CN105043868A - Load-sensitive rock core loading method based on CT (computed tomography) rapid imaging - Google Patents

Abstract

The invention discloses a load-sensitive rock core loading method based on CT rapid imaging, which is mainly used in the compressive performance test of the rock core in a laboratory, in order to obtain the whole stress-strain curve of the rock core. In this method, during the core loading process, the micro-focus CT scanner is used to monitor the axial strain and the hoop strain at a fixed position on the core surface in real time, and the main control computing device scans the strain between images at different times. Then the calculation result is fed back to the mechanical loading device and its loading method is adjusted. When the axial strain or hoop strain of the core surface monitoring point reaches the set threshold, the loading method of the loading device will be changed to Automatically adjust from displacement control to stress control, so as to obtain the whole stress-strain curve of the rock core. The invention can accurately obtain the post-peak deformation and strength characteristics of the rock core, and provides favorable conditions for the research and development of key technologies such as operation form and detection means.

Description

A Load Sensitive Core Loading Method Based on CT Rapid Imaging

technical field

The invention relates to a rock core loading technology and an industrial computed tomography imaging technology, in particular to a load-sensitive rock core loading method based on CT rapid imaging.

Background technique

As the product of the formation of the earth and the evolution of crustal geological activities, rocks are widely used in various engineering construction fields such as building foundations, surrounding rocks or building materials. As one of the important parameters of rock physical and mechanical properties, compressive strength can directly reflect the hardness of rock. In mining, geology, metallurgy, railway, highway, hydropower and water conservancy and other engineering construction fields, rock compressive strength is an important basis for classifying rock hardness, excavation classification and determining drillability.

However, under the conditions of the traditional rock compression testing machine, before the specimen reaches the peak strength, the deformation of the specimen is gradual and slow. When the peak strength is reached, the specimen will be suddenly damaged and the specimen will be cracked Rock fragments flew in all directions, accompanied by loud noises, and the test stopped suddenly. Only the half-way stress-strain curve of the rock specimen could be obtained, but its post-peak deformation and strength characteristics could not be obtained. At present, there have been some studies on how to meet the requirements of the full compression test of rocks. The focus of most of the research is how to improve the stiffness of the testing machine, for which a rigid testing machine has appeared. However, the loading conditions of the rigid testing machine are single, and only a single displacement loading or stress loading condition can be used for a specific test object, which is not conducive to obtaining accurate post-peak deformation and strength characteristics; the requirements for mechanical loading devices such as testing machines are high, and the test equipment is complicated , bulky, unsuitable for popularization and use by general institutions; suitable loading speed or stress conditions cannot be set according to different types of test cores, and the performance of the equipment needs to be continuously improved.

Therefore, how to improve the test loading conditions to obtain the full compressive stress-strain data of the core has become an important research content.

Contents of the invention

The object of the present invention is to provide a load-sensitive rock core loading method based on CT rapid imaging, based on this method, the axial strain amount and the hoop strain amount at a fixed position on the loaded rock core surface can be analyzed by a micro-focus CT scanner Real-time monitoring is carried out, and the results are fed back to the mechanical loading device through the main control computing device and the loading method is adjusted to obtain the full stress-strain curve of the load-sensitive core accurately to the greatest extent.

The technical scheme that its technical problem of the present invention adopts is:

A load-sensitive core loading method based on CT rapid imaging, the required loading system includes: a main control computing device, a heavy metal isolation room, an industrial CT scanning loading test bench and a micro-focus CT scanner, the industrial CT scanning loading test bench A mechanical loading device is provided on the vertical turntable, the main control computing device and the mechanical loading device are remotely connected through a wireless network, and the main control computing device is connected to the data collector of the micro-focus CT scanner through a wired cable connected, the micro-focus CT scanner monitors the axial strain and the hoop strain at a fixed position on the surface of the loaded core in real time, and the result is fed back to the The mechanical loading device and its loading method are adjusted to accurately obtain the full stress-strain curve of the load-sensitive core.

In the above load-sensitive core loading method based on CT rapid imaging, preferably the industrial CT scanning loading test bench is located in the heavy metal isolation room, and a mechanical loading device is arranged in the vertical direction, and the mechanical loading device is connected with a first wireless transceiver , and contains sensors and embedded processing systems.

In the above load-sensitive core loading method based on CT rapid imaging, preferably, the surface of the core is provided with axial strain monitoring points or hoop strain monitoring points, and the axial strain monitoring points should be evenly distributed in the rock core. The two ends of the core shaft are at the center, and the hoop strain monitoring point is near the middle of the core.

In the above load-sensitive core loading method based on CT rapid imaging, preferably the micro-focus CT scanner includes an X-ray tube (source), a fan-shaped X-ray beam, a data collector, a rotation controller, and a rotation controller The turntable on the rotary controller is located above the rotary controller, the X-ray tube (source) emits a fan-shaped X-ray beam, the data collector collects data, and the axial strain and the circumferential strain at the fixed position on the core surface Real-time monitoring is carried out, and the monitoring results on the data collector are transmitted to the main control computing device through wired cables.

In the above load-sensitive core loading method based on CT rapid imaging, preferably the main control computing device is a personal computer connected with a second wireless transceiver connected to the wireless receiving module through a wired cable, and connected to the wireless receiving module through a wired cable. The cable is connected to the data collector of the micro-focus CT scanner, and the man-machine interface module is connected to the bus, and the main control computing device can set the strain variable threshold value. Or when the circumferential strain reaches the set threshold, the main control computing device will adjust the loading mode of the industrial CT scanning loading test bench from displacement control to stress control.

Compared with the prior art, the present invention has the following beneficial effects:

Real-time monitoring of the axial strain and hoop strain at the fixed position on the surface of the loaded core is carried out by the micro-focus CT scanner, and the result is fed back to the mechanical loading device through the main control computing device and its loading method is adjusted to maximize the Accurately obtain the full stress-strain curve of the load-sensitive core. The invention overcomes the long-standing defect that the test piece is suddenly destroyed due to the insufficient rigidity of the "soft" testing machine, so that the full stress-strain curve cannot be obtained, and the post-peak deformation and strength characteristics of the rock core can be accurately obtained, which is an operation form It provides favorable conditions for the research and development of key technologies such as detection methods.

Description of drawings

A more complete and better understanding of the invention, and many of its attendant beneficial effects, are readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings, but the accompanying drawings illustrated herein are intended to provide a further understanding of the invention, Constituting a part of the present invention, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention, wherein:

Fig. 1 is the simple physical structure schematic diagram of the automatic loading system embodiment of industrial CT scanning loading test bench used by the present invention;

Fig. 2 is the top view of the micro-focus CT scanner used in the present invention;

Fig. 3 is a schematic diagram of the arrangement position of rock core monitoring points used in the present invention.

Explanation of reference signs: 110-industrial CT scanning loading test bench; 120-heavy metal isolation room; 130-main control computing equipment; 1-data collector; 2-rotary controller; 3-turntable on the rotary controller; 4- Fan-shaped X-ray beam; 5-X-ray tube (source); 6-rock core; 7-axial strain monitoring point; 8-circumferential strain monitoring point; 9-microfocus CT scanner.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As Fig. 1～3, Fig. 1 is the simple physical structure schematic diagram of the automatic loading system embodiment of the industrial CT scanning loading test bench used in the present invention, Fig. 2 is the top view of the micro-focus CT scanner used in the present invention, Fig. 3 is the rock used in the present invention Schematic diagram of the arrangement position of the core monitoring points, the rock core loading system includes an industrial CT scanning loading test bench 110 located in the heavy metal isolation chamber 120, a main control computing device 130, a rock core 6 and a micro-focus CT scanner, and the micro-focus CT scanning Instrument 9 includes X-ray tube (source) 5, fan-shaped X-ray beam 4, data collector 1, rotation controller 2 and the turntable 3 on the rotation controller, and the rock core 6 is installed on the turntable 3 on the rotation controller , the surface of the core 6 is provided with an axial strain monitoring point 7 or a hoop strain monitoring point 8 . The vertical turntable of the industrial CT scanning loading test bench 110 is provided with a mechanical loading device, and the main control computing device 130 is connected with the data collector 1 of the micro-focus CT scanner 9 through a wired cable. The control computing device 130 is remotely wirelessly connected with the mechanical loading device, and feeds back the calculation result of the strain amount to the mechanical loading device, so as to control the scanning loading movement of the industrial CT scanning loading test bench 110 .

In order to ensure that the micro-focus CT scanner 9 can accurately monitor the strain of the rock core 6 in real time, the surface of the rock core 6 is provided with an axial strain monitoring point 7 or a circumferential strain monitoring point 8, and an axial strain monitoring point 7 It should be evenly distributed at both ends of the axial center of the core, and the circumferential strain monitoring point 8 should be selected as close to the middle of the core as possible.

Wherein, the rock core 6 can be an actual rock material, or a simulated rock material; the rock core 6 can be designed as a cylinder with a diameter of 25 mm and a height of 50 mm; Realize automatic loading of maximum axial force load of 2 tons; the minimum scanning resolution of the micro-focus CT scanner 9 can reach 5 μm, and the scanning image interval is about 8 μs.

An Example of Load Sensitive Core Loading Method Based on CT Rapid Imaging

The specific implementation manner of the present invention will be further described in detail below with reference to FIG. 2 and FIG. 3 .

In this embodiment, at the initial stage of core loading, the micro-focus CT scanner promptly monitors and quickly scans the axial strain monitoring point 7 or the circumferential strain monitoring point 8 on the surface of the rock core 6, and the scanned image is captured by the data collector 1 through The wired cable is transmitted to the main control computing device 130, and the bus of the main control computing device 130 is connected with a man-machine interface module, which receives control instructions issued by the operator and displays the loading status and The micro-focus CT scanner 9 monitors the changes in axial strain and circumferential strain at fixed positions on the surface of the rock core, and analyzes the transmitted scanning images in real time to calculate the change in axial strain at the monitoring point Or the circumferential strain change value, in the data processing module of the main control computing device 130, the appropriate strain change threshold can be set in advance according to the 6 types of rock cores, when the axial strain change value or the circumferential strain change value of the monitoring point When the change value of the strain amount reaches the threshold value, it means that the rock core has reached its peak strength, and the main control computing device 130 will feed back the calculation result to the mechanical loading device and adjust its loading mode, and the loading mode of the rock core 6 will automatically Adjusting from displacement control to stress control, and according to the images quickly scanned by the micro-focus CT scanner 9, real-time adjustment of the loading stress of the core 6 is performed to obtain the strength characteristics of the core 6 after peak failure, and finally obtain the described The full compressive stress-strain curve of core 6.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and replacements can also be made, these improvements and replacements It should also be regarded as the protection scope of the present invention.

Claims (5)

1. A load-sensitive rock core loading method based on CT fast imaging, comprising rock core, main control computing equipment, heavy metal isolation room, industrial CT scanning loading test bench and micro-focus CT scanner, it is characterized in that the rock core Installed on the turntable of the industrial CT scanning loading test bench located in the heavy metal isolation chamber, the micro-focus CT scanner monitors the axial strain amount and the hoop strain amount at a fixed position on the surface of the rock core in real time, and Through the main control computing device, the comparative calculation of the strain amount between the scanning images at different times is carried out, and then the calculation result is fed back to the mechanical loading device of the industrial CT scanning loading test bench and its loading mode is adjusted. When the surface of the rock core is monitored When the point axial strain or hoop strain reaches the set threshold, the loading mode of the loading device will be automatically adjusted from displacement control to stress control, so as to obtain the full compressive stress-strain curve of the rock core. 2. a kind of load-sensitive rock core loading method based on CT rapid imaging according to claim 1, is characterized in that, described industrial CT scanning loading experiment bench is positioned at heavy metal isolation room, and its vertical direction is provided with mechanical loading device, mechanical The loading device is connected to the first wireless transceiver and contains sensors and an embedded processing system. 3. a kind of load sensitive rock core loading method based on CT fast imaging according to claim 1, is characterized in that, described rock core surface is provided with axial strain amount monitoring point or hoop strain amount monitoring point, axial strain amount monitoring point The strain monitoring points should be evenly distributed at both ends of the axial center of the core, and the circumferential strain monitoring points should be near the middle of the core. 4. a kind of load sensitive rock core loading method based on CT rapid imaging according to claim 1, is characterized in that, described micro-focus CT scanner comprises X-ray tube (source), fan-shaped X-ray beam, data collector , the rotary controller and the turntable on the rotary controller, the turntable on the rotary controller is located above the rotary controller, the X-ray tube (source) emits a fan-shaped X-ray beam, the data collector collects data, and the fixed position on the core surface The axial strain amount and the circumferential strain amount are monitored in real time, and the monitoring results on the data collector are transmitted to the main control computing device through a wired cable. 5. a kind of load-sensitive rock core loading method based on CT fast imaging according to claim 1, is characterized in that, described main control computing device is personal computer, is connected with the second wireless transceiver, communicates with by wired cable The wireless receiving module is connected to the data collector of the micro-focus CT scanner through a wired cable, and the man-machine interface module is connected to the bus, and the main control computing device can set the strain variable threshold value, when the When the axial strain or circumferential strain of the core surface monitoring point reaches the set threshold, the main control computing device will adjust the loading mode of the industrial CT scanning loading test bench from displacement control to stress control.