Device and method for simulating coal mine dense drilling top-cutting pressure relief
By using conductive heating wires to heat paraffin to form holes in the model, the shortcomings of rigid embedded parts and mechanical drilling are solved, achieving high-quality simulation of dense drilling and improving the accuracy and reliability of the experiment.
Patent Information
- Application Number
- CN202511836108.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-02-27
AI Technical Summary
In existing methods for simulating dense drilling and roof cutting to relieve pressure in coal mines, the additional support effect of rigid embedded parts or the large disturbance of mechanical drilling limits the accuracy and reliability of experimental results.
A paraffin column containing conductive heating wires is pre-embedded inside the model. The paraffin is melted by electric heating and then guided out through a wax tube to form holes, thus simulating dense drilling with different hole diameters and depths.
It effectively maintains the continuity of rock strata stress, precisely controls the borehole diameter and depth, reduces costs, improves the authenticity and flexibility of experiments, and ensures the repeatability of experimental data.
Smart Images
Figure CN121577519A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of three-dimensional similar simulation experiment of coal mine, and particularly relates to a device and method for simulating coal mine intensive drilling top cutting pressure relief. BACKGROUND
[0002] Three-dimensional similar simulation experiment is an important technical means for studying the breaking and caving law of underground rock stratum and the variation characteristics of ground stress in the field of geotechnical engineering. Its implementation process usually involves selecting quartz sand, gypsum and other similar materials to construct a physical model based on actual engineering conditions, excavating the model after it is solidified, and monitoring relevant parameters. In the study of coal mining, intensive drilling top cutting pressure relief technology is a key measure to control the deformation of surrounding rock. How to scientifically and accurately reproduce this process in similar simulation experiments is a current research difficulty.
[0003] Currently, in three-dimensional similar simulation, the simulation of intensive drilling mainly relies on two methods: one is to pre-bury rigid materials such as steel pipes and wooden rods, and the other is to use mechanical devices to drill holes. However, the method of pre-burying rigid materials has significant drawbacks. If the material is cemented with the rock stratum, the rigid body will provide additional support, severely weakening the effect of top cutting pressure relief. If it cannot be effectively cemented, it will form artificial structural plane defects at the beginning of the experiment, leading to premature destruction of the rock stratum and failing to truly reflect the drilling pressure relief mechanism. Using a miniature drilling machine to drill mechanically not only requires expensive equipment and limited operating space, but also causes vibrations during drilling that cannot be ignored, which will disturb the model and destroy the original stress balance of the rock stratum.
[0004] In summary, the existing simulation methods cannot achieve high-quality drilling simulation without disturbing the model stress field, which limits the accuracy and reliability of the experimental results. Therefore, there is an urgent need to find a new method for simulating intensive drilling that can avoid the rigid support effect and eliminate mechanical disturbance, while being convenient to operate and low in cost, to meet the urgent needs of coal mine top cutting pressure relief mechanism research. SUMMARY
[0005] The present application aims to overcome the deficiencies of rigid pre-buried parts producing additional support effect and mechanical drilling disturbance in the prior art, and provides a device and method for simulating coal mine intensive drilling top cutting pressure relief. By pre-burying a paraffin column containing electrically conductive heating resistance wire inside the model, the paraffin is melted by electric heating and removed through the wax guide pipe to form a hole, thereby achieving accurate simulation of intensive drilling with different hole diameters and depths while maintaining the continuity of the rock stratum stress.
[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a device for simulating coal mine intensive drilling top cutting pressure relief, comprising:
[0007] A box made of transparent hard material, the inside of which defines an experimental space for containing similar simulation materials, the side wall of the box is provided with a wax pipe outlet, and the bottom is provided with a wire hole;
[0008] A rock stratum simulation structure arranged inside the box, including a floor rock stratum, a coal seam and an overburden rock stratum from bottom to top;
[0009] A dense drilling simulation device pre-embedded at a predetermined position inside the overburden rock stratum;
[0010] The dense drilling simulation device includes a drilling simulation material body, a conductive heating assembly, a temperature control assembly, a wax pipe, a wax storage tank and a negative pressure generating device;
[0011] The drilling simulation material body includes a columnar paraffin wax, which is used to form a simulated drilling hole after being heated and melted;
[0012] The conductive heating assembly includes a conductive heating resistance wire uniformly distributed inside the paraffin wax, and a wire electrically connected to the conductive heating resistance wire and extending outside the box;
[0013] The temperature control assembly includes a temperature sensor attached to the surface of the conductive heating resistance wire, and a temperature controller connected to the conductive heating resistance wire and the temperature sensor through the wire;
[0014] One end of the wax pipe is in communication with the bottom of the paraffin wax, and the other end passes through the overburden rock stratum, the coal seam and the floor rock stratum and extends to the wax pipe outlet of the side wall of the box, for guiding the melted paraffin wax out of the box; the wax pipe is arranged along the horizontal direction, and the path has less interference to the model;
[0015] A detachable guide bracket is arranged in the wax pipe for temporarily fixing the path and providing support force in the wax pipe;
[0016] The wax storage tank is connected with the wax pipe for storing the discharged paraffin wax;
[0017] The negative pressure generating device is used to generate negative pressure to extract the melted paraffin wax.
[0018] Further, the coal seam is assembled by a plurality of independent solid pads, the material of the solid pad is iron or wood; the solid pad is configured to be manually removed to simulate the coal seam excavation process;
[0019] The floor rock stratum and the overburden rock stratum are made of similar simulation materials, including quartz sand, water, cement and dimethyl silicone oil.
[0020] Furthermore, the conductive heating wire is arranged along the axial length direction of the paraffin wax; the wires are respectively connected to the top and bottom of the dense drilling simulation device;
[0021] The temperature controller is configured to adjust the heating power and heating time of the conductive heating wire to control the melting radius of the paraffin.
[0022] Furthermore, the conductive heating wire is divided into several independent control segments according to a preset length. Each segment of the conductive heating wire can be independently connected to the temperature controller through the wire, so as to simulate drilling at different depths by controlling the length of the wire connected to the circuit.
[0023] Furthermore, the number of the wax guide tube outlets and wire holes corresponds to the number of the dense drilling simulation devices.
[0024] Secondly, the present invention provides a method for simulating dense drilling and roof cutting pressure relief in a coal mine using the aforementioned device for simulating dense drilling and roof cutting pressure relief in a coal mine, comprising the following steps:
[0025] Step S1: Lay a similar simulated material at the bottom of the box and compact it to form the bottom rock layer;
[0026] Step S2: Based on the actual engineering geological conditions of the coal seam, a specific number of solid pads are laid on top of the bottom rock layer to form the coal seam;
[0027] Step S3: According to the preset dense borehole cutting and pressure relief design scheme, install several dense borehole simulation devices at a predetermined position above the coal seam, connect the wax guide tube to the bottom of the dense borehole simulation device, install a detachable guide bracket and lead the wax guide tube out to the side wall of the box along the shortest horizontal path, and arrange the wire.
[0028] Step S4: Lay a similar simulation material over the coal seam to wrap the dense borehole simulation device, forming the overlying rock layer, and wait for the model to solidify;
[0029] Step S5: Connect the wax storage tank to the negative pressure generating device, turn on the negative pressure generating device, and connect the power supply through the temperature controller to heat the conductive heating wire inside the dense drilling simulation device, so that the paraffin wax is heated and melted.
[0030] Step S6: Molten paraffin wax flows out of the box and into the wax storage box through the wax guide tube under negative pressure. The wax discharge situation in the wax storage box is observed and the negative pressure is adjusted in real time until the paraffin wax is completely discharged and forms holes in the overlying rock layer, thereby simulating the process of dense drilling and top cutting to relieve pressure.
[0031] Further, in step S5, the heating temperature and heating time of the conductive heating wire are adjusted by the temperature controller to control the melting range of the paraffin wax, thereby simulating dense drilling of different pore sizes; wherein, if simulating dense drilling of the first pore size, the temperature of the conductive heating wire is controlled to be... Heating time is If simulating dense drilling with a second aperture larger than the first aperture, the temperature of the conductive heating wire is controlled as follows: Heating time is ,in Greater than .
[0032] Further, in step S3, the length of the conductive heating wire connected to the circuit is selected according to the preset drilling depth requirement;
[0033] In step S5, only the conductive heating wire connected to the circuit is heated to melt the paraffin wax within the corresponding length range, thereby forming holes of a specific depth in the overlying rock layer to simulate dense drilling at different depths.
[0034] Furthermore, it also includes a calibration step: before proceeding to step S5, a calibration experiment is conducted to establish a curve showing the relationship between the heating parameters of the conductive heating wire and the melting diameter of the paraffin wax; the heating parameters include heating power, heating temperature, and heating time;
[0035] In step S5, the parameters of the temperature controller are set according to the corresponding relationship curve to accurately simulate the target aperture.
[0036] Furthermore, after completing the borehole simulation in step S6, the solid pad of the coal seam is manually removed to simulate coal seam excavation, and the collapse and migration patterns of the overlying strata under the pressure relief effect of dense borehole cutting are observed and recorded through the box.
[0037] Compared with the prior art, the present invention has the following beneficial effects:
[0038] (1) This invention solves the problem of additional support force generated by the bonding of traditional rigid embedded parts with rock strata, or artificial defects caused by non-bonding, by pre-setting a simulation device containing paraffin wax, conductive heating wire and wax tube inside the model and forming holes by using the phase change principle. It does not require physical excavation or external mechanical disturbance, avoids damage to the original stress field of the model, effectively maintains the continuity of the stress state of the rock strata, and significantly improves the realism of the top cutting and pressure relief simulation.
[0039] (2) The application can monitor and adjust the heating power and time length of the conductive heating resistance wire in real time through the temperature sensor and the temperature controller, accurately control the melting radius of the paraffin based on the preset calibration relationship, flexibly adjust the diameter of the formed hole in the same experimental model according to the needs, realize the quantitative control and accurate simulation of different hole diameter dense drilling parameters, and overcome the defect that the drilling hole diameter is difficult to dynamically adjust in the prior art.
[0040] (3) The application can accurately control the melting length of the paraffin column in the axial direction by setting the conductive heating resistance wire which can be controlled or accessed in segments or different lengths, so that the experiment can simulate the drilling arrangement scheme at different depths in the actual engineering, effectively solve the problems of difficult hole depth adjustment and difficult adaptation to complex top unloading engineering design in the traditional simulation method, and improve the flexibility and adaptability of the experimental scheme.
[0041] (4) The application uses a transparent box body to construct a simulation system with low-cost materials such as paraffin and resistance wire, compared with complex hydraulic or mechanical drilling equipment, the system structure is simple and the cost is low; at the same time, cooperating with the temperature control system realizes the digital recording and standardized operation of the experimental process parameters, not only greatly reduces the experimental difficulty and cost, but also ensures the repeatability and high credibility of the experimental data, which is convenient for large-scale comparative research in laboratory environment. BRIEF DESCRIPTION OF DRAWINGS
[0042] Figure 1 It is a structure schematic view of the simulation coal mine dense drilling top unloading device of the application;
[0043] Figure 2 It is a structure schematic view of the dense drilling simulation device of the application;
[0044] Figure 3 It is a schematic view of controlling the simulation drilling diameter of the application;
[0045] Figure 4 It is a schematic view of controlling the simulation drilling hole depth of the application;
[0046] Figure 5 It is a flowchart of the method part of the application;
[0047] The drawings show that: 1, box; 2, bottom plate rock stratum; 3, coal seam; 4, overburden; 5, dense drilling simulation device; 6, conductive heating resistance wire; 7, paraffin; 8, wire; 9, temperature sensor; 10, temperature controller; 11, wax guide pipe; 12, wax storage tank; 13, negative pressure generating device. DETAILED DESCRIPTION
[0048] The application will be further described below in conjunction with the drawings. The following examples are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.
[0049] In the description of the present application, it needs to be understood that the terms "center", "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.
[0050] In the description of the present application, it needs to be understood that the terms "connected", "connected" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.
[0051] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.
[0052] Embodiment 1
[0053] As shown in Figure 1 and Figure 2 A specific embodiment of the present application discloses a device for simulating the cutting of the top of a dense drill hole in a coal mine, which comprises a box body 1, a bottom rock layer 2, a coal seam 3, an overburden 4 and a dense drill hole simulation device 5. The dense drill hole simulation device 5 comprises a conductive heating resistance wire 6, paraffin 7, a wire 8, a temperature sensor 9, a temperature controller 10, a wax guide pipe 11, a wax storage tank 12 and a negative pressure generating device 13.
[0054] As shown in Figure 1As shown, the floor strata 2, coal seam 3 and overburden 4 are arranged in the box 1 from bottom to top, and the dense drilling simulation device 5 is embedded above the coal seam 3 and in the overburden 4. The conductive heating resistance wire 6 is uniformly distributed and wrapped in the paraffin 7, and the temperature sensor 9 is attached to the surface of the conductive heating resistance wire 6. The temperature controller 10 is electrically connected to the conductive heating resistance wire 6 and the temperature sensor 9 through the wire 8. The molten paraffin is led out from the bottom of the dense drilling simulation device 5 through the wax guide pipe 11, passes through the overburden 4, the coal seam 3 and the floor strata 2, and finally collects in the wax guide pipe outlet reserved in the side wall of the box 1.
[0055] As shown in Figure 1 The box 1 is made of transparent hard material, which defines an experimental space for accommodating the floor strata 2, coal seam 3, overburden 4 and dense drilling simulation device 5. The side wall of the box 1 is provided with a wax guide pipe outlet, and the bottom is provided with a wire hole. The material of the box is transparent and hard, which can clearly observe the caving and migration process of the internal strata during the experiment. The number of wax outlets and wire holes corresponds to the number of dense drilling simulation devices 5 to meet the needs of multi-hole synchronous simulation.
[0056] As shown in Figure 1 The floor strata 2 and overburden 4 are made of similar simulation materials. The similar simulation materials include quartz sand, water, cement, dimethyl silicone oil and other components. The physical and mechanical properties of each component are strictly corresponding to the physical and mechanical properties of the actual strata according to the similarity principle. The coal seam 3 is assembled by several independent solid pads. The material of the solid pad can be iron or wood. The solid pad is configured to be manually removed to simulate the coal seam excavation process.
[0057] As shown in Figure 2 The drilling simulation material of the dense drilling simulation device 5 is columnar paraffin 7. The paraffin 7 is a fusible material and has a cylindrical structure. The conductive heating resistance wire 6 is uniformly distributed in the paraffin 7 along the axial length direction of the paraffin 7, which is used to heat and melt the paraffin 7 to simulate the drilling excavation. By changing the heating temperature of the conductive heating resistance wire 6, the diameter of the hole formed by the melting of the paraffin 7 can be controlled, thereby simulating the excavation of dense drilling with different hole diameters. By changing the length of the conductive heating resistance wire 6 connected to the circuit, the length of the hole formed by the melting of the paraffin 7 can be controlled, thereby simulating the excavation of dense drilling with different hole depths.
[0058] As shown in Figure 2As shown, the wires 8 are connected to the top and bottom of the dense drilling simulation device 5, respectively, for connecting the power supply, the conductive heating resistance wire 6 inside the dense drilling simulation device 5, the temperature sensor 9, and the temperature controller 10. One end of the wax guide pipe 11 is in communication with the paraffin 7 at the bottom of the dense drilling simulation device 5, and the other end is arranged in the horizontal direction, selecting a path (i.e., the shortest path) that has the least impact on the movement of the rock stratum, extending to the wax guide pipe outlet at the side wall of the box 1. In order to avoid the dense ramming of the similar simulation material causing the wax guide pipe 11 to be closed, a detachable guide bracket is used inside the wax guide pipe 11 to temporarily fix the path and provide support. The outlet of the wax guide pipe 11 is connected to the wax storage tank 12, which is further connected to the negative pressure generating device 13 for generating negative pressure to extract the molten paraffin. The temperature sensor 9 is attached to the surface of the conductive heating resistance wire 6 and is electrically connected through the wire 8 for real-time monitoring of the temperature of the conductive heating resistance wire 6. The temperature controller 10 is configured to adjust the heating power and heating time of the conductive heating resistance wire 6 to accurately control the melting radius of the paraffin 7.
[0059] Embodiment 2
[0060] Another specific embodiment of the present application discloses a method for simulating the cutting and pressure relief of dense drilling in a coal mine, which uses the device described in Embodiment 1, and includes the following steps:
[0061] Step S1, based on the actual engineering geological conditions of the coal mine and the physical and mechanical properties of the floor rock stratum, using quartz sand, kaolin, water, cement, dimethyl silicone oil and other similar simulation materials, the similar simulation materials are laid and rammed at the bottom of the box 1 based on the similarity principle to form the floor rock stratum 2.
[0062] Step S2, based on the actual engineering geological conditions of the coal seam, a certain number of solid pads are laid on the floor rock stratum 2 to form the coal seam 3. The solid pads can be made of iron or wood materials.
[0063] Step S3, according to the pre-set dense drilling cutting and pressure relief design scheme under the actual engineering geological conditions of the coal mine, the arrangement mode and key parameters of the dense drilling simulation device 5 are determined. The key parameters include the drilling diameter and the drilling depth. A plurality of dense drilling simulation devices 5 are installed at predetermined positions above the coal seam 3, the wax guide pipe 11 is connected to the bottom of the dense drilling simulation device 5, and the detachable guide bracket is installed in the wax guide pipe 11, the wax guide pipe 11 is led out to the outlet at the side wall of the box 1 in the horizontal direction with the shortest path, and the wires 8 are arranged. The arrangement mode of the dense drilling simulation device 5 corresponds to the actual dense drilling engineering design.
[0064] Step S4, according to the actual engineering geological conditions of the coal mine and the physical and mechanical properties of the overburden strata, similar simulation materials such as quartz sand, kaolin, water, cement, and dimethyl silicone oil are used to lay similar simulation materials on the coal seam 3 to wrap the dense drilling simulation device 5 based on the similarity principle, and form the overburden strata 4. After the model is built, it is dried, and the drying time depends on the laboratory temperature and the similarity ratio of the similar materials.
[0065] Step S5, after the model is solidified, the wax storage box 12 is connected with the wax guide pipe 11, and the negative pressure generating device 13 is connected with the wax storage box 12. The wax discharge process is: opening the negative pressure generating device 13; opening the paraffin heating, that is, connecting the power supply through the temperature controller 10 and adjusting the temperature control switch, heating the conductive heating resistance wire 6 inside the dense drilling simulation device 5, melting the internal paraffin 7; observing the wax discharge in the wax storage box 12 to adjust the negative pressure in real time.
[0066] Step S6, the molten paraffin flows out of the box 1 under the action of gravity and negative pressure through the wax guide pipe 11, forming a hole inside the overburden strata 4, thereby simulating the dense drilling and cutting top pressure relief process.
[0067] Further, in step S5, the heating temperature and heating time of the conductive heating resistance wire 6 are adjusted through the temperature controller 10 to control the melting range of the paraffin 7, thereby simulating dense drilling with different diameters. In order to accurately achieve the target diameter, it is necessary to establish a corresponding relationship curve between the heating parameters and the melting diameter in advance through calibration experiments. As shown in FIG. 6, where D is the diameter of the paraffin 7, if the first diameter of the simulated dense drilling is D1, the temperature of the conductive heating resistance wire 6 is controlled by the temperature controller 10 to be T1, and the heating time is t1, so that part of the paraffin 7 is heated and melted and guided out through the wax guide pipe 11, forming a hole with a diameter of D1 in the overburden strata 4; as shown in FIG. 7, if the second diameter of the simulated dense drilling is D2 which is greater than the first diameter, the temperature of the conductive heating resistance wire 6 is controlled by the temperature controller 10 to be T2 which is greater than T1, and the heating time is t2 which is greater than t1, where D2>T1, because the temperature of the conductive heating resistance wire 6 is higher, the paraffin 7 inside is all in a molten state and guided out through the wax guide pipe 11, forming a hole with a diameter of D2 in the overburden strata 4. Figure 3 Figure 3
[0068] Figure 4 As shown, further, in step S3, if the borehole depths of the borehole cutting top pressure relief design scheme under the actual engineering geological conditions are different, the length of the conductive heating resistance wire 6 connected to the circuit is selected according to the preset borehole depth requirement through the lead 8. The conductive heating resistance wire 6 is divided into several independently controlled sections according to the preset length, and each section of the conductive heating resistance wire 6 can be independently connected to the temperature controller 10. In step S5, only the conductive heating resistance wire 6 in the circuit part is heated to melt the paraffin 7 in the corresponding length range, the heated length of the paraffin 7 is changed, and a hole with a specific depth is formed in the overburden 4 to simulate the dense borehole with different depths.
[0069] Further, before step S5, a calibration step is also included: a calibration experiment is performed in advance to establish a corresponding relationship curve between the heating parameters of the conductive heating resistance wire 6 and the melting diameter of the paraffin 7. The heating parameters include heating power, heating temperature and heating time. In step S5, the parameters of the temperature controller 10 are set according to the corresponding relationship curve to accurately simulate the target hole diameter.
[0070] Further, after the dense borehole simulation in step S6 is completed, the solid pad of the coal seam 3 is manually removed to simulate the coal seam excavation, and the caving and migration law of the overburden 4 under the action of the dense borehole cutting top pressure relief is observed and recorded.
[0071] Compared with the prior art, the simulation coal mine dense borehole cutting top pressure relief device and method provided by the above embodiment has the following beneficial effects:
[0072] First, through the cooperation of the conductive heating resistance wire 6, the temperature sensor 9 and the temperature controller 10, the heating parameters of the conductive heating resistance wire 6 can be accurately controlled, and the borehole shape with different diameters, depths and spatial distributions can be accurately reproduced, so that the borehole parameters are controllable and the experiment is accurately simulated.
[0073] Second, the dense borehole is simulated by melting the paraffin 7, and through the cooperation of the conductive heating resistance wire 6, the temperature sensor 9 and the temperature controller 10, the borehole simulation device is pre-embedded in the model without physical excavation or external mechanical disturbance, so that the borehole simulation does not need to be excavated, the continuity of the original stress state of the rock stratum is maintained, the continuity of the rock stratum stress state is effectively maintained, the support effect of the rigid pre-embedded part and the stress disturbance of the mechanical drilling are eliminated, and the authenticity of the top cutting and pressure relief simulation is significantly improved.
[0074] Third, by adjusting the heating scheme of the conductive heating resistance wire 6, the comparative study of various borehole arrangement schemes can be realized in the same model, the flexibility of the experimental scheme implementation is improved, and the experimental efficiency is greatly improved.
[0075] Fourthly, the device saves complicated hydraulic or mechanical transmission mechanism, compared with traditional hydraulic or mechanical drilling device, the scheme has simple structure, convenient operation and low cost, which greatly reduces experimental cost and operation difficulty.
[0076] Fifthly, through cooperation of temperature sensor 9 and temperature controller 10, all control conditions can be parameterized, experimental process parameter can be recorded systematically, and experimental repeatability can be ensured, so that the obtained result is more accurate and reliable, and the reliability of data is improved.
[0077] It should be noted that, in this article, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device.
[0078] The above description is only the preferred embodiment of the present application, and it should be pointed out that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should be considered as the protection scope of the present application.
Claims
1. A device for simulating dense drilling and roof cutting for pressure relief in coal mines, characterized in that, include: Box (1), the box (1) is made of transparent hard material, and its interior is defined as an experimental space for accommodating similar simulated materials. The side wall of the box (1) is provided with a wax guide tube outlet and the bottom is provided with a wire hole. The simulated rock strata structure is arranged inside the box (1), and from bottom to top includes the bottom rock strata (2), the coal seam (3) and the overlying rock strata (4). A dense drilling simulation device (5) is pre-embedded in a predetermined position inside the overlying rock layer (4); The dense drilling simulation device (5) includes a drilling simulation material body, a conductive heating component, and a temperature control component; The main body of the drilling simulation material includes columnar paraffin (7), which is used to form holes for simulating drilling after being heated and melted; The conductive heating component includes conductive heating wires (6) evenly distributed inside the paraffin (7), and wires (8) electrically connected to the conductive heating wires (6) and extending to the outside of the housing (1). The temperature control component includes a temperature sensor (9) attached to the surface of the conductive heating wire (6), and a temperature controller (10) connected to the conductive heating wire (6) and the temperature sensor (9) via the wire (8). The dense drilling simulation device (5) also includes a wax guide tube (11), one end of which is connected to the bottom of the paraffin wax (7), and the other end passes through the rock stratum simulation structure and extends to the wax guide tube outlet on the side wall of the box (1) to discharge the molten paraffin wax from the box (1); the wax guide tube (11) is arranged in a horizontal direction, and the path is selected to be the shortest path with the least impact on the movement of the rock stratum. A detachable guide bracket is provided inside to temporarily fix the path and provide support during the model laying stage, so as to avoid the wax guide tube (11) from being closed due to the compaction of similar simulation materials; The device also includes a wax storage tank (12) and a negative pressure generating device (13); the wax storage tank (12) is connected to the outlet end of the wax guide tube (11) and is used to store the discharged paraffin wax; the negative pressure generating device (13) is connected to the wax storage tank (12) and is used to generate negative pressure to extract the molten paraffin wax.
2. The device for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 1, characterized in that, The coal seam (3) is assembled from several independent solid pads, the solid pads being made of iron or wood; the solid pads are configured to be manually removed to simulate the coal seam excavation process. The bottom rock layer (2) and the overlying rock layer (4) are formed by laying and solidifying similar simulation materials, including quartz sand, water, cement and dimethyl silicone oil.
3. The device for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 1, characterized in that, The conductive heating wire (6) is arranged along the axial length direction of the paraffin (7); the wires (8) are respectively connected to the top and bottom of the dense drilling simulation device (5); The temperature controller (10) is configured to adjust the heating power and heating time of the conductive heating wire (6) to control the melting radius of the paraffin (7).
4. The device for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 1, characterized in that, The conductive heating wire (6) is divided into several independent control segments according to a preset length. Each segment of the conductive heating wire (6) can be independently connected to the temperature controller (10) through the wire (8) so as to simulate drilling at different depths by controlling the length of the wire connected to the circuit.
5. The device for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 1, characterized in that, The box (1) is made of transparent material, which makes it easy to observe the collapse and movement process inside the simulated rock strata structure; the diameter of the wax guide tube outlet hole opened on the side wall of the box (1) is slightly larger than the outer diameter of the wax guide tube (11); the number of wax guide tube outlets and wire holes corresponds to the number of dense drilling simulation devices (5).
6. A method for simulating intensive borehole cutting and pressure relief in a coal mine using the apparatus of claim 1, characterized in that, Includes the following steps: Step S1: Lay similar simulated material at the bottom of the box (1) and compact it to form the bottom rock layer (2). Step S2: Based on the actual engineering geological conditions of the coal seam, a specific number of solid pads are laid on top of the bottom rock layer (2) to form the coal seam (3). Step S3: According to the preset dense borehole cutting and pressure relief design scheme, install several dense borehole simulation devices (5) at a predetermined position above the coal seam (3), connect the wax guide tube (11) to the bottom of the dense borehole simulation device (5), install a detachable guide bracket in the wax guide tube (11), lead the wax guide tube (11) out to the side wall of the box (1) in the horizontal direction with the shortest path, and arrange the wire (8). Step S4: Lay a similar simulation material over the coal seam (3) to wrap the dense borehole simulation device (5) to form the overlying rock layer (4), and wait for the model to solidify; Step S5: Connect the wax storage tank (12) to the negative pressure generating device (13); Step S6: Perform wax removal operation: First, turn on the negative pressure generating device (13); then, turn on the power through the temperature controller (10) to heat the conductive heating wire (6) inside the dense drilling simulation device (5), so that the paraffin (7) is heated and melted; observe the wax removal situation in the wax storage box (12) and adjust the negative pressure in real time. The molten paraffin flows out of the box (1) through the wax guide tube (11) under the negative pressure suction, forming holes inside the overlying rock layer (4), thereby simulating the dense drilling top cutting and pressure relief process.
7. The method for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 6, characterized in that, In step S6, the heating temperature and heating time of the conductive heating wire (6) are adjusted by the temperature controller (10) to control the melting range of the paraffin (7), thereby simulating dense drilling of different hole diameters; In this case, if we simulate dense drilling with the first aperture, the temperature of the conductive heating wire is controlled to be... Heating time is If simulating dense drilling with a second aperture larger than the first aperture, the temperature of the conductive heating wire is controlled as follows: Heating time is ,in Greater than .
8. The method for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 6, characterized in that, In step S3, the length of the conductive heating wire (6) connected to the circuit is selected according to the preset drilling depth requirement; In step S6, only the conductive heating wire (6) connected to the circuit is heated to melt the paraffin (7) within the corresponding length range, thereby forming holes of a specific depth in the overlying rock layer (4) to simulate dense drilling of different hole depths.
9. The method for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 7, characterized in that, It also includes calibration steps: Before proceeding to step S6, a calibration experiment is conducted to establish a curve showing the relationship between the heating parameters of the conductive heating wire and the diameter of the paraffin melt; the heating parameters include heating power, heating temperature, and heating time. In step S6, the parameters of the temperature controller (10) are set according to the corresponding relationship curve to accurately simulate the target aperture.
10. The method for simulating dense drilling and roof cutting for pressure relief in a coal mine according to claim 6, characterized in that, After completing the borehole simulation in step S6, the solid pad of the coal seam (3) is manually removed to simulate coal seam excavation, and the collapse and migration patterns of the overlying strata (4) under the pressure relief effect of dense borehole cutting are observed and recorded through the box (1).