A gob broken zone double casing pipe drilling coring device and dynamic adaptation method

Abstract

This invention discloses a double-casing drilling and coring device and dynamic adaptation method for fractured zones in goaf areas. The device includes: a drilling rig connecting base mounted on a connecting casing; the connecting casing, extension casing, and coring casing form an inner and outer double-casing structure; the outer casing of the connecting casing connects to the outer casing of the extension casing or the outer casing of the coring casing; a coring drill bit is mounted on the coring casing; a permanent magnet array is mounted on the rotating base of the coring drilling rig; and a sensor module is mounted on the coring casing. In this invention, the outer casing of the coring casing rotates to drill through the rock, while the inner casing remains stationary by using electromagnetic damping force to counteract the rotational interference of the outer casing. This invention utilizes electromagnetic induction technology to avoid the failure of traditional mechanical limiting mechanisms at high speeds, effectively ensuring core stability; and proposes a dynamic adaptation method based on the core condition. This invention is widely applicable to core collection in complex strata such as fractured zones and soft coal seams, significantly reducing core breakage rates and improving core integrity.

Description

Technical Field

[0001] This invention relates to a double-casing drilling and coring device and a dynamic adaptation method for fractured zones in goaf areas, belonging to the technical field of such a device and method. Background Technology

[0002] In the exploration of fractured zones at the edge of coal mine goafs, obtaining intact core samples is crucial for assessing the stability of the surrounding rock, which includes residual strength and the degree of fracture development. However, under complex conditions, especially in fractured zones at the edge of goafs, where the surrounding rock is mostly silty mudstone affected by mining, conventional coring tools face the following main problems:

[0003] During coring, the rotation of the coring tube and the core sample causes additional torsional or radial forces to interfere with the core, leading to fracture development and core dispersion, making it difficult to effectively preserve the original distribution of the core. Currently used single-axis rotary drilling relies solely on mechanical restraint and lubrication to separate the inner and outer casings. However, under high rotation speeds and complex impacts, drilling vibrations can cause fracture propagation, and water-bearing strata and centrifugal forces can cause mechanical restraint failure. An ideal double-casing structure in the fractured zone at the edge of a goaf should achieve a design where the outer casing rotates to complete drilling and core collection, while the inner casing remains stationary to reduce core loss. However, current equipment has not solved the technical challenge of inner casing fixation, and in particular, it lacks a dynamic adaptation mechanism for changes in coring angle, core length, and weight. Summary of the Invention

[0004] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a dual-casing drilling and coring device and dynamic adaptation method for fractured zones in goaf areas. This reduces core breakage caused by mechanical interference such as rotation and overload, and improves the integrity of core samples. This invention resolves the contradiction between "fidelity, efficiency, and adaptability" in the field of dual-casing drilling and coring by employing non-contact power transmission technology and a dynamic adaptive control system based on real-time magnetic field adjustment with multi-parameter feedback including core length, core weight, and core dip angle, and responding to changes in strata state in milliseconds.

[0005] Prior to this invention, a double-casing drilling and coring device for fractured zones in goaf areas is provided, comprising a drilling rig connecting base, a connecting casing, an extension casing, a coring casing, a coring drill bit, a permanent magnet array, and a sensor module. The drilling rig connecting base is mounted on the connecting casing. The connecting casing, extension casing, and coring casing have an inner and outer double-casing structure. The outer casing of the connecting casing is connected to the outer casing of the extension casing or the outer casing of the coring casing. A coring drill bit is mounted on the coring casing. The permanent magnet array is mounted on the rotating base of the coring drilling rig. The sensor module is mounted on the coring casing.

[0006] Preferably, it includes an annular copper conductor ring, with the annular copper conductor ring spirally embedded in the surface of the connecting sleeve, and the annular copper conductor ring having embedded microchannels. In a rotating magnetic field, the annular copper conductor ring will cut magnetic field lines and generate eddy currents.

[0007] Preferably, the connecting sleeve includes an excitation coil, an electromagnetic shielding layer, and a soft magnetic alloy ring. Several sets of distributed excitation coils are arranged on the inner wall of the outer tube of the connecting sleeve. The electromagnetic shielding layer is set between the outer tube and the inner tube of the connecting sleeve. The soft magnetic alloy ring is installed on the outer wall of the inner tube of the connecting sleeve. When the outer tube of the connecting sleeve rotates, the distributed excitation coils are energized to generate an alternating magnetic field, which induces reverse eddy currents in the soft magnetic alloy ring and generates a Lorentz force opposite to the rotation direction of the outer tube of the connecting sleeve, keeping the inner tube of the connecting sleeve stationary.

[0008] Preferredly, a thrust ball bearing-spring clip is provided between the outer tube and the inner tube of the connecting sleeve, between the outer tube and the inner tube of the extension sleeve, and between the outer tube and the inner tube of the core sampling sleeve. The thrust ball bearing-spring clip engages when the distributed excitation coil is de-energized.

[0009] Preferably, the drill rig connection seat includes a casing connection shaft, a connecting piece, and a connecting thread. The casing connection shaft is installed on the non-rotating part of the core drilling rig. The casing connection shaft is installed on the connecting casing through the connecting piece. A connecting thread is opened on the outer tube of the connecting casing. The outer tube of the connecting casing is connected to the outer tube of the extension casing or the outer tube of the core casing through the connecting thread.

[0010] Preferably, the sensor module includes a laser rangefinder, a piezoelectric ceramic array, a MEMS gyroscope, and a Hall sensor. The laser rangefinder is located at the top of the inner tube of the connecting sleeve, the piezoelectric ceramic array is located at the bottom of the inner tube of the connecting sleeve, the MEMS gyroscope is located in the middle of the inner tube of the connecting sleeve, and the Hall sensor is located on the inner wall of the outer tube of the connecting sleeve.

[0011] Prior to this, a dynamic adaptation method for a double-casing coring device in a fractured goaf area, utilizing any one of the described double-casing coring devices in a fractured goaf area, includes the following steps:

[0012] Start the coring drill and use the coring drill bit to drive the coring casing to advance gradually. The obtained rock core enters the inner tube of the coring casing. The electromagnetic field parameters are adjusted in real time. When the rock core reaches the flexible seal in the inner tube of the coring casing, the coring drill is shut down.

[0013] Remove the permanent magnet array, extension casing, and core casing, and take out the rock core from the inner tube of the core casing.

[0014] Prioritize real-time control of electromagnetic field parameters, including:

[0015] Step 1: Use a laser rangefinder to collect the length of the rock core in the inner tube of the coring casing, use a piezoelectric ceramic array to collect the weight of the rock core in the inner tube of the coring casing, use a MEMS gyroscope to collect the tilt angle of the rock core in the inner tube of the coring casing, and use a Hall sensor to collect the magnetic field strength and angular displacement in the inner tube of the coring casing.

[0016] Step 2: Based on the particle swarm optimization algorithm, global optimization of the electromagnetic field parameter combination, including the magnetic induction intensity B, is performed at preset intervals.

[0017] Step 3, determine the permeability μ(t):

[0018]

[0019] Where L(t) is the change in core length over time, Δθ(t) is the core angle offset, and k1, k2, and k3 are constant coefficients;

[0020] Step 3: Solve Maxwell's equations using a simplified model derived from the finite element method:

[0021]

[0022] In the formula, Here, H is the vector differential operator, D is the magnetic field strength vector, t is time, and J is the current density vector.

[0023] Step 4: Based on the measured data including core length, core weight, and core dip angle, iteratively correct the boundary conditions.

[0024] Prioritizing step 4, based on measured data including core length, core weight, and core dip angle, the boundary conditions are iteratively corrected, including:

[0025] Step 41, set the initial baseline values: core length Lintial, core weight Wintial, and core dip angle θinitial;

[0026] The core length Lcurrent in the inner tube of the coring casing was acquired by the laser rangefinder, the core weight Wcurrent in the inner tube of the coring casing was acquired by the piezoelectric ceramic array, and the core tilt angle θcurrent in the inner tube of the coring casing was acquired by the MEMS gyroscope.

[0027] Step 42: Calculate the core length change, core angle offset, and core weight increment.

[0028] The change in core length L(t) = Lcurrent - Linitial,

[0029] Core angle offset Δθ(t) = θcurrent - θinitial,

[0030] Core weight increment ΔW(t) = Wcurrent – ​​Winitial;

[0031] Step 43: Input the core length change and core angle offset into the magnetic permeability model to calculate the magnetic permeability μ(t):

[0032]

[0033] Solving Maxwell's equations containing μ(t) using the finite element method Obtain the predicted core length L-model and the predicted core dip angle θ-model at the current moment;

[0034] Step 44: Determine whether the interpolation between the predicted core length L-model and the core length Lcurrent collected by the laser rangefinder in the inner tube of the core casing is within the first preset error range, and whether the interpolation between the predicted core dip angle θ-model and the core dip angle θcurrentt collected by the MEMS gyroscope in the inner tube of the core casing is within the second preset error range. If both are true, the boundary conditions are corrected and the iteration ends; otherwise, proceed to the next step.

[0035] Step 45: If Lcurrent > Linitial, then update the magnetic field strength according to B = B0(1 + 0.05L(t)), where L(t) is the change in core length and B0 is the initial value of magnetic induction.

[0036] Step 46: If |Δθ(t)|>preset threshold, then adjust the energizing phase of the excitation coil group by space vector to compensate for the asymmetric torque;

[0037] Step 47: If the current core weight Wcurrent exceeds the preset maximum weight threshold, the damping force will be increased to 1.5 times the rated damping force value.

[0038] Step 48: Determine whether the interpolation between the predicted core length L-model and the core length Lcurrent collected by the laser rangefinder in the inner tube of the core casing is within the first preset error range, and whether the interpolation between the predicted core dip angle θ-model and the core dip angle θcurrentt collected by the MEMS gyroscope in the inner tube of the core casing is within the second preset error range. If both are within the preset error range, the boundary conditions are corrected and the iteration ends; otherwise, Lcurrent from the previous time step is used to replace L. ′ The initial value is used to replace θ′initial with θcurrent from the previous moment, and the change in core length L is... ′ (t)=L ′ current-L ′initial, i.e. L ′ (t) is actually the measured value L at this moment. ′ Subtract the previous current from the current; calculate the core angle offset Δθ. ′ (t)=θ ′ current-θ′initial, that is Δθ ′ (t) is actually the measured value θ at this moment. ′ Subtract θcurrent from the previous time step from current, and repeat steps 42 to 44.

[0039] The beneficial effects achieved by this invention are as follows:

[0040] This invention features millisecond-level electromagnetic field adjustment for dynamic response to abrupt geological changes. It employs a synergistic design of corrosion-resistant, magnetically permeable, and structural materials, along with a triple coupling mechanism of mechanical, electromagnetic, and sensing elements. It is suitable for underground coal mine operations and other complex strata drilling and coring scenarios. During drilling and coring, the device utilizes electromagnetic eddy current effects to drive the outer tube of the connecting casing to rotate. This continuous rotation, without mechanical contact, completes drilling or cuttings removal. Meanwhile, the inner tube of the connecting casing is prevented from rotating by electromagnetic damping force, offsetting the torque interference from the outer tube's rotation. Even under complex torques or overload impacts transmitted through the core, it ensures unwavering inner-layer coring function, meeting high stability requirements in fractured coal mine surrounding rock. The introduction of electromagnetic induction technology aims to reliably fix the inner tube of the coring casing during sampling, reducing failures caused by equipment vibration and impacts, as seen in traditional mechanical limiting components or hydraulic fixing schemes. This invention proposes a scientific dynamic adaptation method, combining variables such as core dip angle, core length, and core weight changes under fractured coal mine surrounding rock conditions, enabling traditional exploration equipment to gradually enter a new stage of intelligence, greening, and extreme performance. Attached Figure Description

[0041] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the operation of the double-casing drilling and coring device provided in an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of a drilling rig connection seat provided in an embodiment of the present invention;

[0044] Figure 3 This is a cross-sectional view of the drilling rig connection seat provided in an embodiment of the present invention;

[0045] Figure 4This is a schematic diagram of the connecting sleeve provided in an embodiment of the present invention;

[0046] Figure 5 This is a cross-sectional view of the connecting sleeve provided in an embodiment of the present invention;

[0047] Figure 6 This is a side view of the connecting sleeve provided in an embodiment of the present invention;

[0048] Figure 7 This is a schematic diagram of an extension sleeve or core-taking sleeve provided in an embodiment of the present invention;

[0049] Figure 8 This is a cross-sectional view of the extension sleeve or coring sleeve provided in an embodiment of the present invention;

[0050] Figure 9 This is a schematic diagram of a permanent magnet array provided in an embodiment of the present invention;

[0051] Figure 10 This is a cross-sectional view of the permanent magnet array provided in an embodiment of the present invention;

[0052] The following are the meanings of the reference numerals in the attached diagram: 1. Tunnel; 2. Core drilling rig; 3. Drilling rig connecting seat; 4. Connecting casing; 5. Extension casing; 6. Core casing; 7. Core drill bit; 8. Surrounding rock; 9. Permanent magnet array; 10. Casing connecting shaft; 11. Connecting piece; 12. Connecting thread; 13. Annular copper conductor ring; 14. Distributed excitation coil; 15. Electromagnetic shielding layer; 16. Thrust ball bearing-spring clip; 17. Soft magnetic alloy ring; 18. Laser rangefinder; 19. Piezoelectric ceramic array; 20. MEMS gyroscope; 21. Hall sensor. Detailed Implementation

[0053] In this invention, the terms "first" and "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0054] See Figure 1 This application provides a double-casing drilling and coring device for broken zones in goaf areas, including a drilling rig connecting seat 3, a connecting sleeve 4, an extension sleeve 5, a coring sleeve 6, a coring drill bit 7, a permanent magnet array 9, a copper conductor ring 13, an excitation coil 14, a soft magnetic alloy ring 17, an electromagnetic shielding layer 15, a sensor module, and a cooling system.

[0055] The casing connecting shaft 10 is connected to the non-rotating part of the core drilling rig 2. The casing connecting shaft 10 is connected to the connecting casing 4 via a connecting piece 11. The connecting casing 4, the extension casing 5, and the core drilling casing 6 form a double-casing structure. The outer tube of the connecting casing 4 is connected to the outer tube of the extension casing 5 or the outer tube of the core drilling casing 6 via an internal connecting thread 12. A 2mm outer diameter annular copper conductor ring 13 is spirally embedded on the surface of the connecting casing 4. The annular copper conductor ring 13 has embedded microchannels. The permanent magnet array 9 is installed on the rotating base of the core drilling rig 2. The rotating base is driven by a motor to form a spatial rotating magnetic field. The copper conductor ring 13, acting as a conductor, cuts magnetic field lines in the rotating magnetic field, generating eddy currents. According to Lenz's law, these eddy currents experience an Ampere force in the magnetic field, which generates torque, thus transmitting the rotational power of each outer tube. The extension casing 5 does not preserve the core sample; it is connected to the front end of the connecting casing 4. The connecting casing 4 is connected to the drilling rig 2 via the drilling rig connecting seat 3, which only serves a connecting function. The drilling rig 2 provides the power required for core sampling through the rotating permanent magnet array 9 and the copper conductor ring 13, enabling the double-casing drilling and coring device to operate. Figures 2 to 4 As shown, the left end of the drill rig connecting seat 3 is fixedly connected to the drill rig, and the right end of the drill rig connecting seat 3 is connected to the connecting sleeve 4. The right end of the connecting sleeve 4 can be connected to the extension sleeve 5 or the core sleeve 6 according to the core sampling progress. Figures 7 to 8 As shown, the outer tube of the core casing 6 can be connected to the outer tube of the extension casing 5 or the connecting casing 4 on the left side of the core casing 6 via the connecting thread 12. The outer tube of the core casing 6 can also be connected to the core drill bit 7 on the right side via the connecting thread 12. The inner tube of the core casing 6 can be connected to the inner tube of the extension casing 5 or the connecting casing 4 on the left side of the core casing 6 via the connecting thread 12. A flexible seal is provided near the left end of the core casing 6 to seal the left end of the core casing 6 for storing the obtained rock core. The core drill bit 7 is connected to the outer tube of the core casing 6 via the connecting thread 12. The inner diameter of the core drill bit 7 is the same as that of the inner tube of the core casing 6. The rock core obtained by the core drill bit 7 can be directly stored inside the inner tube of the core casing 6.

[0056] In the connecting sleeve 4, a composite fixing structure of electromagnetic locking + mechanical backup is selected for the double sleeves. The extension sleeve 5 and the core-taking sleeve 6 only require a mechanical backup structure: the electromagnetic locking part consists of several sets of distributed excitation coils 14 arranged on the inner wall of the outer tube of the connecting sleeve 4, with one set of distributed excitation coils 14 every 15°, for a total of 24 sets of distributed excitation coils 14. A soft magnetic alloy ring 17 is installed on the outer wall of the inner tube of the connecting sleeve 4. When the outer tube of the connecting sleeve 4 rotates, the distributed excitation coils 14 are energized to generate an alternating magnetic field, inducing an magnetic field in the soft magnetic alloy ring 17. A reverse eddy current should be generated, producing a Lorentz force opposite to the direction of rotation, keeping the inner tube of the connecting sleeve 4 stationary, similar to the principle of an electromagnetic brake; the mechanical backup part is an annular groove on the outer wall of the inner tube of the connecting sleeve 4, and a thrust ball bearing-spring clip 16 is installed on the inner wall of the outer tube of the connecting sleeve 4. When the distributed excitation coil 14 is de-energized, the thrust ball bearing-spring clip 16 automatically engages; after energization, the electromagnetic coil generates a magnetic field to attract the soft magnetic ring, achieving fixation; when the distributed excitation coil 14 is de-energized, the thrust ball bearing-spring clip automatically engages the inner tube groove, providing backup fixation; such as Figures 5 to 6 As shown, the connecting sleeve 4 can connect the inner tube of the extension sleeve 5 and the core-taking sleeve 6 through the internal connecting thread 12, thereby completing the fixation of the inner tube of the connecting sleeve 4, the inner tube of the extension sleeve 5 and the inner tube of the core-taking sleeve 6, and meeting the requirement that the inner tube remains fixed while the outer tube rotates.

[0057] Furthermore, the drilling rig connecting seat 3, connecting sleeve 4, extension sleeve 5, core sleeve 6 and core drill bit 7 are detachably and fixedly connected by connecting thread 12.

[0058] Furthermore, a thrust ball bearing-spring clip 16 is provided between the outer tube and the inner tube of the connecting sleeve 4, between the outer tube and the inner tube of the extension sleeve 5, and between the outer tube and the inner tube of the core-taking sleeve 6. The thrust ball bearing-spring clip 16 between the outer tube and the inner tube of the extension sleeve 5 and the core-taking sleeve 6 allows for highly reliable separation of the rotational movements between them, meeting the requirement that the inner tube remains fixed while the outer tube rotates.

[0059] Furthermore, the connecting piece 11 is made of 316L stainless steel, the permanent magnet array 9 is made of neodymium iron boron magnets, the soft magnetic alloy ring 17 is made of silicon steel sheet stacks, and the electromagnetic shielding layer 15 used between the outer tube and the inner tube of the connecting sleeve 4 is made of permalloy. Specifically, the permanent magnet array 9 is made of neodymium iron boron permanent magnets, which have strong magnetic properties and can generate high magnetic force in a small size. The connecting piece 11 is made of 316L stainless steel, which is corrosion resistant and does not change the distribution of the core magnetic field or the direction of the magnetic field lines. The impact is very weak and will not significantly affect the performance and stability of the equipment. It also has the advantages of controllable eddy currents and high strength. The soft magnetic alloy ring 17 is made of silicon steel sheet stacks, which has high magnetic permeability. The insulating coating between the stacks can absorb high-frequency vibration energy and is suitable for the typical vibration spectrum of coal mine goaf areas. The electromagnetic shielding layer 15 used between the outer tube of the core sleeve 6 and the outer and inner tubes of the extension sleeve 5 is made of permalloy, which can block the interference of water molecules on the magnetic circuit. After completing the non-contact force transmission steps, it is also necessary to develop corresponding dynamic adaptation methods to address changes in core sampling angle, core length, and weight.

[0060] Furthermore, since the electromagnetic field is primarily modulated by changing the magnitude, frequency, and phase of the coil current, for example, when torque interference is detected in the inner tube, the current in the damping coil is increased to strengthen the magnetic field and generate a larger eddy current damping force to counteract the torque. Simultaneously, the electromagnetic eddy currents driving the outer tube may need to have their frequency adjusted according to the rotational speed and load to maintain stable rotational power to meet the need for fixing the inner tubes during core removal. Therefore, this invention includes the following steps:

[0061] a. Monitoring and obtaining multiple parameters: The multiple parameters include the core length data collected by the laser rangefinder 18, the core weight collected by the piezoelectric ceramic array 19, and the core tilt angle collected by the MEMS gyroscope; the laser rangefinder 18 is set at the top of the inner tube of the connecting sleeve 4 to monitor the core length with an accuracy of ±0.1mm; the piezoelectric ceramic array 19 is set at the bottom of the inner tube of the connecting sleeve 4 to sense the core weight with a sensitivity of 0.1kg; the MEMS gyroscope 20 is set in the middle of the inner tube of the connecting sleeve 4 to detect the core tilt angle with a range of ±30° and a resolution of 0.01°; the Hall sensor 21 is set on the inner wall of the outer tube of the connecting sleeve 4 to detect the magnetic field strength and angular displacement.

[0062] b. Feedback control layer:

[0063] 1) PID-PSO hybrid controller:

[0064] The basic layer uses the classic PID algorithm to achieve a fast response adjustment period of 50ms;

[0065] The optimization layer introduces the Particle Swarm Optimization (PSO) algorithm, which performs global optimization every 10 seconds, including the combination of electromagnetic field parameters for the magnetic induction intensity B; 2) Dynamic modeling of magnetic permeability:

[0066] Determine the permeability:

[0067]

[0068] Where L(t) is the change in core length over time, Δθ(t) is the core angle offset, and k1, k2, and k3 are constant coefficients;

[0069] 3) Real-time solution of electromagnetic field coupling equations:

[0070] Solving Maxwell's equations using a simplified model derived from the finite element method (FEM):

[0071]

[0072] In the formula, Let H be the vector differential operator, D be the magnetic field strength vector, t be the electric displacement vector, and J be the current density vector. It is a vector differential operator, called the Hamiltonian operator. H is called the magnetic field strength vector: it describes the characteristics of the magnetic field and is related to the magnetic induction intensity B, with the relationship B = μ * H (where μ is the permeability), and the unit is amperes per meter (A / m). D is called the electric displacement vector: it is related to the electric field strength E, D = ε * E (where ε is the permittivity), and the unit is coulombs per square meter (C / m). 2 J is called the current density vector: it represents the magnitude of the current passing through a unit area, and the unit is amperes per square meter (A / m²). 2 ).

[0073] The boundary conditions are iteratively corrected by combining measured data including core length, core weight, and core dip angle.

[0074] Setting initial boundary conditions: The initial boundary conditions are set based on past experience or theoretical models. For example, for the initial core length, it can be assumed that the initial position of the core length inside the core casing is determined; for the initial core weight, the core weight can be preliminarily estimated based on the core density and volume; for the initial core dip angle, it can be assumed that its initial state is vertical or horizontal, etc.

[0075] Boundary condition correction. Step 4: Based on the measured data including core length, core weight, and core dip angle, iteratively correct the boundary conditions, including: Step 41: Set initial baseline values: core length Lintial, core weight Wintial, and core dip angle θtial;

[0076] The core length Lcurrent in the inner tube of the coring casing was acquired by the laser rangefinder, the core weight Wcurrent in the inner tube of the coring casing was acquired by the piezoelectric ceramic array, and the core tilt angle θcurrent in the inner tube of the coring casing was acquired by the MEMS gyroscope.

[0077] Step 42: Calculate the core length change, core angle offset, and core weight increment.

[0078] The change in core length L(t) = Lcurrent - Linitial,

[0079] Core angle offset Δθ(t) = θcurrent - θinitial,

[0080] Core weight increment ΔW(t) = Wcurrent – ​​Winitial;

[0081] Step 43: Input the core length change and core angle offset into the magnetic permeability model to calculate the magnetic permeability μ(t):

[0082]

[0083] Solving Maxwell's equations containing μ(t) using the finite element method Obtain the predicted core length L-model and the predicted core dip angle θ-model at the current moment;

[0084] Step 44: Determine whether the interpolation between the predicted core length L-model and the core length Lcurrent collected by the laser rangefinder in the inner tube of the core casing is within the first preset error range, and whether the interpolation between the predicted core dip angle θ-model and the core dip angle θcurrentt collected by the MEMS gyroscope in the inner tube of the core casing is within the second preset error range. If both are true, the boundary conditions are corrected and the iteration ends; otherwise, proceed to the next step.

[0085] Step 45: If Lcurrent > Linitial, then update the magnetic field strength according to B = B0(1 + 0.05L(t)), where L(t) is the change in core length and B0 is the initial value of magnetic induction.

[0086] Step 46: If |Δθ(t)|>preset threshold, then adjust the energizing phase of the excitation coil group by space vector to compensate for the asymmetric torque;

[0087] Step 47: If the current core weight Wcurrent exceeds the preset maximum weight threshold, the damping force will be increased to 1.5 times the rated damping force value.

[0088] Step 48: Determine whether the interpolation between the predicted core length L-model and the core length Lcurrent collected by the laser rangefinder in the inner tube of the core casing is within the first preset error range, and whether the interpolation between the predicted core dip angle θ-model and the core dip angle θcurrentt collected by the MEMS gyroscope in the inner tube of the core casing is within the second preset error range. If both are within the preset error range, the boundary conditions are corrected and the iteration ends; otherwise, Lcurrent from the previous time step is used to replace L. ′ The initial value is used to replace θ′initial with θcurrent from the previous moment, and the change in core length L is... ′ (t)=L ′ current-L ′ initial, i.e. L ′ (t) is actually the measured value L at this moment. ′ Subtract the previous current from the current; calculate the core angle offset Δθ. ′ (t)=θ ′ current-θ′initial, that is Δθ ′ (t) is actually the measured value θ at this moment. ′ Subtract θcurrent from the previous time step from current, and repeat steps 42 to 44.

[0089] Apply the adjusted boundary conditions to the above formula and re-simulate. Compare the new simulation results with the latest measured data collected by the sensor to evaluate the simulation effect after boundary condition adjustment. If the difference between the simulation results and the measured data is still large, repeat the previous error analysis and boundary condition adjustment process. Check whether the difference between the simulation results and the measured data is within the preset error range. If it is within the preset error range, it is determined that the boundary conditions have been reasonably corrected, and the iteration process can end; if it is not within the preset error range, continue iteratively correcting the boundary conditions until they are within the preset error range.

[0090] c. Precise control of electromagnetic fields:

[0091] 1) When the core length increases, the magnetic field is strengthened according to B = B0(1 + 0.05L(t)), where L(t) is the change in core length and B0 is the initial value of magnetic induction intensity;

[0092] 2. When the rock core tilt angle changes, the energizing phase of the excitation coil group is adjusted by spatial vector modulation to compensate for the asymmetric torque; 3. When the rock core weight exceeds the preset maximum weight threshold, the preset maximum weight threshold of more than 20kg triggers the safety mode and increases the damping force to 1.5 times the rated value.

[0093] Furthermore, a double-casing core drilling device for fractured zones in goaf areas includes the following steps:

[0094] S1. Connect the connecting sleeve 4 to the drilling rig connecting seat 3. Connect an appropriate number of extension sleeves 5 to the connecting sleeve 4 according to the drilling situation. Connect the core casing 6 to the extension sleeve 5. Connect the core drill bit 7 to the core casing 6. Insert the core drill bit 7 into the borehole of the surrounding rock 8.

[0095] S2. After powering on, prepare to drill and core the sample, and precisely control the electromagnetic field parameters to achieve dynamic adaptation.

[0096] S3. Start the coring drill 2. The coring drill bit 7 drives the coring casing 6 to advance continuously. The obtained rock core enters the inner tube of the coring casing 6. When the rock core reaches the flexible seal in the inner tube of the coring casing 6, shut down the coring drill 2.

[0097] S4. Remove the permanent magnet array 9, the extension sleeve 5 and the core sampling sleeve 6, slowly remove the rock core inside the core sampling sleeve 6, promptly load the removed rock core into the core box to complete the core sampling, and transport it to the laboratory for related experiments.

[0098] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0099] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention described herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not invented herein. The specification and embodiments are to be considered exemplary only.

[0100] Finally, the following points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection", "joining", and "fitting" should be interpreted broadly, and can refer to mechanical or electrical connections, or internal connections between two components, or direct connections. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change.

[0101] Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. The above specific embodiments have further described the purpose, technical solution and beneficial effects of this application in detail. It should be understood that the above are only specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solution of this application should be included within the scope of protection of this application.

Claims

1. A dynamic adaptation method for a double-casing core drilling device in a broken zone of a goaf, characterized in that, The double-casing core drilling device for the broken zone of the goaf includes a drill rig connecting seat (3), a connecting sleeve (4), an extension sleeve (5), a core casing (6), a core drill bit (7), a permanent magnet array (9), and a sensor module. The drill rig connecting seat (3) is installed on the connecting sleeve (4). The connecting sleeve (4), the extension sleeve (5), and the core casing (6) are double-casing structures. The outer tube of the connecting sleeve (4) is connected to the outer tube of the extension sleeve (5) or the outer tube of the core casing (6). The core drill bit (7) is installed on the core casing (6). The permanent magnet array (9) is installed on the rotating base of the core drilling rig (2). The sensor module is installed on the core casing (6). It includes an annular copper conductor ring (13) and a spiral embedded ring on the surface of the connecting sleeve (4). A copper conductor ring (13) is formed, with a microchannel embedded inside. In the rotating magnetic field, the copper conductor ring (13) cuts the magnetic field lines and generates eddy currents. The connecting sleeve (4) includes an excitation coil (14), an electromagnetic shielding layer (15), and a soft magnetic alloy ring (17). Several sets of distributed excitation coils (14) are arranged on the inner wall of the outer tube of the connecting sleeve (4). The electromagnetic shielding layer (15) is set between the outer tube of the connecting sleeve (4) and the inner tube of the connecting sleeve (4). The soft magnetic alloy ring (17) is installed on the outer wall of the inner tube of the connecting sleeve (4). When the outer tube of the connecting sleeve (4) rotates, the distributed excitation coils (14) are energized to generate an alternating magnetic field, which induces reverse eddy currents in the soft magnetic alloy ring (17) and generates eddy currents that rotate with the outer tube of the connecting sleeve (4). A Lorentz force in the opposite direction keeps the inner tube of the connecting sleeve (4) stationary; including a thrust ball bearing-spring clip (16), a thrust ball bearing-spring clip (16) is provided between the outer tube of the connecting sleeve (4) and the inner tube of the connecting sleeve (4), a thrust ball bearing-spring clip (16) is provided between the outer tube of the extension sleeve (5) and the inner tube of the extension sleeve (5), a thrust ball bearing-spring clip (16) is provided between the outer tube of the core casing (6) and the inner tube of the core casing (6), and the thrust ball bearing-spring clip (16) engages when the distributed excitation coil (14) is de-energized; the drilling rig connecting seat (3) includes a casing connecting shaft (10), a connecting piece (11) and a connecting thread (12), and the casing connecting shaft (10) is installed on the non-rotating part of the core drilling rig (2). At the rotating part, the sleeve connecting shaft (10) is installed on the connecting sleeve (4) through the connecting piece (11). The connecting sleeve (4) has a connecting thread (12) on the outer tube. The outer tube of the connecting sleeve (4) is connected to the outer tube of the extension sleeve (5) or the outer tube of the core-taking sleeve (6) through the connecting thread (12). The sensor module includes a laser rangefinder (18), a piezoelectric ceramic array (19), a MEMS gyroscope (20), and a Hall sensor (21). The laser rangefinder (18) is set at the top of the inner tube of the connecting sleeve (4), the piezoelectric ceramic array (19) is set at the bottom of the inner tube of the connecting sleeve (4), the MEMS gyroscope (20) is set in the middle of the inner tube of the connecting sleeve (4), and the Hall sensor (21) is set on the inner wall of the outer tube of the connecting sleeve (4). A dynamic adaptation method for a double-casing core drilling device in a fractured goaf area involves performing the following steps using the aforementioned double-casing core drilling device: Start the core drilling machine (2), use the core drill bit (7) to drive the core casing (6) to advance gradually, and the obtained rock core enters the inner tube of the core casing (6). The electromagnetic field parameters are adjusted in real time. When the rock core reaches the flexible seal in the inner tube of the core casing (6), the core drilling machine (2) is shut down. Remove the permanent magnet array (9), the extension sleeve (5) and the core tube (6), and take out the rock core inside the inner tube of the core tube (6); Real-time control of electromagnetic field parameters, including: Step 1: Use a laser rangefinder (18) to collect the length of the rock core in the inner tube of the core casing (6), use a piezoelectric ceramic array (19) to collect the weight of the rock core in the inner tube of the core casing (6), use a MEMS gyroscope (20) to collect the tilt angle of the rock core in the inner tube of the core casing (6), and use a Hall sensor (21) to collect the magnetic field strength and angular displacement in the inner tube of the core casing (6); Step 2: Based on the particle swarm optimization algorithm, global optimization of the electromagnetic field parameter combination, including the magnetic induction intensity B, is performed at preset intervals. Step 3, determine the permeability μ(t): ， Where L(t) is the change in core length over time, Δθ(t) is the core angle offset, and k1, k2 and k3 are constant coefficients; Step 3: Solve Maxwell's equations using a simplified model derived from the finite element method: ， In the formula, Here, H is the vector differential operator, D is the magnetic field strength vector, t is time, and J is the current density vector. Step 4: Based on the measured data including core length, core weight, and core dip angle, iteratively correct the boundary conditions.

2. The dynamic adaptation method of the double-casing core drilling device for fractured zones in goaf areas according to claim 1, characterized in that, Step 4: Based on measured data including core length, core weight, and core dip angle, iteratively correct the boundary conditions, including: Step 41, set the initial baseline values: core length (Linitial), core weight (Winitial), and core dip angle. initial; The core length Lcurrent in the inner tube of the coring sleeve (6) is acquired by the laser rangefinder (18), the core weight Wcurrent in the inner tube of the coring sleeve (6) is acquired by the piezoelectric ceramic array (19), and the core tilt angle in the inner tube of the coring sleeve (6) is acquired by the MEMS gyroscope (20). current; Step 42: Calculate the core length change, core angle offset, and core weight increment. Core length change L(t) = Lcurrent - Linitial Core angle offset Δθ(t) = current - initial, Core weight increment ΔW(t) = Wcurrent – ​​Winitial; Step 43: Input the core length change and core angle offset into the magnetic permeability model to calculate the magnetic permeability. : ， Solving the problem using the finite element method Maxwell's equations This yields the predicted core length L-model and the predicted core dip angle at the current moment. -model; Step 44: Determine whether the interpolation between the predicted core length L-model and the core length Lcurrent collected by the laser rangefinder (18) in the inner tube of the coring casing (6) is within the first preset error range, and whether the predicted core dip angle is within the first preset error range. -model and MEMS gyroscope (20) acquire the rock core dip angle in the inner tube of the core casing (6). If the interpolation of currentt is within the second preset error range, then the boundary conditions are determined to be corrected and the iteration ends; otherwise, the next step is executed. Step 45: If Lcurrent > Linitial, then update the magnetic field strength according to B = B0(1 + 0.05L(t)), where L(t) is the change in core length and B0 is the initial value of magnetic induction. Step 46: If |Δθ(t)| > preset threshold, then adjust the energizing phase of the excitation coil group by space vector to compensate for the asymmetric torque; Step 47: If the current core weight Wcurrent exceeds the preset maximum weight threshold, the damping force will be increased to 1.5 times the rated damping force value. Step 48: Determine whether the interpolation between the predicted core length L-model and the core length Lcurrent collected by the laser rangefinder (18) in the inner tube of the coring casing (6) is within the first preset error range, and whether the predicted core dip angle is within the first preset error range. -model and MEMS gyroscope (20) acquire the rock core dip angle in the inner tube of the core casing (6). If the interpolation of currentt is within the second preset error range, then the boundary conditions are determined to be corrected and the iteration ends; otherwise, Lcurrent from the previous time step is used to replace L. ′ initial and utilizing the previous moment current replacement Initially, the change in core length L ′ (t)= L ′ current - L ′ initial; calculate the core angle offset Δθ. ′ (t)= ′ current - Initially, repeat steps 42 to 44.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 2.

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