Method for measuring inclination angle of planar structure in rock core and rock core inclination angle measuring plate

Abstract

The invention discloses a method for measuring the inclination angle of a planar structure in a rock core. The method comprises the following steps: (1) converting a three-dimensional track curve on the surface of a rock core cylinder into a two-dimensional plane graph; (2) according to a geometric model, any plane not perpendicular to the bottom surface of the cylinder intersects with the cylinder, the track curve of the plane on the surface of the cylinder is a circle with the diameter equal to the diameter d of the bottom surface of the cylinder or a series of ellipses with long axes a different in size and short axes b equal to the diameter d of the bottom surface of the cylinder, the short axes b = d, and the long axes a = d / cos theta; (3) for any rock core with the determined diameter, drawing a series of different curves with the inclination angle theta in the range of 0-90 degrees on a plane; and (4) directly sleeving the curve drawn in the step (3) with a track curve of the to-be-measured planar structure on the rock core cylinder, wherein an angle marked on the matched curve is the inclination angle of the to-be-measured planar structure. The measurement method is simple and effective, and the measurement error does not exceed 1 degree.

Description

Technical Field

[0001] The invention relates to the technical field of geological exploration, and in particular to a method for measuring the dip angle of a planar structure in a rock core and a rock core dip angle measuring plate. Background Art

[0002] Core logging is the detailed observation, description, measurement and recording of drilled cores, and is an important basic work in geological / mineral deposit exploration. Among them, the accuracy of the dip measurement of planar structures in the core (including faults, joints, bedding, schistosity, gneissism, veins, fold wings and axial surfaces, and contact surfaces of different geological bodies) is the key to the correct geological structure analysis, mineral deposit genesis research, and mineral resource evaluation.

[0003] A geological compass is a tool used to measure the inclination of planar structures in geological bodies. However, because rock cores are cylindrical, direct measurements on the core using a geological compass are not possible. Therefore, there has been no effective measurement method or tool that can directly measure the inclination of planar structures in rock cores. The current common practice is to extend an imaginary surface parallel to the planar structure to be measured in the rock core, and then measure it using a geological compass, protractor, or visual inspection. This requires the cooperation of at least two people, making the entire operation complex and time-consuming, and resulting in highly inaccurate measurement data.

[0004] Before the 21st century, mineral exploration was mainly focused on surface outcrops and shallow mines (the exploration depth generally did not exceed 500m), and tunnel engineering was the main prospecting technology. On the surface and in the tunnels, the compass could be used to directly measure the planar structures. Drilling projects were relatively rare, and mainly focused on shallow drilling (the depth generally did not exceed 300m). The number of planar structures that needed to be measured on the core surface was relatively small, and the accuracy requirements for the measured inclination were not too high. Generally, an inclination error of 5°-7° was sufficient to meet the accuracy of the data required for cores within 300m. Therefore, even if there were no special methods and tools for measuring the inclination of planar structures in cores, the existing indirect measurement methods, although time-consuming and inaccurate, could barely meet the requirements.

[0005] Currently, most easily discovered and mined surface and shallow deposits have been discovered. However, after long-term mining, mineral resources are becoming increasingly scarce, making prospecting more challenging. The search for hidden deposits deep within covered areas is a matter of considerable concern worldwide. However, due to the complex construction technology of deep pit exploration, which requires significant power and specialized equipment, resulting in low efficiency and high costs, deep exploration primarily relies on deep drilling. Therefore, rapidly and accurately obtaining inclination data on planar structures in core drilling is a key challenge that we must overcome.

[0006] Given that the trajectory of the surface structure on the surface of the core cylinder is a curve of different curvatures, all previous solutions have focused on adding an arc structure with adjustable curvature to the existing compass to achieve the goal of measuring the inclination of the surface structure directly on the core surface. However, due to the complexity of the compass structure itself, this makes the measuring tool difficult and costly to manufacture, and it is also complicated and time-consuming to operate, difficult to learn, and difficult to popularize, especially the measurement accuracy is difficult to guarantee.

[0007] Therefore, there is an urgent need to invent an effective measurement method and then design a measuring tool for measuring the inclination of planar structures in rock cores. Summary of the Invention

[0008] In response to the current technical problems, the present invention provides a method for measuring the inclination of planar structures in a rock core and a rock core inclination measurement plate to solve the problems in the prior art.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A method for measuring the dip angle of a planar structure in a rock core comprises the following steps: (1) Convert the three-dimensional trajectory curve of the core cylinder surface into a two-dimensional plane graph The trajectory of the intersection of the surface structure and the core cylinder is a curve. For core cylinders of the same diameter, the shape and size of these trajectory curves are determined by the angle between the surface structure to be measured and the bottom surface of the core cylinder. In other words, the inclination of the surface structure and the shape and size of the trajectory curve are one-to-one corresponding. Therefore, the measurement of the inclination of the surface structure in the core is transformed into drawing a series of curves of specific shapes and sizes on a plane to represent the inclination of the surface structure in the core. (2) According to the geometric model, any plane that is not perpendicular to the base of a cylinder and intersects the cylinder has a trajectory on the surface of the cylinder that is a circle with a diameter equal to the diameter d of the base of the cylinder, or a series of ellipses with different major axes a and minor axes b equal to the diameter d of the base of the cylinder, where the minor axis b = d and the major axis a = d / cosθ, where θ is the inclination angle of the surface structure to be measured; (3) For any core with a certain diameter, the major axis and minor axis of the curve can be determined according to step (2), and then a series of different curves with an inclination angle θ ranging from 0° to 90° can be drawn on the plane; (4) directly fitting the curve drawn in step (3) with the trajectory curve of the surface structure to be measured on the core cylinder. The angle marked on the matching curve is the inclination angle of the surface structure to be measured.

[0010] Preferably, in geological research, when performing statistical analysis on the occurrence of planar structures, classification is usually performed at intervals of 5°, so the curve in step (3) is drawn at intervals of 5°.

[0011] A core dip measurement plate is manufactured according to the method for measuring the dip of the planar structure in the core. The plate comprises a plate body on which a plurality of different curves are distributed. Each curve is marked with a corresponding angle, which corresponds to the dip of the planar structure in the core.

[0012] Preferably, eighteen different curves are distributed on the plate body.

[0013] Preferably, the eighteen different curves are distributed on the same plate body.

[0014] Preferably, the eighteen different curves are distributed on different plate bodies.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the measurement method of the present invention is simple and effective. Under normal circumstances, the measurement of the inclination of a planar structure in the core can be completed within 15-30 seconds, and the error does not exceed 1°; the core inclination measurement plate manufactured by the method of the present invention has a simple structure, is easy to manufacture, has low cost, and has a simple and convenient operation process. It does not require special training for operators and is simple, easy to learn and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of a core measurement plate manufactured according to the method of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with test examples and specific embodiments. However, this should not be understood as limiting the scope of the present invention to the following embodiments, and all technologies implemented based on the present invention fall within the scope of the present invention.

[0018] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0019] A method for measuring the dip angle of a planar structure in a rock core comprises the following steps: (1) Convert the three-dimensional trajectory curve of the core cylinder surface into a two-dimensional plane graph Since the trajectory of the intersection of the surface structure and the core cylinder is a curve (only when the surface structure is perpendicular to the bottom of the core cylinder, its trajectory is two parallel straight lines), it is impossible to directly measure its inclination using a geological compass; although the curve is intuitively a three-dimensional curve, in fact, since it is the intersection of the cylinder and the surface structure, the curve is also a curve in a two-dimensional plane; in addition, for core cylinders with the same diameter, the shape and size of these trajectory curves are determined by the angle between the surface structure to be measured and the bottom of the core cylinder (for straight drilling, this angle is The inclination of the planar structure to be measured is determined by the inclination of the planar structure, that is, the shape and size of its curve trajectory are determined by the inclination of the planar structure, that is, the size of the inclination and the shape and size of the trajectory are in a one-to-one correspondence; therefore, a series of curves of specific shapes and sizes in the plane represent a certain inclination. This is equivalent to converting the trajectory curve in three-dimensional space into a curve in a two-dimensional plane. Based on the above ideas, the problem of measuring the inclination of the planar structure in the core is transformed into drawing a series of curves of specific shapes and sizes on a plane to represent the inclination of the planar structure; (2) According to the geometric model, any plane that is not perpendicular to the base of a cylinder and intersects the cylinder has a trajectory on the surface of the cylinder that is a circle with a diameter equal to the diameter d of the base of the cylinder, or a series of ellipses with different major axes a and minor axes b equal to the diameter d of the base of the cylinder, where the minor axis b = d and the major axis a = d / cosθ, where θ is the inclination angle of the surface structure to be measured; (3) For any core with a certain diameter, the major axis and minor axis of the curve can be determined according to step (2), and then a series of different curves with an inclination angle θ ranging from 0° to 90° can be drawn on the plane; Theoretically, we can use 1° as an interval and draw 90 ellipses of different shapes and sizes from 0° to 90° on a plane to represent 90 different angles. However, in practice, this is unrealistic. For example, taking the maximum diameter of a core as an example, the semi-major axis difference of 1° and 2° is 0.02mm, which is far less than the accuracy that the human eye can recognize. In addition, drawing 90 ellipses of different shapes and sizes on a plane does not conform to the principle of optimization design. In geological research, when statistically analyzing the occurrence of planar structures, they are usually classified at intervals of 5°. Therefore, we also draw curves at intervals of 5°. In addition, the measurement accuracy of curves drawn at intervals of 5° is ≤1°, which fully meets the accuracy requirements of geological research. Let's take a planar structure with an inclination between 40° and 45° as an example: if the trajectory curve to be measured is in the middle of the ellipse represented by 40° and 45° on the core inclination measurement plate, the error between the measured inclination value and the true value will not be greater than 1°, regardless of whether it is estimated to be 42° or 43°. (4) Directly fit the curve drawn in step (3) with the trajectory curve of the surface structure to be measured on the core cylinder. The angle marked on the matching curve is the inclination angle of the surface structure to be measured.

[0020] As attached Figure 1 As shown, a core inclination measurement plate is made according to the method for measuring the inclination of the surface structure in the core. It includes a plate body, and eighteen different curves are distributed on the plate body. Each curve is marked with a corresponding angle, which is the inclination of the surface structure in the core to be measured.

[0021] The eighteen different curves may be distributed on the same plate body or on different plate bodies.

[0022] Since the common drilling core diameter is 50 mm, taking d=50 mm as an example, based on the short axis b=d and the long axis a=d / cosθ (θ is the inclination angle of the surface structure to be measured), the trajectory curves represented by different inclination angles at intervals of 5° are simulated on the plane. The details are as follows: ① The inclination angle is 0°, and the trajectory is a circle with a radius of 25 mm; ② The inclination angle is 5°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 25.10 mm; ③ The inclination angle is 10°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 25.39 mm; ④ The inclination angle is 15°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 25.88 mm; ⑤ The inclination angle is 20°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 26.61 mm; ⑥ The inclination angle is 25°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 27.59 mm; ⑦ The inclination angle is 30°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 28.87 mm; ⑧ The inclination angle is 35°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 30.52 mm; ⑨ The inclination angle is 40°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 32.64 mm; ⑩ The inclination angle is 45°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 35.36 mm; ⑾ The inclination angle is 50°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 38.90 mm; ⑿ The inclination angle is 55°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 43.59 mm; ⒀ The inclination angle is 60°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 50.00 mm; ⒁ The inclination angle is 65°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 59.16 mm; ⒂ The inclination angle is 70°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 73.10 mm; ⒃ The inclination angle is 75°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 96.596 mm; ⒄ The inclination angle is 80°, and the trajectory is an ellipse with a minor semi-axis of 25 mm and a major semi-axis of 143.97 mm; ⒅The inclination angle is 85°, and the trajectory is an ellipse with a minor semi-axis of 25mm and a major semi-axis of 286.84mm.

[0023] In summary, eighteen curves with different shapes and sizes marked with corresponding angles were designed for the core with a diameter of 50 mm (see attached). Figure 1 As shown in the figure, when measuring, the curve on the core inclination measurement plate is directly matched with the trajectory curve of the surface structure to be measured on the core cylinder. The angle marked on the matching curve is the inclination of the surface structure to be measured; when the curve to be measured falls between the curves on the core inclination measurement plate, the difference method is used to estimate the angle.

[0024] The above describes preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for measuring the dip angle of planar structures in a rock core, characterized in that: The following steps are involved: (1) Convert the three-dimensional trajectory curve of the core cylinder surface into a two-dimensional plane graph The trajectory of the intersection of the surface structure and the core cylinder is a curve. For core cylinders of the same diameter, the shape and size of these trajectory curves are determined by the angle between the surface structure to be measured and the bottom surface of the core cylinder. In other words, the inclination of the surface structure and the shape and size of the trajectory curve are one-to-one corresponding. Therefore, the measurement of the inclination of the surface structure in the core is transformed into drawing a series of curves of specific shapes and sizes on a plane to represent the inclination of the surface structure in the core. (2) According to the geometric model, any plane that is not perpendicular to the base of a cylinder and intersects the cylinder has a trajectory on the surface of the cylinder that is a circle with a diameter equal to the diameter d of the base of the cylinder, or a series of ellipses with different major axes a and minor axes b equal to the diameter d of the base of the cylinder, where the minor axis b = d and the major axis a = d / cosθ, where θ is the inclination angle of the surface structure to be measured; (3) For any core with a certain diameter, the major axis and minor axis of the curve can be determined according to step (2), and then a series of different curves with an inclination angle θ ranging from 0° to 90° can be drawn on the plane; (4) directly fitting the curve drawn in step (3) with the trajectory curve of the surface structure to be measured on the core cylinder. The angle marked on the matching curve is the inclination angle of the surface structure to be measured.

2. The method for measuring the inclination angle of planar structures in a rock core according to claim 1, wherein: In geological research, when performing statistical analysis on the occurrence of planar structures, classification is usually performed at intervals of 5°, so the curves in step (3) are drawn at intervals of 5°.

3. A core inclination measurement plate, characterized in that: The method for measuring the inclination of the planar structure in the rock core according to claim 2 includes a plate body, on which a plurality of different curves are distributed, and each curve is marked with a corresponding angle, which corresponds to the inclination of the planar structure in the rock core.

4. A core inclination measurement plate according to claim 3, characterized in that: Eighteen different curves are distributed on the plate body.

5. The core inclination measurement plate according to claim 4, characterized in that: The eighteen different curves are distributed on the same plate body.

6. The core inclination measurement plate according to claim 4, characterized in that: The eighteen different curves are distributed on different plate bodies.

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