Pressure relief caving method for accelerating goaf collapse

Abstract

The invention discloses a pressure relief caving method for accelerating goaf collapse, relates to the technical field of underground metal mine mining, and is suitable for a goaf of which the earth surface is allowed to collapse and the burial depth is less than or equal to 100m. A rock drilling chamber is arranged at a proper underground position, and large-range rock mass forced caving is formed in a local area in a downward parallel deep hole and upward parallel medium-length hole blasting caving mode, so that the goaf is completely exposed from the ground surface in the area to form a shock wave pressure relief space, meanwhile, goaf rock covering layer supplementation is completed, and the goaf pressure relief effect is improved. And an original goaf roof pressure dispersion transmission path is destroyed, so that goaf roof collapse is accelerated until the goaf is fully collapsed or collapsed to the ground surface, and goaf harm is thoroughly eradicated. According to the method, the pressure relief top caving project amount investment is small, a safety monitoring and early warning means is adopted, the construction environment is good, safety is high, the blasting construction technical difficulty is low, and the overall technical economic benefit effect is remarkable.

Description

Technical Field

[0001] The present application relates to the technical field of underground metal mining, and in particular to a pressure relief and roof caving method for accelerating the collapse of a goaf area. Background Art

[0002] As an efficient and low-cost mining method, caving is widely used in large metal mines such as copper and iron. In mines that use caving, regardless of the continuity of the ore body in spatial distribution, after the mining of each segment is completed, it is easy to produce the phenomenon of the upper and lower middle sections of the goaf being connected. At this time, if the natural collapse speed of the roof is lower than the speed of the production level decline, the rock cover layer will separate from the goaf roof in the mining area, forming a hidden danger of a super-large goaf, which will cause safety hazards to the normal production below.

[0003] At present, the measures to deal with the hazards of such goafs are: artificially blocking the goaf passage, increasing the thickness of the rock buffer layer by induced collapse and forced collapse to weaken the shock wave; digging a channel directly to the surface to reduce the shock wave pressure; monitoring and early warning of the pressure of the upper surrounding rock. However, all the above measures have not directly eliminated the goaf from the root, and long-term dynamic tracking of the goaf and repeated governance work are required in the later stage. At the same time, with the expansion of the height and space of the goaf, induced collapse or forced collapse will not be able to completely cover the entire goaf. The sporadic collapse in the goaf will gradually turn into large-scale chain collapse, and the shock wave pressure of the fall will increase dramatically. There is no sufficient data and theoretical support for the decompression effect of the pressure relief channel or "skylight". Mines often need to continue to increase the cover layer to fight against disasters, and the subsequent supplementary cover rock is mainly the ore retained in the mining area after the lower recovery, which will also cause a lot of economic losses to the mine. The invention patent with the publication number CN114810209A provides a method for processing and eliminating the large goaf in underground mines by caving the roof. 2 to 6 working areas or blasting areas are divided in the surrounding rock of the goaf around the goaf; 3 to 6 deep-hole rock drilling chambers are arranged in the surrounding rock of the goaf in each working area or blasting area, and the deep-hole rock drilling chambers in each layer are connected by chamber communication shafts; shaft and tunnel engineering—communication horizontal tunnels, communication inclined shafts or communication skylights—are arranged between the existing engineering and the deep-hole rock drilling chambers; caving horizontal deep holes are arranged in the deep-hole rock drilling chambers in the middle and lower layers, and horizontal and upward fan-shaped cutting weakened deep holes are arranged in the deep-hole rock drilling chambers in the upper layers. However, the roof thickness of the goaf area applicable to this roof caving method is 50 to 130m. The designed roof caving thickness and cutting weakening height cannot completely cover the entire roof thickness. After the implementation of the plan, there is still a certain thickness of roof remaining undisturbed and undisturbed, and it is questionable whether the surface can collapse and the goaf area can be eliminated. Moreover, its roof caving method arranges several roof caving and rock drilling chambers around the goaf on the plane. On the one hand, the chambers are close to the goaf, which poses a certain construction safety risk. On the other hand, the implementation plan has a large amount of engineering work.

[0004] In view of this, it is still necessary to continue researching the goaf roof treatment plan until a suitable pressure relief and roof release method that accelerates the collapse of the goaf is found to completely eliminate the safety problems caused by the goaf. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides a pressure relief and roof caving method for accelerating the collapse of goaf. The pressure relief and roof caving method is suitable for goafs where the surface is allowed to collapse and the burial depth is ≤100m. By arranging rock drilling chambers at appropriate locations underground and using the method of blasting and collapsing with downward parallel deep holes and upward parallel medium-deep holes, a large-scale rock mass forced roof caving is formed in a local area, so that the goaf is completely exposed in this area and the surface to form a shock wave pressure relief space, and the rock cover 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 full or collapses to the surface, completely eradicating the hazards of the goaf.

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

[0007] S1, goaf shape adjustment: find out the specific shape and scale of the goaf, and ensure that the existing goaf volume is 1.5 times greater than the top volume by caving the ore from the bottom; if the height of the goaf roof is greater than 100m from the ground surface, adopt the conventional forced caving method to continuously caving the top to meet the condition that the goaf burial depth is ≤100m;

[0008] S2, caving blasting project layout: arrange the rock drilling chamber at the predetermined position underground, as well as the rock drilling chamber auxiliary ramp and upward cutting shaft connected to the rock drilling chamber, and adopt the combined rock drilling operation of drilling upward parallel medium-deep holes and downward parallel deep holes to arrange the blast holes;

[0009] S3, top blasting construction and safety early warning monitoring: Utilize the method of combined blasting collapse of downward parallel deep holes and upward parallel medium-deep holes, adopt the multi-stage blasting construction technology, form a large-scale rock forced top blasting in local areas; and, in the construction process, combine the ground pressure monitoring means to continuously monitor the ground pressure activities in the goaf.

[0010] As a further improvement of the present invention, in step S2, the drilling chamber is arranged along the strike length of the goaf, and is located within a range of 15 to 25 m below the ground surface, on the lower side of the ore body, and the angle between the line above the goaf top plate and the goaf side wall and the horizontal plane is greater than 60°, and the vertical distance between the drilling chamber and the goaf top plate is greater than 1 / 2 of the span of the goaf top plate.

[0011] As a further improvement of the present invention, in step S2, the top area of ​​the extremely stable rock mass is controlled to be 800-1000m2 , the area of ​​top caving for stabilizing rock mass should be controlled between 200 and 500 m 2 , the width or span is controlled at 10 to 20 meters.

[0012] As a further improvement of the present invention, in the blasthole arrangement of the combined rock drilling operation in step S2, the upper parallel medium-deep holes are constructed vertically on the top plate, with a hole diameter of 65 to 76 mm and a row spacing of 1.4 to 1.8 m; the downward parallel deep holes have an angle of ≥60° with the horizontal plane, a hole diameter of ≥150 mm, and the row spacing of the downward parallel deep holes is about twice the row spacing of the upper parallel medium-deep holes.

[0013] As a further improvement of the present invention, in step S3, based on the downward parallel deep hole caving process and the upward parallel medium-deep hole caving process, the goaf top is broken by the coordinated blasting method of the upper parallel medium-deep hole and the downward parallel deep hole multiple free surfaces. The specific process is as follows: First, the downward parallel deep hole layered blasting is carried out, with the goaf top plate as the free surface and the one-time caving height of 8 to 12 m; the top plate of the top caving area is gradually raised until the top plate of the top caving area is 10 to 15 m away from the bottom plate of the rock drilling space; then, the remaining length blastholes are coordinated with the upward parallel medium-deep hole blastholes to break the goaf top.

[0014] As a further improvement of the present invention, in the downward parallel deep hole caving process, the downward parallel deep hole penetrates deeply into the roof of the lower goaf, and the hole mouth is promptly blocked with a sealing plug after the blasthole is constructed; the VCR spherical charge caving process is adopted, and the goaf roof is used as the free surface for layered blasting. After the blasting, the blasthole length is remeasured before the next blasting organization cycle can be carried out.

[0015] As a further improvement of the present invention, in the upward parallel medium-deep hole collapse process, the upward parallel medium-deep hole has several cut ceilings as free surfaces on the horizontal plane, and has the ground surface and the underground rock drilling chamber space, and the space formed by the lower rock falling as free surfaces on the vertical plane, and the hole depth penetrates the ground surface; after the blasthole is constructed, the bottom of the blasthole is blocked with a sealing plug from the ground surface; during blasting, the upward parallel medium-deep hole and the last section of the blasthole of the downward parallel deep hole are blasted in coordination, and the blasting arrangement lags slightly behind the blasting of the downward parallel deep hole by more than 500ms.

[0016] As a further improvement of the present invention, when the rock drilling site needs to be arranged on the surface, there is no need to use the upward parallel medium-deep holes to collapse the top plate of the rock drilling space. The downward parallel deep hole collapse process is the VCR spherical charge collapse process.

[0017] As a further improvement of the present invention, after the top of the roof area is broken in step S3, an ultra-large pressure relief channel is formed between the goaf and the surface, and surface fencing and ground pressure monitoring work are carried out. When the goaf collapses rapidly, fencing work is further increased according to the rock movement circle of the goaf.

[0018] As a further improvement of the present invention, in step S2, a predetermined number of point columns and strip columns are reserved inside the rock drilling chamber space for supporting the top plate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The decompression and roof-releasing method for accelerating the collapse of the goaf provided by the present invention can effectively supplement the underground rock cover layer and cut off the stress dispersion transmission path of the roof while achieving the decompression of the goaf's falling shock wave by penetrating the ground surface, thereby accelerating the instability and falling rate of the goaf's roof, causing it to quickly fill up or collapse to the ground 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 invention has the following characteristics: the rock drilling chamber is mainly located underground, the working environment is not affected by the changes in the slope terrain, a cutting skylight is made on the upper part to connect with the ground surface, the ventilation conditions are good, and during the rock drilling and blasting construction process, there is a ground pressure monitoring safety warning. When the roof caving area is finally broken, a collaborative blasting method of multiple free surfaces of upper parallel medium-deep holes and lower parallel deep holes is adopted, which can completely avoid accidental injuries to personnel and equipment that may be caused by direct exposure of the goaf and the rock drilling and blasting working space, and greatly protect the safety of personnel and equipment during the roof caving operation.

[0022] 3. The pressure relief and roof caving method for accelerating the collapse of the goaf provided by the present invention requires the excavation of the rock drilling chamber and the auxiliary ramp connected thereto, and the upward cutting skylight. The amount of engineering invested is small, and the cost of roof caving construction is not high. The rock drilling blasting adopts a combination blasting method of downward parallel deep holes and upward parallel medium-deep holes. The construction of upward and downward blast holes does not affect each other. More than one rock drilling equipment can be used for construction at the same time, which speeds up the construction speed. The overall technical and economic benefits are remarkable.

[0023] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a side cross-sectional view of the positions 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 invention.

[0026] Figure 2 It is a side cross-sectional view of the pressure relief and roof caving engineering and the arrangement of medium-deep holes in the pressure relief and roof caving method for accelerating the collapse of goaf areas provided by the present invention.

[0027] Figure 3 It is a plan view of the arrangement points of the rock drilling chamber and the upward parallel medium-deep holes in the pressure relief and roof caving method for accelerating the collapse of the goaf provided by the present invention.

[0028] Figure 4 It is a schematic diagram of accelerated roof collapse after a pressure relief channel is formed in the pressure relief and roof caving method for accelerating goaf collapse provided by the present invention.

[0029] Description of reference numerals:

[0030] 1. Rock drilling chamber; 2. Surface topography line; 3. Schematic line of pressure transfer arch on the roof of goaf; 4. Surrounding rock; 5. Prediction of natural collapse pattern; 6. Goaf; 7. Rock cover layer; 8. Deep ore body to be mined; 9. Upward parallel medium-deep holes; 10. Cutting shaft; 11. Downward parallel deep holes; 12. Layered collapse line; 13. Through-surface passage formed after pressure relief and roof release; 14. Schematic diagram of rock cracks; 15. Schematic diagram of surface settlement; 16. Schematic diagram of collapsed rocks; 17. Auxiliary ramp of rock drilling chamber; 18. Point column of rock drilling chamber. DETAILED DESCRIPTION

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

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[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 "multiple" is more than two, unless otherwise clearly and specifically defined.

[0034] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0036] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0037] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0038] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0039] In order to solve the technical problem in the prior art that as the height and space of the goaf expand, induced collapse or forced collapse will not be able to completely cover the entire goaf, and sporadic collapse in the goaf will gradually transform into large-scale chain collapse, and the pressure of the caving shock wave will increase dramatically, the present application provides a pressure relief and roof release method for accelerating the collapse of the goaf. The pressure relief and roof release method is suitable for goafs where the surface allows collapse and the burial depth is ≤100m. By arranging rock drilling chambers at appropriate positions underground and using downward parallel deep holes and upward parallel medium-deep holes for blasting and collapse, a large-scale rock mass is forced to be released in a local area, so that the goaf is completely exposed to the surface in this area to form a shock wave pressure relief space, and at the same time, the rock cover 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 full or collapses to the surface, completely eradicating the hazards of the goaf. It specifically includes the following steps:

[0040] S1, goaf shape adjustment: find out the specific shape and scale of the goaf, and ensure that the existing goaf volume is 1.5 times greater than the top volume by caving the ore from the bottom; if the height of the goaf roof is greater than 100m from the ground surface, adopt the conventional forced caving method and continue caving the top to meet the condition that the goaf burial depth is ≤100m;

[0041] S2, caving blasting project layout: arrange the rock drilling chamber at the predetermined position underground, as well as the rock drilling chamber auxiliary ramp and upward cutting shaft connected to the rock drilling chamber, and adopt the combined rock drilling operation of drilling upward parallel medium-deep holes and downward parallel deep holes to arrange the blast holes;

[0042] S3, top blasting construction and safety early warning monitoring: Utilize the method of combined blasting collapse of downward parallel deep holes and upward parallel medium-deep holes, adopt the multi-stage blasting construction technology, form a large-scale rock forced top blasting in local areas; and, in the construction process, combine the ground pressure monitoring means to continuously monitor the ground pressure activities in the goaf.

[0043] Preferably, in step S2, the drilling chamber is arranged along the strike length of the goaf, and is located within a range of 15 to 25 m below the ground surface, on the footwall side of the ore body, and the angle between the line above the goaf top plate and the goaf side wall and the horizontal plane is greater than 60°, and the vertical distance between the drilling chamber and the goaf top plate is greater than 1 / 2 of the span of the goaf top plate.

[0044] Preferably, in step S2, the top area of ​​the extremely stable rock mass is controlled to be 800-1000m 2 , the area of ​​top caving for stabilizing rock mass should be controlled between 200 and 500 m 2 , the width or span is controlled at 10 to 20 meters.

[0045] Preferably, in the blasthole arrangement of the combined rock drilling operation in step S2, the upper parallel medium-deep holes are constructed vertically on the top plate, with a hole diameter of 65 to 76 mm and a row spacing of 1.4 to 1.8 m; the downward parallel deep holes have an angle of ≥60° with the horizontal plane, a hole diameter of ≥150 mm, and the row spacing of the downward parallel deep holes is about twice the row spacing of the upper parallel medium-deep holes.

[0046] Preferably, in step S3, based on the downward parallel deep hole caving process and the upward parallel medium-deep hole caving process, the goaf top is broken by the coordinated blasting method of the upward parallel medium-deep holes and the downward parallel deep holes with multiple free surfaces. The specific process is as follows: First, the downward parallel deep holes are blasted in layers, with the goaf top plate as the free surface and the one-time caving height of 8 to 12 m; the top plate of the top caving area is gradually raised until the top plate of the top caving area is 10 to 15 m away from the bottom plate of the rock drilling space; then, the remaining length blastholes are coordinated with the upward parallel medium-deep holes to break the goaf top.

[0047] Preferably, in the downward parallel deep hole caving process, the downward parallel deep hole penetrates deeply into the roof of the lower goaf, and the hole mouth is promptly blocked with a sealing plug after the blasthole is constructed; the VCR spherical charge caving process is adopted, and the goaf roof is used as the free surface for layered blasting. After the blasting, the length of the blasthole is remeasured before the next blasting organization cycle can be carried out.

[0048] Preferably, in the upward parallel medium-deep hole collapse process, the upward parallel medium-deep hole has several cut ceilings as free surfaces on the horizontal plane, and the surface and underground rock drilling chamber space, and the space formed by the lower rock falling as free surfaces on the vertical plane, and the hole depth penetrates the surface; after the blasthole is constructed, the bottom of the blasthole is blocked with a sealing plug from the surface; during blasting, the upward parallel medium-deep hole and the last section of the blasthole of the downward parallel deep hole are blasted in coordination, and the blasting arrangement lags slightly behind the blasting of the downward parallel deep hole by more than 500ms.

[0049] Preferably, when the rock drilling site needs to be arranged on the surface, there is no need to use upward parallel medium-deep holes to collapse the top plate of the rock drilling space, and the downward parallel deep hole collapse process is a VCR spherical charge collapse process.

[0050] Preferably, after the top of the caving area is broken in step S3, an ultra-large pressure relief channel is formed between the goaf and the surface, and surface fencing and ground pressure monitoring work are carried out. When the goaf collapses rapidly, fencing 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 reserved inside the rock drilling chamber space for supporting the top plate.

[0052] Example 1

[0053] See also Figures 1 to 4As shown, Embodiment 1 of the present invention provides a decompression and roof-caving method for accelerating the collapse of a goaf, comprising the following steps:

[0054] S1. Analysis of method applicability and adjustment of void area morphology.

[0055] The specific shape and scale of the goaf 6 are ascertained by geophysical prospecting methods. The pressure relief and top caving method provided by the present invention is suitable for processing goaf 6 with a buried depth of ≤100m. If the height of the goaf roof is far from the ground surface, a conventional top caving method can be used, that is, arranging inclined medium-deep hole top blasting on the goaf roof to continuously caving the top, so as to meet the buried depth conditions of the pressure relief and top caving method of the goaf 6. At the same time, accurate morphological characteristic data of the goaf 6 will also provide support for the subsequent determination of data such as the safe spacing of the rock drilling chamber 1.

[0056] The spatial morphology survey of goaf 6, in addition to requiring goaf 6 to meet the burial depth conditions, also needs to determine the volume of goaf 6 so that it can meet the compensation space requirements of the top rock mass. Generally, the volume of goaf 6 is required to be 1.5 times larger than the top caving volume. If this condition is not met, the volume of goaf 6 can be continuously increased by exiting the mine through the lower mining route to meet the compensation space requirements of the top caving.

[0057] S2. Determination of structural parameters and engineering design for pressure relief and top release.

[0058] The project needs to be determined in combination with the spatial form of the goaf 6, the stability of the surrounding rock 4, and the construction machinery and equipment. The design elements include: the location and procedure parameters of the rock drilling chamber 1, the location and specification parameters of the cutting shaft 10, the auxiliary ramp of the rock drilling chamber 17, and the parameters and layout of the deep hole drilling in the top caving.

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

[0060] The specifications of the rock drilling chamber 1 need to meet the requirements of blasthole construction in the caving area. The plane specifications and dimensions of the caving area are determined according to the actual rock stability. The caving area of ​​extremely stable rock is controlled within 800-1000m 2 , the area of ​​top caving for stabilizing rock mass should be controlled between 200 and 500 m 2The width or span can be analyzed and calculated according to the "simply supported beam" and "plate" theory and controlled within 10 to 20 m. At this time, the bottom of the caving area and the junction of the goaf 6 should not be deformed or collapsed, resulting in damage to the blasthole, and can damage the arch foot supporting the goaf roof. The surrounding rock 4 of Example 1 is an extremely stable rock mass, and the caving area is determined to be 1000 m 2 , the caving width (limit span) is 20m, the caving length is 50m, and it is arranged along the strike direction of the ore body or goaf 6. In order to meet the construction of caving blastholes, the rock drilling chamber 1 is determined to be 21m wide, 50m long, and 4m high, and 8 rock drilling chamber point columns 18 are set to support the roof and ensure the safety of the rock drilling chamber 1. The cross-sectional specifications of the rock drilling chamber point columns 18 are 4×5m. Figure 3 shown.

[0061] The cutting riser 10 is constructed from the rock drilling chamber 1 to the ground surface, serving as the blasting free surface of the upward blasthole and also as a ventilation riser during the blasthole rock drilling construction process. In order to meet the requirements of one-time blasting, several cutting risers 10 should be arranged, and the riser specification parameters should be expanded as much as possible. In this embodiment 1, the height of the cutting riser 10 is 16m, the cross-section regularization parameters are: 2.0m×2.0m, and a total of 3 are arranged.

[0062] The auxiliary ramp 17 of the rock drilling chamber should be arranged on the safe side of the lower wall away from the goaf 6, and should be opened from a suitable position on the surface or underground, and connected with the rock drilling chamber 1 from one side in the length direction of the rock drilling chamber 1.

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

[0064] See also Figure 2 The parameters and arrangement of the top-caving medium-deep hole drilling shown in the figure adopt the top-caving scheme of the upper parallel medium-deep hole 9 and the lower parallel deep hole 11. The upper parallel medium-deep hole 9 is arranged in parallel around the cutting skylight 10, and the lower parallel deep hole 11 blasthole is arranged in parallel. In this embodiment 1, the combined rock drilling operation of drilling the upper parallel medium-deep hole 9 and the lower parallel deep hole 11 is adopted. The upper parallel medium-deep hole 9 is constructed vertically on the top plate. The upper parallel medium-deep hole 9 has a hole diameter of 65 to 76 mm, a row spacing of 1.4 to 1.8 m, and a hole depth that penetrates the surface. After the blasthole is constructed, a wooden sealing plug is used from the surface to block the bottom of the blasthole to prevent blockage by surface gravel; the lower parallel deep hole 11 has an angle of ≥60° with the horizontal plane, a hole diameter of ≥150 mm, and a row spacing of 3.0 to 3.5 m, which is about twice the row spacing of the upper hole. Since the upward and downward drilling equipment are different, multiple equipment can be used to carry out parallel construction operations without affecting each other, thus speeding up the construction speed.

[0065] The pressure relief and top-caving method provided by the present invention accelerates the collapse of the goaf 6 by destroying the pressure arch support feet of the goaf roof and cutting off the ground pressure stress transmission support structure of the goaf roof, so that the goaf 6 is in a state of continuous stress instability. That is, the goaf 6 is destroyed. Figure 1 The schematic line 3 of the pressure transfer arch of the goaf roof shown in the figure makes the goaf roof form a "cantilever" state, inducing the occurrence of transverse cracks, resulting in the risk of goaf 6 falling, such as Figure 4 Among them, rock drilling chamber 1 is an important project to achieve blasting and cut off the supporting structure on the side of the ground pressure stress transmission of the goaf roof. It is arranged on the lower side of the goaf, with the angle between the line connecting the side of the goaf and the horizontal plane greater than 60°, and the vertical distance from the goaf roof greater than 1 / 2 of the span of the goaf roof, within the range of 15 to 25 meters below the surface. At this time, the spatial relationship between rock drilling chamber 1 and goaf 6 and the ground surface, as well as the construction process of medium-deep holes and deep holes were considered, and a safe distance was set, with low safety risks and less engineering workload.

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

[0067] Adopt a technically feasible, safe and reliable blasting plan, organize the blasting construction in batches, and combine certain ground pressure monitoring methods to continuously monitor the ground pressure activities in the goaf 6 during the construction process, such as ground pressure monitoring and microseismic monitoring, so as to provide safety warnings for operators and equipment, and improve the safety of personnel and equipment operations. Use the method of combined blasting collapse of the downward parallel deep hole 11 and the upward parallel medium-deep hole 9, adopt the multi-stage blasting construction process, and form a large-scale rock mass forced top caving in the local area; and combine the ground pressure monitoring methods to continuously monitor the ground pressure activities in the goaf 6 during the construction process.

[0068] The top of the goaf 6 is broken by the coordinated blasting organization of the upper parallel medium-deep holes 9 and the lower parallel deep holes 11 with multiple free surfaces. In terms of blasting arrangement, the lower parallel deep holes 11 are firstly blasted in layers, with the top plate of the goaf as the free surface, and the collapse height is 8 to 12m at a time, and the top plate of the top-release area is gradually raised until the top plate of the top-release area is 10 to 15m away from the bottom plate of the rock drilling space; then the remaining length blastholes are coordinated with the upper parallel medium-deep holes 9 blastholes to break the top of the goaf 6. The upper parallel medium-deep holes 9 use several cutting skylights 10 as free surfaces on the horizontal plane, and the space formed by the surface and the underground rock drilling chamber 1 and the lower rock falling space as free surfaces on the vertical plane. The arrangement is slightly delayed by more than 500ms from the blasting time of the lower parallel deep holes 11, so that the lower collapsed rock can fall fully.

[0069] The downward parallel deep hole 11 caving process is to construct the downward parallel deep hole 11 with an angle of ≥60° between the blasthole and the horizontal plane, and a hole diameter of ≥150mm. The hole depth is required to penetrate the roof of the lower goaf. After the blasthole is constructed, a wooden sealing plug is used to block the hole mouth in time to prevent the air defense zone shock wave from flowing along the blasthole to damage the blasthole and the personnel and equipment at the hole mouth. During blasting, a VCR spherical charge caving process is used, and the goaf roof is used as the free face for blasting. The caving height is 8 to 12m at a time. After the blasting, the blasthole length needs to be remeasured before the next blasting organization cycle can be carried out, until the top plate of the top area is 10 to 15m away from the bottom plate of the rock drilling space, leaving it for the final top breaking blasting operation with the upward parallel medium and deep hole 9 blasthole.

[0070] The caving process of the upward parallel medium-deep hole 9 is to construct 1 to 4 cutting shafts 10 connected with the surface around the top area before drilling the blasthole. The upward parallel medium-deep hole 9 is arranged in parallel around the cutting shaft 10, with a hole diameter of 76 mm and a hole depth required to penetrate the surface. After the blasthole is constructed, the bottom of the blasthole is blocked with a wooden sealing plug from the surface to prevent blockage by surface gravel. During blasting, the upward parallel medium-deep hole 9 and the last section of the blasthole of the downward parallel deep hole 11 are blasted in coordination, and the blasting arrangement lags slightly behind the blasting of the downward parallel deep hole 11 by more than 500ms to allow the rock to fully fall.

[0071] In the blasting of the downward parallel deep hole 11, the VCR spherical charge caving process is adopted, and the roof of the goaf is used as the free surface for blasting. The collapse height is 8 to 12 meters at a time. After the blasting, the length of the blasthole needs to be re-measured before the next blasting organization cycle can be carried out; the upward parallel medium-deep hole 9 blasting is carried out with the cutting skylight 10 as the free surface for blasting, and the collapse is carried out once. During the blasting construction, the downward parallel deep hole 11 is first blasted in layers, and the roof of the roof area is raised until the roof of the roof area is 10 to 15 meters away from the bottom of the rock drilling space, and then coordinated with the upward parallel medium-deep hole 9 blasting hole, and the blasting arrangement is slightly delayed by more than 500ms from the blasting of the downward parallel deep hole 11, so that the rock can fall fully.

[0072] When the rock drilling site needs to be arranged on the surface, there is no need to use upward blastholes to collapse the top plate of the rock drilling space. It is only necessary to consider whether the surface environment has the construction conditions. The downward parallel deep hole 11 collapse process is still the VCR spherical charge collapse process.

[0073] See also Figure 4 As shown, after the top of the caving area is broken, a super-large pressure relief channel is formed between the goaf 6 and the surface. In order to protect the safety of surface personnel and equipment, surface fencing and ground pressure monitoring work are required. When the goaf 6 collapses rapidly, further fencing work needs to be added according to the rock movement circle of the goaf 6.

[0074] The safety monitoring and early warning is a preventive measure to ensure the safety of construction personnel and equipment during the implementation of pressure relief and roof release. During the construction work in the drilling chamber 1, the ground pressure activity in the goaf 6 will be continuously monitored in combination with ground pressure monitoring means, such as ground pressure monitoring, microseismic monitoring, etc. The monitoring probe can be installed in the bottom plate, side wall or auxiliary ramp of the drilling chamber 1. When the monitoring early warning value is reached, the operating personnel should be notified in time to evacuate, and the changes in the goaf 6 should be further analyzed. When major changes occur in the goaf 6, the safety of the drilling chamber 1 is checked to determine whether the position of the drilling chamber 1 needs to be changed.

[0075] In summary, the present invention discloses a pressure relief and roof release method for accelerating the collapse of goaf, which is suitable for goafs where the surface is allowed to collapse and the burial depth is ≤100m. By arranging rock drilling chambers at appropriate positions underground and utilizing downward parallel deep holes and upward parallel medium-deep holes for blasting and collapse, a large range of rock mass is forced to be released in a local area, so that the goaf is completely exposed from the surface to form a shock wave pressure relief space, while the rock cover 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 filled or collapsed to the surface, thereby completely eradicating the hazards of the goaf. In this method, the amount of pressure relief and roof release engineering is relatively small. The working chamber is located underground, leaving a certain safety distance from the goaf. Point columns are set inside the chamber to support the roof, and there are several cutting shafts that penetrate the surface, accompanied by safety monitoring and early warning means. The construction environment is good and the safety is high. The blasthole rock drilling is divided into upward and downward hole construction. Multiple rock drilling equipment can be used for parallel construction to speed up the construction speed. At the same time, there are more blasting free faces, and the blasting construction technology is not difficult. The overall technical and economic benefits are obvious, and the implementation safety is high. For mines that use the caving method to treat goaf, the method has good application value. At the same time, it is also of great reference significance for other types of mines that use the caving method to treat goaf.

[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 the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A pressure relief and roof caving method for accelerating the collapse of goaf, characterized in that: The steps include: S1, goaf shape adjustment: find out the specific shape and scale of the goaf, and ensure that the existing goaf volume is 1.5 times greater than the top volume by caving the ore from the bottom; if the height of the goaf roof is greater than 100m from the ground surface, adopt the conventional forced caving method to continuously caving the top to meet the condition that the goaf burial depth is ≤100m; S2, caving structure and blasting engineering layout: arrange the rock drilling chamber at the predetermined position underground, as well as the rock drilling chamber auxiliary ramp and upward cutting shaft connected to the rock drilling chamber, and adopt the combined rock drilling operation of drilling upward parallel medium-deep holes and downward parallel deep holes to arrange the blast holes; S3, caving blasting construction and safety early warning monitoring: using the method of combined blasting and caving of downward parallel deep holes and upward parallel medium-deep holes, adopting the multi-stage blasting construction technology, a large-scale rock mass forced caving is formed in the local area; In addition, during the construction process, ground pressure monitoring methods are used to continuously monitor the ground pressure activities in the goaf.

2. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 1, characterized in that: In step S2, the drilling chamber is arranged along the strike length of the goaf, and is located within a range of 15 to 25 m below the ground surface, on the footwall side of the ore body, and the angle between the line above the goaf roof and the goaf side wall and the horizontal plane is greater than 60°, and the vertical distance between the drilling chamber and the goaf roof is greater than 1 / 2 of the span of the goaf roof.

3. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 1, characterized in that: In step S2, the top area of ​​extremely stable rock mass is controlled to be 800-1000m 2 , the area of ​​top caving for stabilizing rock mass should be controlled between 200 and 500 m 2 , the width or span is controlled at 10 to 20 meters.

4. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 1, characterized in that: In the blasthole arrangement of the combined rock drilling operation in step S2, the upper parallel medium-deep holes are constructed vertically on the top plate, with a hole diameter of 65-76 mm and a row spacing of 1.4-1.8 m; the downward parallel deep holes have an angle of ≥60° with the horizontal plane, a hole diameter of ≥150 mm, and the row spacing of the downward parallel deep holes is twice the row spacing of the upper parallel medium-deep holes.

5. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 1, characterized in that: In step S3, based on the downward parallel deep hole caving process and the upward parallel medium-deep hole caving process, the goaf roof is broken by the coordinated blasting method of the upward parallel medium-deep hole and the downward parallel deep hole multiple free surfaces. The specific process is as follows: First, the downward parallel deep hole layered blasting is carried out, with the goaf roof as the free surface and the one-time caving height of 8 to 12 m; the top plate of the top caving area is gradually raised until the top plate of the top caving area is 10 to 15 m away from the bottom plate of the rock drilling space; then, the remaining length blastholes are coordinated with the upward parallel medium-deep hole blastholes to break the goaf roof.

6. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 5, characterized in that: In the downward parallel deep hole caving process, the downward parallel deep hole penetrates deeply into the roof of the lower goaf, and the hole mouth is promptly blocked with a sealing plug after the blasthole is constructed; the VCR spherical charge caving process is adopted, and the goaf roof is used as the free surface for layered blasting. After the blasting, the length of the blasthole is remeasured before the next blasting organization cycle can be carried out.

7. A pressure relief and roof caving method for accelerating the collapse of goaf according to claim 5, characterized in that: In the upward parallel medium-deep hole collapse process, the upward parallel medium-deep hole uses a number of cut ceilings as free surfaces on the horizontal plane, and uses the surface and underground rock drilling chamber space, and the space formed by the lower rock falling as free surfaces on the vertical plane, and the hole depth penetrates the surface; after the blasthole is constructed, the bottom of the blasthole is blocked with a sealing plug from the surface; during blasting, the upward parallel medium-deep hole and the last section of the downward parallel deep hole are blasted in coordination, and the blasting arrangement lags slightly behind the blasting of the downward parallel deep hole by more than 500ms.

8. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 6, characterized in that: When the rock drilling site needs to be arranged on the surface, there is no need to use upward parallel medium-deep holes to collapse the top plate of the rock drilling space. The downward parallel deep hole collapse process is the VCR spherical charge collapse process.

9. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 1, characterized in that: In step S3, after the top of the caving area is broken, a super-large pressure relief channel is formed between the goaf and the surface, and surface enclosure and ground pressure monitoring work are carried out; when the goaf collapses rapidly, the enclosure work is further increased according to the rock movement circle of the goaf.

10. A method for decompression and roof caving to accelerate the collapse of goaf according to claim 2, characterized in that: In step S2, a predetermined number of point columns and strip columns of the rock drilling chamber are reserved inside the rock drilling chamber space for supporting the top plate.

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