between the product modulus K, the elastic modulus (or young) E, and the poisson ratio μ:
the device has simple structure, flexible and convenient use and high detection operation efficiency and detection precision, effectively improves the working efficiency and precision of the coal mechanical property detection operation on one hand, and can simultaneously obtain elastic parameters such as Young modulus, volume modulus, poisson ratio, longitudinal wave velocity, transverse wave velocity and the like through one-time detection on the other hand, thereby effectively improving the general type and application range of the detection device while improving the detection operation efficiency.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (4)
1. An experimental method of a single-shaft loading coal body ultrasonic velocity testing device is characterized in that: the experimental method of the uniaxial loading coal body ultrasonic velocity testing device comprises the following steps:
firstly, collecting a coal sample, namely observing to find out a bedding surface, determining the type (original/structural coal) of the coal, roughly observing coal and rock components, determining the directions of end cutting and surface cutting according to the bedding surface, measuring the length, width and height of the coal block, taking a coal pillar with the diameter of 50mm of a rock core according to the requirement, drilling the coal pillars in the same coal block as much as possible, if the coal block is larger, reasonably dividing the coal pillar as much as possible, and taking out the coal cores in three directions, wherein the size of the coal sample is phi 50mm multiplied by 100mm;
the method according to the first step requirement, wherein the three directional coal cores are respectively defined as X, Y, Z direction, and the X direction is parallel to the surface cleat direction or perpendicular to the end cleat direction; the Y direction is perpendicular to the face cleat or parallel to the end cleat direction; the Z direction refers to the direction perpendicular to the bedding;
setting an original point position on a coal body to be detected, establishing a three-axis coordinate system by taking the original point as a reference point, sampling by sampling equipment along the X-axis, Y-axis and Z-axis directions of the three-axis coordinate system to obtain three detected coal samples with the same diameter and length, and labeling and storing the coal samples for later use respectively;
secondly, coal sample detection, after the first operation is finished, sequentially detecting three coal samples obtained from the same coal body to be detected according to the sequence of an X axis, a Y axis and a Z axis, when the detection operation is carried out, firstly, an upper detection body and a lower detection body are respectively installed on a base and a worktable on a cross beam, then a lifting driving mechanism adjusts the distance between the base and the worktable on the cross beam, so that the distance between the upper detection body and the lower detection body is at least 0.5-1 cm greater than the height of the coal sample, then, the tail end of the coal sample is connected with the detection end of the lower detection body, then, the distance between the base and the worktable on the cross beam is adjusted through the lifting driving mechanism, so that the detection end of the upper detection body is connected with the upper end surface of the coal sample, axial pressure of 0-10 MPa is applied to the coal sample, pressure is maintained for 10-20 min after certain numerical pressure is required by loading axial pressure according to a scheme, after the axial pressure is stable, firstly, independently starting an acoustic transducer in an upper detection body to perform ultrasonic oscillation on a coal sample for 1-5 minutes, then standing for 5-30 seconds, independently starting an acoustic transducer in a lower detection body again to perform ultrasonic oscillation on the coal sample for 1-5 minutes, then standing for 5-30 seconds, simultaneously starting the acoustic transducers in the upper detection body and the lower detection body to perform ultrasonic oscillation on the coal sample until 30-60 seconds before pressure maintaining operation is stopped, respectively acquiring longitudinal and transverse strain values generated by the coal sample during each group of ultrasonic oscillation operation through a resistance strain gauge during oscillation operation, then transmitting the acquired parameters to a control circuit, and after the detection of three coal sample parameters of an X axis, a Y axis and a Z axis is completed, classifying and summarizing the detected data;
and thirdly, detecting data summarizing operation, performing data operation by the control circuit after the second operation is completed, and performing data operation on the collected coal samples in the X-axis direction, the Y-axis direction and the Z-axis direction during data operation, and then performing summarizing operation on the data of the coal samples in the X-axis direction, the Y-axis direction and the Z-axis direction so as to obtain longitudinal and transverse wave speeds and strain parameters of the coal body to be detected.
2. The experimental method of the uniaxial loading coal body ultrasonic velocity testing device according to claim 1, characterized in that: in the second step, the operation frequency of the acoustic wave transducer is 0.3-2 MHz.
3. The experimental method of the uniaxial loading coal body ultrasonic velocity testing device according to claim 1, characterized in that: in the third step, the data operation function is:
longitudinal and transverse wave velocity calculation function: vp = L/tp-t0 Vs = L/ts-t0;
wherein: vp-longitudinal wave velocity (m/s);
vs — transverse wave velocity (m/s);
l is the distance (m) between the centers of the upper and lower plug transducers;
tp is the time(s) taken by the longitudinal wave in the sample;
ts is the time(s) the shear wave takes in the sample;
t 0-zero delay(s) of the instrument system;
poisson ratio calculation function:
wherein: v-poisson's ratio;
ε d -transverse strain of the coal sample;
ε 1 -axial strain of the coal sample;
young's modulus calculation function:
wherein: E-Young's modulus;
σ -represents the forward stress (force F/S received per unit area);
ε -represents the forward strain (relative deformation Δ L/L under external force);
bulk modulus calculation function:
wherein: k-bulk modulus;
v0-volume of coal sample under the action of axial pressure;
dP is the difference between the pressure of the final state and the pressure of the initial state;
dV is the difference value between the volume of the final state coal sample and the volume of the initial state coal sample;
volume strain calculation function: θ = Δ V/V;
wherein: theta is the volume strain value;
v is the volume of the coal sample;
delta V is the variation of the volume of the coal sample under the action of axial pressure;
comprehensive strain calculation function of coal sample, epsilon v ＝ε 1 +2ε 3
Wherein: epsilon v Is the volume strain of the coal sample;
ε 1 is the axial strain;
ε 2 is the transverse strain.
4. The experimental method for the uniaxial loading coal body ultrasonic velocity testing device according to claim 3, characterized by comprising the following steps: the relationship function between the bulk modulus K, the elastic modulus (or Young) E and the Poisson ratio mu is as follows:
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| CN108761531B (en) * | 2018-04-12 | 2019-06-21 | 中国矿业大学 | A kind of Coal Pore Structure intelligent Forecasting based on SVM theory |
| CN108982211B (en) * | 2018-08-30 | 2020-05-26 | 中钢集团新型材料（浙江）有限公司 | Operation method of equipment for measuring elastic modulus of graphite by sonic velocity method |
| CN109708975B (en) * | 2019-01-24 | 2021-07-30 | 河南城建学院 | Anti-noise interference type single-shaft loading sample cylinder and using method thereof |
| CN109696479B (en) * | 2019-01-28 | 2024-04-16 | 四川大学 | Acoustic emission test system and method for asymmetric arrangement of cuboid samples |
| CN109946379B (en) * | 2019-04-01 | 2020-02-18 | 大连理工大学 | Electromagnetic ultrasonic detection method for unidirectional stress |
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