False roof construction method under mixed cementitious body condition

Abstract

The invention provides a false roof construction method under a mixed cementitious body condition, relates to the technical field of mining and false roof construction, is suitable for extremely-broken and extremely-thick large ore bodies, and adopts a process of firstly constructing a grouting layer and an N-layer false roof and then constructing all false roofs. According to the method, on the premise that safety is guaranteed, the false roof forming process of the extremely-broken and extremely-thick large ore body can be achieved, meanwhile, a recoverable foundation is provided for a downward mining method, and therefore the purposes of reducing dilution losses and improving the economic benefits of mines are achieved. Moreover, the method not only can realize the penetrating work of the upper and lower walls of the extremely thick and large ore body, but also can avoid the defects caused by long-distance pipe-following drilling, advanced pipe roofs and the like; and the method has relatively wide practicability for many mines under the condition of ore rock crushing or mixed cementitious bodies or poor filling bodies caused by disordered mining in the early stage.

Description

Technical Field

[0001] The present application relates to the technical field of mining and false roof construction, and in particular to a false roof construction method under mixed cementing conditions. Background Art

[0002] With the continuous development of the mining industry, many mines are facing historical problems. Looking back, the disorderly mining, lack of long-term planning and design, lack of targeted problem solving, illegal mining and other reasons have caused the underground mining technical conditions of most old mines to be extremely complicated, and the underground resource losses are incalculable, which has caused a great waste of national resources. Based on the gradual innovation of technology, the gradual innovation of mining methods, and the new heights of green mining requirements, mining companies have begun to gradually change their mining thinking, recycle underground resources as much as possible, and count and reasonably design the recycling of valuable residual ores in the past. Although the current mining methods are relatively advanced, there are still problems that need to be broken through. For example, the false roof manufacturing process of the downward mining method, the traditional broken ore body is assumed to be simpler to manufacture, but due to the collapse caused by disorderly planning mining, the overlying ore rocks such as loose bodies and mixed cement bodies, the traditional means cannot bear the force or are difficult to excavate, making the downward mining method empty talk.

[0003] The traditional method of tunneling with one-time pipe drilling or advanced pipe shed and other support measures will face the problems of pipe drilling stuck, deviation, and even the inability to effectively implement pipe drilling when encountering mixed cement bodies; while advanced pipe sheds can be used step by step with shed support to tunnel in, but this will result in the first layer of false roof with small upward force points, or no force points, and there will be no force when making the second layer of false roof at the bottom, and safety cannot be guaranteed. In addition, due to the extremely broken and thick ore body, the surrounding area of ​​the ore body has collapsed due to disorderly mining, and historical reasons have not paid enough attention to filling, resulting in the appearance of mixed cement bodies on the overlying surface. The traditional mining method has poor recovery safety.

[0004] In view of this, it is necessary to study a false roof construction method under mixed cementing conditions to solve the above technical problems. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present invention provides a method for constructing a false roof under mixed cementing conditions. Under the premise of ensuring safety, this method can not only realize the false roof formation process of extremely broken and thick large ore bodies, but also provide a mineable basis for the downward mining method, thereby achieving the purpose of reducing depletion losses and improving the economic benefits of mines.

[0006] Based on the above technical purpose, the present invention provides a method for constructing a false roof under mixed cementing conditions, which is suitable for extremely broken and thick large ore bodies. The process of first constructing a grouting layer and N layers of false roofs and then constructing the entire false roof is adopted. The specific steps are as follows:

[0007] S1, constructing a grouting layer: arranging a vein tunnel in the footwall of the ore body, arranging holes in the horizontal and vertical directions to obtain a drilling unit, and further arranging N groups of drilling units in the horizontal direction; after the drilling of the holes is completed, grouting support treatment is performed on the holes to obtain a grouting layer;

[0008] S2, construct the first false roof: dig a rectangular tunnel with a predetermined cross-sectional size below the grouting layer, with a digging length of M; dig N groups of tunnels in the horizontal direction, and arrange N groups of drilling units accordingly, and the drill holes of the first false roof and the drill holes of the grouting layer are arranged in a vertically staggered manner; after the drilling of the holes is completed, the holes are grouting-supported, and the excavated tunnels are reinforced and meshed and filled, and the first false roof is obtained after the top is fully connected;

[0009] S3, construct the second false roof: continue to excavate a rectangular tunnel with a predetermined cross-sectional size under the first false roof using a "pin"-shaped staggered arrangement structure, with an excavation length of 2M; excavate N-1 groups of tunnels in the horizontal direction, and arrange N-1 groups of drilling units accordingly, and the drilling holes of the second false roof and the first false roof are arranged in a vertically staggered manner; after the drilling of the holes is completed, repeat the grouting support, reinforcement mesh laying, filling and roof connection processes in step S2 to obtain the second false roof;

[0010] S4, cyclic construction until the Nth layer of false roof is constructed: after the filling and curing of the N-1th layer of false roof reaches the designed strength, the Nth layer of tunnel is excavated, and the excavation length is N×M; a group of tunnels are excavated in the horizontal direction to complete the penetration of the lower plate and the upper plate of the ore body. After the tunnel is filled with reinforcement and mesh, the N layers of false roof formed present an "inverted triangle" structure in the vertical direction, and a staggered arrangement in the direction perpendicular to the ore body strike;

[0011] S5, construct the entire false roof: using the "inverted triangle" structure of the false roof as the base, gradually expand it in the direction of the ore body, and finally construct a false roof with an overall square structure.

[0012] As a further improvement of the present invention, after all the false roofs in step S5 are constructed, when lower mining is carried out, the first layer of access is arranged perpendicular to the ore body, and the second layer of access is arranged along the direction of the ore body, and a circular arrangement is performed in this way, thereby forming an upper and lower "cross-shaped" staggered access arrangement until the ore body is completely mined.

[0013] As a further improvement of the present invention, N=0.1×thickness of the ore body (N is an integer); wherein the thickness of the extremely broken and thick ore body is ≥40 meters.

[0014] As a further improvement of the present invention, M=12m~15m; in the drilling unit, a hole is arranged every 1m~1.5m horizontally, 3~4 holes are arranged at a time, and a hole is arranged every 1m~1.5m vertically, 2~3 rows of holes are arranged at a time.

[0015] As a further improvement of the present invention, in step S2, the cross-sectional dimensions of the rectangular tunnel are A×B, wherein A=3m~4m, and B=3m~4m.

[0016] As a further improvement of the present invention, in step S2, tunnel excavation is carried out in a method of excavating one tunnel at a time.

[0017] As a further improvement of the present invention, in step S2, the drilling arrangement position of the first layer of false ceiling is staggered at a height C with respect to the drilling holes of the upper grouting layer in the vertical direction, wherein C=0.5m-1.5m.

[0018] As a further improvement of the present invention, C=1m~1.5m.

[0019] As a further improvement of the present invention, in step S4, the lower plate and the upper plate of the ore body are completely penetrated to form a stepped isolation layer with a maximum thickness of nearly B×(N+1).

[0020] As a further improvement of the present invention, in steps S1 to S4, after the drilling of the borehole is completed, the borehole is immediately grouting, and the grouting tube remains in the borehole after the grouting is completed; in steps S2 to S4, all the grouting anchor rods and grouting anchor cables are staggered with the positions of the grouting tubes of the upper layer of boreholes to form a three-dimensional hierarchical support system.

[0021] As a further improvement of the present invention, the grouting anchor adopts a grouting anchor while drilling; the grouting anchor while drilling includes a flexible drill rod and an adaptive impact drill bit; one end of the flexible drill rod is connected to the adaptive impact drill bit, and the other end is connected to a drive motor; the drive motor is started to drive the flexible drill rod to rotate, so as to drive the adaptive impact drill bit to perform rotational drilling.

[0022] Beneficial effects:

[0023] 1. The false roof construction method under mixed cementing conditions provided by the present invention can not only realize the false roof formation process of extremely broken and thick large ore bodies under the premise of ensuring safety, but also provide a mineable basis for the downward mining method, thereby achieving the purpose of reducing dilution losses and improving the economic benefits of mines.

[0024] 2. The false roof construction method under mixed cementation provided by the present invention can not only realize the penetration work of the upper and lower plates of extremely thick and large ore bodies, but also avoid the disadvantages of long-distance pipe drilling and advanced pipe racking. It has a wide range of practicality for many mines with conditions such as ore rock fragmentation, mixed cementation or poor filling bodies caused by disorderly mining in the early stage.

[0025] 3. The false roof construction method under the mixed cementation conditions provided by the present invention forms an "inverted triangle" engineering layout in the vertical height direction, and forms a stepped staggered layout in the vertical ore body strike direction, thereby reducing the pressure brought by the overall overlying mixed cementation body, while completely connecting the upper and lower plates to form an extremely thick stepped isolation layer, laying the foundation for safe mining at the lower part; and, after the entire false roof design is completed, during lower mining, the first-level approach is arranged perpendicular to the ore body, the second-level approach is arranged along the strike of the ore body, and the third-level approach is arranged perpendicular to the strike of the ore body, thereby forming a "cross-shaped" staggered approach arrangement of the upper and lower layers in a cycle, further alleviating the mine pressure brought by the overlying mixed cementation body and the false roof.

[0026] 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

[0027] 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.

[0028] Figure 1 It is a schematic diagram of the construction structure of the grouting layer of the false roof construction method under the mixed cementing body condition provided in Example 1 of the present invention;

[0029] Figure 2 It is a schematic diagram of the construction structure of the first layer of the false roof in the false roof construction method under the condition of mixed cementing body provided in Example 1 of the present invention;

[0030] Figure 3 Schematic diagram of the construction structure of the second layer of the false roof in the false roof construction method under the condition of mixed cementing body provided in Example 1 of the present invention

[0031] Figure 4 It is a schematic diagram of the construction structure of the third layer of the false roof in the false roof construction method under the condition of mixed cementing body provided in Example 1 of the present invention;

[0032] Figure 5It is a schematic diagram of the construction structure of the fourth-layer false ceiling of the false ceiling construction method under the condition of mixed cementing body provided in Example 1 of the present invention;

[0033] Figure 6 It is a schematic diagram of the construction structure of the fifth false ceiling of the false ceiling construction method under the condition of mixed cementing body provided in Example 1 of the present invention;

[0034] Figure 7 It is a schematic structural diagram of the first-layer approach and the second-layer approach of the false roof construction method under mixed cementing conditions provided in Example 1 of the present invention;

[0035] Figure 8 It is a structural schematic diagram of a false roof with an "inverted triangle" structure in the false roof construction method under mixed cementing conditions provided in Example 1 of the present invention;

[0036] Fig. 9 It is a schematic structural diagram of a grouting-while-drilling anchor cable in a false roof construction method under mixed cementing conditions provided in Example 1 of the present invention;

[0037] Fig.10 It is a schematic diagram of the cross-sectional structure of the grouting-while-drilling anchor cable of the false roof construction method under the mixed cementing body conditions provided in Example 1 of the present invention.

[0038] Description of reference numerals:

[0039] 1. Ore body; 2. High-strength filling body; 3. Grouting flower tube; 4. Mixed cementing body; 5. Grouting anchor rod; 6. Grouting anchor cable;

[0040] 7. Hollow casing; 8. Steel strand; 9. Internal high-pressure grouting pipe; 10. Flexible drill rod; 11. High-pressure water pipe; 12. External high-pressure grouting pipe; 13. Adaptive impact drill bit; 14. Drilling. DETAILED DESCRIPTION

[0041] The following embodiments of the technical solution of the present application will be 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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).

[0047] 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.

[0048] 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.

[0049] In order to solve the problem of conventional excavation methods using one-time follow-up pipe drilling or advanced pipe shed and other support measures, the following pipe drilling may be stuck, skewed, or even unable to be effectively implemented when encountering mixed cementing bodies; and the advanced pipe shed and the like can be excavated step by step with the support of the shed, but this will result in a small upward force point for the first layer of false roof, or no force point, and there will be no force to be applied when making the second layer of false roof at the bottom, and safety cannot be guaranteed; and, based on extremely broken and thick large ore bodies, the periphery of the ore bodies has collapsed due to disorderly mining, and historical reasons have not paid enough attention to filling, resulting in the appearance of mixed cementing bodies on the overlying surface, and many technical problems of poor recovery safety of traditional mining methods, the present invention provides a false roof construction method under mixed cementing body conditions, which is suitable for extremely broken and thick large ore bodies, and adopts a process of first constructing a grouting layer and N layers of false roofs and then constructing all false roofs, and the specific steps are as follows:

[0050] S1, constructing a grouting layer: arranging a vein tunnel in the footwall of the ore body, arranging holes in the horizontal and vertical directions to obtain a drilling unit, and further arranging N groups of drilling units in the horizontal direction; after the drilling of the holes is completed, grouting support treatment is performed on the holes to obtain a grouting layer;

[0051] S2, construct the first false roof: dig a rectangular tunnel with a predetermined cross-sectional size below the grouting layer, with a digging length of M; dig N groups of tunnels in the horizontal direction, and arrange N groups of drilling units accordingly, and the drill holes of the first false roof and the drill holes of the grouting layer are arranged in a vertically staggered manner; after the drilling of the holes is completed, the holes are grouting-supported, and the excavated tunnels are reinforced and meshed and filled, and the first false roof is obtained after the top is fully connected;

[0052] S3, construct the second false roof: continue to excavate a rectangular tunnel with a predetermined cross-sectional size under the first false roof using a "pin"-shaped staggered arrangement structure, with an excavation length of 2M; excavate N-1 groups of tunnels in the horizontal direction, and arrange N-1 groups of drilling units accordingly, and the drilling holes of the second false roof and the first false roof are arranged in a vertically staggered manner; after the drilling of the holes is completed, repeat the grouting support, reinforcement mesh laying, filling and roof connection processes in step S2 to obtain the second false roof;

[0053] S4, cyclic construction until the Nth layer of false roof is constructed: after the filling and curing of the N-1th layer of false roof reaches the designed strength, the Nth layer of tunnel is excavated, and the excavation length is N×M; a group of tunnels are excavated in the horizontal direction to complete the penetration of the lower plate and the upper plate of the ore body. After the tunnel is filled with reinforcement and mesh, the N layers of false roof formed present an "inverted triangle" structure in the vertical direction, and a staggered arrangement in the direction perpendicular to the ore body strike;

[0054] S5, construct the entire false roof: using the "inverted triangle" structure of the false roof as the base, gradually expand it in the direction of the ore body, and finally construct a false roof with an overall square structure.

[0055] Preferably, after all the false roofs in step S5 are constructed, when lower mining is carried out, the first layer of access is arranged perpendicular to the ore body, and the second layer of access is arranged along the direction of the ore body, and a cycle is performed in this way, thereby forming a "cross-shaped" staggered access arrangement of the upper and lower layers until the ore body is completely mined.

[0056] Preferably, N=0.1×thickness of the ore body; wherein the thickness of the extremely broken and thick ore body is ≥40 meters.

[0057] Preferably, M=12m~15m; in the drilling unit, a hole is arranged every 1m~1.5m horizontally, 3~4 holes are arranged at a time, and a hole is arranged every 1m~1.5m vertically, 2~3 rows of holes are arranged at a time.

[0058] Preferably, in step S2, the cross-sectional dimensions of the rectangular tunnel are A×B, wherein A=3m-4m, and B=3m-4m.

[0059] Preferably, in step S2, tunnel excavation is carried out in a one-to-one excavation manner.

[0060] Preferably, in step S2, the drilling arrangement positions of the first layer of false ceiling are staggered at a height C in the vertical direction with the drilling holes of the upper grouting layer, wherein C=0.5m-1.5m.

[0061] Preferably, in step S4, the lower plate and the upper plate of the ore body are completely penetrated to form a stepped isolation layer with a maximum thickness of approximately B×(N+1).

[0062] Preferably, in steps S1 to S4, after the drilling of the borehole is completed, the borehole is immediately grouting, and the grouting tube remains in the borehole after the grouting is completed; in steps S2 to S4, all the grouting anchor rods and grouting anchor cables are staggered with the positions of the grouting tubes of the upper layer of boreholes to form a three-dimensional hierarchical support system.

[0063] Preferably, the grouting anchor cable adopts a grouting anchor cable while drilling; the grouting anchor cable while drilling is composed of a shell, a steel strand, a hollow casing, a high-pressure water pipe, an internal high-pressure grouting pipe, an external high-pressure grouting pipe, a flexible drill rod, an adaptive impact drill bit and the like, one end of the flexible drill rod is connected to an adaptive impact drill bit, and the other end is connected to a drive motor; the drive motor is started to drive the flexible drill rod to rotate, so as to drive the adaptive impact drill bit to perform rotary drilling. The specific operation steps are as follows: the flexible drill rod is connected to the adaptive impact drill bit, the flexible drill rod is covered with a hollow casing, the inner wall of the hollow casing is symmetrically connected to the high-pressure water pipe and the internal high-pressure grouting pipe, the steel strand is installed on the periphery of the hollow casing, the steel strand is tightly combined with the hollow casing, and plum blossom holes are arranged on the steel strand and the hollow casing for high-pressure water flow to flush the dust generated while drilling and high-pressure grouting, and the gap between the outermost steel strand and the borehole is symmetrically installed with an external high-pressure grouting pipe, which is used to further tightly combine the anchor cable with the borehole wall to form an anchor support body.

[0064] Example 1

[0065] For the extremely broken and thick ore body 1 with a vertical strike length of about 50m, the upper part of the ore body 1 collapsed due to disorderly mining and was later covered by a low-strength cementing filling body, forming a mixed cementing body with the broken ore rock. Please refer to the environmental conditions Figures 1 to 8 As shown, the present invention provides a false roof construction method under mixed cementing conditions, comprising the following steps:

[0066] S1, construct grouting layer: please refer to Figure 1 As shown, a tunnel along the vein is arranged at a position of about 5m below the lower plate of the ore body 1. In the tunnel, a hole is drilled in the mixed cement body 4 using traditional pipe drilling. The length of the hole is 15m, of which 5m is retained in the original rock of the lower plate, and 10m is drilled into the mixed cement body 4. The length of the hole is relatively close, which can ensure the position of the hole and the speed of drilling. A hole is arranged every 1m horizontally, and 4 holes are arranged at a time. A hole is arranged every 1m vertically, and 3 rows of holes are arranged at a time. A total of 12 holes are arranged in the horizontal and vertical directions. 12 holes form a group, and a total of 5 groups of holes are arranged in the horizontal direction; after the drilling of the hole is completed, the hole is immediately grouting. After the grouting is completed, the grouting flower tube 3 is left in the hole to play the role of a horizontal anchor. Thus, a grouting layer is obtained.

[0067] S2, build the first false roof: please refer to Figure 2As shown, after the strength of the grouting body in the layer to be grouted reaches the design requirements, a rectangular roadway with a cross-section of 4.0 m × 3.0 m is driven below it, with a driving length of 12 m. Grouting bolts 5 and grouting cables 6 are used for three-dimensional stepped support, and the support parameters of the grouting bolts 5 and grouting cables 6 are arranged in a staggered manner according to the positions of the upper drill holes and the grouting perforated pipes 3. The driving of the roadway adopts the method of driving one and leaving one. Initially, 3 roadways are driven, and the length of each roadway is 12 m. After the roadway is driven to the 12 m position, drill holes are arranged in the manner described in step S1 above. At this time, the arrangement position of the drill holes is staggered by about 1 m in the vertical height direction from the upper drill holes, the length of the drill holes is 15 m. After the drilling of the drill holes is completed, the drill holes are immediately grouted. After the grouting is completed, the grouting perforated pipes 3 remain in the drill holes to play the role of horizontal bolts. After the grouting of the drill holes is completed, the first-driven 12 m roadway is reinforced with steel bars and meshed, and the 12 m roadway is filled in the normal downward drift false roof arrangement method, and the roof is fully contacted. After all 3 initially-driven roadways are filled, they are left standing until their strength reaches the design requirements of the high-strength filling body 2. Then, the remaining 2 adjacent roadways are driven again. The cross-section size and length of the driving are the same as those of the initial driving. At the same time, the previous steps of drilling, grouting, filling, etc. are repeated to obtain the first layer of false roof.

[0068] S3. Construct the second layer of false roof: Please refer to Figure 3 As shown, after all the filling work of the 5 roadways in the above-mentioned first layer of false roof is completed, roadways are continuously driven in a staggered "pin" shape arrangement below it. At this time, the number of roadways driven in the second layer is 4, the cross-section specification of the driving is 4.0 m × 3.0 m, and the driving length is 24 m. The same method of driving one and leaving one is also adopted. When the roadway is driven to the 24 m position, the drilling grouting method is continued to drill forward for 15 m. The drill holes in this layer are still staggered by about 1 m in the vertical height direction from the upper drill holes, and the grouting perforated pipe 3 is used for grouting. After the grouting is completed, the grouting perforated pipe 3 remains in the drill hole to play the role of a horizontal bolt. After grouting, each roadway is reinforced with steel bars, meshed, filled, etc. until all are completed, and thus the second layer of false roof is obtained.

[0069] S4. Construct the third layer of false roof: Please refer to Figure 4 As shown, after all the filling and curing of the above-mentioned second layer reach the design strength, the third layer starts to be driven. The third layer also adopts a staggered "pin" shape arrangement. At this time, only 3 roadways can be driven in the third layer. The same method of driving one and leaving one is also adopted. The cross-section specification of the driving is 4.0 m × 3.0 m, and the driving length is 36 m. After the driving is completed, drilling and grouting are carried out. The length of the drill holes is 15 m. The drill holes in this layer are still staggered by about 1 m in the vertical height direction from the upper drill holes, and the grouting perforated pipe 3 is used for grouting. After the grouting is completed, the grouting perforated pipe 3 remains in the drill hole to play the role of a horizontal bolt. After grouting, each roadway is reinforced with steel bars, meshed, filled, etc. until all are completed, and thus the third layer of false roof is obtained.

[0070] S5, Construct the fourth false roof: Please refer to Figure 5 As shown, after all the above-mentioned third layer is filled and cured to reach the design strength, the fifth layer of roadway excavation is carried out. There are only 2 roadways in the fourth layer, and the excavation section specification is 4.0m×3.0m. The two roadways are excavated in batches, with an excavation length of 48m. After the excavation is completed, grouting is carried out through drilling. The drilling length is 15m. There is still about 1m stagger in the vertical height direction between the drill holes in this layer and the upper drill holes, and grouting is carried out using the grouting perforated pipe 3. After the grouting is completed, the grouting perforated pipe 3 remains in the drill hole to play the role of a horizontal bolt. After grouting, work such as laying steel bars, weaving wire meshes, and filling is carried out for each roadway until all are completed, and thus the fourth false roof is obtained.

[0071] S6, Construct the fifth false roof: Please refer to Figure 6 As shown, after all the above-mentioned fourth layer is filled and cured to reach the design strength, the fifth layer of roadway excavation is carried out. According to the "pin" - shaped staggered arrangement, only one roadway is excavated in this layer. The excavation section specification is 4.0m×3.0m, and the excavation length is 60m. This roadway has completed the penetration from the footwall to the hanging wall of the ore body 1. After the excavation is completed, the roadway is laid with steel bars, woven wire meshes, and filled. At this time, both the footwall and the hanging wall ends of the roadway are on the original rock.

[0072] After all the above work is completed, a "reverse triangle" engineering layout form is formed in the vertical height direction of the ore body 1, and a stepped staggered layout is formed in the vertical strike direction of the ore body 1. Thus, the pressure brought by the overall overlying mixed cemented body 4 can be reduced, and at the same time, the footwall and the hanging wall are completely penetrated, forming a stepped isolation layer with a maximum thickness of nearly 18m, laying a foundation for the safe mining of the lower part.至此第一步工作全部结束。上述所有掘进巷道全部采用注浆锚杆5、注浆锚索6与上部钻孔注浆花管3位置交错布置,形成立体级式支护系统。所述注浆锚索6采用一种新型随钻注浆锚索。

[0073] Please refer to Fig. 9 and Fig.10 As shown, the grouting - while - drilling anchor cable is composed of a steel strand 8, a hollow casing 7, a high - pressure water pipe 11, an internal high - pressure grouting pipe 9, an external high - pressure grouting pipe 12, a flexible drill pipe 10, an adaptive impact drill bit 13, etc. Among them, the other end of the flexible drill pipe 10 is connected to a driving motor (not shown in the figure). The driving motor is started to drive the flexible drill pipe 10 to rotate, so as to drive the adaptive impact drill bit 13 to rotate for drilling. The adaptive impact drill bit 13 is rotatably connected to the hollow casing 7. Specifically, a circular ring rotary connector is arranged at the end of the hollow casing 7, and the bottom of the adaptive impact drill bit 13 is connected to the circular ring rotary connector, so as to realize the rotation of the adaptive impact drill bit 13 driven by the flexible drill pipe 10 while the hollow casing 7 remains relatively stationary.

[0074] The flexible drill rod 10 is connected to the adaptive impact drill bit 13. The flexible drill rod 10 is covered with a hollow casing 7. The inner wall of the hollow casing 7 is symmetrically connected to a high-pressure water pipe 11 and a built-in high-pressure grouting pipe 9. A steel strand 8 is installed on the periphery of the hollow casing 7. The steel strand 8 is tightly combined with the hollow casing 7, and plum blossom holes are arranged on the steel strand 8 and the hollow casing 7 for high-pressure water flow to flush dust generated while drilling and high-pressure grouting. The gap between the outermost steel strand 8 and the drill hole is symmetrically installed with an external high-pressure grouting pipe 12.

[0075] Start the drive motor to drive the flexible drill rod 10 to rotate, so as to drive the adaptive impact drill bit 13 to perform rotary drilling. Synchronously start the high-pressure water injection process, and the high-pressure water in the high-pressure water pipe 11 is used to clean the gravel and dust generated by drilling, and impact the gravel and dust to the outside of the borehole 14. Until the adaptive impact drill bit 13 drills to a predetermined depth, turn off the drive motor. Then, after the gravel and dust are cleaned by the high-pressure water pipe 11, start the high-pressure grouting process, and inject the anchor slurry synchronously through the internal high-pressure grouting pipe 9 and the external high-pressure grouting pipe 12, so that the anchor slurry fills the entire internal space of the grouting anchor cable suitable for extremely broken ore and rock conditions and the gap between the anchor cable and the borehole 14, and tightly anchors the anchor cable to the wall of the borehole 14 to form a stable anchor support body.

[0076] S7, build all false ceilings: After all the above work is completed, please refer to Figure 8 As shown, with the "inverted triangle" layout structure as the false roof base, the excavation process is gradually carried out in the direction of the ore body 1, and the step-by-step downward excavation work and subsequent drilling, grouting and support work are repeated to realize the entire false roof design in the direction of the ore body 1 step by step, preparing for the next step of mining until a complete rectangular artificial false roof is formed.

[0077] S8, please refer to Figure 7 As shown, after the design of all the false roofs is completed, during lower mining, the first layer of access is arranged perpendicular to the ore body 1, the second layer is arranged along the direction of the ore body 1, and the third layer is arranged perpendicular to the direction of the ore body 1. This pattern is used for cyclic arrangement, thereby forming a "cross-shaped" staggered arrangement of the upper and lower layers, further alleviating the mine pressure caused by the overlying mixed cementation body 4 and the false roof.

[0078] In summary, the present invention provides a method for constructing a false roof under mixed cementing conditions, which is suitable for extremely broken and thick large ore bodies, and adopts a process of first constructing a grouting layer and N layers of false roofs and then constructing all the false roofs. Under the premise of ensuring safety, this method can not only realize the false roof formation process of extremely broken and thick large ore bodies, but also provide a mining basis for the downward mining method, thereby achieving the purpose of reducing depletion losses and improving the economic benefits of the mine. In addition, this method can not only realize the penetration work of the upper and lower plates of extremely thick large ore bodies, but also avoid the disadvantages brought about by long-distance pipe drilling and advanced pipe sheds; it has a wide range of practicality for many mines with conditions such as broken ore rocks or mixed cementing bodies or poor filling bodies caused by disorderly mining in the early stage. An "inverted triangle" engineering layout is formed in the vertical height direction, and a stepped staggered layout is formed in the vertical ore body strike direction, which can reduce the pressure brought by the overall overlying mixed cementation body. At the same time, the upper and lower plates are completely connected to form an extremely thick stepped isolation layer, laying the foundation for safe mining in the lower part. Moreover, after the design of all false roofs is completed, when mining in the lower part, the first approach is arranged perpendicular to the ore body, the second approach is arranged along the strike of the ore body, and the third approach is arranged perpendicular to the strike. The circular arrangement forms an upper and lower "cross-shaped" staggered approach layout, which further alleviates the mine pressure brought by the overlying mixed cementation body and the false roof.

[0079] 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 method for constructing a false roof under mixed cementing conditions, characterized in that: Applicable to extremely fragmented and extremely thick ore bodies, the process of first constructing a grouting layer and N false roofs and then constructing all the false roofs is as follows: S1. Construct the grouting layer: Layout a drift along the footwall of the ore body, drill holes in the horizontal and vertical directions respectively to obtain a drilling unit, and further layout N groups of drilling units in the horizontal direction; after the drilling is completed, carry out grouting support treatment on the drill holes to obtain the grouting layer; S2. Construct the first false roof: Drive a rectangular roadway with a predetermined cross-sectional size under the grouting layer, and the driving length is M; drive N groups of roadways in the horizontal direction, and correspondingly layout N groups of drilling units. The drill holes of the first false roof are arranged in a vertical dislocation with the drill holes of the grouting layer; after the drilling is completed, carry out grouting support treatment on the drill holes, and carry out steel bar laying, net weaving and filling work on the driven roadway. After fully contacting the roof, the first false roof is obtained; S3. Construct the second false roof: Continue to drive a rectangular roadway with a predetermined cross-sectional size under the first false roof in a "pin" shape staggered layout structure, and the driving length is 2M; drive N-1 groups of roadways in the horizontal direction, and correspondingly layout N-1 groups of drilling units. The drill holes of the second false roof are arranged in a vertical dislocation with the drill holes of the first false roof; after the drilling is completed, repeat the grouting support, steel bar laying, net weaving, filling and roof contacting processes in step S2 to obtain the second false roof; S4. Carry out cyclic construction until the Nth false roof is constructed: After the filling and curing of the (N-1)th false roof reach the design strength, carry out the driving of the Nth roadway, and the driving length is N×M; drive 1 group of roadways in the horizontal direction to complete the penetration of the footwall and hanging wall of the ore body. After the roadway is steel bar laid, net woven and filled, the N false roofs formed are arranged in an "inverted triangle" structure in the vertical direction and in a stepped staggered layout in the direction perpendicular to the ore body strike; S5. Construct all the false roofs: Taking the false roof with an "inverted triangle" structure as the base, gradually expand it in the direction of the ore body strike, and finally construct a false roof with an overall square structure.

2. The method for constructing a false roof under mixed cementing conditions according to claim 1, characterized in that: After the construction of all the false roofs in step S5 is completed, when mining the lower part, the first drift is arranged vertically to the ore body, and the second drift is arranged along the ore body strike, and cycle the layout in this way, thus forming a "cross-shaped" staggered drift layout of the upper and lower layers until the entire ore body is mined out.

3. The method for constructing a false roof under mixed cementing conditions according to claim 1, characterized in that: N = 0.1×ore body thickness; wherein, the ore body thickness of the extremely fragmented and extremely thick ore body ≥ 40 m.

4. The method for constructing a false roof under mixed cementing conditions according to claim 1, characterized in that: M = 12m - 15m; in the drilling unit, one hole is arranged every 1m - 1.5m horizontally, and 3 - 4 holes are arranged at one time, and one hole is arranged every 1m - 1.5m vertically, and 2 - 3 rows of holes are arranged at one time.

5. The method for constructing a false roof under mixed cementing conditions according to claim 3, characterized in that: In step S2, the cross-sectional size of the rectangular roadway is A×B, wherein, A = 3m - 4m, B = 3m - 4m.

6. The method for constructing a false roof under mixed cementing conditions according to claim 1, characterized in that: In step S2, the roadway driving is carried out in the way of driving one and leaving one.

7. The method for constructing a false roof under mixed cementing conditions according to claim 3, characterized in that: In step S2, the staggered height of the drill hole layout position of the first false roof in the vertical direction from the drill holes of the upper grouting layer is C, wherein, C = 1m - 1.5m.

8. The method for constructing a false roof under mixed cementing conditions according to claim 5, characterized in that: In step S4, the footwall and hanging wall of the ore body are completely penetrated to form a stepped isolation layer with a maximum thickness of nearly B×(N + 1).

9. The method for constructing a false roof under mixed cementing conditions according to claim 1, characterized in that: In steps S1 to S4, after the drilling of the borehole is completed, the borehole is immediately grouting, and the grouting tube remains in the borehole after the grouting is completed; in steps S2 to S4, all the grouting anchor rods and grouting anchor cables are staggered with the positions of the grouting tubes of the upper layer of boreholes to form a three-dimensional support system.

10. The method for constructing a false roof under mixed cementing conditions according to claim 9, characterized in that: The grouting anchor cable adopts a grouting anchor cable while drilling; the grouting anchor cable while drilling includes a flexible drill rod and an adaptive impact drill bit; one end of the flexible drill rod is connected to the adaptive impact drill bit, and the other end is connected to a driving motor; the driving motor is started to drive the flexible drill rod to rotate, so as to drive the adaptive impact drill bit to perform rotational drilling.

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