Rock fracture expansion detection system and method based on thermal imaging and image recognition
Technical Field
The invention relates to the technical field of rock mechanical tests, in particular to a rock test piece fracture expansion detection system and method based on thermal imaging and image recognition.
Background
When the non-confining pressure rock sample is subjected to compression failure under the action of longitudinal pressure, the load borne on a unit area is called the uniaxial compressive strength of the rock. Indoor uniaxial compressive strength tests are usually carried out on uniaxial loading testers, and the properties of a rock after compression until it loses its strength completely can be represented by a load-deformation full-process curve. The load-bearing capacity is reduced after the rock is damaged, mainly caused by the reduction of the effective area due to the sample fracture, and the load deformation overall process curve shows that the rock still has the characteristic of certain load-bearing capacity after the rock is damaged, so that the method has important value in the research of the stability of rock engineering.
The uniaxial compression test is an important means for solving the problem of actual engineering, the observation of the crack expansion of a rock test piece in the uniaxial compression test process is the key for researching the rock property and solving the engineering problem, and the expansion of the crack of the rock test piece is usually detected by adopting infrared detection, CT scanning, acoustic emission and the like in a laboratory. Most of infrared thermal imaging detection only observes the change of the cracks on the surface of the rock test piece, and the development condition of the cracks in the rock test piece cannot be obtained; the application cost of CT scanning is high, acoustic emission is very sensitive to the property of materials, and is easily interfered by electromechanical noise, only the activity and the strength of an acoustic emission source part can be given, and acoustic emission signals are not generated due to defect stabilization, so that the detection accuracy is not high.
Therefore, a simple, efficient, economic and reliable rock fracture expansion detection system and method are provided, the fracture expansion process in the rock test piece loading process is detected, the fracture development of the rock test piece is qualitatively analyzed, and the fracture development characteristics of the near-surface rock test piece are obtained.
Disclosure of Invention
The invention provides a rock fracture expansion detection system and method based on thermal imaging and image recognition, and the specific technical scheme is as follows.
A rock fracture expansion detection system based on thermal imaging and image recognition comprises a single-shaft loading device, a rock test piece, a heat source, a thermal imager, a support and a computer, wherein the rock test piece is arranged on a loading base of the single-shaft loading device, the support and the rock test piece are oppositely arranged, a plurality of two-dimensional slide rails are arranged on the support, the thermal imager and the heat source are installed on the two-dimensional slide rails, and the thermal imager is connected with the computer; the heat source radiates the heat source to the rock test piece, the thermal imager acquires temperature distribution information of the rock surface, and the computer processes the temperature distribution picture information; the support is further provided with a base and a lifting support, and the two-dimensional sliding rail is connected with the lifting support through a rotating disk.
Preferably, the two-dimensional sliding rails are independently arranged and rotate along the lifting support; the two-dimensional slide rail comprises a rotating rod and a connecting rod, and the rotating rod and the connecting rod are connected through a rotating shaft.
Preferably, the dwang and connecting rod are provided with wedge groove along pole length direction, and the block is in the recess of dwang and connecting rod respectively at the pivot both ends.
Preferably, the heat source comprises a lampshade and a bulb, and the base is provided with a telescopic supporting rod.
A rock fracture expansion detection method based on thermal imaging and image recognition utilizes the rock fracture expansion detection system based on thermal imaging and image recognition, and comprises the following steps:
placing a rock test piece on a loading base of a single-shaft loading device, fixing a heat source and a thermal imager on a support, and connecting the thermal imager with a computer;
adjusting the height of the lifting support and the size of a supporting surface of the base, adjusting the relative positions of a heat source and the thermal imager with the rock test piece by the sliding slide rail, and focusing the heat source on the rock test piece;
adjusting the focus of a calibration heat source of the thermal imager, and fixing the power of a plurality of heat sources to stabilize the surface temperature of the test piece;
loading the rock test piece by using the single-shaft loading device, and acquiring thermal image data of rock surface temperature distribution information by using a thermal imager while loading the rock test piece;
step five, closing the heat source, cooling the rock test piece, and recording thermal image data of the rock test piece when the thermal imager is cooled;
processing thermal image data when the rock test piece is loaded by the computer to obtain the change of a fracture expansion three-dimensional graph of the rock test piece along with time;
and step seven, processing the thermal image data of the rock test piece in the cooling process by the computer to obtain the fracture close to the surface of the rock test piece.
Preferably, in the sixth step, the raw format file obtained by the thermal imager is imported into Avizo, subjected to median filtering and binarization, subjected to threshold separation, and displayed to form a fracture expansion three-dimensional graph of the rock specimen at each time point in the loading state.
Preferably, in the seventh step, the raw format file obtained by the thermal imager is imported into Avizo, the JPEG format file is exported to Matlab through median filtering and binarization, and the crack development of the near surface of the rock test piece is obtained through gradient change of gray values of pixel points.
The rock test piece fracture expansion detection system and method based on thermal imaging and image recognition have the advantages that thermal imaging of the rock test piece in a stress loading state is obtained through thermal imaging under the condition of non-contact of the rock test piece, fracture detection data of a plurality of set time points under a continuous loading state are obtained through analysis, damage starting points, fracture expansion paths and development processes of the rock test piece in the loading state can be better analyzed, thermal imaging data in the cooling process of the rock test piece are analyzed after the test piece is heated, fracture development conditions of the near surface of the rock are obtained, qualitative analysis of the uniaxial loading process of the rock test piece is achieved, and the fracture development characteristics of the rock test piece are convenient to study.
Drawings
FIG. 1 is a schematic diagram of a rock fracture propagation detection system based on thermal imaging and image recognition;
FIG. 2 is a front view of the stent structure;
FIG. 3 is a schematic view of a stent structure;
FIG. 4 is a top view of a rock fracture propagation detection system;
FIG. 5 is a side view of a rock fracture propagation detection system;
FIG. 6 is a schematic view of a base structure;
FIG. 7 is a schematic diagram of a two-dimensional slide rail configuration;
FIG. 8 is a schematic flow chart of a rock fracture propagation detection method based on thermal imaging and image recognition;
in the figure: 1-uniaxial loading means; 2-a rock test piece; 3-a heat source; 4-a thermal imager; 5-a bracket; 51-a two-dimensional slide rail; 511-rotating rods; 512-connecting rod; 513-a rotating shaft; 52-a base; 53-lifting support; 54-rotating disc; 6-computer.
Detailed Description
Referring to fig. 1 to 8, the rock specimen fracture propagation detection system and method based on thermal imaging and image recognition provided by the invention have the following specific embodiments.
A rock fracture expansion detection system based on thermal imaging and image recognition specifically comprises a single-shaft loading device 1, a rock test piece 2, a heat source 3, a thermal imager 4, a support 5 and a computer 6. The uniaxial loading device 1 can perform uniaxial compression on the rock test piece, the heat source 3 mainly provides heat and can focus the heat, the thermal imager 4 observes the rock test piece to obtain a thermal image, the support 5 is used for supporting the heat source and the thermal imager, the relative position of the device and the rock test piece is adjusted, and the computer 6 is used for processing the thermal image to obtain the fracture development condition of the rock test piece. The thermal imaging is carried out under the condition of non-contact rock test pieces, the thermal imaging of the rock test pieces in a stress loading state is obtained, and the fracture detection data of a plurality of set time points in a continuous loading state are obtained through analysis, so that the damage starting points of the rock test pieces in the loading state, the expansion paths of the fractures and the development process can be better analyzed. The overall structure of the system realizes the detection of the rock test piece crack expansion, thereby providing a simple, convenient, efficient, economic and reliable rock crack expansion detection means and providing convenience for the research of the properties of the rock test piece.
On the loading base of unipolar loading device 1 was arranged in to the rock test piece, exerted pressure to the rock test piece through pressure head and base, support 5 and rock test piece 2 mutual disposition are provided with a plurality of two-dimensional slide rails on the support 5 to conveniently adjust the relative position with the test piece, thermal imaging system 4 and heat source 3 install on two-dimensional slide rail, thereby make the test process nimble more convenient, thermal imaging system 4 and computer 6 link to each other, make things convenient for the transmission of data. The heat source 3 radiates a heat source to the rock test piece, the thermal imager 4 obtains temperature distribution information of the rock surface, and the computer 6 processes the temperature distribution picture information. The support 5 is further provided with a base 52 and a lifting support 53, the base ensures the stability of the support, the lifting support is convenient for height adjustment, a two-dimensional sliding rail 51 is connected with the lifting support through a rotating disk 54, the two-dimensional sliding rail ensures that the positions of the thermal imager and the heat source are adjusted on a plane, the height is adjusted by combining the lifting support 53, and the three-dimensional adjustment of the thermal imager and the heat source is realized, so that the detection is more convenient.
The two-dimensional sliding rails 51 are independently arranged, so that the two-dimensional sliding rails can be independently adjusted, the heat source 3 and the thermal imager 4 are used according to test requirements, the two-dimensional sliding rails can rotate along the lifting support 53, and the two-dimensional sliding rails and the lifting support can be sleeved with each other to be conveniently rotated on the lifting support. The two-dimensional slide rail comprises a rotating rod and a connecting rod, the rotating rod 511 is connected with the connecting rod 512 through a rotating shaft, and the rotating rod 511 is connected to the lifting support 53. Dwang and connecting rod are provided with the wedge recess along pole length direction, and pivot 513 both ends block respectively in the recess of dwang and connecting rod, and two parts can rotate relatively about the pivot 513 to can realize the flexible rotation of dwang and connecting rod of two-dimensional slide rail.
The heat source 3 comprises a lampshade and a bulb, the bulb uses a light source capable of condensing light and heat, the lampshade enables the light source to better condense light and heat, the radiation direction of the heat source can be adjusted to be condensed around the rock test piece, the power of the heat source can be electrically adjusted, and the fixed power can be kept for irradiating the rock test piece.
The base 52 is provided with a plurality of telescopic supporting rods which can be arranged around the bottom end of the lifting support, so that the supporting area can be adjusted, and the stability of the support is ensured.
A rock fracture expansion detection method based on thermal imaging and image recognition utilizes the rock fracture expansion detection system based on thermal imaging and image recognition, and comprises the following specific steps:
the rock test piece is placed on a loading base of a single-shaft loading device, a heat source and a thermal imager are fixed on a support, and the thermal imager is connected with a computer. The size of the rock test piece is selected according to test requirements, the surface of the rock test piece is guaranteed to be smooth as much as possible, the thermal imager is connected with the computer through a data line, and stable data transmission between the computer and the thermal imager is guaranteed.
And step two, adjusting the height of the lifting support and the size of the supporting surface of the base, adjusting the relative positions of a heat source and the thermal imager with the rock test piece by the sliding slide rail, and focusing the heat source on the rock test piece. And the heat source is focused near the test piece by adjusting the height of the lifting support and the two-dimensional slide rail.
And step three, adjusting the focus of the thermal imager calibration heat source, and fixing the power of a plurality of heat sources to stabilize the surface temperature of the test piece.
And step four, loading the rock test piece by the single-shaft loading device, and acquiring thermal image data of the temperature distribution information of the surface of the rock by the thermal imager while loading the rock test piece.
And step five, closing all or part of the heat sources to cool the rock test piece, recording thermal image data of the rock test piece during cooling by the thermal imager, and transmitting the thermal image to the computer by the thermal imager.
And step six, processing the thermal image data when the rock test piece is loaded by the computer to obtain the change of the fracture expansion three-dimensional graph of the rock test piece along with time. Specifically, a raw format file obtained by a thermal imager is imported into Avizo, threshold value separation is carried out after median filtering and binaryzation, so that the fracture is displayed more clearly, and a fracture expansion three-dimensional graph of the rock test piece at each time point in a loading state is displayed by a computer, so that the damage starting point of the rock test piece in the loading state, the fracture expansion path and the development process can be better analyzed.
And step seven, processing the thermal image data of the rock test piece in the cooling process by the computer to obtain the fracture close to the surface of the rock test piece. Specifically, a raw format file obtained by a thermal imager is imported into Avizo, a JPEG format file is exported to Matlab through median filtering and binarization, and crack development of the near surface of the rock test piece is obtained through gradient change of gray values of pixel points; by analyzing thermal imaging data in the cooling process of the rock test piece, the crack development condition of the near-surface rock is obtained, the qualitative analysis of the uniaxial loading process of the rock test piece is realized, and the research on the crack development characteristic of the rock test piece is convenient
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.