Dynamic grading support system for underlying roadway roof of extremely close coal seam

Abstract

The utility model discloses a dynamic grading support system for an underlying roadway roof of an extremely close coal seam, which relates to the technical field of roadway support and comprises a dynamic surveying structure and a grading support structure which are used for surveying and supporting the underlying coal seam mining roadway roof. The underlying coal seam mining roadway roof comprises an upper coal seam goaf, a coal pillar area with an obviously developed upper coal seam fracture structure and a coal pillar area with a complete upper coal seam. According to the dynamic grading supporting system for the underlying roadway roof of the extremely close coal seam, supporting insufficiency of partial areas of a roadway and the roof management safety problem caused by supporting insufficiency can be effectively prevented; excessive support of partial areas of the roadway and the benefit problem caused by excessive support are effectively prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of roadway support, in particular to a dynamic hierarchical support system for the roof of a roadway under a very close coal seam. Background Technique

[0002] In coal mining activities, as the exploitation of single coal seams with good occurrence conditions is exhausted, many mining areas are faced with the problem of mining very close coal seam groups. In the mining of very close coal seam groups, the mining of the upper coal seam has a great influence on the mining of the underlying coal seam, especially in terms of the surrounding rock control of the roadway for the extraction of the underlying coal seam.

[0003] During the mining process of very close coal seam groups, goafs and remaining coal pillar groups are formed after the upper coal seam is mined. The coal pillars include stopped coal pillars, roadway safety coal pillars, working face section coal pillars, etc. The layout position and mining method of the working face for the extraction of the underlying coal seam may lead to various situations that the roof of the roadway for the extraction of the underlying coal seam may face. When the underlying roadway is arranged under the goaf of the upper coal seam or under the coal pillar group, the rock layer structure of the roadway roof is not the same. Therefore, it is unreasonable to generally adopt a single support scheme for one roadway. For example, when the underlying roadway is arranged under the goaf of the upper coal seam, the roof of the underlying roadway is damaged by the mining of the upper coal seam, resulting in discontinuous roof rock layer structure, unstable roof structure and prone to roof accidents; when the underlying roadway is arranged under coal pillars with less developed fissure structures such as roadway safety coal pillars of the overlying coal seam, the roof rock layer structure is continuous, basically the same as the roof situation in single coal seam mining, and the support difficulty is small; when the underlying roadway is arranged under coal pillars with more obvious fissure structures such as section coal pillars of the overlying coal seam, the support strength and scope should be strengthened to prevent the roof stress concentration from causing support failure. In addition, the underlying coal seam roadway may be arranged entirely under the goaf or under the coal pillar of the overlying coal seam, or may be partially under the goaf and partially under the coal pillar, etc. For very close coal seams, the distance between the interlayer rock layers also varies. Therefore, in practice, the roof conditions of the underlying roadway are different, and using the same support scheme for the roof of the underlying roadway will not be able to meet the roof management and control of the whole roadway.

[0004] Therefore, in order to overcome the drawbacks of blindly adopting a single support scheme for various roof conditions of the underlying roadway in the mining of very close coal seams, and effectively prevent the safety and benefit problems brought by insufficient or excessive support of the roadway roof, it is necessary to establish a dynamic hierarchical support system for the roof of the underlying roadway in very close coal seams. Content of the Utility Model

[0005] The purpose of the utility model is to provide a dynamic hierarchical support system for the roof of a roadway under a very close coal seam to solve the problems of low safety and low efficiency of a single support method for the roof of a roadway under a very close coal seam.

[0006] To achieve the above object, the utility model provides a dynamic hierarchical support system for the roof of the underlying roadway in extremely close coal seams, which includes a dynamic survey structure and a hierarchical support structure for surveying and supporting the roof of the underlying coal seam mining roadway. The roof of the underlying coal seam mining roadway includes the goaf of the upper coal seam, the coal pillar area with obvious development of fissure structures in the upper coal seam, and the intact coal pillar area of the upper coal seam. The roof dynamic survey structure and the hierarchical support structure are provided in the underlying coal seam mining roadways corresponding to the goaf of the upper coal seam, the coal pillar area with obvious development of fissure structures in the upper coal seam, and the intact coal pillar area of the upper coal seam.

[0007] Preferably, the dynamic survey structure includes multiple rows of peepholes opened on the roof of the underlying coal seam mining roadway, with three peepholes in each row; the three peepholes include a middle vertical peephole and two side top-angle peepholes, and the two side top-angle peepholes are 1 m away from both sides of the roadway and the inclination angles towards both sides of the roadway are set to 45°.

[0008] Preferably, the elongation rate of the high-strength anchor cable is greater than 3.5%, and the spacing of the high-strength anchor cables is set to 1500 - 2000 mm.

[0009] Preferably, the spacing of the high-prestressed anchor bolts is set to 600 - 800 mm, and the length is set to 2000 - 2400 mm.

[0010] Preferably, the hierarchical support structure for the roof of the underlying coal seam mining roadway corresponding to the goaf of the upper coal seam includes active support and passive support. The passive support includes the shed frames arranged in the section, and the active support includes the metal mesh arranged on the side walls. A plurality of high-prestressed anchor bolts are arranged around the outer periphery of the metal mesh, and the plurality of high-prestressed anchor bolts penetrate into the shallow rock formation of the roof of the underlying coal seam mining roadway. A plurality of high-strength anchor cables are arranged outside the metal mesh at the roof, and the plurality of high-strength anchor cables penetrate into the interlayer rock formation below the goaf of the upper coal seam.

[0011] Preferably, the shed frame includes a plurality of I-shaped steel plates, and adjacent two I-shaped steel plates are connected horizontally through buckles and vertically through buckles and high-strength rod bodies.

[0012] Preferably, the hierarchical support structures for the roofs of the underlying coal seam mining roadways corresponding to the coal pillar area with obvious development of fissure structures in the upper coal seam and the intact coal pillar area of the upper coal seam both include the metal mesh arranged in the section. A plurality of high-prestressed anchor bolts are arranged around the outer periphery of the metal mesh, and the plurality of high-prestressed anchor bolts penetrate into the shallow rock formation. A plurality of high-strength anchor cables are arranged outside the metal mesh at the roof; the high-strength anchor cables in the roof of the underlying coal seam roadway corresponding to the coal pillar area with obvious development of fissure structures in the upper coal seam grow and are anchored in the intact rock formation deep in the roof of the upper coal seam, and the high-strength anchor cables in the roof of the underlying coal seam roadway corresponding to the intact coal pillar area of the upper coal seam are anchored in the intact rock formation deep in the roof of the underlying coal seam.

[0013] Therefore, the utility model adopts a dynamic grading support system for the roof of the underlying roadway in extremely close coal seams with the above structure, which can effectively prevent the problem of insufficient support in some areas of the roadway and the safety problem of roof management caused by insufficient support to a certain extent; effectively prevent the problem of over-support in some areas of the roadway and the benefit problem caused by over-support; effectively control different situations of the rock stratum structure of the underlying roadway roof, and specifically improve the safety and long-term effectiveness of the roof support of the whole underlying roadway.

[0014] The technical solution of the utility model will be further described in detail below with reference to the drawings and embodiments. Brief Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of an embodiment of a dynamic grading support system for the roof of the underlying roadway in extremely close coal seams of the utility model;

[0016] Figure 2 It is a front view schematic diagram of the primary support structure of a dynamic grading support system for the roof of the underlying roadway in extremely close coal seams of the utility model;

[0017] Figure 3 It is a front view schematic diagram of the secondary support structure of a dynamic grading support system for the roof of the underlying roadway in extremely close coal seams of the utility model;

[0018] Figure 4 It is a front view schematic diagram of the tertiary support structure of a dynamic grading support system for the roof of the underlying roadway in extremely close coal seams of the utility model;

[0019] Reference numerals: 1, goaf of the upper coal seam; 2, coal pillar area with obvious development of fissure structure in the upper coal seam; 3, intact coal pillar area in the upper coal seam; 4, broken area of the floor of the goaf of the upper coal seam; 5, intact area of the floor of the goaf of the upper coal seam; 6, high-strength anchor cable; 7, high-prestressed bolt; 8, metal mesh; 9, shed. Detailed Embodiment

[0020] The technical solution of the utility model will be further described below with reference to the drawings and embodiments.

[0021] Unless otherwise defined, the technical terms or scientific terms used in this utility model shall have the ordinary meanings understood by those with ordinary skills in the field to which this utility model belongs. The "first", "second" and similar words used in this utility model do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0022] Embodiment

[0023] Please refer to Figures 1-4 , this utility model provides a dynamic hierarchical support system for the roof of the underlying roadway in extremely close coal seams, including a dynamic survey structure and a hierarchical support structure for surveying and supporting the roof of the underlying coal seam extraction roadway. The dynamic survey structure includes multiple rows of peepholes opened on the roof of the underlying coal seam extraction roadway, with three peepholes in each row; the three peepholes include a middle vertical peephole and two side apex peepholes, and the two side apex peepholes are 1 m away from both sides of the roadway and the inclination angles towards both sides of the roadway are set to 45°. The roof of the underlying coal seam extraction roadway includes the gob area 1 of the upper coal seam, the coal pillar area 2 with more obvious development of fissure structures in the upper coal seam, and the intact coal pillar area 3 of the upper coal seam. The roof dynamic survey structure and the hierarchical support structure are provided in the underlying coal seam extraction roadway corresponding to the gob area 1 of the upper coal seam, the coal pillar area 2 with more obvious development of fissure structures in the upper coal seam, and the intact coal pillar area 3 of the upper coal seam.

[0024] The dynamic survey structure includes roof basic borehole peeping at fixed intervals and refined peeping at the key roof areas at the boundaries of the gob areas of the upper coal seam, to determine the scope and fissure development status of the roof of the lower coal seam roadway under the gob area, under the deteriorated coal pillars and under the intact coal bodies, and to establish a hierarchical support method for different fissure states of the roof within their respective scopes.

[0025] In order to achieve the purpose of dynamic hierarchical classification of the roof rock formation structure, a combined survey method of basic borehole peeping and local refined peeping for the roof of the underlying coal seam extraction roadway is proposed, which specifically includes the following steps:

[0026] Step 1. Basic Borehole Peering: Conduct basic borehole peering on the roof of the underlying roadway at intervals of 20 m. Set 3 peering holes in each row for basic borehole peering. Among them, the peering hole in the middle of the roadway roof is perpendicular to the roof, and the peering holes on both sides of the roadway roof are 1 m away from both sides of the roadway and offset 45° towards both sides of the roadway. The borehole depth reaches the goaf of the upper coal seam or the roof of the coal pillar to understand the structure of the overlying strata of the roof.

[0027] Step 2. Local Refined Peering: Combine the mining engineering plane layout maps of the upper and lower coal seams to obtain the on-map coordinates at the junction of the coal pillar and the roof of the upper coal seam. Conduct local refined peering on the roof of the underlying roadway within a range of 10 m in the corresponding coordinate area. Open 3 rows of peering holes on the roof of the underlying roadway, with three peering holes arranged in each row, and the spacing is set at 5 m. After obtaining the accurate position of the change in the rock stratum structure of the roof of the underlying roadway, determine the position and axial range of the roof where the support plan needs to be changed.

[0028] Step 3. During the tunneling of the roadway in the underlying coal seam, conduct joint surveys on the roof along with the tunneling, and divide the roof into three categories according to the survey results: First, when the goaf of the upper coal seam can be directly peered, it is the roof of the roadway under the goaf, that is, the goaf 1 of the upper coal seam; Second, when the broken zone or fissure zone of the upper coal seam can be peered, this is the area that is significantly affected by mining and deteriorated and damaged, and it is the roof of the roadway under the deteriorated coal pillar (body), that is, the coal pillar area 2 with obvious fissure structure development in the upper coal seam; Third, when the intact coal body of the upper coal seam can be peered and there is no obvious broken zone until its roof, it is the roof of the roadway under the intact coal pillar (body), that is, the intact coal pillar area 3 of the upper coal seam. Corresponding to the three different roof conditions of the roof of the underlying roadway, establish three levels of support methods to form a dynamic grading support system.

[0029] In the mining of close-distance coal seams, some sections of the underlying roadway are located under the goaf 1 of the upper coal seam, some sections are located under the coal pillar area 2 with obvious fissure structure development in the upper coal seam, or some sections are located under the intact coal pillar area 3 of the upper coal seam. Determine the range and fissure development state of the lower coal seam roadway under the goaf, under the deteriorated coal pillar, and under the intact coal body according to the peering results of the dynamic survey structure, and establish a three-level support structure for different fissure states of the roof within their respective ranges.

[0030] The roof of the underlying roadway includes the goaf 1 of the upper coal seam, the coal pillar area 2 with obvious fissure structure development in the upper coal seam, and the intact coal pillar area 3 of the upper coal seam. Roadways are set in the intact coal pillar area 3 of the upper coal seam, the coal pillar area 2 with obvious fissure structure development in the upper coal seam, and the goaf 1 of the upper coal seam, and a grading support structure is set on the roadways. The grading support structure is divided into Grade I support, Grade II support, and Grade III support.

[0031] Class I support structure: The underlying roadway is located under the goaf. The combined active and passive support method is adopted. The classified support structure of the roof of the underlying coal seam roadway corresponding to the goaf 1 of the upper coal seam includes active support and passive support. The passive support includes the shed 9 set in the roadway. The shed 9 includes multiple I-shaped steel plates. Adjacent two I-shaped steel plates are connected horizontally through buckles and longitudinally through buckles and high-strength rod bodies. The shed 9 can be selected as U-shaped steel shed 9, I-shaped steel shed 9, single prop, etc. according to the actual situation on site, but it needs to meet the axial connection condition to ensure the overall stability of the passive support system.

[0032] The active support includes the metal mesh 8 set on the side wall of the roadway. A plurality of high-prestressed anchor bolts 7 are arranged around the outer periphery of the metal mesh 8. The plurality of high-prestressed anchor bolts 7 are inserted into the shallow rock stratum of the roof of the underlying coal seam roadway. The high-prestressed anchor bolts 7 are densely supported in the shallow rock stratum of the roof. The spacing of the high-prestressed anchor bolts 7 is set to 600 - 800 mm, and the length is set to 2000 - 2400 mm. A plurality of high-strength anchor cables 6 are arranged outside the metal mesh 8 at the roof. The plurality of high-strength anchor cables 6 are inserted into the interlayer rock stratum below the goaf 1 of the upper coal seam. The elongation rate of the high-strength anchor cables 6 is greater than 3.5%. The spacing of the high-strength anchor cables 6 is set to 1500 - 2000 mm. The high-strength anchor cables 6 are anchored in the interlayer rock stratum, and the length covers a relatively complete area of the basic roof. Its length should be less than the difference between the interlayer spacing and the depth of the fracture zone at the bottom of the observed goaf. The surrounding rock is laid with the metal mesh 8 to construct a high-strength reinforcement arch for the shallow roof surrounding rock.

[0033] Class II support structure: The underlying roadway is located under the coal pillar (body) with obvious development of fracture structure. The method mainly using active high-strength anchor cables 6 for support is adopted. The high-prestressed anchor bolts 7 are used to support the shallow rock stratum of the roof, the anchoring length of the high-strength anchor cables 6 is increased, and it is anchored into a relatively complete rock stratum area in the roof rock stratum of the upper coal seam, and the surrounding rock is laid with the metal mesh 8.

[0034] The classified support structure of the roof of the underlying coal seam roadway corresponding to the coal pillar area 2 with obvious development of fracture structure in the upper coal seam includes the metal mesh 8 set in the roadway. A plurality of high-prestressed anchor bolts 7 are arranged around the outer periphery of the metal mesh 8. The plurality of high-prestressed anchor bolts 7 are inserted into the shallow rock stratum of the coal pillar area 2 with obvious development of fracture structure in the upper coal seam. The spacing of the high-prestressed anchor bolts 7 is set to 600 - 800 mm, and the length is set to 2000 - 2400 mm. A plurality of high-strength anchor cables 6 are arranged above the metal mesh 8 at the roof. The high-strength anchor cables 6 in the roof of the underlying coal seam roadway corresponding to the coal pillar area with obvious development of fracture structure in the upper coal seam are lengthened and anchored into the complete rock stratum deep in the roof of the upper coal seam. The elongation rate of the high-strength anchor cables 6 is greater than 3.5%. The spacing of the high-strength anchor cables 6 is set to 1500 - 2000 mm.

[0035] Class Ⅲ support structure: When the underlying roadway is located under a complete coal pillar (body), a method mainly based on active high-strength support is adopted. High-strength prestressed anchor cables are used for support. The anchor cables are anchored in a relatively complete area of the roof rock layer of the coal seam covering the main roof, and a metal mesh is laid around the surrounding rock.

[0036] The graded support structure of the roof of the mined roadway in the underlying coal seam corresponding to the complete coal pillar area 3 of the upper coal seam includes a metal mesh 8 arranged in the roadway. A plurality of high-prestressed anchor bolts 7 are arranged around the outer periphery of the metal mesh 8. The plurality of high-prestressed anchor bolts 7 penetrate into the shallow rock layer of the complete coal pillar area 3 of the upper coal seam. The spacing of the high-prestressed anchor bolts 7 is set to 600 - 800 mm, and the length is set to 2000 - 2400 mm. A plurality of high-strength anchor cables 6 are arranged above the metal mesh 8. The high-strength anchor cables 6 in the roof of the underlying coal seam roadway corresponding to the complete coal pillar area 3 of the upper coal seam are anchored in the deep and complete rock layer of the roof of the underlying coal seam. The elongation rate of the high-strength anchor cables 6 is greater than 3.5%. The spacing of the high-strength anchor cables 6 is set to 1500 - 2000 mm, and the length is determined according to the development status of roof fissures of different types.

[0037] The construction steps of a dynamic graded support system for the roof of an underlying roadway in extremely close coal seams are as follows:

[0038] (1) Wall surface finishing: Cleaning the crushed rock and local rock blocks on the wall surface;

[0039] (2) Laying a metal mesh on the wall surface: Laying a diamond-shaped metal mesh on the wall surface;

[0040] (3) Drilling operation: Conducting basic borehole peeping and local refined peeping on the roof of the underlying roadway to understand the structure of the overlying rock layer of the roof and determine the precise position of the change in the structure of the roof rock layer of the underlying roadway. Refer to Figure 1 to classify the specific conditions of the overlying rock layer of the roof of the underlying roadway.

[0041] (4) Dynamically selecting the support plan: Selecting different support plans according to the classification of the specific conditions of the roof.

[0042] Refer to Figure 1 As shown, classify the conditions of the roof rock layer of the underlying roadway in extremely close coal seams. When the roof of the underlying roadway is in different situations of 1, 2, and 3, namely, when the roof of the underlying roadway is under the goaf of the upper coal seam, under the deteriorated coal pillar (body) of the upper coal seam, and under the complete coal pillar (body) of the upper coal seam, it is necessary to dynamically and hierarchically select the roof support plan during tunneling.

[0043] Example 1

[0044] Please refer to Figure 2, when the roof of the underlying roadway is under the gob area 1 of the upper coal seam, a Class I support structure is adopted. The support structure includes active support and passive support. The passive support includes the shed 9 arranged in the roadway, and the active support includes the wire mesh 8 arranged on the sidewall of the roadway. A plurality of high-prestressed bolts 7 are arranged around the periphery of the wire mesh 8, and the plurality of high-prestressed bolts 7 penetrate into the shallow rock stratum of the roof of the gob area 1 of the upper coal seam. A plurality of high-strength cable bolts 6 are arranged above the wire mesh 8, and the plurality of high-strength cable bolts 6 penetrate into the interlayer rock stratum of the gob area 1 of the upper coal seam. The mining of the upper coal seam causes a broken area 4 on the floor of the gob area, with a thickness of S. Below the broken area 4 on the floor of the gob area of the upper coal seam is the intact area 5 of the floor of the gob area of the upper coal seam. The anchoring length L of the high-strength cable bolt 6 should satisfy L≥H - S, where S is the depth of the damaged area caused by the mining of the upper coal seam on the floor of the gob area, and H is the vertical distance between the two coal seams. At the same time, it should be anchored to the basic roof of the gob area 1 of the upper coal seam.

[0045] Taking a roadway width of 5m as an example, the roof of the roadway is densely supported by high-prestressed bolts 7. 8 high-prestressed bolts 7 are arranged in each row, the spacing of the high-prestressed bolts 7 is set to 600mm, and the length is set to 2400mm. The high-strength cable bolts 6 adopt high-strength cable bodies, 4 high-strength cable bolts 6 are arranged in each row, the spacing of the high-strength cable bolts 6 is set to 1500mm, and the cable bodies of the high-strength cable bolts 6 at the positions near both sides of the roadway are offset about 15° outward.

[0046] Example 2

[0047] Please refer to Figure 3 , when the roof of the underlying roadway is under the coal pillar area 2 where the fissure structure of the upper coal seam is more developed, a Class II support structure is adopted. The support structure includes the wire mesh 8 arranged in the roadway. A plurality of high-prestressed bolts 7 are arranged around the periphery of the wire mesh 8, and the plurality of high-prestressed bolts 7 penetrate into the shallow rock stratum of the coal pillar area 2 where the fissure structure of the upper coal seam is more developed. A plurality of high-strength cable bolts 6 are arranged above the wire mesh 8, and the plurality of high-strength cable bolts 6 penetrate into the intact rock stratum of the coal pillar area 2 where the fissure structure of the upper coal seam is more developed.

[0048] Taking a roadway width of 5m as an example, when the roof of the underlying roadway is at the junction of the sectional coal pillar, gob area and safety coal pillar, at this time, the coal pillar fissures are more developed and it is difficult for the coal pillar to be anchored and stressed. The high-strength cable bolts 6 adopt high-strength cable bodies, 4 high-strength cable bolts 6 are arranged in each row, the spacing of the high-strength cable bolts 6 is set to 1500mm. 2 high-strength cable bolts 6 are arranged in the middle of the roadway and anchored to the stable area of the roof rock stratum of the upper coal seam, and the high-strength cable bolts 6 on both sides of the roadway are anchored to the stable area of the floor rock stratum of the upper coal seam. Dense support is adopted with high-prestressed bolts 7, 8 are arranged in each row, the spacing of the high-prestressed bolts 7 is set to 600mm, the length is set to 2400mm, and the cable bodies of the high-prestressed bolts 7 at the positions near both sides of the roadway are offset about 15° outward.

[0049] Example 3

[0050] Please refer to Figure 4 When the roof of the underlying roadway is in the intact coal pillar area 3 of the upper coal seam, a Class III support structure is adopted, including a wire mesh 8 arranged in the roadway. A plurality of high-prestressed bolts 7 are arranged around the outer periphery of the wire mesh 8. The plurality of high-prestressed bolts 7 penetrate into the shallow rock stratum of the intact coal pillar area 3 of the upper coal seam. A plurality of high-strength cable bolts 6 are arranged above the wire mesh 8. The plurality of high-strength cable bolts 6 penetrate into the intact rock stratum of the intact coal pillar area 3 of the upper coal seam.

[0051] When the roof of the underlying roadway is under a coal pillar with less developed fissures such as a safety coal pillar, at this time, the roof rock stratum of the underlying roadway is relatively stable, and the active support of the bolt and cable adopts the normal support method to support the roof of the coal seam. Taking a roadway width of 5 m as an example, the roof of the roadway is supported by high-prestressed bolts 7. Six high-prestressed bolts 7 are arranged in each row. The spacing of the high-prestressed bolts 7 is set to 800 mm, and the length is set to 2400 mm. The high-strength cable bolts 6 adopt high-strength cable bodies. The anchoring length of the high-strength cable bolts 6 is greater than the height of the basic roof of the coal seam. Four high-strength cable bolts 6 are arranged in each row. The spacing of the high-strength cable bolts 6 is set to 1500 mm. The cable bodies of the high-strength cable bolts 6 at the positions near both sides of the roadway are offset 15° outward.

[0052] Therefore, the dynamic grading support system for the roof of the underlying roadway in extremely close coal seams of the present utility model adopts the above structure, which can effectively prevent the problem of insufficient support in some areas of the roadway and the safety problem of roof management caused by insufficient support to a certain extent; effectively prevent the problem of over-support in some areas of the roadway and the benefit problem caused by over-support; effectively control different situations of the roof rock stratum structure of the underlying roadway, and specifically improve the safety and long-term effectiveness of the support for the entire roof of the underlying roadway.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit them. Although the present utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present utility model, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present utility model.

Claims

1. A dynamic graded support system for the roof of a tunnel under a very close coal seam, characterized by: It includes a dynamic survey structure and a graded support structure for surveying and supporting the roof of the underlying coal seam mining tunnel. The roof of the underlying coal seam mining tunnel includes the upper coal seam goaf area, the coal pillar area with obvious development of fracture structure in the upper coal seam and the complete coal pillar area of ​​the upper coal seam. The roof dynamic survey structure and the graded support structure are provided in the underlying coal seam mining tunnel corresponding to the upper coal seam goaf area, the coal pillar area with obvious development of fracture structure in the upper coal seam and the complete coal pillar area of ​​the upper coal seam.

2. The dynamic graded support system for the roof of a tunnel under a very close coal seam according to claim 1 is characterized by: The dynamic survey structure includes multiple rows of peepholes opened on the roof of the underlying coal seam mining tunnel, with three peepholes in each row; the three peepholes include a central vertical peephole and two side corner peepholes, and the two side corner peepholes are 1m away from both sides of the tunnel and the inclination angle to both sides of the tunnel is set to 45°.

3. The dynamic graded support system for the roof of a tunnel under a very close coal seam according to claim 2 is characterized by: The elongation of the high-strength anchor cable is greater than 3.5%, and the spacing of the high-strength anchor cables is set to 1500-2000mm.

4. The dynamic graded support system for the roof of a tunnel under a very close coal seam according to claim 3 is characterized by: The spacing of high prestressed anchor rods is set to 600-800mm and the length is set to 2000-2400mm.

5. The dynamic graded support system for the roof of a tunnel under a very close coal seam according to claim 1 is characterized by: The graded support structure of the roof of the underlying coal seam mining tunnel corresponding to the upper coal seam goaf includes active support and passive support. The passive support includes a scaffolding arranged in the section, and the active support includes a metal mesh arranged on the side wall. A plurality of high prestressed anchor rods are arranged around the outer periphery of the metal mesh. The plurality of high prestressed anchor rods are penetrated into the shallow rock layer of the roof of the underlying coal seam mining tunnel. A plurality of high-strength anchor cables are arranged outside the metal mesh at the roof. The plurality of high-strength anchor cables are penetrated into the interlayer rock layer below the upper coal seam goaf.

6. The dynamic graded support system for the roof of a tunnel under a very close coal seam according to claim 5 is characterized by: The scaffolding comprises a plurality of I-shaped steel plates, wherein two adjacent I-shaped steel plates are connected horizontally by buckles and longitudinally by buckles and high-strength rods.

7. The dynamic graded support system for the roof of a tunnel under a very close coal seam according to claim 1 is characterized by: The graded support structures of the roof of the mining roadway of the underlying coal seam corresponding to the coal pillar area with obvious development of fracture structure in the upper coal seam and the coal pillar area with complete upper coal seam both include a metal mesh arranged in the section, a plurality of high prestressed anchor rods are arranged around the outer periphery of the metal mesh, the plurality of high prestressed anchor rods are penetrated in the shallow rock strata, and a plurality of high-strength anchor cables are arranged outside the metal mesh at the roof; the high-strength anchor cables in the roof of the roadway of the lower coal seam corresponding to the coal pillar area with obvious development of fracture structure in the upper coal seam grow and are anchored in the complete rock strata deep in the roof of the upper coal seam, and the high-strength anchor cables in the roof of the roadway of the lower coal seam corresponding to the coal pillar area with complete upper coal seam are anchored in the complete rock strata deep in the roof of the lower coal seam.

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