Drilling coring equipment simulating mechanical disturbance and methods for identifying core fracture types

Abstract

This invention discloses a core drilling device that simulates mechanical disturbance and a method for identifying core fracture types. An eccentric conversion joint is added to the core drill bit of the core drilling equipment to simulate the vibration of the drill rod caused by eccentricity during actual core drilling. A method for identifying core fracture types is proposed, namely, establishing a core fracture type discrimination model. This model includes: test specimen preparation, core drilling, collecting drilling parameters during core drilling, collecting geometric features of the core cross-section, and marking the target core fracture characteristic type. The drilling parameters and the geometric features of the core cross-section are used as inputs to train the core fracture type discrimination model, outputting the core fracture characteristic type to distinguish between primary core fractures and mechanical fractures. This eliminates interference from mechanical fractures, thereby more accurately identifying the primary structural surfaces of the rock mass.

Description

Technical Field

[0001] This invention belongs to the fields of underground engineering, rock engineering technology, exploration technology, and rock quality evaluation, and particularly relates to a core drilling device that simulates mechanical disturbance and a method for identifying rock core fracture types. Background Technology

[0002] With the increasing depletion of shallow resources, the exploitation of deep resources is gradually advancing. For deep underground engineering, rock mass structure is a crucial factor in evaluating and analyzing the stability of the project. In the preliminary work of engineering geological exploration, the distribution of underground rock mass structural planes and the integrity of the rock mass are often analyzed by examining the fracture patterns of core samples obtained from drilling, and it is assumed that structural planes exist at the locations of core fractures. However, the process of drilling and coring rocks involves complex mechanical behavior. Core fractures are affected by the properties of the rock itself, mechanical factors, and in-situ stress. Simply treating core fractures as primary fissures in the rock mass will lead to errors in the statistical analysis of structural plane distribution and the evaluation of rock mass quality.

[0003] Among currently available technologies, core fracture is analyzed by observing rock mass fractures under different damage levels and geostress conditions in the field. The impact of rock mass damage and geostress on core fracture is analyzed. In studies of core fractures caused by mechanical factors, a rough fracture surface is assumed to be mechanical fracture, while a smooth fracture surface is considered a primary structural surface. Algorithms for calculating surface roughness and other geometric parameters are proposed, but algorithms for differentiating different types of core fractures through experiments are lacking. Existing research lacks quantitative studies on the influence of different mechanical factors on core fracture, corresponding methods for analyzing core fracture characteristics, and also lacks the necessary equipment and experimental conditions to support this research. Summary of the Invention

[0004] In view of the above, the present invention is disclosed, and the specific solution is as follows:

[0005] A method for identifying fracture types in rock core samples includes the following steps:

[0006] S1. Preparation of test specimens: Prepare complete specimens and cracked specimens respectively. The complete specimen is a specimen that is intact and does not have pre-existing cracks, and the cracked specimen is a specimen that has pre-existing cracks.

[0007] S2. Core drilling: Set different core drilling parameters, use a core drilling device to drill cores from intact specimens and fractured specimens respectively, obtain target cores, and collect drilling parameters during the core drilling process;

[0008] S3. Mark the fracture feature type of the target rock core:

[0009] Remove target cores that do not exhibit fracture characteristics, and mark the fracture characteristics on the remaining target cores; the fracture characteristics include primary fractures and mechanical fractures;

[0010] The location of the fracture in the target rock core is compared with that of the pre-fabricated crack in the fracture specimen. If the location of the fracture in the target rock core is consistent with that of the pre-fabricated crack in the fracture specimen, the fracture in this rock core is marked as a primary fracture.

[0011] If the fracture of the target rock core is located at a different location than the pre-fabricated crack in the fracture specimen, this rock core fracture is marked as a mechanical fracture.

[0012] S4. Filter the corresponding drilling parameters of primary and mechanical fractures in the target core, calculate the geometric features of the core cross-section, and establish a dataset:

[0013] For the primary fractures in the target core, the corresponding drilling parameters are selected, and the geometric characteristics of the core cross-section are calculated; the drilling parameters and geometric characteristics of the core cross-section under this condition are used as the primary fracture data.

[0014] For mechanical fractures in the target core, the corresponding drilling parameters are selected, and the geometric characteristics of the core cross-section are calculated; the drilling parameters and geometric characteristics of the core cross-section under this condition are used as mechanical fracture data.

[0015] The above mechanical fracture data and native fracture data are summarized and a dataset is created.

[0016] S5. Establish a core fracture type discrimination model that determines whether the core fracture feature type is a primary fracture or a mechanical fracture based on drilling parameters and core cross-sectional geometric features. Divide the dataset described in step S4 into a training set and a test set, and train and test the core fracture type discrimination model. When the model accuracy exceeds 95%, the model parameters are determined.

[0017] S6. Input the drilling parameters of the core with fracture characteristics and the geometric features of the core cross-section into the core fracture type discrimination model established in step S5, and output the fracture characteristic type of the core cross-section.

[0018] As a supplement to the above technical solution, the drilling and coring parameters in step S2 include: the drilling speed, rotation speed, diameter, and diamond content of the coring drill bit, as well as the eccentricity of the drill rod spindle.

[0019] The drilling parameters in step S4 are the drilling speed, rotation speed, thrust, torque, and vibration waveform data of the coring drill bit collected by sensors during the actual drilling and coring process.

[0020] As a supplement to the above technical solution, the method for obtaining the target rock core in step S2 is as follows:

[0021] (1) Use reasonable drilling and coring parameters to drill and cor the complete specimen to obtain a complete rock core;

[0022] (2) The same drilling parameters as in scheme (1) were used to drill and core the fractured specimen to obtain the rock core of the fractured specimen;

[0023] (3) Using unreasonable drilling and coring parameters to drill and cor the complete specimen to obtain n sets of rock cores with fracture characteristics, where n≥2.

[0024] As a supplement to the above technical solution, the step S4 of collecting drilling parameters during core sampling specifically includes the following steps:

[0025] Sensors are used to collect the actual rotational speed, drilling speed, thrust, torque, and vibration waveform of the coring bit during the drilling and coring process. The raw data collected by the sensors is a voltage signal. First, the raw voltage signal is amplified to 0-10V by an amplifier and then transferred to a computer via USB for storage. According to the conversion formula between the voltage signal collected by the sensor and the monitored physical quantity, the voltage signal collected by the sensor is converted into the monitored physical quantities, namely the actual rotational speed, drilling speed, thrust, torque, and vibration waveform of the coring bit. To eliminate the influence of noise points in the drilling parameter signal, the drilling parameters are filtered to obtain the filtered rotational speed, drilling speed, thrust, torque, and vibration waveform data.

[0026] As a supplement to the above technical solution, the geometric features of the core cross-section in step S4 include: trace fitting line residual e i Roughness of the core cross-section;

[0027] The drilling parameters and geometric features of the core section collected from the target rock core include the following types:

[0028] For the native fractures in the target core, the corresponding drilling parameters are selected, and the roughness of the core cross-section and the residual e of the trace fitting line of the native fracture are calculated. i1 ;

[0029] For mechanical fractures in the target core, the corresponding drilling parameters are selected, and the surface roughness of the core cross-section and the residual e of the mechanical fracture trace fitting line are calculated. i2 .

[0030] As a supplement to the above technical solution, the step of obtaining the residual e of the trace fitting line is... i Includes the following steps:

[0031] Take pictures of the rock core, extract the fracture lines of the rock core, obtain the coordinates of the fracture lines, and convert the fracture line pixels into coordinates in a coordinate system (X). i Y i Fit the coordinates of the fracture trace to a straight line equation: y = kx + b, and then use X... i Substitute into the fitted linear equation to calculate yi 'Calculate the residual e of the fitted trace line. i =Y i '-y i '.

[0032] As a supplement to the above technical solution, obtaining the roughness of the core cross-section includes the following steps:

[0033] Core cross-section scanning is performed using a laser scanner. During the scanning process, the core cross-section is parallel to the laser scanner to generate a point cloud model. The point cloud model of the core cross-section is required to have no tilt angle. For the point cloud model of the core cross-section, the roughness in different directions is calculated.

[0034] This invention also discloses a core drilling device for simulating mechanical disturbance used in the core fracture type discrimination model of any of the above-described methods, comprising a drilling unit, a rotating unit, a monitoring unit, a support frame, and a specimen clamp.

[0035] The support frame includes a base and columns, which are used to maintain the overall stability of the device;

[0036] The drilling unit is mounted above the rotating unit via a column. The drilling unit can apply tension or thrust to the rotating unit. The lower end of the column is mounted on the base, and the upper end of the column is used to support the drilling unit. The base is located below the rotating unit, and the specimen clamp is mounted on the base.

[0037] The rotating unit includes a drill rod spindle, an eccentric conversion joint, a core drill bit, a second motor, and a rotating unit housing. The drill rod spindle and the second motor are both mounted on the rotating unit housing, and the drill rod spindle and the rotating unit housing are rotatably connected. The second motor is connected to the drill rod spindle via a chain and is used to drive the drill rod spindle to rotate. The lower end of the drill rod spindle is provided with an eccentric conversion joint, and the upper end of the core drill bit is connected to the eccentric conversion joint.

[0038] The monitoring unit is used to monitor the rotational speed, drilling speed, thrust, torque, and vibration waveform of the coring drill bit.

[0039] As a supplement to the above technical solution, the drilling unit includes a drilling unit housing, a first motor, and a tension screw;

[0040] The drilling unit housing is connected to the upper end of the column. The first motor is located inside the drilling unit housing. The upper end of the tension screw is rotatably connected to the drilling unit housing. The first motor is connected to the screw via a chain. The rotation of the first motor can drive the tension screw to rotate.

[0041] As a supplement to the above technical solution, the monitoring unit also includes a vibration sensor, a drilling speed sensor, a rotational speed and torque sensor, and a thrust sensor.

[0042] The vibration sensor is mounted on one side of the core drill bit via a bracket;

[0043] The drilling speed sensor is mounted on the housing of the drilling unit;

[0044] The speed and torque sensor is installed at the upper end of the drill pipe spindle to monitor the speed and torque of the drill pipe spindle.

[0045] The thrust sensor has a threaded hole at its upper end, and the lower end of the tension screw is screwed into the threaded hole at the upper end of the thrust sensor; the thrust sensor is fixedly connected to the rotating unit housing.

[0046] Beneficial effects: This invention, through the design of core fracture type identification, can train a core fracture type discrimination model, helping to determine the original structural surface of the core during actual drilling and core extraction, and distinguishing whether the fractured core is mechanically fractured or intrinsically fractured. In another aspect of this invention, through the design of a rock drilling and core extraction device that simulates mechanical disturbance, it is possible to simulate different degrees of vibration of the core drill bit during actual core extraction, and it can be equipped with different rotational speeds and speed functions, enabling arbitrary adjustment of drilling parameters. Attached Figure Description

[0047] Figure 1 This is a three-dimensional structural diagram of the rock drilling and coring device of the present invention.

[0048] Figure 2 This is a three-dimensional structural diagram of the rock drilling and coring device of the present invention.

[0049] Figure 3 This is a side view of the rock drilling and coring device of the present invention.

[0050] Figure 4 This is a technical roadmap for the core fracture type identification method of the present invention.

[0051] In the figure: 1. Drilling unit housing, 2. Rotating unit housing, 3. 4. Base, 5. Control panel, 6. First motor, 7. First frequency converter, 8. Tension screw, 9. Second motor, 10. Second frequency converter, 11. Drill rod spindle, 12. Core drill bit, 13. Eccentric conversion joint, 14. Drill speed sensor, 15. Thrust sensor, 16. Speed ​​and torque sensor, 17. Vibration sensor, 18. Specimen fixture. Detailed Implementation

[0052] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0053] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] This invention discloses a method for identifying fracture types in rock core samples, comprising the following steps:

[0055] S1. Prepare test specimens, including complete specimens and cracked specimens. The complete specimens are specimens that are intact and do not have pre-existing cracks, while the cracked specimens are specimens that have pre-existing cracks.

[0056] S2. Drilling and core sampling: Set different drilling and core sampling parameters for the core sampling device, and use the core sampling device to drill and core samples from intact specimens and fractured specimens respectively to obtain the target core samples and collect the drilling parameters during the core sampling process;

[0057] S3. Mark the fracture feature type of the target rock core:

[0058] Core samples lacking fracture characteristics were discarded. The remaining core samples were then labeled with fracture characteristics, including primary fractures and mechanical fractures. Primary fractures are pre-existing cracks on the original structural surface of the specimen before core drilling, not caused by mechanical factors during the drilling process. Mechanical fractures are fractures that did not exist on the original structural surface of the specimen before core drilling, but were caused by mechanical factors during the drilling process.

[0059] The location of the fracture in the target rock core is compared with that of the pre-fabricated crack in the fracture specimen. If the location of the fracture in the target rock core is consistent with that of the pre-fabricated crack in the fracture specimen, the fracture in this rock core is marked as a primary fracture.

[0060] If the fracture in the target core is located at a different location than the pre-existing crack in the fractured specimen, this core fracture is marked as a mechanical fracture.

[0061] After drilling and obtaining rock cores from complete specimens, the fracture characteristics on the rock cores were marked as mechanical fractures.

[0062] During the drilling and core extraction process of fractured specimens, there are two scenarios: one is a core with no new fractures compared to the fractured specimen, in which case all fractures on the core are primary fractures and no mechanical fractures appear; the other is a core with new fractures compared to the fractured specimen, in which case the new fractures on the core are mechanical fractures.

[0063] S4. Filter the corresponding drilling parameters of primary and mechanical fractures in the target core, calculate the geometric features of the core cross-section, and establish a dataset:

[0064] For the primary fractures in the target core, the corresponding drilling parameters are selected, and the geometric characteristics of the core cross-section are calculated. The drilling parameters and geometric characteristics of the core cross-section under this condition are used as the primary fracture data.

[0065] The mechanical fracture data includes multiple categories, specifically:

[0066] For the primary fractures in the target core, the corresponding drilling parameters are selected, and the geometric characteristics of the core cross-section are calculated. The drilling parameters and geometric characteristics of the core cross-section under this condition are used as the primary fracture data.

[0067] For mechanical fractures in the target core, the corresponding drilling parameters are selected, and the geometric characteristics of the core cross-section are calculated. The drilling parameters and geometric characteristics of the core cross-section under this condition are used as mechanical fracture data.

[0068] The above mechanical fracture data and native fracture data are summarized and a dataset is established.

[0069] S5. Establish a core fracture type discrimination model that determines whether the core fracture feature type is a primary fracture or a mechanical fracture based on drilling parameters and core cross-sectional geometric features. Divide the dataset mentioned in step S4 into a training set and a test set, and train and test the core fracture type discrimination model. When the accuracy of the model exceeds 95%, the model parameters are determined.

[0070] S6. Input the drilling parameters of the core with fracture characteristics and the geometric features of the core cross-section into the core fracture type discrimination model established in step S5, and output the fracture characteristic type of the core cross-section.

[0071] As a preferred technical solution of the present invention, step S1 specifically includes:

[0072] S1.1, Preparation of complete specimens: A complete specimen is a complete concrete specimen made of cement, quartz sand and water in a certain proportion. The size of the specimen is determined according to the borehole diameter and the size of the specimen fixture.

[0073] S1.2, Crack Specimen Preparation, including crack specimens with different angles, thicknesses, and spacings. Mica powder is used as the crack material, and the preparation method involves layered casting. In the layered method, after pouring one layer of concrete, a certain thickness of mica powder is evenly sprinkled on top. After the first layer of concrete and mica powder has initially set, a second layer of concrete and mica powder is poured using the same method. The mold's tilt angle is controlled by elevating one side to a fixed height, thus creating different angles for the cracks in the specimens. The crack thickness is controlled by adjusting the thickness of the mica powder. The spacing of the cracks in the specimens is controlled by adjusting the thickness of the concrete.

[0074] S1.3, Specimen curing: After all materials have initially set, the specimens are demolded and cured according to concrete curing standards before being used for the next test.

[0075] As a preferred technical solution of the present invention, the drilling and coring parameters in step S2 include: the drilling speed, rotation speed, diameter, diamond content of the coring drill bit, and the degree of eccentricity of the drill rod spindle.

[0076] As a preferred technical solution of the present invention, since the actual drilling and coring parameters set by the core drilling device may differ from the set values ​​due to errors during the actual core drilling process, a sensor is used to collect the drilling parameters of the core drill bit to improve the accuracy of the test.

[0077] The drilling parameters in step S4 are the drilling speed, rotation speed, thrust, torque, and vibration waveform data of the coring drill bit collected by sensors during the actual drilling and coring process.

[0078] In step S2, the core drilling device drills a co-drilling hole to obtain the target rock core from both the intact and fractured specimens. The core drilling parameters and target rock cores for both the intact and fractured specimens are as follows:

[0079] (1) This group serves as the control group, where intact specimens are cored under normal mechanical conditions. Specifically, reasonable cored drilling parameters are used to cored intact specimens to obtain intact rock cores, which are rock cores without fracture characteristics. The reasonable cored drilling parameters are: setting the rotation speed, drilling speed, diamond content, and diameter of the cored drill bit within a reasonable range for the cored drilling device, and setting the eccentricity of the drill rod spindle within a reasonable range to ensure that the core obtained by drilling does not fracture.

[0080] (2) To study the influence of structural planes on core fracture, the same drilling parameters as in group (1) were used to drill and core the fractured specimens under normal mechanical conditions. The core samples obtained from the drilling may fall into two categories: one is cores with no new fracture features compared to the fractured specimens, in which case all fracture features on the core are primary fracture features; the other is cores with new fracture features compared to the fractured specimens, in which case the new fracture features on the core are mechanical fracture features. The purpose of this group of experiments is to determine whether drilling and core sampling of fractured specimens under normal mechanical conditions can cause mechanical fracture. Multiple sets of fractured specimens can be prepared, allowing the prepared specimens to have different numbers of fractures and fracture angles to meet the diversity of experiments and simulate actual geological conditions.

[0081] (3) Investigate the influence of drilling and coring parameters on core fracture, and perform drilling and coring on intact specimens under normal mechanical conditions. Specifically, use unreasonable drilling and coring parameters to perform drilling and coring on intact specimens to obtain n sets of cores with fracture characteristics. Where n ≥ 2.

[0082] To further investigate the influence of borehole coring parameter diversity on core fracture, the n=4 scheme is as follows:

[0083] (3.1) The influence of mechanical factors such as rotational speed and drilling speed settings on core fracture in core drilling was studied. Different rotational speeds and drilling speeds were set for intact specimens for core drilling. Specifically, unreasonable core drilling parameters were used to obtain cores with fracture characteristics from intact specimens. In this group, unreasonable drilling parameters were set to diamond content and diameter within a reasonable range for the core drill bit of the core drilling device, to eccentricity within a reasonable range for the drill rod spindle, and to rotational speed and drilling speed within an unreasonable range for the core drill bit.

[0084] (3.2) The influence of drill rod vibration on the fracture of core samples in mechanical factors was studied. Specifically, the intact specimens were drilled and cored using unreasonable drilling parameters to obtain core samples with fracture characteristics. The unreasonable drilling parameters in this group were the rotation speed, drilling speed, diamond content and diameter of the core drill bit of the drilling device within a reasonable range, and the degree of eccentricity of the drill rod spindle within an unreasonable range.

[0085] (3.3) The influence of drill bit diamond content in mechanical factors on the fracture of core samples obtained by drilling is studied. Specifically, unreasonable drilling parameters are used to drill and core intact specimens to obtain core samples with fracture characteristics. In this group, unreasonable drilling parameters are: setting the rotation speed, drilling speed and diameter of the core drill bit in the drilling and core sampling device within a reasonable range; setting the degree of eccentricity of the drill rod spindle within a reasonable range; and setting the diamond content of the core drill bit within an unreasonable range.

[0086] (3.4) The influence of borehole diameter on the fracture of core samples from boreholes is studied. Specifically, unreasonable drilling parameters are used to drill and core intact specimens to obtain core samples with fracture characteristics. In this group, the unreasonable drilling parameters are: setting the rotation speed, drilling speed and diamond content of the core drill bit within a reasonable range, setting the eccentricity of the drill rod spindle within a reasonable range, and setting the diameter of the core drill bit within an unreasonable range.

[0087] As a preferred technical solution of the present invention, the step S4 of collecting drilling parameters during core sampling specifically includes the following steps:

[0088] (1) Drilling parameter acquisition and storage: Sensors are used to acquire the rotational speed, drilling speed, thrust, torque and vibration waveform of the core drill bit. The raw data acquired by the sensors is a voltage signal. First, the raw voltage signal is amplified to 0-10V by an amplifier. The 0-10V voltage signal is then transferred to the computer via USB for storage.

[0089] (2) Drilling parameter processing: Based on the conversion formula between the voltage signal collected by the sensor and the monitored physical quantity, the voltage signal collected by the sensor is converted into the monitored rotational speed, drilling speed, thrust, torque and vibration waveform.

[0090] (3) Filtering of drilling parameters: In order to eliminate the influence of noise points in the drilling parameter signal, the drilling parameters are filtered to obtain the filtered rotational speed, drilling speed, thrust, torque and vibration waveform data.

[0091] As a preferred embodiment of the present invention, the geometric features of the core cross-section in step S4 include: trace fitting line residual e i Roughness of the core cross-section;

[0092] The following are some specific methods for collecting drilling parameters and geometric features of the core cross-section:

[0093] For the native fractures in the target core, the corresponding drilling parameters are selected, and the roughness of the core cross-section and the residual e of the trace fitting line of the native fracture are calculated. i1 ;

[0094] For mechanical fractures in the target core, the corresponding drilling parameters are selected, and the surface roughness of the core cross-section and the residual e of the mechanical fracture trace fitting line are calculated. i2 .

[0095] Accordingly, in the core fracture type discrimination model, the drilling parameters, core cross-sectional roughness, and trace fitting line residuals e collected for the above three types should be included. i The grouped inputs are then fed into the core fracture type discrimination model.

[0096] As a preferred technical solution of the above embodiments, the residual e of the trace fitting line is obtained. i The process includes the following steps: photographing the rock core and extracting the fracture lines. Specifically, the extracted rock core is photographed horizontally, placed in a core box with the box horizontally positioned, and the camera angle is parallel to the core box when taking the picture. For the core box image, the fracture lines are extracted. The coordinates of the fracture lines are obtained, and the pixels of the fracture lines are converted into coordinates (X, Y, F, 1) in a coordinate system. i Y i Specifically, for fracture traces in rock cores, an index is defined to calculate the degree of bend in the trace: the residual of the trace fitting line. The calculation method for the trace fitting line is as follows: First, for the traces extracted from the image, the coordinates of the trace pixels are extracted, and the trace pixels are converted into coordinates (X, Y, X) in a coordinate system. i Y i Fit the linear equation to the coordinates of the fracture trace: y = kx + b, by X i Substitute into the fitted linear equation to calculate y i ';Calculate the residual e of the fitted trace line i =Y i '-y i '.

[0097] As a preferred technical solution of the above embodiments, obtaining the roughness of the core cross-section includes the following steps:

[0098] Core cross-section scanning is performed using a laser scanner. During the scanning process, the core cross-section is parallel to the laser scanner to generate a point cloud model. The point cloud model of the core cross-section is required to have no tilt angle. For the point cloud model of the core cross-section, the roughness in different directions is calculated.

[0099] like Figures 1 to 3 As shown, the core sampling device used in the above-mentioned core fracture type identification method is specifically a core sampling device that simulates mechanical disturbance. It can simulate the eccentricity of the drill rod caused by the uncalibrated core drill bit during actual core drilling. The core sampling device includes a drilling unit, a rotation unit, a monitoring unit, a support unit, and a specimen clamp 18.

[0100] The support frame includes a base 4 and a column 3, which are used to maintain the overall stability of the device.

[0101] The drilling unit is mounted above the rotating unit via a column 3. The lower end of the column 3 is mounted on the base 4, and the upper end of the column 3 supports the drilling unit. The drilling unit applies vertical tension or thrust to the rotating unit. The base 4 is located below the rotating unit, and a specimen clamp 18 is mounted on the base for clamping the specimen. The specimen clamp 18 consists of two L-shaped iron plates and a disc. The two L-shaped iron plates are assembled into a cubic container by screws to hold and stabilize the specimen. The two iron plates are then assembled together on the disc by screws and placed on the base 4 of the supporting frame to prevent the specimen from sliding on the base during the drilling process.

[0102] The rotating unit includes a drill rod spindle 11, an eccentric conversion joint 13, a core drill bit 12, a second motor 9, and a rotating unit housing 2. The drill rod spindle 11 and the second motor 9 are both mounted on the rotating unit housing 2, and the drill rod spindle 11 is rotatably connected to the rotating unit housing 2. The second motor 9 is connected to the drill rod spindle 11 via a chain and is used to drive the drill rod spindle 11 to rotate. The lower end of the drill rod spindle 11 is provided with the eccentric conversion joint 13, and the upper end of the core drill bit 12 is connected to the eccentric conversion joint 13. The eccentric conversion joint 13 causes the core drill bit 12 to vibrate during operation. The eccentricity of the eccentric conversion joint 13 can be set to different degrees, producing different degrees of shaking and vibration of the core drill bit, simulating the drill rod vibration caused when the mechanical shaft center is not calibrated on-site. In the above-mentioned technical solution of the present invention, "A method for identifying rock core fracture types," the degree of eccentricity of the drill rod spindle 11 is simulated by setting the eccentric conversion joint 13. The drilling unit applies downward pressure to the rotating unit, causing the core drill bit 12 to move toward the rock mass, and the core drill bit 12 is rotated to extract cores from the rock mass.

[0103] The monitoring unit is installed on the rock drilling and coring device to monitor the rotation speed, drilling speed, thrust, torque and vibration waveform of the coring drill bit 12 during the drilling and coring process.

[0104] As a supplement to the above technical solution, the rotating unit further includes a rotating unit housing 2. The second motor 9 and the drill rod spindle 11 are both mounted on the rotating unit housing 2, and the drill rod spindle 11 is rotatably connected to the rotating unit housing 2. The second motor 9 is connected to the drill rod spindle 11 via a chain and is used to drive the drill rod spindle 11 to rotate.

[0105] As a preferred embodiment of the present invention, the drilling unit includes a drilling unit housing 1, a first motor 6, and a tension screw 8.

[0106] The drilling unit housing 1 is connected to the upper end of the column 3. The first motor 6 is disposed inside the drilling unit housing 1. The upper end of the tension screw 8 is rotatably connected to the drilling unit housing 1. The first motor 6 is connected to the screw 8 via a chain. The rotation of the first motor 6 drives the tension screw 8 to rotate. During the core extraction process, the first motor 6 drives the tension screw 8 to rotate, causing the rotating unit housing 2 to move the core drill bit 12 downwards, drilling and core extracting the specimen located on the specimen fixture 18.

[0107] As a preferred technical solution of the present invention, the monitoring unit includes a drilling speed sensor 14 and a rotation speed and torque sensor 16. The drilling speed sensor 14 is a laser displacement sensor, which is installed on the drilling unit housing 1 and is used to emit laser to the rotating unit encapsulation shell 2, collect distance data, and calculate the drilling speed based on the time data.

[0108] The speed and torque sensor 16 is installed at the upper end of the drill pipe spindle 11 to monitor the speed and torque of the drill pipe spindle 11.

[0109] As a supplement to the above technical solution, the monitoring unit also includes a vibration sensor 17 and a thrust sensor 15; the vibration sensor 17 is a non-contact eddy current vibration sensor, which is set on one side of the core drill bit 12 by a bracket so that it does not directly contact the core drill bit 12, and collects vibration data of the core drill bit 12 when it rotates.

[0110] The thrust sensor 15 is a spoke-type load cell. The upper end of the thrust sensor 15 has a threaded hole, and the lower end of the tension screw 8 is screwed into the threaded hole at the upper end of the thrust sensor 15. The thrust sensor 15 is fixedly connected to the rotating unit housing 2. The rotation of the tension screw 8 can drive the rotating unit housing 2 to move up and down, thereby driving the core drill bit 12 to move up and down. The thrust sensor 15 is used to monitor the downward pressure applied by the tension screw 8 to the rotating unit housing 2.

[0111] As a preferred embodiment of the present invention, the system further includes a control panel 5. The drilling unit also includes a first frequency converter 7, and the rotating unit also includes a second frequency converter 10. The first frequency converter 7 is connected to the first motor 6 and is used to change the speed of the first motor 6. The second frequency converter 10 is connected to the second motor 9 and is used to change the speed of the second motor 9. Both the first frequency converter 7 and the second frequency converter 10 are connected to the control panel 5, and the speeds of the first motor 6 and the second motor 9 are adjusted through the control panel 5.

[0112] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for identifying fracture types in rock core samples, characterized in that, Includes the following steps: S1. Preparation of test specimens: Prepare complete specimens and cracked specimens respectively. The complete specimen is a specimen that is intact and does not have pre-existing cracks, and the cracked specimen is a specimen that has pre-existing cracks. S2. Core drilling: Set different core drilling parameters, use a core drilling device to drill cores from intact specimens and fractured specimens respectively, obtain target cores, and collect drilling parameters during the core drilling process; S3. Mark the fracture feature type of the target rock core: Remove target cores that do not exhibit fracture characteristics, and mark the fracture characteristics on the remaining target cores; the fracture characteristics include primary fractures and mechanical fractures; The location of the fracture in the target rock core is compared with that of the pre-fabricated crack in the fracture specimen. If the location of the fracture in the target rock core is consistent with that of the pre-fabricated crack in the fracture specimen, the fracture in this rock core is marked as a primary fracture. If the fracture of the target rock core is located at a different location than the pre-fabricated crack in the fracture specimen, this rock core fracture is marked as a mechanical fracture. S4. Filter the corresponding drilling parameters of primary and mechanical fractures in the target core, calculate the geometric features of the core cross-section, and establish a dataset: For the primary fractures in the target core, the corresponding drilling parameters are selected, and the geometric characteristics of the core cross-section are calculated; the drilling parameters and geometric characteristics of the core cross-section under this condition are used as the primary fracture data. For mechanical fractures in the target core, the corresponding drilling parameters are selected, and the geometric characteristics of the core cross-section are calculated; the drilling parameters and geometric characteristics of the core cross-section under this condition are used as mechanical fracture data. The above mechanical fracture data and native fracture data are summarized and a dataset is created. S5. Establish a core fracture type discrimination model that determines whether the core fracture feature type is a primary fracture or a mechanical fracture based on drilling parameters and core cross-sectional geometric features. Divide the dataset mentioned in step S4 into a training set and a test set, train and test the core fracture type discrimination model, and determine the model parameters when the model accuracy exceeds 95%. S6. Input the drilling parameters of the core with fracture characteristics and the geometric features of the core cross-section into the core fracture type discrimination model established in step S5, and output the fracture characteristic type of the core cross-section.

2. The method for identifying core fracture types according to claim 1, characterized in that, The core drilling parameters in step S2 include: the drilling speed, rotation speed, diameter, and diamond content of the core drill bit, as well as the eccentricity of the drill rod spindle. The drilling parameters in step S4 are the drilling speed, rotation speed, thrust, torque, and vibration waveform data of the coring drill bit collected by sensors during the actual drilling and coring process.

3. The method for identifying core fracture types according to claim 2, characterized in that, The method for obtaining the target rock core in step S2 is as follows: (1) Use reasonable drilling and coring parameters to drill and cor the complete specimen to obtain a complete rock core; (2) The same drilling parameters as in scheme (1) were used to drill and core the fractured specimen to obtain the rock core of the fractured specimen; (3) Using unreasonable drilling and coring parameters to drill and cor the complete specimen to obtain n sets of rock cores with fracture characteristics, where n≥2.

4. The method for identifying core fracture types according to claim 2, characterized in that, The step S4, which involves collecting drilling parameters during core sampling, specifically includes the following steps: Sensors are used to collect the actual rotational speed, drilling speed, thrust, torque, and vibration waveform of the coring bit during the drilling and coring process. The raw data collected by the sensors is a voltage signal. First, the raw voltage signal is amplified to 0-10V by an amplifier, and then the 0-10V voltage signal is transferred to a computer via USB for storage. According to the conversion formula between the voltage signal collected by the sensor and the monitored physical quantity, the voltage signal collected by the sensor is converted into the monitored physical quantities, namely the actual rotational speed, drilling speed, thrust, torque, and vibration waveform of the coring bit. In order to eliminate the influence of noise points in the drilling parameter signal, the drilling parameters are filtered to obtain the filtered rotational speed, drilling speed, thrust, torque, and vibration waveform data.

5. The method for identifying core fracture types according to claim 1, characterized in that, The geometric features of the core section in step S4 include: trace fitting line residual. Roughness of the core cross-section; The drilling parameters and geometric features of the core section collected from the target rock core include the following types: For the native fractures in the target core, the corresponding drilling parameters are selected, and the roughness of the core cross-section and the residual of the trace fitting line of the native fracture are calculated. ; For mechanical fractures in the target core, the corresponding drilling parameters are selected, and the surface roughness of the core cross-section and the residual of the mechanical fracture trace fitting line are calculated. .

6. The method for identifying core fracture types according to claim 5, characterized in that, The calculated trace fitting line residual Includes the following steps: Take pictures of the rock core, extract the fracture lines of the rock core fracture, obtain the coordinates of the fracture lines, and convert the fracture line pixels into coordinates in a coordinate system. , Fit a straight line equation to the coordinate points of the fracture trace: By Substitute into the fitted straight line equation to calculate 'Calculate the residual of the fitted trace line'. .

7. The method for identifying core fracture types according to claim 5, characterized in that, The calculation of the roughness of the core cross-section includes the following steps: Core cross-section scanning is performed using a laser scanner. During the scanning process, the core cross-section is parallel to the laser scanner to generate a point cloud model. The point cloud model of the core cross-section is required to have no tilt angle. For the point cloud model of the core cross-section, the roughness in different directions is calculated.

8. A core drilling device for simulating mechanical disturbance used in the core fracture type discrimination model of any one of claims 1-7, characterized in that, It includes a drilling unit, a rotating unit, a monitoring unit, a support frame, and a specimen fixture (18). The support frame includes a base (4) and a column (3) to maintain the overall stability of the device; The drilling unit is mounted above the rotating unit via a column (3). The drilling unit can apply tension or thrust to the rotating unit. The lower end of the column (3) is mounted on the base (4), and the upper end of the column (3) is used to support the drilling unit. The base (4) is located below the rotating unit, and the specimen clamp (18) is mounted on the base. The rotating unit includes a drill rod spindle (11), an eccentric conversion joint (13), a core drill bit (12), a second motor (9), and a rotating unit housing (2). The drill rod spindle (11) and the second motor (9) are both mounted on the rotating unit housing (2), and the drill rod spindle (11) and the rotating unit housing (2) are rotatably connected. The second motor (9) is connected to the drill rod spindle (11) via a chain and is used to drive the drill rod spindle (11) to rotate. The lower end of the drill rod spindle (11) is provided with an eccentric conversion joint (13), and the upper end of the core drill bit (12) is connected to the eccentric conversion joint (13). The monitoring unit is installed on the rock drilling core sampling device and is used to monitor the rotation speed, drilling speed, thrust, torque and vibration waveform of the core drill bit (12).

9. The drilling core sampling device for simulating mechanical disturbance according to claim 8, characterized in that, The drilling unit includes a drilling unit housing (1), a first motor (6), and a tension screw (8); The upper end of the drilling unit housing (1) is connected to the column (3). The first motor (6) is located inside the drilling unit housing (1). The upper end of the tension screw (8) is rotatably connected to the drilling unit housing (1). The first motor (6) is connected to the screw 8 via a chain. The rotation of the first motor (6) can drive the tension screw (8) to rotate.

10. The drilling core sampling device for simulating mechanical disturbance according to claim 9, characterized in that, The monitoring unit also includes a vibration sensor (17), a drilling speed sensor (14), a rotational speed and torque sensor (16), and a thrust sensor (15). The vibration sensor (17) is mounted on one side of the core drill bit (12) via a bracket; The drilling speed sensor (14) is mounted on the drilling unit housing (1); The speed and torque sensor (16) is installed at the upper end of the drill pipe spindle 11 to monitor the speed and torque of the drill pipe spindle 11. The thrust sensor (15) has a threaded hole at its upper end, and the lower end of the tension screw (8) is screwed into the threaded hole at the upper end of the thrust sensor (15); the thrust sensor (15) is fixedly connected to the rotating unit housing (2).

Images