Method and system for pre-treatment and induced caving of ultra thick ore bodies based on high energy electric detonation

Abstract

The application provides a method and system for pretreatment and induced caving of super-thick ore body based on high-energy electric detonation, which comprises the following steps: S1, designing a drilling scheme and injecting a liquid medium; S2, lowering and positioning an electric detonation generator in the hole; S3, setting parameters such as discharge energy, frequency, interval and the like; S4, generating an impact wave and a stress wave through discharge, forming a three-dimensional crack network through multiple accumulations, and dynamically adjusting the parameters in real time through feedback of a monitoring system; and S5, inducing caving after the rock body is weakened to the standard. The application replaces the traditional hydraulic fracturing with high-energy electric detonation, generates a spherical impact wave through instantaneous discharge of high-voltage pulse electric energy, causes crack propagation and structural damage in the rock body, and forms a volumetric weakening area. Through multiple discharge actions, radial cracks can be induced to initiate and branch and expand in multiple directions in the rock body, forming a three-dimensional crack network instead of a single plane crack, and the overall weakening effect of the super-thick ore body is improved, thereby laying a solid foundation for subsequent induced caving.

Description

Technical Field

[0001] This invention belongs to the field of extra-thick ore body mining technology, specifically relating to a method and system for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric blasting. Background Technology

[0002] Caving mining, as the mainstream process for mining deep and extra-thick ore bodies, relies on human intervention to induce continuous caving of the rock mass, achieving natural ore fragmentation and efficient recovery. In this process, rock mass pretreatment is a crucial technical step to ensure smooth ore discharge, control block size, and maintain the stability of extraction levels. For over two decades, hydraulic fracturing has been the industry standard for rock mass pretreatment. This technology injects high-pressure fluid into the borehole to create tensile fractures in the rock mass, thereby reducing its stiffness and inducing caving. In shallow ore bodies or those with simple stress states, hydraulic fracturing can effectively generate horizontal fractures perpendicular to the direction of the minimum principal stress, significantly improving the cavingability of the rock mass.

[0003] However, as mining depths extend to the kilometer level, the geostress environment of modern deep mines has undergone fundamental changes, rendering traditional hydraulic fracturing and caving mining methods (such as...) ineffective. Figure 1 As shown in the figure, numerous intractable technical defects have gradually been exposed, making it unable to meet the mining needs of deep and extra-thick ore bodies. Specifically, the following problems exist:

[0004] 1) Uncontrollable fracture propagation direction and poor adaptability: The fracture morphology formed by existing hydraulic fracturing is strictly controlled by the in-situ stress field. In deep mining environments (>1000m), the minimum principal stress direction is often horizontal or nearly horizontal, resulting in hydraulic fracturing fractures that are mostly steeply dipping or vertically oriented. This single-planar fracture network is difficult to effectively weaken the rock mass in three-dimensional space, cannot form the transverse weak surfaces required to promote gravity collapse, and may even exacerbate the impact load at the ore outlet by forming large vertical rock blocks, thus failing to achieve effective rock mass collapse induction.

[0005] 2) Failure of operations near goaf areas, creating a technological blind spot: Existing hydraulic fracturing technology relies on the pressure-sealing effect of high-pressure fluids to initiate and propagate fractures. Near existing goaf areas or collapse boundaries (typically within 20-30 meters), due to severe rock mass expansion and extremely high permeability, the injected fluid rapidly leaks into the goaf, preventing the establishment of sufficient initiation pressure—a phenomenon known as the "near-hole short-circuit" effect. This renders hydraulic fracturing technology completely ineffective in the collapse-induced zones and stope boundary control areas where weakening is most crucial, failing to create effective weakening zones and severely impacting the continuity and safety of mining operations.

[0006] 3) Single damage mode and insufficient controllability: Existing hydraulic fracturing technology mainly forms tension fractures or shear failure zones in a single plane, making it difficult to achieve gradual and quantifiable control from microcrack initiation to block-scale fragmentation. This results in insufficient reduction of rock mass stiffness, making it prone to sudden large-scale rock bursts or the formation of ultra-large blocks of ore, increasing the difficulty and risk of subsequent ore extraction.

[0007] Faced with challenges such as the rotation of the geostress field, the expansion of the stress shadow zone, and the restriction of operations near the goaf in the mining of deep and extra-thick ore bodies, traditional pretreatment methods based on fluid pressure have gradually reached technical bottlenecks. There is an urgent need for a new type of rock mass weakening technology that does not depend on the direction of geostress and can effectively propagate and generate volumetric damage in highly permeable fractured rock masses in order to restore the engineering controllability of the deep collapse process. Summary of the Invention

[0008] To address the technical problems existing in the prior art, the first objective of this invention is to provide a method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric blast shocks. This method replaces traditional high-pressure fluids with shock waves and stress waves generated by the instantaneous release of high-pressure pulsed electrical energy, achieving volumetric damage and three-dimensional controllable weakening of the rock mass. The second objective of this invention is to provide a system for the aforementioned method for pretreatment and induced caving of extra-thick ore bodies.

[0009] In this embodiment of the invention, the method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation includes the following steps:

[0010] S1. Design a drilling scheme based on the thickness of the extra-thick ore body, arrange boreholes in the ore body area to be treated, inject a pre-set type of liquid medium into the boreholes, and ensure that the liquid level exceeds the uppermost discharge position by a certain distance.

[0011] S2. The in-hole electric detonation generator is lowered to the target weakened layer in the borehole through the downhole high-pressure transmission subsystem to locate the in-hole electric detonation generator.

[0012] S3. Set the discharge parameters through the control unit of the ground high-energy pulse power supply subsystem. The discharge parameters include discharge energy, number of discharges and discharge interval.

[0013] S4. The rock mass is pretreated by electric blasting through discharge operation. The electric blasting generator in the borehole releases high-voltage pulse electrical energy to generate shock waves and stress waves. Through the cumulative effect of multiple pulse discharges, a three-dimensional fracture network is formed inside the ore body, thereby weakening the rock mass.

[0014] During the discharge process, the fracture development status is fed back in real time through the monitoring and feedback control subsystem, and a closed-loop control model is built based on the collected rock mass response data. The discharge parameters are dynamically adjusted by the deviation between the target weakening degree and the current rock mass response.

[0015] S5. After the rock mass weakens to the preset level, the ore body collapses along the weakened area.

[0016] In this embodiment of the invention, the high-energy electric blasting system for pretreatment and induced collapse of extra-thick ore bodies includes a ground high-energy pulse power supply subsystem, an underground high-voltage transmission subsystem, an in-hole electric blasting generator, and a monitoring and feedback control subsystem.

[0017] The ground-based high-energy pulse power supply subsystem is used to provide high-voltage pulse power with preset parameters, including a charging unit for converting external power into high-voltage power, an energy storage unit for storing power, and a control unit for controlling discharge parameters and discharge timing.

[0018] One end of the downhole high-pressure transmission subsystem is electrically connected to the surface high-energy pulse power supply subsystem, and the other end is electrically connected to the in-hole electric detonation generator. It is used to realize the downhole transmission of high-pressure pulse power and to lower the in-hole electric detonation generator.

[0019] The in-hole electric blast generator is installed inside the borehole of an extra-thick ore body. It includes an electrode assembly and a discharge structure. The electrode assembly forms a discharge gap, and the discharge structure is used to generate instantaneous discharge under the action of high-voltage pulsed electric energy, so as to generate shock waves and stress waves in the surrounding medium to achieve volumetric damage to the rock mass.

[0020] The monitoring and feedback control subsystem is electrically connected to the control unit of the ground high-energy pulse power supply subsystem. It is used to collect discharge process parameters and rock mass response data, and dynamically adjust the discharge parameters according to the collected data to form a closed-loop control.

[0021] Compared with the prior art, the advantages of the preferred technical solution of the present invention include:

[0022] 1. This invention employs high-energy electro-detonation to replace traditional hydraulic fracturing. High-voltage pulsed electrical energy is released between electrodes within the borehole, causing breakdown of the dielectric medium and instantaneous discharge. This generates shock waves and stress waves, which propagate into the surrounding rock mass as spherical waves, inducing fracture propagation and structural damage within the rock mass, forming volumetric weakened zones. Through repeated discharges, the damage to the rock mass is gradually accumulated, inducing radial fracture initiation and multi-directional branching propagation within the rock mass, forming a three-dimensional fracture network rather than a single planar fracture. This improves the overall weakening effect of extra-thick ore bodies, laying a solid foundation for subsequent induced collapse.

[0023] 2. This invention does not rely on the direction of the in-situ stress field or pressure sealing conditions. Regardless of whether the minimum principal stress is distributed horizontally or vertically, the multi-directional shock waves generated by the electric blast can form a transverse weak surface that is conducive to gravity collapse, thus avoiding the formation of vertical rock blocks that exacerbate the impact load at the ore outlet. At the same time, it does not rely on pressure sealing inside the borehole. In areas near the goaf and in high-permeability fractured rock mass regions, the shock waves can still effectively propagate and induce rock mass damage, eliminating the "near-hole short-circuit" failure problem of existing technologies and expanding the scope of application of the technology.

[0024] 3. This invention achieves controllable rock mass damage by adjusting discharge energy, discharge frequency, and discharge interval. It can realize customized pretreatment according to different ore body thicknesses, lithologies, and stress states. It adopts an energy gradient strategy of "high in the middle and low at both ends", which not only ensures the effective weakening of the high stress area in the core of the ore body, but also avoids excessive damage to the top and bottom plates. At the same time, the damage is gradually accumulated through multiple pulse discharges, avoiding local over-damage caused by a single high-energy action, improving the uniformity of rock mass weakening, effectively controlling the block size distribution of collapsed ore, and reducing the operational risks brought by rock bursts and ultra-large block ore.

[0025] 4. This invention constructs an integrated process of "pretreatment-induced collapse-full monitoring", realizing remote control of the entire process of electric blast pretreatment and induced collapse. Operators do not need to enter the dangerous area downhole, which greatly improves construction safety and reduces personnel operation risks. At the same time, by collecting rock mass response and discharge parameter data in real time, the discharge parameters and collapse strategy are dynamically optimized to ensure that the rock mass weakening effect reaches the preset index, which improves the controllability of the project and the efficiency of operation, and reduces the error caused by human intervention.

[0026] 5. This invention achieves integrated operation of pretreatment and caving mining of extra-thick ore bodies, avoiding problems such as low efficiency and data deviation caused by transferring samples (rock mass) between different equipment, and shortening the mining cycle; it designs drilling schemes for ore bodies of different thicknesses to ensure that the weakening range covers the entire thickness of the ore body, and combined with clear weakening evaluation indicators, it can accurately judge the degree of rock mass weakening, avoid over-weakening or under-weakening, ensure the smooth progress of subsequent induced caving, and improve the ore recovery rate. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the hydraulic fracturing and caving mining method in the background art.

[0028] Figure 2 This is a schematic diagram of an embodiment of a method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric blast. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] Example 1

[0031] This embodiment provides a method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation, such as... Figure 2 As shown, in a preferred embodiment, the method includes the following steps:

[0032] S1. Design a drilling scheme based on the thickness of the extra-thick ore body, arrange boreholes in the ore body area to be treated, inject a preset type of liquid medium into the boreholes, and ensure that the liquid level is higher than the uppermost discharge position by a certain distance, for example, the liquid level should be more than 3m higher than the uppermost discharge position.

[0033] The borehole layout is determined based on the ore body thickness H: when 20m≤H<30m, a single or multiple layer of vertical boreholes is used, with 1 to 2 layers and a layer spacing of 8m to 15m; when 30m≤H<50m, a multi-layer or fan-shaped borehole layout is used, with 2 to 3 layers and a layer spacing of 10m to 18m; when H≥50m, a combined vertical-inclined borehole network is used, with 3 to 5 layers and a layer spacing of 12m to 20m.

[0034] The borehole diameter is 90mm–200mm (preferably 110mm–150mm), and the borehole depth extends 1.0m–3.0m to the top and bottom plates of the ore body, ensuring full coverage while also considering the weakened connection of the surrounding rock at the top and bottom plates. Boreholes are arranged along the strike and dip of the ore body, with the hole spacing determined according to lithological conditions: for hard rock bodies (UCS>100MPa), the hole spacing is 2.0m–3.5m, and the row spacing is 2.5m–4.0m; for medium-hard rock bodies (UCS 50–100MPa), the hole spacing is 2.5m–4.0m, and the row spacing is 3.0m–5.0m; for soft rock bodies (UCS<50MPa), the hole spacing is 3.0m–5.0m, and the row spacing is 4.0m–6.0m.

[0035] Selection principles for liquid media: For normal conditions, use clean water or salt water containing 1% to 3% NaCl (conductivity 0.1S / m to 0.5S / m); for high-stress environments, add 5% to 10% inhibitor to suppress shock wave attenuation.

[0036] S2. The in-hole electric detonation generator is lowered to the target weakened stratum within the borehole via the downhole high-pressure transmission subsystem, and its location is then determined. The downhole high-pressure transmission subsystem is equipped with a depth measuring device. During the lowering process, the depth measuring device monitors the generator's position in real time. Upon reaching the target stratum, the generator is positioned using a borehole fixing device or an in-hole support structure to ensure it is located in the middle of the ore body or at a pre-set weakened key stratum, with positioning accuracy controlled within ±0.3m.

[0037] The in-hole electric detonation generator has an electrode assembly consisting of opposing electrodes forming a discharge gap. The discharge gap is the distance between the two electrodes, and its value is related to the applied voltage and the dielectric breakdown characteristics, satisfying the following relationship:

[0038]

[0039] in, The electric field strength between the electrodes; To apply voltage; The discharge gap can be adjusted according to the voltage level and dielectric characteristics, with a preferred range of 1mm to 20mm to adapt to different ore body conditions.

[0040] The electrode positions are arranged according to the target weakened area, and different areas are treated by moving them in segments along the borehole axis or by arranging them at multiple points.

[0041] S3. Through the control unit of the ground high-energy pulse power supply subsystem, discharge parameters are set, including discharge energy, number of discharges, and discharge interval. The discharge energy increases with the thickness of the extra-thick ore body and the volume of the target weakened stratum to meet the requirements for fracture propagation and penetration. The number of discharges is determined based on the layered fracturing requirements along the thickness of the ore body; the greater the thickness, the more discharges are needed to achieve segmented progressive fracturing. The discharge interval is determined based on fracture propagation and stress release time, and is appropriately extended with increasing ore body thickness to ensure stable fracture propagation.

[0042] Specifically, energy of a single discharge Obtain it using the following method:

[0043]

[0044] in, This represents the structural characteristic coefficient of an extra-thick ore body. For the uniaxial compressive strength of extra-thick ore bodies, This refers to the pretreatment volume for extra-thick ore bodies. Specifically, the pretreatment volume... Uniaxial compressive strength can be obtained through geological borehole data, tunnel exposure, and 3D geological modeling calculations. The structural characteristic coefficient can be obtained by conducting indoor compression tests according to relevant rock mechanics test standards and taking the average of multiple sets, while the structural characteristic coefficient... The classification can be determined by the RQD index, joint density, and rock mass structure type, and the value is usually taken in the range of 0.2 to 1.0 from high to low according to the rock mass integrity.

[0045] At the same time, by adjusting the capacitance of the energy storage unit and charging voltage To ensure that the discharge energy meets the requirements The energy of a single discharge can be adjusted according to the compressive strength and structural characteristics of the rock mass, and its value ranges from 10kJ to 1000kJ.

[0046] In this invention, the number of discharges is determined based on the cumulative degree of rock mass damage. Multiple pulse loading methods are used to gradually weaken the rock mass, and the adjustment principle is as follows:

[0047] ,

[0048] in, The number of discharges is 1 to 20 per hole. For the current rock mass response, , It is the first The wave velocity or elastic wave propagation speed after the second discharge It is the initial intact rock mass wave velocity. The specific rock mass response can be obtained through acoustic testing, microseismic monitoring, or stress wave propagation velocity measurement. To the degree of weakening of the target, , It is the target wave velocity required to induce collapse.

[0049] In this invention, the discharge interval is determined based on the dielectric recovery time and stress wave attenuation characteristics, satisfying the following:

[0050] ,

[0051] in, The time interval between two consecutive discharges is 0.1 s to 10 s; For medium recovery or stress decay time, , The thickness of the ore body. The velocity of stress waves in the rock mass. The correction factor related to attenuation and multiple reflections is generally >1. This refers to the medium's recovery or stress decay time. It is related to the thickness of the ore body and the propagation characteristics of stress waves. It increases with the increase of the ore body thickness, reflecting the multiple propagation and attenuation processes of stress waves in the ore body.

[0052] The present invention preferably adopts an energy gradient strategy of "high in the middle and low at both ends" based on the thickness of the ore body and the stress state of the strata: the stratification location is located in the lower part (near the goaf or free face), which is a stress concentration area, and moderate energy can trigger fractures, with a single discharge capacity of 15kJ to 30kJ; the stratification location is located in the middle part (the core area of ​​the ore body), which is high-stress locked and requires high energy to break through, with a single discharge capacity of 30kJ to 80kJ; the stratification location is located in the upper part (near the roof), which needs to protect the roof, and medium energy forms a weakening zone, with a single discharge capacity of 20kJ to 50kJ.

[0053] The cumulative number of discharges per hole is dynamically adjusted based on the fracture development monitoring results. The time interval between two adjacent discharges is adjusted according to actual conditions to ensure sufficient adjustment of rock mass stress and avoid heat accumulation effects. A "high-low-high" or gradual energy loading strategy is adopted, using higher energy in the initial stage to form initial fractures, reducing energy in the middle stage to promote fracture propagation, and increasing energy again in the later stage to achieve fracture connection.

[0054] S4. The rock mass is pretreated by electric blasting through discharge operation. The electric blasting generator in the borehole releases high-voltage pulse electrical energy to generate shock waves and stress waves. Through the cumulative effect of multiple pulse discharges, a three-dimensional fracture network is formed inside the ore body, thereby weakening the rock mass.

[0055] During the discharge process, the liquid medium between the electrodes vaporizes instantaneously to form a plasma channel, generating a peak pressure shock wave of 100MPa to 500MPa, which propagates to the surrounding rock mass in the form of a spherical wave. The shock wave generates a dynamic stress field inside the rock mass. When the tensile stress exceeds the dynamic tensile strength of the rock, radial fractures are induced. In the subsequent bubble pulsation stage of the shock wave, a periodic loading effect is generated, promoting fracture propagation and branching. Through the cumulative effect of multiple pulsed discharges, a fracture network with a density of 0.5 fractures / m to 3 fractures / m is formed inside the rock mass. Under the preset strength and stress conditions of the target weakened layer, the high-pressure pulsed shock wave, through multiple cycles, induces the initiation and propagation of microfractures in the rock mass, and under the control of stress in different directions, forms a spatial fracture structure that penetrates and connects. Its formation process originates from the superposition effect of fracture propagation under impact loading and cumulative damage from multiple pulses, forming a three-dimensional fracture network. Therefore, it is an inevitable evolutionary result under specific engineering conditions, rather than an instantaneous result of a single action.

[0056] After multiple rounds of discharge operations, a three-dimensional fracture network is formed inside the ore body, including: main fractures, which are distributed radially along the discharge holes and can reach a length of 1.0m to 3.0m; secondary fractures, which connect and penetrate between the main fractures to form weakened zones; and micro fractures, which increase the porosity of the rock mass and reduce the overall strength.

[0057] The rock mass weakening effect is comprehensively evaluated by the following indicators: fracture density reaches 1.0 m / m³ to 5.0 m / m³, rock mass acoustic velocity decreases by 15% to 40%, uniaxial compressive strength decreases by 20% to 50%, and elastic modulus decreases by 25% to 55%. At this time, a continuous weakening zone is formed in the ore body along the borehole layout direction, creating favorable conditions for subsequent induced collapse.

[0058] During the discharge process, the monitoring and feedback control subsystem in the mine (roadway / chamber) provides real-time feedback on the fracture development status, and a closed-loop control model is built based on the collected rock mass response data. The discharge parameters are dynamically adjusted by the deviation between the target weakening degree and the current rock mass response.

[0059] Specifically, the monitoring and feedback control subsystem provides real-time feedback on fracture development status as follows: Acoustic and microseismic sensors deployed in the mine / roadway / tunnel collect the stress wave propagation characteristics and microseismic signals generated by the rock mass during discharge. Based on acoustic wave propagation velocity attenuation, signal amplitude changes, and the spatial distribution characteristics of microseismic events, the fracture propagation process is inverted and identified to obtain the fracture development status of the target area. The monitoring data is transmitted in real-time to the ground control unit and compared with a criterion model established based on historical engineering test data and on-site calibration results. When the acoustic wave propagation velocity attenuation rate reaches a set range, the microseismic event density increases significantly, and energy release enters a stable fluctuation range, the fracture propagation is determined to have reached a preset threshold. Based on this, the subsequent discharge energy, frequency, and interval parameters are dynamically adjusted or terminated.

[0060] The method for dynamically adjusting discharge parameters is as follows:

[0061]

[0062] in, This represents the current discharge energy. The adjusted discharge energy; This is the adjustment coefficient; The degree of weakening of the target; This represents the current rock mass response.

[0063] S5. After the rock mass weakens to the preset level, the ore body collapses along the weakened area.

[0064] After pretreatment of the extra-thick ore body, one of the following methods can be used to induce ore body caving:

[0065] Method 1: Mining disturbance induction. Mining operations are carried out in the lower or lateral part of the ore body to form a free face. The stress redistribution and blasting vibration generated by mining are used to trigger the weakened ore body to collapse along the preset fracture surface. The size of the collapsed blocks is controlled between 300mm and 800mm to meet the requirements for subsequent ore extraction.

[0066] Method 2: Decompression blasting induction. Auxiliary blasting holes are arranged at the edge of the weakened area. The charge is designed to be 30% to 60% of that of normal blasting. After detonation, the stress wave superposition effect is generated, which causes the weakened ore body to become unstable and collapse instantly.

[0067] Method 3: Natural caving induction. For high-stress or fractured ore bodies, after removing the bottom support, the weakened ore body will naturally collapse under its own weight and ground stress.

[0068] During the collapse, the collapse status is assessed in real time through methods such as surface subsidence monitoring and underground ground pressure monitoring to ensure operational safety. The collapsed ore body is extracted through the bottom structure to complete resource recovery.

[0069] In step S2 of the present invention, the target weakening layer is determined in the following manner:

[0070] First, the lithological structure characteristics, wave velocity response characteristics, and rock mass fracture development characteristics in the borehole axial direction are obtained through borehole core logging, well logging curves, and geophysical exploration. At the same time, the compressive strength, elastic modulus, and integrity index of rock masses at different depths are obtained through indoor rock mechanics tests or in-situ tests, and the in-situ stress distribution around the borehole is obtained through in-situ stress tests or numerical simulation methods.

[0071] Secondly, the above-mentioned multi-source parameters are subjected to unified scaling. The unified scaling method adopts the range standardization method or the Z-score standardization method to convert the parameters with different dimensions into dimensionless indices, and respectively construct the intensity deterioration index, wave velocity attenuation index and stress concentration index.

[0072] Then, based on the Analytic Hierarchy Process (AHP) or regression analysis based on historical engineering data, the weight coefficients of each index are determined, and a comprehensive evaluation model for rock mass weakening is constructed. Its expression form is a weighted linear combination model, thereby obtaining a rock mass weakening index curve that is continuously distributed along the borehole axis.

[0073] Finally, based on the rock mass weakening index curve, the target weakened layer is determined by either the extreme value discrimination method or the threshold screening method. The extreme value discrimination method is used to select the depth interval corresponding to the local minimum weakening index, while the threshold screening method is used to select continuous segments that meet the preset weakening threshold conditions. The preset threshold is determined by statistical distribution of historical engineering data or obtained by calibration through field tests.

[0074] Example 2

[0075] This embodiment provides a high-energy electro-blasting system for pretreatment and induced caving of extra-thick ore bodies, used in the high-energy electro-blasting-based method for pretreatment and induced caving of extra-thick ore bodies in Embodiment 1. Figure 2As shown, the high-energy electric explosion system includes a ground high-energy pulse power supply subsystem, an underground high-voltage transmission subsystem, an in-hole electric explosion generator, and a monitoring and feedback control subsystem.

[0076] The ground-based high-energy pulsed power supply subsystem provides high-voltage pulsed electrical energy with preset parameters. It includes a charging unit for converting external electrical energy into high-voltage electrical energy, an energy storage unit for storing electrical energy, and a control unit for controlling discharge parameters and timing. The preset parameters for the high-voltage pulsed electrical energy are not fixed values ​​but are predetermined based on the mechanical properties and structural characteristics of the extra-thick ore body, including ore body thickness, uniaxial compressive strength, and fracture development. Based on these parameters, parameters such as discharge energy, number of discharges, and discharge intervals are matched and set to meet the needs of pretreatment and induced caving of the extra-thick ore body.

[0077] The underground high-voltage transmission subsystem includes a high-voltage transmission cable, an armored sheath, and a depth metering device, with a withstand voltage rating of no less than 30kV. One end of the high-voltage transmission cable is electrically connected to the surface high-energy pulse power supply subsystem, and the other end is electrically connected to the in-hole electric detonation generator, used for underground transmission of high-voltage pulsed electrical energy, and also for the lowering, suspension, and positioning of the in-hole electric detonation generator. This underground high-voltage transmission subsystem is equipped with a depth metering device. During the lowering of the in-hole electric detonation generator, the depth metering device monitors the generator's position in real time. After reaching the target stratum, it is positioned using a borehole fixing device or an in-hole support structure to ensure that the electric detonation generator is located in the middle of the ore body or a pre-set weakened key stratum.

[0078] The in-hole electric blast generator is installed inside the borehole of an extra-thick ore body. It includes an electrode assembly and a discharge structure. The electrode assembly includes electrodes arranged opposite each other, forming a discharge gap between the electrodes. The discharge structure is used to generate instantaneous discharge under the action of high-voltage pulsed electrical energy, so that the surrounding medium forms shock waves and stress waves to achieve volumetric damage to the rock mass.

[0079] The monitoring and feedback control subsystem is electrically connected to the control unit of the ground high-energy pulse power supply subsystem. It is used to collect discharge process parameters and rock mass response data, and dynamically adjusts the discharge parameters based on the collected data to form a closed-loop control. Through acoustic and microseismic sensor receivers deployed in the mine / roadway / tunnel, the stress wave propagation characteristics and microseismic signals generated by the rock mass during the discharge process are collected in real time. Based on acoustic wave propagation velocity attenuation, signal amplitude changes, and the spatial distribution characteristics of microseismic events, the fracture propagation process is inverted and identified to obtain the fracture development status of the target area. The monitoring data is transmitted to the ground control unit in real time and compared with a criterion model established based on historical engineering test data and on-site calibration results. When the acoustic wave propagation velocity attenuation rate reaches a set range, the microseismic event density increases significantly, and the energy release enters a stable fluctuation range, it is determined that the fracture propagation has reached a preset threshold. Based on this, the subsequent discharge energy, frequency, and interval parameters are dynamically adjusted or terminated.

[0080] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation, characterized in that, Includes the following steps: S1. Design a drilling scheme based on the thickness of the extra-thick ore body, arrange boreholes in the ore body area to be treated, inject a pre-set type of liquid medium into the boreholes, and ensure that the liquid level exceeds the uppermost discharge position by a certain distance. S2. The in-hole electric detonation generator is lowered to the target weakened layer in the borehole through the downhole high-pressure transmission subsystem to locate the in-hole electric detonation generator. S3. Set the discharge parameters through the control unit of the ground high-energy pulse power supply subsystem. The discharge parameters include discharge energy, number of discharges and discharge interval. S4. The rock mass is pretreated by electric blasting through discharge operation. The electric blasting generator in the borehole releases high-voltage pulse electrical energy to generate shock waves and stress waves. Through the cumulative effect of multiple pulse discharges, a three-dimensional fracture network is formed inside the ore body, thereby weakening the rock mass. During the discharge process, the fracture development status is fed back in real time through the monitoring and feedback control subsystem, and a closed-loop control model is built based on the collected rock mass response data. The discharge parameters are dynamically adjusted by the deviation between the target weakening degree and the current rock mass response. S5. After the rock mass weakens to the preset level, the ore body collapses along the weakened area.

2. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to claim 1, characterized in that, In step S1, the borehole layout is determined based on the ore body thickness H: When 20m≤H<30m, vertical holes are arranged in a single or multiple layer, with 1 to 2 layers and a layer spacing of 8m to 15m. When 30m≤H<50m, vertical holes are arranged in multiple layers or fan-shaped hole groups, with 2 to 3 layers and a layer spacing of 10m to 18m. When H≥50m, a vertical-inclined combined perforated mesh arrangement is adopted, with 3 to 5 layers and a layer spacing of 12m to 20m.

3. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to claim 1, characterized in that, In step S2, the underground high-pressure transmission subsystem is equipped with a depth measuring device. During the process of lowering the electric blast generator into the hole, the depth measuring device monitors the position of the electric blast generator in real time. After reaching the target layer, the hole opening fixing device or the hole support structure is used for positioning to ensure that the electric blast generator is located in the middle of the ore body or the preset weakened key layer.

4. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to claim 1, characterized in that, In step S3, the energy of a single discharge... Obtain it using the following method: in, This represents the structural characteristic coefficient of an extra-thick ore body. For the uniaxial compressive strength of extra-thick ore bodies, This refers to the pretreatment volume of an extra-thick ore body; At the same time, by adjusting the capacitance of the energy storage unit and charging voltage To ensure that the discharge energy meets the requirements .

5. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to claim 1, characterized in that, In step S3, the number of discharges is determined based on the cumulative degree of rock mass damage. Multiple pulse loading methods are used to gradually weaken the rock mass. The adjustment principle is as follows: ， in, Number of discharges; For the current rock mass response, , It is the first The wave velocity or elastic wave propagation speed after the second discharge It is the initial intact rock mass wave velocity; To the degree of weakening of the target, , It is the target wave velocity required to induce collapse.

6. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to claim 1, characterized in that, In step S3, the discharge interval is determined based on the dielectric recovery time and stress wave attenuation characteristics, satisfying the following: ， in, This is the discharge interval; For medium recovery or stress decay time, , The thickness of the ore body. The velocity of stress waves in the rock mass. This is a correction factor related to attenuation and multiple reflections.

7. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to claim 1, characterized in that, In step S4, the evaluation indicators for rock mass weakening include: fracture density reaching 1.0 m / m³ to 5.0 m / m³, rock mass acoustic velocity decreasing by 15% to 40%, uniaxial compressive strength decreasing by 20% to 50%, and elastic modulus decreasing by 25% to 55%.

8. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to claim 1, characterized in that, In step S4, the method for dynamically adjusting the discharge parameters is as follows: in, This represents the current discharge energy. The adjusted discharge energy; This is the adjustment coefficient; The degree of weakening of the target; This represents the current rock mass response.

9. The method for pretreatment and induced caving of extra-thick ore bodies based on high-energy electric detonation according to any one of claims 1-8, characterized in that, Step S5: The weakened ore body is triggered to collapse along the preset fracture surface by means of mining disturbance, pressure relief blasting or natural collapse. During the collapse, the collapse status is assessed in real time by means of surface subsidence monitoring and underground ground pressure monitoring. The collapsed ore body is extracted through the bottom structure to complete resource recovery.

10. A high-energy electro-blasting system for pretreatment and induced caving of extra-thick ore bodies, used in any one of the high-energy electro-blasting methods for pretreatment and induced caving of extra-thick ore bodies according to claims 1-9, characterized in that, It includes a surface high-energy pulse power supply subsystem, an underground high-pressure transmission subsystem, an in-hole electric detonation generator, and a monitoring and feedback control subsystem; The ground high-energy pulse power supply subsystem is used to provide high-voltage pulse power with preset parameters, including a charging unit for converting external power into high-voltage power, an energy storage unit for storing power, and a control unit for controlling discharge parameters and discharge timing. One end of the downhole high-voltage transmission subsystem is electrically connected to the surface high-energy pulse power supply subsystem, and the other end is electrically connected to the in-hole electric detonation generator. It is used to realize the downhole transmission of high-voltage pulse power and to lower the in-hole electric detonation generator. The in-hole electric blast generator is installed inside the borehole of the extra-thick ore body and includes an electrode assembly and a discharge structure. The electrode assembly forms a discharge gap, and the discharge structure is used to generate instantaneous discharge under the action of high-voltage pulsed electric energy, so as to form shock waves and stress waves in the surrounding medium to achieve volumetric damage to the rock mass. The monitoring and feedback control subsystem is electrically connected to the control unit of the ground high-energy pulse power supply subsystem. It is used to collect discharge process parameters and rock mass response data, and dynamically adjust the discharge parameters according to the collected data to form a closed-loop control.

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