A pressure-relief caving method for accelerating the collapse of a goaf

Abstract

The application discloses a pressure-releasing roof caving method for accelerating the collapse of a goaf, relates to the underground metal mine mining technical field, and is suitable for the goaf with a surface allowed to collapse and a buried depth of less than or equal to 100 m. A rock drilling chamber is arranged at a suitable position underground, a downward parallel deep hole and an upward parallel medium-deep hole are used to form a large-range rock body forced roof caving in a local area in a blasting collapse mode, the goaf is completely exposed to the surface in the area to form an impact wave pressure-releasing space, the rock covering layer of the goaf is supplemented, the pressure dispersion transmission path of the roof of the original goaf is damaged, and then the collapse of the roof of the goaf is accelerated until the goaf is completely collapsed to the surface or collapsed to the ground, and the goaf hazard is completely eliminated. In the method, the pressure-releasing roof caving engineering quantity input is less, safety monitoring and early warning means are accompanied, the construction environment is better, the safety is higher, the blasting construction technical difficulty is low, and the overall technical and economic benefit effect is remarkable.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of underground metal mine mining, and particularly relates to a pressure relief and roof falling method for accelerating collapse of a goaf. BACKGROUND

[0002] The caving method is widely used in large metal mines such as copper and iron mines as an efficient and low-cost mining method. Regardless of the continuity of the ore body in space distribution, after the recovery of each section, the upper and lower sections of the goaf are often connected. At this time, if the natural roof collapse speed is less than the production level descending speed, the rock covering layer will separate from the goaf roof in the stope, forming a super large goaf hazard, which will pose a safety hazard to the normal production of the lower part.

[0003] At present, the measures for treating such goaf hazards include artificially plugging the goaf channel, increasing the thickness of the rock buffer layer by induced caving and forced caving to weaken the collapse shock wave, excavating a channel directly to the surface to reduce the shock wave pressure, and monitoring and warning the pressure of the upper wall rock. However, none of the above measures directly eliminates the goaf from the root, and long-term dynamic tracking and repeated treatment of the goaf are required in the later stage. At the same time, as the collapse height and space of the goaf expand, induced caving or forced caving cannot completely cover the entire goaf, and the sporadic collapse in the goaf will gradually turn into large-area chain collapse, and the collapse shock wave pressure will increase dramatically. The pressure relief effect of the pressure relief channel or the "sky window" still lacks sufficient data and theoretical support, and the mine often needs to continuously increase the covering layer to resist disasters, and the rock of the subsequent supplemented covering layer is mainly the ore retained in the stope during the lower recovery, which will also cause a large economic loss to the mine. The patent with the publication number CN114810209A provides a method for treating and eliminating a large goaf in an underground mine. 2-6 operation areas or blasting areas are divided in the goaf surrounding rock of the goaf; 3-6 deep hole drilling chambers are arranged in the goaf surrounding rock in each operation area or blasting area, and the deep hole drilling chambers in each layer are connected by a chamber connecting shaft; a shaft engineering connecting roadway, connecting inclined shaft or connecting raise is arranged between the existing engineering and the deep hole drilling chamber; a roof falling horizontal deep hole is arranged in the deep hole drilling chamber in the middle and lower layers, and a horizontal and upward fan-shaped cutting weakening deep hole is arranged in the deep hole drilling chamber in the upper layer. However, the roof falling method is applicable to the goaf roof thickness of 50-130 m, and the design of the roof falling thickness and the cutting weakening height cannot completely cover the entire roof thickness. After the implementation of the scheme, a certain thickness of the roof remains undisturbed and damaged, and it is questionable whether the surface can collapse and eliminate the goaf.

[0004] Therefore, it is still necessary to continue to study the goaf roof treatment scheme until a suitable pressure relief and roof caving method for accelerating the collapse of the goaf is found to completely eliminate the safety problems caused by the goaf. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a pressure relief and roof caving method for accelerating the collapse of a goaf. The pressure relief and roof caving method is suitable for a goaf with a surface allowed to collapse and a buried depth ≤100 m. A rock drilling chamber is arranged at a suitable position underground, and a downward parallel deep hole and an upward parallel medium-deep hole are used to form a large range of rock mass forced roof caving in a local area in a blasting collapse manner, so that the goaf is completely exposed to the surface in the area to form an impact wave pressure relief space, the goaf rock cover layer is supplemented, and the original goaf roof pressure dispersion transmission path is destroyed, thereby accelerating the collapse of the goaf roof until the goaf is completely collapsed or collapsed to the surface, and the goaf hazard is completely eliminated.

[0006] Based on the above technical purpose, the present application provides a pressure relief and roof caving method for accelerating the collapse of a goaf, which comprises the following steps:

[0007] S1, goaf form adjustment: the specific form and size of the goaf are ascertained, and the existing goaf volume is ensured to be 1.5 times greater than the roof caving volume by means of lower ore drawing; if the goaf roof height is greater than 100 m from the surface, a conventional forced roof caving method is used to continuously caving the roof to meet the condition of goaf buried depth ≤100 m;

[0008] S2, roof caving blasting engineering arrangement: a rock drilling chamber and a rock drilling chamber auxiliary slope connected with the rock drilling chamber and an upward cutting raise are arranged at a predetermined position underground, and a combined rock drilling operation of drilling an upward parallel medium-deep hole and a downward parallel deep hole is used for blast hole arrangement;

[0009] S3, roof caving blasting construction and safety early warning monitoring: a downward parallel deep hole and an upward parallel medium-deep hole are used to form a large range of rock mass forced roof caving in a local area by means of combined blasting collapse in a step-by-step blasting construction process; and during the construction process, the goaf ground pressure activity is continuously monitored by means of ground pressure monitoring means.

[0010] As a further improvement of the present application, in step S2, the rock drilling chamber is arranged along the goaf strike length, located within 15-25 m below the surface, on the lower side of the ore body, and above the goaf roof, the angle between the goaf roof and the horizontal line connected with the goaf side is greater than 60°, and the vertical distance between the rock drilling chamber and the goaf roof is greater than 1 / 2 of the goaf roof span.

[0011] As a further improvement of the present application, in step S2, the extremely stable rock mass roof caving area is controlled to be 800-1000 m2 The stable rock mass roof-falling area is controlled in 200-500m 2 The width or span is controlled in 10-20m.

[0012] As a further improvement of the present application, in the combined drilling operation of step S2, the upward parallel medium-length hole is vertically constructed on the roof of the top plate, the hole diameter is 65-76mm, the row distance and hole distance are 1.4-1.8m; the downward parallel long hole is at an angle of ≥60° with the horizontal plane, the hole diameter is ≥150mm, and the row distance and hole distance of the downward parallel long hole is about twice that of the upward parallel medium-length hole.

[0013] As a further improvement of the present application, in step S3, based on the downward parallel long hole caving process and the upward parallel medium-length hole caving process, the multi-free surface coordinated blasting of the upward parallel medium-length hole and the downward parallel long hole is used to break the roof of the mined-out area, and the specific process is as follows: first, the downward parallel long hole is blasted in layers, taking the roof of the mined-out area as the free surface, and the caving height is 8-12m; the roof of the roof-falling area is gradually raised until the roof of the roof-falling area is 10-15m away from the floor of the drilling space; then, the remaining length of the hole is coordinated with the upward parallel medium-length hole to break the roof of the mined-out area.

[0014] As a further improvement of the present application, in the downward parallel long hole caving process, the downward parallel long hole penetrates the lower roof of the mined-out area, and after the hole is constructed, a sealing plug is used to block the hole; the VCR spherical charge caving process is used to blast in layers, taking the roof of the mined-out area as the free surface, and after blasting, the hole length is re-measured, and the next blasting cycle can be organized.

[0015] As a further improvement of the present application, in the upward parallel medium-length hole caving process, the upward parallel medium-length hole takes several cutting shafts as the free surface on the horizontal plane, and takes the surface and the drilling chamber space and the space formed by the falling of the lower rock as the free surface on the vertical plane, and the hole penetrates the surface; after the hole is constructed, a sealing plug is used to block the hole bottom from the surface; when blasting, the last section of the upward parallel medium-length hole and the downward parallel long hole are coordinated, and the blasting of the upward parallel medium-length hole is delayed by more than 500ms after the blasting of the downward parallel long hole.

[0016] As a further improvement of the present application, when the drilling site needs to be arranged on the surface, the upward parallel medium-length hole does not need to be used to cave the roof of the drilling space, and the downward parallel long hole caving process is the VCR spherical charge caving process.

[0017] As a further improvement of the present application, after the roof-falling area is broken in step S3, a super-large pressure relief channel is formed between the mined-out area and the surface, and the surface containment and ground pressure monitoring work is carried out, and when the mined-out area collapses rapidly, the containment work is further increased according to the rock movement circle of the mined-out area.

[0018] As a further improvement of the present application, a predetermined number of point columns and strip columns are arranged inside the rock drilling chamber space in step S2 to support the roof.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] 1. The pressure relief and roof caving method for accelerating the collapse of the goaf provided by the present application can effectively supplement the underground rock cover layer while achieving pressure relief of the mining cavity through the surface, cut off the stress dispersion transmission path of the roof, accelerate the instability and caving rate of the goaf roof, and make the goaf quickly collapse to the surface, thereby completely solving the goaf problem.

[0021] 2. The pressure relief and roof caving method for accelerating the collapse of the goaf provided by the present application is mainly located underground, and the operation environment is not affected by the change of the slope terrain. The upper part is cut to form a cutting shaft connected with the surface, and the ventilation condition is good. During the rock drilling and blasting construction process, the ground pressure monitoring and safety warning are accompanied. When the roof is broken in the final roof caving area, the cooperative blasting method of the upper parallel medium-deep hole and the lower parallel deep hole with multiple free surfaces is adopted, which can completely avoid the accidental injury of personnel and equipment caused by the direct exposure of the goaf and the rock drilling and blasting operation space, and greatly protect the safety of the operating personnel and equipment during the roof caving operation process.

[0022] 3. The pressure relief and roof caving method for accelerating the collapse of the goaf provided by the present application needs to excavate the rock drilling chamber and the auxiliary slope connected therewith, and the upper cutting shaft. The amount of engineering investment is less, and the roof caving construction cost is not high. The rock drilling and blasting adopts the combined blasting method of the lower parallel deep hole and the upper parallel medium-deep hole. The upper and lower blast holes do not affect each other, and multiple rock drilling equipment can be used for construction at the same time to speed up the construction speed. The overall technical and economic benefits are remarkable.

[0023] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following will specifically describe the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating any creative labor.

[0025] Figure 1 is the position side view of the goaf and the rock drilling chamber in the pressure relief and roof caving method for accelerating the collapse of the goaf provided by the present application.

[0026] Figure 2 is the side view profile of the pressure relief caving engineering and the arrangement of the medium-length hole in the pressure relief caving method for accelerating the collapse of the goaf provided by the application.

[0027] Figure 3 is the plan scheme of the arrangement of the rock drilling chamber and the arrangement point of the upward parallel medium-length hole in the pressure relief caving method for accelerating the collapse of the goaf provided by the application.

[0028] Figure 4 is the schematic diagram of the accelerated collapse of the roof after the formation of the pressure relief channel in the pressure relief caving method for accelerating the collapse of the goaf provided by the application.

[0029] Explanation of reference signs:

[0030] 1, rock drilling chamber; 2, surface terrain line; 3, schematic line of pressure transmission arch of goaf roof; 4, surrounding rock; 5, natural caving form prediction; 6, goaf; 7, rock cover layer; 8, deep ore body to be mined; 9, upward parallel medium-length hole; 10, cutting shaft; 11, downward parallel deep hole; 12, layering caving line; 13, surface channel formed after pressure relief caving; 14, schematic of rock fissure; 15, schematic of surface subsidence; 16, schematic of collapsed block stone; 17, rock drilling chamber auxiliary slope; 18, rock drilling chamber point column. DETAILED DESCRIPTION

[0031] The embodiments of the technical scheme of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical scheme of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0033] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0034] Reference to“an embodiment” herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in an embodiment” in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments in accordance with the application.

[0035] In the description of the embodiments of the application, the term“and / or” only means an association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character“ / ” herein generally means that the front and rear associated objects have an“or” relationship.

[0036] In the description of the embodiments of the application, the term“a plurality of” means more than two (including two), and similarly, “a plurality of groups” means more than two groups (including two groups), and “a plurality of pieces” means more than two pieces (including two pieces).

[0037] In the description of the embodiments of the application, the technical terms“center”,“longitudinal”,“transverse”,“length”,“width”,“thickness”,“upper”,“lower”,“front”,“rear”,“left”,“right”,“vertical”,“horizontal”,“top”,“bottom”,“inner”,“outer”,“clockwise”,“counterclockwise”,“axial”,“radial”,“circumferential” 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 embodiments of the 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 embodiments of the application.

[0038] In the description of the embodiments of the application, unless otherwise explicitly specified and limited, the technical terms“mounting”,“connection”,“connection”,“fixing” and the like should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the application can be understood according to the specific circumstances.

[0039] In order to solve the technical problems that with the expansion of the goaf falling height and space, induced collapse or forced collapse will not be able to completely cover the entire goaf, and the sporadic collapse in the goaf will gradually turn into large-area chain collapse, and the pressure of the collapse shock wave will increase dramatically in the prior art, the application provides a pressure relief and roof caving method for accelerating the collapse of the goaf. The pressure relief and roof caving method is suitable for the goaf with a surface allowed to collapse and a buried depth of ≤100 m. A rock drilling chamber is arranged at a suitable position underground, a downward parallel deep hole and an upward parallel medium-deep hole are used for blasting collapse, a large range of rock mass forced roof caving is formed in a local area, the goaf is completely exposed to the surface in the area to form a shock wave pressure relief space, the goaf rock covering layer is supplemented, the original goaf roof pressure dispersion transmission path is destroyed, and then the goaf roof collapse is accelerated until the goaf is full of collapse or collapses to the surface, and the goaf hazard is completely eliminated. The specific steps include the following steps:

[0040] S1, goaf form adjustment: the specific form and size of the goaf are verified, and the existing goaf volume is ensured to be 1.5 times greater than the roof caving volume by the way of lower ore drawing; if the goaf roof height is greater than 100 m from the surface, the conventional forced roof caving is used for continuous roof caving to meet the condition of goaf buried depth ≤100 m;

[0041] S2, roof caving blasting engineering arrangement: a rock drilling chamber and a rock drilling chamber auxiliary slope connected with the rock drilling chamber and an upward cutting raise are arranged at a predetermined position underground, and a combined rock drilling operation of drilling an upward parallel medium-deep hole and a downward parallel deep hole is used for blast hole arrangement;

[0042] S3, roof caving blasting construction and safety early warning monitoring: a downward parallel deep hole and an upward parallel medium-deep hole are used for combined blasting collapse, a local area is formed by forced roof caving of a large range of rock mass by using a step-by-step blasting construction process, and the goaf ground pressure activity is continuously monitored by combining with the ground pressure monitoring means during the construction process.

[0043] Preferably, in step S2, the rock drilling chamber is arranged along the strike length of the goaf, is located on the ore body footwall side within the range of 15-25 m below the surface, and is located at a position where the angle between the goaf roof above and the goaf side slope connecting line and the horizontal plane is greater than 60°, and the vertical distance between the rock drilling chamber and the goaf roof is greater than 1 / 2 of the goaf roof span.

[0044] Preferably, in step S2, the extremely stable rock mass roof caving area is controlled to be 800-1000 m 2 , the stable rock mass roof caving area is controlled to be 200-500 m 2 , and the width or span is controlled to be 10-20 m.

[0045] Preferably, in the combined drilling operation hole arrangement of step S2, the upward parallel medium-length hole is vertically constructed on the roof, the hole diameter is 65-76mm, the row distance and hole distance is 1.4-1.8m; the downward parallel long hole is at an angle of ≥60° with the horizontal plane, the hole diameter is ≥150mm, the row distance and hole distance of the downward parallel long hole is about twice that of the upward parallel medium-length hole.

[0046] Preferably, in step S3, based on the downward parallel long hole caving process and the upward parallel medium-length hole caving process, the upward parallel medium-length hole and the downward parallel long hole multi-free surface coordinated blasting mode is used to break the roof of the goaf, the specific process is as follows: first, the downward parallel long hole is blasted in layers, taking the roof of the goaf as the free surface, and the caving height is 8-12m; the roof of the roof caving area is gradually raised until the roof caving area is 10-15m away from the floor of the drilling space; then, the remaining length hole and the upward parallel medium-length hole are blasted to break the roof of the goaf.

[0047] Preferably, in the downward parallel long hole caving process, the downward parallel long hole penetrates the lower goaf roof, and the hole is plugged with a sealing plug after the hole is constructed; the VCR spherical charge caving process is used to blast in layers taking the goaf roof as the free surface, the hole length is re-measured after blasting, and the next blasting cycle can be organized.

[0048] Preferably, in the upward parallel medium-length hole caving process, the upward parallel medium-length hole takes several cutting shafts as the free surface on the horizontal plane, and takes the surface and the drilling chamber space and the space formed by the falling of the lower rock as the free surface on the vertical plane, and the hole penetrates the surface; after the hole is constructed, the hole bottom is plugged with a sealing plug from the surface; the last section of the upward parallel medium-length hole and the downward parallel long hole are blasted in coordination, and the blasting of the upward parallel medium-length hole lags behind the blasting of the downward parallel long hole by more than 500ms.

[0049] Preferably, when the drilling site needs to be arranged on the surface, the upward parallel medium-length hole is not needed to be used to caving the roof of the drilling space, and the downward parallel long hole caving process is the VCR spherical charge caving process.

[0050] Preferably, after the roof caving area is broken in step S3, a super large pressure relief channel is formed between the goaf and the surface, and the surface containment and ground pressure monitoring work is carried out, and when the goaf collapses rapidly, the containment work is further increased according to the rock movement circle of the goaf.

[0051] Preferably, in step S2, a predetermined number of point columns and strip columns are left in the drilling chamber space to support the roof.

[0052] Example 1

[0053] Please refer to Figures 1 to 4As shown, the embodiment 1 of the present application provides a pressure relief caving method for accelerating the collapse of the goaf, which comprises the following steps:

[0054] S1, method applicability analysis and goaf shape adjustment.

[0055] The specific shape and size of the goaf 6 are determined by using geophysical prospecting methods, and the pressure relief caving method provided by the present application is applicable to the treatment of the goaf 6 with a buried depth of less than or equal to 100 m. If the height of the goaf roof is far from the ground surface, the conventional caving method can be used, that is, the inclined medium-length hole pressure caving method is arranged on the goaf roof to continuously caving, so as to meet the buried depth condition of the goaf 6 pressure relief caving method. At the same time, the accurate goaf 6 shape feature data will also provide support for subsequent determination of the safe distance of the rock drilling chamber 1 and other data.

[0056] In addition to the requirement that the goaf 6 meets the buried depth condition, the goaf 6 space shape investigation also needs to determine the goaf 6 volume to meet the compensation space requirement of the caving rock mass. Generally, the goaf 6 volume is required to be greater than 1.5 times the caving volume. If this condition is not met, the goaf 6 volume can be continuously increased by mining through the lower mining access, so as to meet the compensation space requirement of the caving.

[0057] S2, determination of pressure relief caving structure parameters and engineering design.

[0058] The engineering needs to be determined in combination with the goaf 6 space shape, the stability of the surrounding rock 4, and the construction machinery and equipment. The design elements include: the position and regulation parameters of the rock drilling chamber 1, the position and specification parameters of the cutting shaft 10, the rock drilling parameters and arrangement of the auxiliary slope 17 of the rock drilling chamber, and the rock drilling parameters and arrangement of the caving medium-length hole.

[0059] Please refer to Figure 1 As shown, the position of the rock drilling chamber 1 is generally arranged within the range of 15-25 m below the ground surface, along the length of the goaf 6. The specific position should be located on the lower side of the ore body, above the goaf roof, and the included angle between the goaf roof and the horizontal plane should be greater than 60°. The vertical distance between the rock drilling chamber 1 and the goaf roof is calculated according to the load transmission intersection line and the thickness-span ratio theory, and is generally greater than 1 / 2 of the width or span of the goaf roof. In the embodiment 1, the rock drilling chamber 1 is arranged on the lower side of the ore body 20 m below the ground surface, and the included angle between the goaf roof and the horizontal plane is 60°. The vertical distance between the rock drilling chamber 1 and the goaf roof is 70 m.

[0060] The specification parameters of the rock drilling chamber 1 need to meet the requirements of the caving area blast hole construction. The planar specification size of the caving area is determined according to the actual rock stability, and the caving area of the extremely stable rock mass is controlled within 800-1000 m 2 , and the caving area of the stable rock mass is controlled within 200-500 m 2, the width or span can be calculated according to the "simply supported beam" and "plate" theory, and controlled within 10-20m, at this time the bottom of the top release area and the position connected with the goaf 6 should not be deformed and collapsed, which can cause the hole damage and destroy the arch foot of the goaf roof. The surrounding rock 4 of the embodiment 1 is a very stable rock mass, the top release area is determined as 1000m 2 , the top release width (limit span) is 20m, the top release length is 50m, and is arranged along the strike direction of the ore body or goaf 6. In order to meet the top release hole construction, the drilling chamber 1 is determined as a width of 21m, a length of 50m, and a height of 4m, and is provided with 8 drilling chamber point columns 18 for supporting the roof and ensuring the safety of the drilling chamber 1. The cross-sectional size of the drilling chamber point column 18 is 4x5m, as shown in Figure 3 .

[0061] The cutting shaft 10 is constructed through the drilling chamber 1 to the ground surface, and is used as a free surface of the upward hole blasting and a ventilation shaft in the hole drilling process. In order to meet the requirement of one-time blasting and top release, several cutting shafts 10 should be arranged, and the size parameters of the cutting shafts should be as large as possible. In the embodiment 1, the height of the cutting shaft 10 is 16m, the cross-sectional size is 2.0m x 2.0m, and 3 cutting shafts are arranged.

[0062] The auxiliary slope 17 of the drilling chamber should be arranged on the safe side of the lower plate far away from the goaf 6, and is constructed from the suitable position on the ground surface or underground to the drilling chamber 1 from one side of the length direction of the drilling chamber 1.

[0063] The drilling chamber 1 should be able to meet the construction of all holes in the forced top release area, and a certain number of drilling chamber point columns 18 and strip columns can be arranged inside the space to support the roof and ensure the stability of the working space.

[0064] Please refer to the top release medium-length hole drilling parameters and arrangement shown in Figure 2 . The upward parallel medium-length hole 9 and the downward parallel deep hole 11 are used for top release scheme. The upward parallel medium-length hole 9 is arranged around the cutting shaft 10 in parallel, and the downward parallel deep hole 11 is arranged in parallel. In the embodiment 1, the upward parallel medium-length hole 9 and the downward parallel deep hole 11 are combined for drilling operation. The upward parallel medium-length hole 9 is constructed vertically to the roof, the hole diameter of the upward parallel medium-length hole 9 is 65-76mm, the row and hole distance is 1.4-1.8m, and the hole depth is required to penetrate the ground surface. After the construction of the hole, the hole bottom is blocked by using wooden plugs from the ground surface to prevent the ground surface from being blocked by the debris; the downward parallel deep hole 11 has an angle ≥60° with the horizontal plane, the hole diameter is ≥150mm, and the row and hole distance is 3.0-3.5m, which is about twice the row and hole distance of the upward hole. Because the upward hole and the downward hole have different drilling equipment, multiple equipment can be used for parallel operation without affecting each other, and the construction speed is accelerated.

[0065] The pressure relief and roof release method provided by this invention accelerates the collapse of the goaf by destroying the pressure-bearing arch support feet of the goaf roof and severing the stress transmission support structure of the goaf roof, causing the goaf 6 to be in a state of continuous stress instability. Figure 1 The schematic line 3, representing the pressure transmission arch in the goaf roof, causes the goaf roof to form a "cantilever" state, inducing transverse cracks and leading to the risky collapse of goaf 6. Figure 4 Among them, rock drilling chamber 1 is a crucial component for achieving blasting to break through the roof and sever the supporting structure on one side of the goaf roof to transmit ground pressure stress. It is located on the lower side of the goaf, with the angle between the line connecting it to the goaf sidewall and the horizontal plane greater than 60°, and the vertical distance from the goaf roof greater than half the span of the goaf roof, within a range of 15–25 meters below the ground surface. Considering the spatial relationship between rock drilling chamber 1, goaf 6, and the ground surface, as well as the construction techniques for medium-deep and deep holes, a safe distance was established, resulting in low safety risks and a relatively small workload.

[0066] Step S3: Control and safety early warning monitoring of top blasting construction.

[0067] A technically feasible and safe blasting scheme will be adopted, with blasting operations conducted in stages. During construction, specific ground pressure monitoring methods, such as ground pressure monitoring and microseismic monitoring, will be continuously used to monitor ground pressure activity in the goaf area 6, providing safety warnings for workers and equipment and improving operational safety. A combined blasting and collapse method using downward parallel deep holes 11 and upward parallel medium-deep holes 9 will be employed, employing a staged blasting construction process to create a large-scale forced roof collapse in localized areas. Furthermore, ground pressure monitoring methods will be used to continuously monitor ground pressure activity in the goaf area 6 during construction.

[0068] The goaf 6 was breached using a coordinated blasting method involving multiple free faces of upward parallel deep holes 9 and downward parallel deep holes 11. In terms of blasting arrangement, the downward parallel deep holes 11 were first blasted in layers, with the goaf roof as the free face. The initial collapse height was 8–12 m, gradually raising the roof of the caving area until it was 10–15 m from the bottom of the drilling space. Then, the remaining length of blast holes was coordinated with the upward parallel deep holes 9 to breach the goaf 6. The upward parallel deep holes 9 used several cutting wells 10 as free faces on the horizontal plane, and the surface, the space of the underground drilling chamber 1, and the space formed by the falling lower rock as free faces on the vertical plane. The blasting time of the upward parallel deep holes 9 was slightly delayed by more than 500 ms compared to the downward parallel deep holes 11 to allow for sufficient falling of the lower rock.

[0069] The lower parallel deep hole 11 collapse process, the angle between the construction lower parallel deep hole 11 blast hole and the horizontal plane is greater than or equal to 60 degrees, the hole diameter is greater than or equal to 150 mm, the hole depth requires penetrating the lower goaf roof, after the construction of the blast hole, the hole is plugged in time with a wooden plug to prevent the air area shock wave from flowing along the blast hole to damage the blast hole and the hole personnel equipment, when blasting, the VCR spherical charge collapse process is used, the goaf roof is used as the free surface for blasting, the first collapse height is 8-12 m, after blasting, the blast hole length needs to be re-measured, and the next blasting cycle can be carried out until the roof of the roof area is 10-15 m away from the rock drilling space bottom plate, which is left for the last roof breaking blasting operation with the upper parallel medium deep hole 9 blast hole.

[0070] The upper parallel medium deep hole 9 collapse process, before the blast hole drilling, 1-4 cutting shafts 10 penetrating the ground are constructed around the roof area, the upper parallel medium deep hole 9 is arranged around the cutting shaft 10, the hole diameter is 76 mm, the hole depth requires penetrating the ground surface, after the construction of the blast hole, the hole bottom is plugged with a wooden plug from the ground surface to prevent the ground surface from being blocked, when blasting, the upper parallel medium deep hole 9 and the last section of the lower parallel deep hole 11 blast hole are blasted cooperatively, the blasting arrangement of the upper slightly lags behind the blasting of the lower parallel deep hole 11 by more than 500 ms, so that the rock falls fully.

[0071] In the lower parallel deep hole 11 blasting, the VCR spherical charge collapse process is used, the goaf roof is used as the free surface for blasting, the first collapse height is 8-12 m, after blasting, the blast hole length needs to be re-measured, and the next blasting cycle can be carried out; the upper parallel medium deep hole 9 blasting, the cutting shaft 10 is used as the free surface for blasting, and the first collapse is carried out. When blasting, the lower parallel deep hole 11 is first layered and blasted, the roof of the roof area is raised until the roof area is 10-15 m away from the rock drilling space bottom plate, and then the upper parallel medium deep hole 9 blast hole is blasted cooperatively, the blasting arrangement of the upper slightly lags behind the blasting of the lower parallel deep hole 11 by more than 500 ms, so that the rock falls fully.

[0072] When the rock drilling site needs to be arranged on the ground surface, at this time, the upper blast hole is not needed to be used for collapsing the rock drilling space roof, only the construction conditions of the ground surface environment need to be considered, and the lower parallel deep hole 11 collapse process is still the VCR spherical charge collapse process.

[0073] Please refer to Figure 4 As shown in the figure, after the roof breaking of the roof area, the goaf 6 and the ground surface form a super large pressure relief channel, in order to protect the safety of the ground surface personnel and equipment, the ground surface enclosure and ground pressure monitoring work need to be carried out, when the goaf 6 collapses rapidly, the rock movement circle of the goaf 6 needs to be further increased.

[0074] The safety monitoring and early warning is a preventive measure for ensuring the safety of personnel and equipment during the pressure relief and roof caving, and during the construction operation in the rock drilling chamber 1, the ground pressure activity of the goaf 6 is continuously monitored by combining with the ground pressure monitoring means, such as ground pressure monitoring and microseismic monitoring, the monitoring probe can be installed in the floor, side slope or auxiliary slope of the rock drilling chamber 1, when the monitoring early warning value is reached, the operating personnel should be timely notified to evacuate, and the change of the goaf 6 is further analyzed, when the goaf 6 has a major change, the safety of the rock drilling chamber 1 is checked, and it is judged whether the position of the rock drilling chamber 1 needs to be changed.

[0075] In summary, the application discloses a pressure relief and roof caving method for accelerating the collapse of a goaf, which is suitable for a goaf with a depth of less than or equal to 100 m and allowed to collapse on the ground surface. The method comprises the following steps: arranging a rock drilling chamber at a suitable position in the well, and using downward parallel deep holes and upward parallel medium-depth holes to form a large range of rock mass forced roof caving in a local area, so that the goaf is completely exposed to the ground surface in the area to form an impact wave pressure relief space, the rock covering layer of the goaf is supplemented, and the pressure dispersion transmission path of the original goaf roof is destroyed, thereby accelerating the collapse of the goaf roof until the goaf is completely collapsed or collapsed to the ground surface, and the goaf hazard is completely eliminated. In the method, the pressure relief and roof caving engineering investment is relatively small, the operation chamber is located in the well and has a certain safety distance from the goaf, a point column is arranged in the chamber to support the roof, and several cutting shafts penetrate the ground surface, accompanied by a safety monitoring and early warning means, the construction environment is good and the safety is high, the rock drilling of the blast hole is divided into upward hole and downward hole construction, a plurality of rock drilling equipment can be used for parallel construction to speed up the construction speed, and the blast hole has a large number of free surfaces, so that the blast construction technology is not difficult. The overall technical and economic benefits are obvious, the implementation safety is high, the method has good application value for treating the goaf by using the caving method in the mine, and also has important reference significance for treating the goaf by using the caving method in other types of mines.

[0076] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role and effect within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications of the embodiments, combination of part of the components in the embodiments to construct other ways can also be included in the scope of the present application.

Claims

1. A pressure-relief caving method for accelerating the collapse of a goaf, characterized in that, The method comprises the following steps: S1, adjusting the form of the goaf: the specific form and size of the goaf are ascertained, and the existing goaf volume is ensured to be greater than the top volume by 1.5 times through the way of lower ore drawing; if the height of the goaf roof is greater than 100 m from the surface, the conventional forced top drawing is adopted to continuously draw the top, so that the goaf depth is less than or equal to 100 m; S2, arrangement of the top drawing structure and blasting engineering: the rock drilling chamber, the rock drilling chamber auxiliary slope and the upward cutting raise connected with the rock drilling chamber are arranged at the predetermined position in the mine, and the combined rock drilling operation of the upward parallel medium-length hole and the downward parallel deep hole is adopted to arrange the blast holes; S3, top drawing blasting construction and safety early warning monitoring: the combined blasting of the downward parallel deep hole and the upward parallel medium-length hole is adopted to form the forced top drawing of the large range of rock mass in the local area through the partial blasting construction process, and the ground pressure activity of the goaf is continuously monitored in the construction process by combining the ground pressure monitoring means; In step S3, the forced top breaking of the goaf is carried out by adopting the multi-free surface coordinated blasting of the upward parallel medium-length hole and the downward parallel deep hole based on the downward parallel deep hole caving process and the upward parallel medium-length hole caving process, and the specific process is as follows: first, the downward parallel deep hole layer-by-layer blasting is carried out, the goaf roof is taken as the free surface, and the caving height is 8-12 m; the goaf roof is gradually raised until the goaf roof is 10-15 m away from the rock drilling space bottom; then, the remaining length blast hole and the upward parallel medium-length hole blast hole are cooperatively blasted to break the goaf roof; In the downward parallel deep hole caving process, the downward parallel deep hole penetrates the lower goaf roof, and the hole is plugged with the sealing plug after the blast hole is constructed; the VCR spherical-like charge caving process is adopted to carry out the layer-by-layer blasting with the goaf roof as the free surface, the blast hole length is re-measured after blasting, and the next blasting cycle can be carried out. In step S2, the rock drilling chamber is arranged along the goaf strike length, is located within the range of 15-25 m below the surface, is on the lower wall of the ore body, and is above the goaf roof and the goaf side slope connection line with the horizontal plane at an angle greater than 60°, and the vertical distance between the rock drilling chamber and the goaf roof is greater than 1 / 2 of the goaf roof span.

2. A pressure-relief caving method for accelerating the collapse of a goaf according to claim 1, characterized in that, In the blast hole arrangement of the combined rock drilling operation in step S2, the upward parallel medium-length hole is constructed vertically to the roof, the hole diameter is 65-76 mm, and the row and hole spacing is 1.4-1.8 m; the downward parallel deep hole is greater than or equal to 60° with the horizontal plane, the hole diameter is greater than or equal to 150 mm, and the row and hole spacing of the downward parallel deep hole is twice that of the upward parallel medium-length hole.

3. A pressure-relief caving method for accelerating the collapse of a goaf according to claim 1, characterized in that, In step S2, the stable rock mass roof area is controlled at 800-1000 m 2 , the stable rock mass roof area is controlled at 200-500 m 2 , and the roof width or span is controlled at 10-20 m.

4. The pressure-relief caving method of claim 1, wherein, In the upward parallel medium-length hole caving process, the upward parallel medium-length hole takes several cutting raises as the free surface in the horizontal plane, takes the surface and the rock drilling chamber space and the space formed by the falling of the lower rock as the free surface in the vertical plane, and penetrates the surface; the hole bottom is plugged with the sealing plug after the blast hole is constructed; the last blast hole of the upward parallel medium-length hole and the downward parallel deep hole is cooperatively blasted, and the blasting of the upward parallel medium-length hole is arranged to lag behind the blasting of the downward parallel deep hole by more than 500 ms.

5. A pressure-relief caving method for accelerating the collapse of a goaf according to claim 1, characterized in that, ​ 6. A pressure-relief caving method for accelerating the collapse of a goaf according to claim 1, characterized in that, When the drilling site needs to be arranged on the ground, the upward parallel medium-length hole is not needed to collapse the roof of the drilling space, and the downward parallel deep hole collapse process is the VCR-like spherical explosive collapse process.

7. A pressure-relief caving method for accelerating the collapse of a goaf according to claim 1, characterized in that, After the roof is broken in the roof caving area in step S3, a super large pressure relief channel is formed between the goaf and the ground, and ground containment and ground pressure monitoring are carried out; when the goaf collapses at a high speed, the containment work is further increased according to the rock movement circle of the goaf.

8. A pressure-relief caving method for accelerating the collapse of a goaf according to claim 2, characterized in that, In step S2, a predetermined number of drilling chamber point columns and strip columns are left in the drilling chamber space to support the roof.

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