Goaf fracture zone double-sleeve drilling coring device and dynamic adaptation method

Abstract

The invention discloses a goaf fracture zone double-sleeve drilling coring device and a dynamic adaptation method.The goaf fracture zone double-sleeve drilling coring device is characterized in that a drilling machine connecting base is installed on a connecting sleeve, the connecting sleeve, an extending sleeve and a coring sleeve are of an inner-outer double-sleeve structure, and an outer pipe of the connecting sleeve is connected with an outer pipe of the extending sleeve or an outer pipe of the coring sleeve; a coring drill bit is installed on the coring sleeve, the permanent magnet array is installed on a rotating base of the coring drilling machine, and the sensor module is installed on the coring sleeve. The outer pipe of the coring sleeve rotates to drill rock, and the inner pipe counteracts interference of rotation of the outer pipe through electromagnetic damping force to keep still. By means of the electromagnetic induction technology, failure of traditional mechanical limiting at a high rotating speed is avoided, and stability of a rock core is effectively guaranteed; based on a rock core state, a dynamic adaptation method is provided. The method can be widely applied to rock core collection of complex stratums such as crushed zones and soft coal walls, the rock core breakage rate is greatly reduced, and the coring completeness is improved.

Description

Technical Field

[0001] The invention relates to a double-casing coring device for a broken zone in a goaf and a dynamic adaptation method, belonging to the technical field of double-casing coring device for a broken zone in a goaf and a dynamic adaptation method. Background Art

[0002] In the exploration of rock formations in the fractured zone at the edge of coal mine goafs, obtaining complete cores is crucial for assessing surrounding rock stability, which includes residual strength and the degree of fracture development. However, under complex working conditions, especially in the fractured zone at the edge of goafs, where the surrounding rock is mostly muddy siltstone affected by mining, conventional coring tools have the following major problems:

[0003] During the coring process, the core barrel and the core being extracted rotate together, subjecting the core to additional torsional or radial forces. This can cause cracks to develop, leading to core dispersion and making it difficult to effectively preserve the core's original distribution. Currently, single-axis rotary drilling utilizes mechanical limits and lubrication to separate the inner and outer casings. However, under high rotational speeds and complex impact conditions, drilling vibrations can cause crack expansion, while water-bearing rock formations and centrifugal forces can cause mechanical limits to fail. An ideal dual-casing structure in the fractured zone at the edge of a goaf should feature a design where the outer casing rotates to complete drilling and core collection, while the inner casing remains stationary to minimize core loss. However, current devices fail to address the technical challenges of inner-casing fixation, and in particular, fail to propose a dynamic adaptation mechanism for changes in coring angle, core length, and weight. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the shortcomings of the existing technology by providing a dual-casing coring device and dynamic adaptation method for coring in the fractured zone of a goaf. This device reduces core damage caused by mechanical interference such as rotation and overload, thereby improving the integrity of core sampling. Through non-contact power transmission technology and real-time magnetic field regulation based on multi-parameter feedback including core length, core weight, and core inclination, the invention achieves a dynamic adaptive control system that responds to changes in rock formation conditions in milliseconds. This device resolves the "fidelity-efficiency-adaptability" contradiction in the field of dual-casing coring.

[0005] Preferably, the present invention provides a double-casing drilling and coring device for a broken zone in a goaf, comprising a drilling rig connection seat, a connecting casing, an extension casing, a coring casing, a coring drill bit, a permanent magnet array and a sensor module. The drilling rig connection seat is installed on the connecting casing, the connecting casing, the extension casing and the coring casing are an inner and outer double-casing structure, the outer tube of the connecting casing is connected to the outer tube of the extension casing or the outer tube of the coring casing, a coring drill bit is installed on the coring casing, the permanent magnet array is installed on the rotating base of the coring drill, and the sensor module is installed on the coring casing.

[0006] Preferably, the annular copper conductor ring is included, the surface of the connecting sleeve is spirally embedded with the annular copper conductor ring, the annular copper conductor ring has a micro-channel embedded therein, and the annular copper conductor ring cuts the magnetic flux lines and generates eddy currents in a rotating magnetic field.

[0007] Preferably, the connecting sleeve includes an excitation coil, an electromagnetic shielding layer and a soft magnetic alloy ring. Several groups of distributed excitation coils are arranged on the inner wall of the outer tube of the connecting sleeve. The electromagnetic shielding layer is arranged between the outer tube of the connecting sleeve 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 coil is energized to generate an alternating magnetic field, inducing reverse eddy currents in the soft magnetic alloy ring and generating a Lorentz force opposite to the rotation direction of the outer tube of the connecting sleeve, so that the inner tube of the connecting sleeve remains stationary.

[0008] Preferably, a thrust ball bearing-spring clip is included, a thrust ball bearing-spring clip is provided between the connecting sleeve outer tube and the connecting sleeve inner tube, a thrust ball bearing-spring clip is provided between the extension sleeve outer tube and the extension sleeve inner tube, a thrust ball bearing-spring clip is provided between the core sampling sleeve outer tube and the core sampling sleeve inner tube, and the thrust ball bearing-spring clip is engaged when the distributed excitation coil is powered off.

[0009] Preferably, the drilling rig connecting seat includes a casing connecting shaft, a connecting plate and a connecting thread. The casing connecting shaft is installed on the non-rotating part of the coring drilling rig. The casing connecting shaft is installed on the connecting casing through the connecting plate. A connecting thread is provided on the connecting casing outer tube. The connecting casing outer tube is connected to the extension casing outer tube or the coring casing outer tube 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 arranged at the top of the inner tube of the connecting sleeve, the piezoelectric ceramic array is arranged at the bottom of the inner tube of the connecting sleeve, the MEMS gyroscope is arranged in the middle of the inner tube of the connecting sleeve, and the Hall sensor is arranged on the inner wall of the outer tube of the connecting sleeve.

[0011] Preferably, a dynamic adaptation method of a double-casing coring device for a goaf and a broken zone is provided, using any one of the double-casing coring device for a goaf and a broken zone, and includes the following steps:

[0012] The coring drill is started, and the coring casing is gradually advanced using the coring drill bit. The obtained core enters the inner tube of the coring casing. The electromagnetic field parameters are adjusted in real time. When the 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 coring casing, and take out the core from the inner tube of the coring casing.

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

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

[0016] Step 2, based on the particle swarm 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 magnetic 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: Use the finite element method to simplify the model and solve Maxwell's equations:

[0021]

[0022] Where, is the vector differential operator, H is the magnetic field intensity vector, D is the electric displacement vector, t is the time, and J is the current density vector;

[0023] Step 4: Iteratively modify the boundary conditions based on the measured data including the core length, core weight and core inclination.

[0024] Preferably, step 4, iteratively correcting the boundary conditions based on measured data including core length, core weight, and core inclination, comprises:

[0025] Step 41, setting initial reference values: core length Linitial, core weight Winitial and core inclination θinitial;

[0026] Obtain the core length Lcurrent in the inner tube of the coring casing collected by the laser rangefinder, the core weight Wcurrent in the inner tube of the coring casing collected by the piezoelectric ceramic array, and the core inclination θcurrent in the inner tube of the coring casing collected by the MEMS gyroscope;

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

[0028] Core length change 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 the core angle offset into the magnetic permeability model to calculate the magnetic permeability μ(t):

[0032]

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

[0034] Step 44: Determine whether the interpolation value of the predicted core length L-model and the core length Lcurrent in the inner tube of the coring casing acquired by the laser rangefinder is within a first preset error range, and whether the interpolation value of the predicted core inclination θ-model and the core inclination θcurrentt in the inner tube of the coring casing acquired by the MEMS gyroscope is within a second preset error range. If both are true, it is determined that the boundary condition is corrected and the iteration ends. Otherwise, proceed to the next step.

[0035] Step 45: If Lcurrent>Linitial, update the magnetic field intensity 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;

[0036] Step 46 , if |Δθ(t)|>preset threshold, adjusting the energization phase of the excitation coil group by using the 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 is increased to 1.5 times the rated damping force value;

[0038] Step 48: Determine whether the interpolation value of the predicted core length L-model and the core length Lcurrent in the core casing collected by the laser rangefinder is within a first preset error range, and whether the interpolation value of the predicted core inclination θ-model and the core inclination θcurrentt in the core casing collected by the MEMS gyroscope is within a second preset error range. If both are true, it is determined that the boundary condition is corrected and the iteration ends. Otherwise, Lcurrent is replaced by Lcurrent at the previous moment. ′ Initial and use the θcurrent of the previous moment to replace θ′initial, the change in core length L ′ (t) = L ′ current-L ′initial, that is, L ′ (t) is the actual measured value L at this moment ′ current minus Lcurrent of the previous moment; calculate the core angle offset Δθ ′ (t) = θ ′ current-θ′initial, that is Δθ ′ (t) is the actual measured value θ at this moment ′ current minus the θcurrent of the previous moment, and re-execute steps 42 to 44.

[0039] The beneficial effects achieved by the present invention are:

[0040] The present invention features millisecond-level electromagnetic field regulation to dynamically respond to sudden geological changes. It utilizes a coordinated design of corrosion-resistant, magnetically conductive, and structural materials, along with a triple coupling mechanism of mechanical, electromagnetic, and sensing, making it suitable for underground coal mine operations and other complex formation coring scenarios. During the coring process, the device utilizes the electromagnetic eddy current effect to drive the outer tube of the connecting sleeve to rotate, enabling continuous rotation without mechanical contact to complete drilling or chip removal. The inner tube of the connecting sleeve, through electromagnetic damping, counteracts the torque interference caused by the outer tube's rotation, preventing rotation. This ensures that the inner coring function remains stable even under complex torques or overloads transmitted by the core, ensuring high stability when operating in the fractured surrounding rock of coal mines. The introduction of electromagnetic induction technology ensures reliable fixation of the inner tube of the coring sleeve during sampling, reducing the potential for equipment failure caused by vibration and impact in traditional mechanical limiter assemblies or hydraulic fixation solutions. The present invention proposes a scientific dynamic adaptation method that incorporates variables such as core inclination, core length, and core weight variations under fractured surrounding rock conditions in coal mines, enabling traditional exploration equipment to gradually enter a new stage of intelligent, green, and extreme performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

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

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

[0044] Figure 3 A cross-sectional view of a drilling rig connection base provided by an embodiment of the present invention;

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

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

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

[0048] Figure 7 A schematic diagram of an extension casing or a coring casing provided in an embodiment of the present invention;

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

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

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

[0052] Meaning of the reference numerals in the accompanying drawings: 1. tunnel; 2. core drilling rig; 3. drilling rig connector; 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 buckle; 17. soft magnetic alloy ring; 18. laser rangefinder; 19. piezoelectric ceramic array; 20. MEMS gyroscope; 21. Hall sensor. DETAILED DESCRIPTION

[0053] If the descriptions of "first" and "second" are involved in the present invention, they are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0054] See also Figure 1 The present application provides a double-casing coring device for a goaf and broken zone, comprising a drilling rig connection base 3, a connecting casing 4, an extension casing 5, a coring casing 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 coring drill 2, and the casing connecting shaft 10 is connected to the connecting casing 4 through the connecting piece 11; the connecting casing 4, the extension casing 5 and the coring casing 6 are an inner and outer double-tube structure, and 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 coring casing 6 through an inner connecting thread 12; the surface of the connecting casing 4 is spirally embedded with an annular copper conductor ring 13 with an outer diameter of 2mm, and the annular copper conductor ring 13 is embedded with a microchannel; the permanent magnet array 9 is installed on the rotating base of the coring drill 2, and the rotating base is driven by a motor to form a spatial rotating magnetic field; the annular copper The copper conductor ring 13 acts as a conductor. In a rotating magnetic field, the annular copper conductor ring 13 will cut the magnetic flux lines and generate eddy currents. According to Lenz's law, eddy currents will be affected by the Ampere force in the magnetic field. This force will generate torque, thereby completing the rotational power transmission of each outer tube. The extension sleeve 5 does not store the core. The extension sleeve 5 is connected to the front end of the connecting sleeve 4. The connecting sleeve 4 is connected to the drill rig 2 through the drill rig connector 3. The drill rig connector 3 only plays a connecting role. The drill rig 2 provides the power required for coring through the cooperation of the rotating permanent magnet array 9 and the copper conductor ring 13, so that the double-casing drilling and coring device can operate. Figures 2 to 4 As shown, the left end of the drilling rig connection seat 3 is fixedly connected to the drilling rig, and the right end of the drilling rig connection 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 coring sleeve 6 according to the coring progress. Figures 7 and 8 As shown, the outer tube of the coring 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 coring casing 6 through the connecting thread 12, and the outer tube of the coring casing 6 can be connected to the coring drill bit 7 on the right side through the connecting thread 12. The inner tube of the coring 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 coring casing 6 through the connecting thread 12. A flexible seal is provided near the left end of the coring casing 6 to seal the left end of the coring casing 6 to store the obtained core; the coring drill bit 7 is connected to the outer tube of the coring casing 6 through the connecting thread 12, and the inner diameter of the coring drill bit 7 is consistent with that of the inner tube of the coring casing 6. The core obtained by the coring drill bit 7 can be directly stored in the inner tube of the coring casing 6;

[0056] In the connecting sleeve 4, the double sleeves select a composite fixed structure scheme of electromagnetic locking + mechanical backup. Among them, the extension sleeve 5 and the core sleeve 6 only need a mechanical backup structure scheme: the electromagnetic locking part is a number of groups of distributed excitation coils 14 arranged on the inner wall of the outer tube of the connecting sleeve 4, and a group of distributed excitation coils 14 is set every 15°, with a total of 24 groups 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 coil 14 is energized to generate an alternating magnetic field, and an induction magnetic field is generated in the soft magnetic alloy ring 17. Reverse eddy currents should be generated to generate Lorentz forces opposite to the direction of rotation, so that the inner tube of the connecting sleeve 4 remains stationary, similar to the principle of electromagnetic brakes; the mechanical backup part is to set an annular groove on the outer wall of the inner tube of the connecting sleeve 4, and install a thrust ball bearing-spring buckle 16 on the inner wall of the outer tube of the connecting sleeve 4. When the distributed excitation coil 14 is powered off, the thrust ball bearing-spring buckle 16 automatically engages; after power is turned on, the electromagnetic coil generates a magnetic field to attract the soft magnetic ring to achieve fixation; when the distributed excitation coil 14 is powered off, the thrust ball bearing-spring buckle automatically engages the inner tube groove to provide backup fixation; such as Figures 5 and 6 As shown, the connecting sleeve 4 can be connected to the inner tubes of the extension sleeve 5 and the core sampling sleeve 6 through the internal connecting thread 12, thereby completing the fixation of the inner tubes of the connecting sleeve 4, the inner tubes of the extension sleeve 5 and the inner tubes of the core sampling sleeve 6, meeting the requirement that the inner tube remains fixed while the outer tube rotates.

[0057] Furthermore, the drilling rig connection seat 3 , the connecting sleeve 4 , the extension sleeve 5 , the coring sleeve 6 and the coring drill bit 7 are detachably fixedly connected via the connecting threads 12 .

[0058] Furthermore, a thrust ball bearing-spring clip 16 is provided between the outer and inner tubes of the connecting sleeve 4, between the outer and inner tubes of the extension sleeve 5, and between the outer and inner tubes of the coring sleeve 6. The provision of thrust ball bearings-spring clips 16 between the inner and outer tubes of the extension sleeve 5 and the coring sleeve 6 reliably ensures free rotational separation between the inner and outer tubes of the extension sleeve 5 and the coring sleeve 6, satisfying 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 NdFeB magnets, the soft magnetic alloy ring 17 is a laminate of silicon steel sheets, and the electromagnetic shielding layer 15 used between the outer and inner tubes of the connecting sleeve 4 is made of Permalloy. Specifically, the permanent magnet array 9 is made of NdFeB permanent magnets, which have strong magnetic properties and can generate high magnetic strength despite their small size. The connecting piece 11 is made of 316L stainless steel, which is corrosion-resistant and does not alter the core magnetic field distribution or the direction of magnetic field lines. The effect is very slight 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 a laminate of silicon steel sheets with high magnetic permeability. The insulating coating between the laminations absorbs high-frequency vibration energy and adapts to the typical vibration spectrum of coal mine goafs. The electromagnetic shielding layer 15 used between the outer tube of the core sampling sleeve 6 and the outer and inner tubes of the extension sleeve 5 is made of Permalloy to block interference with the magnetic circuit caused by water molecules. After completing the non-contact force transmission step, it is also necessary to complete the corresponding dynamic adaptation method according to the changes in coring angle, core length and weight.

[0060] Furthermore, since the electromagnetic field is primarily regulated by changing the coil current, frequency, and phase, for example, when torque interference is detected in the inner tube, the current in the damping coil is increased, strengthening the magnetic field and generating a greater eddy current damping force to offset the torque. Simultaneously, the electromagnetic eddy current driving the outer tube may need to adjust its frequency based on the rotational speed and load to maintain stable rotational power to meet the needs of securing each inner tube during coring. The present invention includes the following steps:

[0061] a. Monitoring and obtaining multiple parameters: These multiple parameters include core length data collected by a laser rangefinder 18, core weight data collected by a piezoelectric ceramic array 19, and core inclination data collected by a MEMS gyroscope. The laser rangefinder 18 is located at the top of the inner tube of the connecting sleeve 4 and is used to monitor the core length with an accuracy of ±0.1 mm. The piezoelectric ceramic array 19 is located at the bottom of the inner tube of the connecting sleeve 4 and is used to sense the core weight with a sensitivity of 0.1 kg. The MEMS gyroscope 20 is located in the middle of the inner tube of the connecting sleeve 4 and is used to detect the core inclination with a range of ±30° and a resolution of 0.01°. The Hall effect sensor 21 is located on the inner wall of the outer tube of the connecting sleeve 4 and is used to detect 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 cycle of 50ms;

[0065] The optimization layer introduces the particle swarm optimization (PSO) algorithm to globally optimize the electromagnetic field parameter combination including the magnetic induction intensity B every 10 seconds; 2) Dynamic modeling of magnetic permeability:

[0066] Determine the magnetic 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] Using the finite element method (FEM) to simplify the model and solve Maxwell's equations:

[0071]

[0072] Where, is the vector differential operator, H is the magnetic field intensity vector, D is the electric displacement vector, t is, and J is the current density vector; is a vector differential operator called the Hamiltonian operator, H is called the magnetic field intensity vector: it describes the characteristics of the magnetic field and is related to the magnetic induction intensity B. The relationship between the two is B = μ * H (μ is the magnetic permeability), and the unit is ampere per meter (A / m). D is called the electric displacement vector: it is related to the electric field intensity E, D = ε * E (ε is the dielectric constant), and the unit is coulomb 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 its unit is ampere per square meter (A / m 2 ).

[0073] Iteratively correct boundary conditions by combining measured data including core length, core weight, and core inclination;

[0074] Setting initial boundary conditions: Initial boundary conditions are set based on previous experience or theoretical models. For example, for the initial core length, you can assume that the initial core length and initial position within the coring casing are fixed; for the initial core weight, you can make a preliminary estimate based on the core density and volume; for the initial core inclination, you can assume that its initial state is vertical or horizontal.

[0075] Boundary condition correction. Step 4, based on measured data including core length, core weight and core inclination, iteratively correct the boundary conditions, including: Step 41, setting initial reference values: core length Linitial, core weight Winitial and core inclination θinitial;

[0076] Obtain the core length Lcurrent in the inner tube of the coring casing collected by the laser rangefinder, the core weight Wcurrent in the inner tube of the coring casing collected by the piezoelectric ceramic array, and the core inclination θcurrent in the inner tube of the coring casing collected by the MEMS gyroscope;

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

[0078] Core length change 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 the core angle offset into the magnetic permeability model to calculate the magnetic permeability μ(t):

[0082]

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

[0084] Step 44: Determine whether the interpolation value of the predicted core length L-model and the core length Lcurrent in the inner tube of the coring casing acquired by the laser rangefinder is within a first preset error range, and whether the interpolation value of the predicted core inclination θ-model and the core inclination θcurrentt in the inner tube of the coring casing acquired by the MEMS gyroscope is within a second preset error range. If both are true, it is determined that the boundary condition is corrected and the iteration ends. Otherwise, proceed to the next step.

[0085] Step 45: If Lcurrent>Linitial, update the magnetic field intensity 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;

[0086] Step 46 , if |Δθ(t)|>preset threshold, adjusting the energization phase of the excitation coil group by using the 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 is increased to 1.5 times the rated damping force value;

[0088] Step 48: Determine whether the interpolation value of the predicted core length L-model and the core length Lcurrent in the core casing collected by the laser rangefinder is within a first preset error range, and whether the interpolation value of the predicted core inclination θ-model and the core inclination θcurrentt in the core casing collected by the MEMS gyroscope is within a second preset error range. If both are true, it is determined that the boundary condition is corrected and the iteration ends. Otherwise, Lcurrent is replaced by Lcurrent at the previous moment. ′ Initial and use the θcurrent of the previous moment to replace θ′initial, the change in core length L ′ (t) = L ′ current-L ′ initial, that is, L ′ (t) is the actual measured value L at this moment ′ current minus Lcurrent of the previous moment; calculate the core angle offset Δθ ′ (t) = θ ′ current-θ′initial, that is Δθ ′ (t) is the actual measured value θ at this moment ′ current minus the θcurrent of the previous moment, and re-execute steps 42 to 44.

[0089] Apply the adjusted boundary conditions to the above formula and rerun the simulation. Compare the new simulation results with the latest measured data collected by the sensors to evaluate the simulation performance after the boundary condition adjustments. If the difference between the simulation results and the measured data is still significant, repeat the 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 so, the boundary conditions have been appropriately corrected and the iterative process can be terminated. If not, 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 enhanced 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 core inclination changes, the power-on phase of the excitation coil group is adjusted through space vector modulation to compensate for the asymmetric torque; 3. When the core weight exceeds the preset maximum weight threshold, the preset maximum weight threshold is greater than 20kg, triggering the safety mode and increasing the damping force to 1.5 times the rated value.

[0093] Furthermore, a double-casing coring device for drilling and coring in a broken zone of a goaf includes the following steps:

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

[0095] S2, after power is turned on, prepare to drill and coring, 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 continuously advance, and the obtained core enters the inner tube of the coring casing 6. When the core reaches the flexible seal in the inner tube of the coring casing 6, the coring drill 2 is closed;

[0097] S4. Remove the permanent magnet array 9, the extension sleeve 5 and the coring sleeve 6, slowly remove the core in the inner tube of the coring sleeve 6, and promptly put the removed core into the core box to complete the coring, and transport it to the laboratory for relevant experiments.

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

[0099] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention as disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not invented herein, and the description and examples are to be considered merely as exemplary.

[0100] Finally, a few points should be explained: First, in the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," "connected," and "matched" should be understood in a broad sense, and may refer to mechanical or electrical connections, internal communication between two elements, or direct connection. "Up," "down," "left," and "right" are only used to indicate relative positional relationships. When the absolute positions of the objects being described change, the relative positional relationships may also change.

[0101] Secondly: In the drawings of the embodiments disclosed in the present invention, only the structures involved in the embodiments disclosed in the present invention are involved, and other structures can refer to the general design; the above specific implementation methods further explain the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above are only specific implementation methods of the present application and are not used to limit the scope of protection of the present application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of the present application should be included in the scope of protection of the present application.

Claims

1. A double-casing coring device for goaf and broken zone, characterized in that: The invention comprises a drilling rig connection seat (3), a connecting sleeve (4), an extension sleeve (5), a coring sleeve (6), a coring drill bit (7), a permanent magnet array (9) and a sensor module. The drilling rig connection seat (3) is mounted on the connecting sleeve (4). The connecting sleeve (4), the extension sleeve (5) and the coring sleeve (6) are an inner and outer double sleeve structure. 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 coring sleeve (6). The coring drill bit (7) is mounted on the coring sleeve (6). The permanent magnet array (9) is mounted on the rotating base of the coring drill (2). The sensor module is mounted on the coring sleeve (6).

2. The double-casing coring device for goaf and broken zone according to claim 1 is characterized in that: The invention comprises an annular copper conductor ring (13), the surface of the connecting sleeve (4) is spirally embedded with the annular copper conductor ring (13), and the annular copper conductor ring (13) is embedded with a micro-channel. In a rotating magnetic field, the annular copper conductor ring (13) cuts the magnetic flux lines and generates eddy currents.

3. The double-casing coring device for goaf and broken zone according to claim 1 is characterized in that: The connecting sleeve (4) comprises an excitation coil (14), an electromagnetic shielding layer (15) and a soft magnetic alloy ring (17). Several groups 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 arranged 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 a reverse eddy current in the soft magnetic alloy ring (17) and generates a Lorentz force opposite to the rotation direction of the outer tube of the connecting sleeve (4), so that the inner tube of the connecting sleeve (4) remains stationary.

4. The double-casing coring device for goaf and broken zone according to claim 2 is characterized in that: The invention comprises a thrust ball bearing-spring buckle (16), wherein the thrust ball bearing-spring buckle (16) is arranged between the outer tube of the connecting sleeve (4) and the inner tube of the connecting sleeve (4), the thrust ball bearing-spring buckle (16) is arranged between the outer tube of the extension sleeve (5) and the inner tube of the extension sleeve (5), and the thrust ball bearing-spring buckle (16) is arranged between the outer tube of the core sampling sleeve (6) and the inner tube of the core sampling sleeve (6). When the distributed excitation coil (14) is powered off, the thrust ball bearing-spring buckle (16) is engaged.

5. The double-casing coring device for goaf and broken zone according to claim 4 is characterized in that: The drilling rig connection seat (3) comprises a casing connection shaft (10), a connection piece (11) and a connection thread (12). The casing connection shaft (10) is installed on a non-rotating portion of the core drilling rig (2). The casing connection shaft (10) is installed on a connection casing (4) through the connection piece (11). A connection thread (12) is provided on an outer tube of the connection casing (4). The outer tube of the connection casing (4) is connected to an outer tube of an extension casing (5) or an outer tube of a core drilling casing (6) through the connection thread (12).

6. The double-casing coring device for goaf and broken zone according to claim 1 is characterized in that: The sensor module comprises a laser rangefinder (18), a piezoelectric ceramic array (19), a MEMS gyroscope (20) and a Hall sensor (21); the laser rangefinder (18) is arranged on the top of the inner tube of the connecting sleeve (4); the piezoelectric ceramic array (19) is arranged on the bottom of the inner tube of the connecting sleeve (4); the MEMS gyroscope (20) is arranged in the middle of the inner tube of the connecting sleeve (4); and the Hall sensor (21) is arranged on the inner wall of the outer tube of the connecting sleeve (4).

7. A dynamic adaptation method for a double-casing coring device in a goaf and broken zone, characterized in that: The double-casing coring device for drilling and coring a broken zone in a goaf according to any one of claims 1 to 6 is used to perform the following steps: The coring drill (2) is started, and the coring casing (6) is gradually advanced by using the coring drill bit (7), so that the obtained rock core enters the inner tube of the coring casing (6), and the electromagnetic field parameters are regulated in real time. When the rock core reaches the flexible sealing member in the inner tube of the coring casing (6), the coring drill (2) is closed; Remove the permanent magnet array (9), the extension sleeve (5) and the coring sleeve (6), and take out the rock core in the inner tube of the coring sleeve (6).

8. The dynamic adaptation method of a double-casing coring device for goaf and broken zone according to claim 7 is characterized in that: Real-time control of electromagnetic field parameters, including: Step 1, using a laser rangefinder (18) to collect the length of the core in the inner tube of the coring casing (6), using a piezoelectric ceramic array (19) to collect the weight of the core in the inner tube of the coring casing (6), using a MEMS gyroscope (20) to collect the inclination of the core in the inner tube of the coring casing (6), and using a Hall sensor (21) to collect the magnetic field intensity and angular displacement in the inner tube of the coring casing (6); Step 2, based on the particle swarm algorithm, global optimization of the electromagnetic field parameter combination including the magnetic induction intensity B is performed at preset intervals; Step 3, determine the magnetic 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: Use the finite element method to simplify the model and solve Maxwell's equations: Where, is the vector differential operator, H is the magnetic field intensity vector, D is the electric displacement vector, t is the time, and J is the current density vector; Step 4: Iteratively modify the boundary conditions based on the measured data including the core length, core weight and core inclination.

9. The dynamic adaptation method of a double-casing coring device for goaf and broken zone according to claim 8, characterized in that: Step 4, based on the measured data including core length, core weight and core inclination, iteratively correct the boundary conditions, including: Step 41, setting initial reference values: core length Linitial, core weight Winitial and core inclination θinitial; Obtaining the core length Lcurrent in the inner tube of the coring casing (6) collected by the laser rangefinder (18), the core weight Wcurrent in the inner tube of the coring casing (6) collected by the piezoelectric ceramic array (19), and the core inclination θcurrent in the inner tube of the coring casing (6) collected by the MEMS gyroscope (20); Step 42, calculate and obtain the core length change, core angle offset and core weight increment: Core length change L(t) = Lcurrent - Linitial, Core angle offset Δθ(t) = θcurrent - θinitial, Core weight increment ΔW(t) = Wcurrent – ​​Winitial; Step 43: Input the core length change and the core angle offset into the magnetic permeability model to calculate the magnetic permeability μ(t): Solving Maxwell's equations involving μ(t) using the finite element method Obtain the predicted core length L-model and predicted core inclination θ-model at the current moment; Step 44, judging whether the interpolation value of the predicted core length L-model and the core length Lcurrent in the inner tube of the coring casing (6) collected by the laser rangefinder (18) is within a first preset error range, and whether the interpolation value of the predicted core inclination θ-model and the core inclination θcurrentt in the inner tube of the coring casing (6) collected by the MEMS gyroscope (20) is within a second preset error range, if both are true, it is judged that the boundary condition is corrected and the iteration ends, otherwise the next step is executed; Step 45: If Lcurrent>Linitial, update the magnetic field intensity 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; Step 46 , if |Δθ(t)|>preset threshold, adjusting the energization phase of the excitation coil group by using the 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 is increased to 1.5 times the rated damping force value; Step 48, judging whether the interpolation value of the predicted core length L-model and the core length Lcurrent in the inner tube of the coring casing (6) collected by the laser rangefinder (18) is within a first preset error range, and whether the interpolation value of the predicted core inclination θ-model and the core inclination θcurrentt in the inner tube of the coring casing (6) collected by the MEMS gyroscope (20) is within a second preset error range, if both are true, then it is judged that the boundary condition is corrected and the iteration ends, otherwise Lcurrent is replaced by Lcurrent at the previous moment ′ Initial and use the θcurrent of the previous moment to replace θ′initial, the change in core length L ′ (t) = L ′ current-L ′ initial; calculate the core angle offset Δθ ′ (t) = θ ′ current-θ′initial, re-execute steps 42 to 44.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 7 to 9 are implemented.

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