Large-span roadway interchange structure in coal mine and its construction method

Abstract

The present invention relates to the technical field of coal mines, and specifically to a large-span roadway interchange structure in coal mines and its construction method. In order to solve the problem that there are many defects in the traditional commonly used large-span interchange structures, a new large-span roadway interchange structure in coal mines is provided, which includes an upper roadway and a lower roadway. A thin rock layer is left at the intersection of the upper roadway and the lower roadway in an overpass manner. The bottom of the upper roadway is paved with an upper anchor net, and a middle steel beam and a plurality of upper steel beams are arranged on the upper anchor net. The top of the lower roadway is paved with a lower anchor net, and a plurality of lower steel beams are arranged under the lower anchor net. A plurality of first tension anchor cables are anchored between each upper steel beam and the lower spacing. Oblique tension anchor cables are respectively anchored between the two ends of each lower steel beam and the solid rock on both sides of the side walls of the upper roadway. Second tension anchor cables are anchored between the middle of each lower steel beam and the middle steel beam. This structure applies the four-side fixed plate theory to reinforce the thin rock layer in the large-span interchange structure.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mines, in particular to the technical field of construction at the intersection of large-span roadways in coal mines, and specifically to a large-span roadway interchange structure in coal mines and its construction method. Background Art

[0002] The construction at the intersection of large-span roadways in coal mines has an important impact on the construction period, cost, connection and safety of the mine. For the intersection of coal mine roadways on the same level, according to the positional relationship, it is divided into flat intersection and interchange. For a flat intersection, that is, the top and bottom plates of the two roadways at the intersection are respectively connected through, which is more common and easier to construct. In the following situations, in order to avoid system interference, an interchange is required, that is, the driving roadway at the intersection passes through from above or below the existing roadway, and the two roadways are isolated up and down and do not communicate: (1) at the intersection of the headgate and the panel return airway; (2) at the intersection of the belt headgate and the panel auxiliary haulage roadway; (3) at the intersection of the auxiliary haulage headgate and the panel belt roadway; (4) at the intersection of roadways where the air flow needs to be independent; (5) at the intersection of roadways where the production system needs to be independent. The interchange is not only for forming an independent production system, but also the interchange must have a load-bearing capacity to meet the construction and use requirements.

[0003] There are two traditional and commonly used large-span interchange structures. One is an open intersection, that is, after the driving roadway first penetrates through the existing roadway up and down and passes through, a bridge is constructed at the intersection to achieve the up-and-down isolation of the two roadways and meet the load-bearing capacity. The other is a hidden intersection, that is, the driving slope of the driving roadway is adjusted, and a thick rock stratum that meets the use requirements is left at the interchange without penetrating through the existing roadway. According to the up-and-down relationship with the existing roadway, the way the driving roadway passes through the interchange is divided into passing through from above and passing through from below.

[0004] The traditional and commonly used large-span interchange structures have the following problems: (1) Open intersection: ① The height of the penetration of the two roadways is relatively high, and the penetration causes great damage to the rock mass. It is not easy to leave a rock mass vertical surface, which is not conducive to surrounding rock control and has potential safety hazards; ② The penetration causes air flow disorder, and ventilation facilities need to be constructed in advance to control the air flow, resulting in additional engineering quantity and cost; ③ The penetration causes the interruption of the original existing roadway transportation system and affects normal production; ④ The process of constructing the bridge is complex, with a long construction period and high cost, and there is a safety risk for high-position operation. (2) Hidden intersection: The hidden intersection can effectively avoid the disadvantages of the open intersection, but there are also the following problems: Generally speaking, when two roadways on the same level have a hidden intersection, the thinner the thickness of the rock stratum left, the better, because the thinner the rock stratum left, the smaller the driving slope that the driving roadway needs to adjust, and the shorter the length of the slope-adjusting driving, which is beneficial to the construction of the roadway and the subsequent management and use of the roadway. However, the thin rock stratum left at the large-span roadway interchange is prone to collapse and is not easy to bear enough weight, making it difficult to meet the subsequent use and load-bearing requirements; while leaving a thick rock stratum can meet the subsequent use and load-bearing requirements, but it causes an increase in the driving slope of the driving roadway (generally, the driving slope is greater than 7°), seriously affecting the construction of the roadway and the subsequent management and use of the roadway, and even causing an increase in the amount of rock roadway and water accumulation in low-lying areas. Summary of the Invention

[0005] In order to solve the problems of the above-mentioned defects existing in the traditional large-span interchange structures, the present invention provides a new large-span roadway interchange structure for coal mines and its construction method.

[0006] The present invention is realized by adopting the following technical solutions:

[0007] The large-span roadway interchange structure for coal mines includes an upper roadway and a lower roadway. A thin rock layer is left in the interchange area of the upper roadway and the lower roadway (it is well-known to those skilled in the art that the specific thickness of the thin rock layer depends on the properties of the rock layer, and generally the thickness is taken as 2-3 m. Such a thickness will make the driving slope of the driving roadway not exceed 7°). An upper anchor net is laid on the top of the thin rock layer. In the middle position between the two roadway sides of the upper roadway above the upper anchor net, a middle steel beam arranged along the direction of the roadway side of the upper roadway is provided. Above the upper anchor net, a plurality of upper steel beams arranged along the direction of the roadway side of the upper roadway are distributed on both sides of the middle steel beam (the middle steel beam and the upper steel beam are arranged in parallel). The lengths of the upper steel beam and the middle steel beam are both greater than the roadway width of the lower roadway, so that the two ends of the upper steel beam and the middle steel beam are respectively supported on the solid rock of the two roadway sides of the lower part; a lower anchor net is laid on the bottom of the thin rock layer. Below the lower anchor net, a plurality of lower steel beams are provided, which are evenly distributed along the direction perpendicular to the roadway side of the lower roadway and arranged along the direction of the roadway side of the lower roadway. The two end faces of the lower steel beam are aligned with the two roadway sides of the upper roadway. A lower spacing is provided between adjacent lower steel beams; a first pair of tension cables passing through the thin rock layer are anchored between each upper steel beam and the lower spacing. Oblique tension cables are anchored between the two ends of each lower steel beam and the solid rock of the two roadway sides of the upper roadway respectively. A second pair of tension cables passing through the thin rock layer are anchored between the middle of each lower steel beam and the corresponding position of the middle steel beam (anchoring a second pair of tension cables passing through the thin rock layer between the middle of each lower steel beam and the corresponding position of the middle steel beam means that the middle of the lower steel beam and the corresponding position of the middle steel beam are arranged in a vertically corresponding manner).

[0008] Overall design principle: By designing the lengths of the upper steel beam and the middle steel beam to be greater than the roadway width of the lower roadway, both ends of the upper steel beam and the middle steel beam are respectively supported on the solid rock of the two sidewalls of the lower roadway, so that the bearing stress points at both ends of the upper steel beam and the middle steel beam extend into the solid rock of the two sidewalls of the lower roadway. In combination with the first pair of tension anchor cables, the thin rock layer is carried, lifted and pressed to improve the strength of the thin rock layer, forming a thin plate with both sides fixed on the solid rock of the two sidewalls of the lower roadway. By designing the inclined tension anchor cables, both ends of the lower steel beam are respectively tightened and hung on the solid rock of the two sidewalls of the upper roadway, so that the bearing stress points at both ends of the lower steel beam extend into the solid rock of the two sidewalls of the upper roadway. In combination with the second pair of tension anchor cables, the thin rock layer is supported, lifted and pressed to improve the strength of the thin rock layer, forming a thin plate with the other two sides fixed on the solid rock of the two sidewalls of the upper roadway. Through the above two aspects of design, the stress state of the thin rock layer is completely changed, and the strength of the thin rock layer is greatly improved, so that the thin rock layer forms a large-span thin plate with a rectangular plane having a certain bearing capacity and fixed on the solid rock on all four sides.

[0009] Construction method of large-span roadway interchange structure in coal mine. Among them, the upper roadway is an existing roadway, and the lower roadway is an excavated roadway, including the following steps: 1) Determine the reserved thin rock layer thickness in the interchange area between the upper roadway and the lower roadway (it is well-known to those skilled in the art that the slope of the lower roadway is affected by the reserved thin rock layer thickness, and the thin rock layer thickness is proportional to the slope of the lower roadway. The thicker the rock layer, the steeper the slope; the thinner the rock layer, the gentler the slope. The specific thickness of the thin rock layer is determined according to the properties of the rock layer, and generally takes a thickness of 2-3m), and level the bottom plate of the upper roadway; 2) Lay an upper anchor net at the interchange area between the bottom plate of the upper roadway and the lower roadway. At the middle position between the two sidewalls of the upper roadway above the upper anchor net, lay a middle steel beam arranged along the sidewall direction of the upper roadway. At both sides of the middle steel beam above the upper anchor net, lay a plurality of upper steel beams arranged along the sidewall direction of the upper roadway. The lengths of the upper steel beams and the middle steel beam are both greater than the roadway width of the lower roadway, so that both ends of the upper steel beams and the middle steel beam are respectively supported on the solid rock of the lower two sidewalls; 3) Excavate the lower roadway in small cycles and leave a thin rock layer at the intersection area between the lower roadway and the upper roadway. During excavation, when the lower roadway is excavated in each small cycle to the position corresponding to the upper steel beam, first lay a lower anchor net, then drive the first pair of tension cables between the upper steel beam at the corresponding position, and then carry out the next small cycle of excavation until passing through the interchange area; 4) After the lower roadway passes through the interchange area and all the first pair of tension cables are driven, lay lower steel beams evenly distributed along the direction perpendicular to the sidewall of the lower roadway and arranged along the sidewall direction of the lower roadway below the lower anchor net. The end faces of both ends of the lower steel beam are aligned with the two sidewalls of the upper roadway. The first pair of tension cables are located between two adjacent lower steel beams. Drive inclined tension cables in sequence between the end parts of both ends of each lower steel beam and the solid rock of the two sidewalls of the upper roadway; 5) Drive the second pair of tension cables in sequence between the middle of each lower steel beam and the corresponding position of the middle steel beam.

[0010] Construction method of large-span roadway interchange structure in coal mine, where the lower roadway is an existing roadway and the upper roadway is an excavated roadway, including the following steps: 1) Determine the reserved thickness of the thin rock layer in the interchange area between the upper roadway and the lower roadway (it is well-known to those skilled in the art that the slope of the upper roadway is affected by the thickness of the reserved thin rock layer, and the thickness of the thin rock layer is proportional to the slope of the upper roadway. The thicker the rock layer, the steeper the slope; the thinner the rock layer, the gentler the slope. The specific thickness of the thin rock layer is determined according to the properties of the rock layer, and generally takes a thickness of 2-3m), and spray mortar to level the roof of the lower roadway; 2) Lay a lower anchor net at the interchange area of the roof of the lower roadway and the upper roadway, and lay multiple lower steel beams below the lower anchor net, which are evenly distributed along the direction perpendicular to the sidewall of the lower roadway and arranged along the sidewall of the lower roadway. The end faces of both ends of the lower steel beam are aligned with the sidewalls of both sides of the upper roadway, and there is a lower spacing between adjacent lower steel beams. At both ends of each lower steel beam, inclined stay cables are driven between the end parts and the solid rock of the sidewalls of both sides of the upper roadway; 3) Excavate the upper roadway and leave a thin rock layer at the interchange area between the lower roadway and the upper roadway; 4) Level the bottom plate of the upper roadway, and lay an upper anchor net at the interchange area of the bottom plate of the upper roadway and the lower roadway. A middle steel beam arranged along the sidewall direction of the upper roadway is laid at the middle position between the sidewalls of both sides of the upper roadway above the upper anchor net. Multiple upper steel beams arranged along the sidewall direction of the upper roadway are laid at both sides of the middle steel beam above the upper anchor net. The lengths of the upper steel beam and the middle steel beam are greater than the width of the lower roadway, so that both ends of the upper steel beam and the middle steel beam are respectively supported on the solid rock of the sidewalls of both sides of the lower roadway; 5) Drive all the first pair of tension cables passing through the thin rock layer in sequence between each upper steel beam and the lower spacing; 6) Drive all the second pair of tension cables passing through the thin rock layer in sequence between the middle of each lower steel beam and the corresponding position of the middle steel beam.

[0011] The beneficial effects produced by the present invention are as follows:

[0012] (1) It avoids the interference of traditional interchange (open intersection) construction penetration to the production system and the impact on normal production, and avoids the construction of overpasses in traditional interchange (open intersection) construction, realizing simple process and cost reduction.

[0013] (2) It breaks through the inherent concept of leaving a thick rock layer and a large slope in traditional interchange (hidden intersection), overcomes the disadvantages of large slope of the excavated roadway in traditional thick rock layer interchange (hidden intersection) and the problems existing in future management and use. Through the reinforcement and retention of the thin rock layer, it realizes a small slope of the excavated roadway and convenient future management and use.

[0014] (3) It breaks through the bottleneck of leaving a thin rock layer in large-span interchange. By strengthening the four-sided fixed plate of the thin rock layer, the stress state of the thin rock layer is thoroughly improved, and the strength of the thin rock layer is greatly increased. It not only makes it possible to leave a large-span thin rock layer, but more importantly, makes the thin rock layer meet the load-bearing and use requirements.

[0015] (4) Some viewpoints and methods for rock stratum reinforcement and control are innovatively proposed. By making the lengths of the upper and middle steel beams greater than the width of the lower roadway, the solid rock masses on both sides of the lower roadway can bear and support the thin rock stratum. By using inclined stay cables to tighten the lower steel beam and extend it into the solid rock masses on both sides of the upper roadway, the solid rock masses on both sides of the upper roadway can tighten and lift the thin rock stratum. By using tension cables passing through the thin rock stratum, the thin rock stratum can be compressed and reinforced. By making each load-bearing point penetrate deep into the rock mass, the hanging and supporting are complementary, the bearing and supporting work together, and the four-side fixed support is ingeniously realized. By changing the stress state of the thin rock stratum, the thin rock stratum forms a large-span thin plate with a rectangular plane fixed on the solid rock with a certain bearing capacity. These viewpoints and methods have certain theoretical and practical significance for rock stratum reinforcement and surrounding rock control under special conditions.

[0016] (5) The upper and lower parts are reinforced with concrete to form a large-span load-bearing structure in the form of a thin plate where the anchor steel concrete - thin rock stratum is integrated with the solid rock stratum. Description of the Drawings

[0017] Figure 1 It is a sectional view of the overpass structure for reinforcing the thin rock stratum with four-side fixed support in the form of a plate;

[0018] Figure 2 It is Figure 1 the left view of

[0019] Figure 3 It is Figure 1 the top view of

[0020] Figure 4 It is Figure 1 the bottom view of

[0021] Figure 5 It is a sectional view of the overpass structure for reinforcing the upper thin rock stratum;

[0022] Figure 6 It is Figure 5 the left view of

[0023] Figure 7 It is Figure 5 the top view of

[0024] Figure 8 It is Figure 5 the bottom view of

[0025] Figure 9 It is a sectional view of the overpass structure for reinforcing the lower thin rock stratum;

[0026] Figure 10 It is Figure 9 the left view of

[0027] Figure 11 It is Figure 9 the top view of

[0028] Figure 12 is Figure 9 the upward view;

[0029] Figure 13 is the sectional view of the large-span interchange structure of the reinforced anchor steel-concrete coupling with four-sided fixed plate type.

[0030] In the figure: 1 - upper roadway, 2 - lower roadway, 3 - thin rock stratum, 4 - upper anchor net, 5 - middle steel beam, 6 - upper steel beam, 7 - lower anchor net, 8 - lower steel beam, 9 - first pair of tension anchor cables, 10 - inclined tension anchor cable, 11 - second pair of tension anchor cables. Specific implementation manner

[0031] As Figures 1 to 13 shown, the large-span roadway interchange structure in coal mine includes an upper roadway 1 and a lower roadway 2. There is a thin rock stratum 3 left in the interchange area of the upper roadway 1 and the lower roadway 2. An upper anchor net 4 is laid on the top of the thin rock stratum 3. A middle steel beam 5 arranged along the roadway side direction of the upper roadway 1 is provided at the middle position between the two roadway sides of the upper roadway 1 above the upper anchor net 4. A plurality of upper steel beams 6 arranged along the roadway side direction of the upper roadway 1 are distributed on both sides of the middle steel beam 5 above the upper anchor net 4. The lengths of the upper steel beam 6 and the middle steel beam 5 are both greater than the roadway width of the lower roadway 2, so that both ends of the upper steel beam 6 and the middle steel beam 5 are respectively supported on the solid rock of the lower two roadway sides; A lower anchor net 7 is laid on the bottom of the thin rock stratum 3. A plurality of lower steel beams 8 are provided below the lower anchor net 7, which are evenly distributed along the direction perpendicular to the roadway side of the lower roadway 2 and arranged along the roadway side direction of the lower roadway 2. The end faces of both ends of the lower steel beam 8 are aligned with the two side roadway sides of the upper roadway 1, and there is a lower spacing between adjacent lower steel beams 8; A first pair of tension anchor cables 9 passing through the thin rock stratum 3 are anchored between each upper steel beam 6 and the lower spacing. Oblique tension anchor cables 10 are respectively anchored between the two end parts of each lower steel beam 8 and the solid rock of the two side roadway sides of the upper roadway 1. A second pair of tension anchor cables 11 passing through the thin rock stratum 3 are anchored between the middle of each lower steel beam 8 and the corresponding position of the middle steel beam 5 (anchoring a second pair of tension anchor cables 11 passing through the thin rock stratum 3 between the middle of each lower steel beam 8 and the corresponding position of the middle steel beam 5 means that the middle of the lower steel beam 8 and the corresponding position of the middle steel beam 5 are arranged in an up-and-down corresponding manner).

[0032] During specific implementation, a 250-mm-thick concrete is poured on the floor of the upper roadway 1, so that the upper anchor net 4, the upper steel beams 6, the middle steel beams 5, the second pair of tie-down anchor cables 11, the first pair of tie-down anchor cables 9, and the thin rock stratum 3 solidify into a firm whole; a 120-mm-thick concrete is sprayed on the roof of the lower roadway 2, so that the lower anchor net 7, the lower steel beams 8, the first pair of tie-down anchor cables 9, the second pair of tie-down anchor cables 11, and the thin rock stratum 3 solidify into a firm whole, thereby forming a thin-plate large-span load-bearing structure in which the anchor steel concrete - thin rock stratum 3 is integrated with the solid rock stratum. In this specific implementation manner, the thickness of the thin rock stratum 3 is 2 - 3 m. There is a steel beam spacing of 300 - 500 mm between two adjacent upper steel beams 6 on the same side of the middle steel beam 5, and the lower spacing is 300 - 500 mm.

[0033] Design principle: By designing that the lengths of the upper steel beam 6 and the middle steel beam 5 are both greater than the roadway width of the lower roadway 2, the two ends of the upper steel beam 6 and the middle steel beam 5 are respectively supported on the solid rocks of the two sidewalls of the lower roadway, so that the load-bearing stress points at the two ends of the upper steel beam 6 and the middle steel beam 5 extend into the solid rocks of the two sidewalls of the lower roadway, and by combining the first pair of tie-down anchor cables 9 to bear, lift, and press the thin rock stratum 3, the strength of the thin rock stratum 3 is improved, forming a thin plate with both sides fixed on the solid rocks of the two sidewalls of the lower roadway; by designing the inclined tie-down anchor cables 10, the two ends of the lower steel beam 8 are respectively tightened and hung on the solid rocks of the two sidewalls of the upper roadway 1, so that the load-bearing stress points at the two ends of the lower steel beam 8 extend into the solid rocks of the two sidewalls of the upper roadway 1, and by combining the second pair of tie-down anchor cables 11 to support, lift, and press the thin rock stratum 3, the strength of the thin rock stratum 3 is improved, forming another thin plate with both sides fixed on the solid rocks of the two sidewalls of the upper roadway 1; through the above two aspects of design, the stress state of the thin rock stratum 3 is completely changed, the strength of the thin rock stratum 3 is greatly improved, and the thin rock stratum 3 forms a rectangular-plane large-span thin plate with a certain load-bearing capacity and fixed on the solid rocks on all four sides.

[0034] Embodiment 1: Construction method of large-span roadway interchange structure in coal mine. Among them, the upper roadway 1 is an existing roadway, and the lower roadway 2 is an excavation roadway, including the following steps: 1) Determine the thickness of the reserved thin rock layer 3 in the interchange area between the upper roadway 1 and the lower roadway 2, and level the bottom plate of the upper roadway 1; 2) Lay an upper anchor net 4 at the interchange area between the bottom plate of the upper roadway 1 and the lower roadway 2. In the middle position between the two sidewalls of the upper roadway 1 above the upper anchor net 4, lay a middle steel beam 5 arranged along the sidewall direction of the upper roadway 1. On both sides of the middle steel beam 5 above the upper anchor net 4, lay a plurality of upper steel beams 6 arranged along the sidewall direction of the upper roadway 1. The lengths of the upper steel beams 6 and the middle steel beam 5 are both greater than the roadway width of the lower roadway 2, so that both ends of the upper steel beams 6 and the middle steel beam 5 are respectively supported on the solid rock of the lower two sidewalls; 3) Excavate the lower roadway 2 in small cycles and leave a thin rock layer 3 at the intersection area between the lower roadway 2 and the upper roadway 1. During excavation, when the lower roadway 2 is excavated in each small cycle to the position corresponding to the upper steel beam 6, first lay a lower anchor net 7, then drive the first pair of tension cables 9 between the upper steel beam 6 at the corresponding position, and then carry out the next small cycle of excavation until passing through the interchange area; 4) After the lower roadway 2 passes through the interchange area and all the first pair of tension cables 9 are driven, lay lower steel beams 8 evenly distributed along the direction perpendicular to the sidewall of the lower roadway 2 and arranged along the sidewall direction of the lower roadway 2 below the lower anchor net 7. The end faces of both ends of the lower steel beams 8 are aligned with the two sidewalls of the upper roadway 1. The first pair of tension cables 9 are located between two adjacent lower steel beams 8. Drive inclined tension cables 10 in sequence between the two end parts of each lower steel beam 8 and the solid rock of the two sidewalls of the upper roadway 1; 5) Drive the second pair of tension cables 11 in sequence between the middle of each lower steel beam 8 and the corresponding position of the middle steel beam 5; 6) Pour and grout concrete on the bottom plate of the upper roadway 1 to make the upper anchor net 4, the upper steel beams 6, the middle steel beam 5, the second pair of tension cables 11, the first pair of tension cables 9 and the thin rock layer 3 solidify into a solid whole; Spray concrete on the roof of the lower roadway 2 to make the lower anchor net 7, the lower steel beams 8, the first pair of tension cables 9, the second pair of tension cables 11 and the thin rock layer 3 solidify into a solid whole, and carry out anchor net spraying support on both sidewalls of the lower roadway 2.

[0035] Embodiment 2: Construction method of large-span roadway interchange structure in coal mine. Among them, the lower roadway 2 is an existing roadway, and the upper roadway 1 is an excavation roadway, including the following steps: 1) Determine the thickness of the reserved thin rock layer 3 in the interchange area between the upper roadway 1 and the lower roadway 2, and spray mortar to level the roof of the lower roadway 2; 2) Lay a lower anchor net 7 at the interchange area of the roof of the lower roadway 2 and the upper roadway 1. A plurality of lower steel beams 8 are laid below the lower anchor net 7, which are evenly distributed along the direction perpendicular to the roadway side of the lower roadway 2 and arranged along the roadway side of the lower roadway 2. The end faces of both ends of the lower steel beam 8 are aligned with the entity rocks on both sides of the roadway side of the upper roadway 1. There is a lower spacing between adjacent lower steel beams 8. Oblique stay cables 10 are driven between the two ends of each lower steel beam 8 and the entity rocks on both sides of the roadway side of the upper roadway 1; 3) Excavate the upper roadway 1 so that a thin rock layer 3 is left at the interchange intersection area between the lower roadway 2 and the upper roadway 1; 4) Level the bottom plate of the upper roadway 1, and lay an upper anchor net 4 at the interchange area of the bottom plate of the upper roadway 1 and the lower roadway 2. A middle steel beam 5 arranged along the roadway side of the upper roadway 1 is laid at the middle position between the upper anchor net 4 and between the roadway sides of the upper roadway 1. A plurality of upper steel beams 6 arranged along the roadway side of the upper roadway 1 are laid at both sides of the middle steel beam 5 above the upper anchor net 4. The lengths of the upper steel beam 6 and the middle steel beam 5 are greater than the roadway width of the lower roadway 2, so that both ends of the upper steel beam 6 and the middle steel beam 5 are respectively supported on the entity rocks on both sides of the roadway side of the lower roadway 2; 5) Drive all the first pair of tie cables 9 passing through the thin rock layer 3 in sequence between each upper steel beam 6 and the lower spacing; 6) Drive all the second pair of tie cables 11 passing through the thin rock layer 3 in sequence between the middle of each lower steel beam 8 and the corresponding position of the middle steel beam 5; 7) Pour and grout concrete on the bottom plate of the upper roadway 1, so that the upper anchor net 4, the upper steel beam 6, the middle steel beam 5, the second pair of tie cables 11, the first pair of tie cables 9 and the thin rock layer 3 solidify into a solid whole; Spray concrete on the roof of the lower roadway 2, so that the lower anchor net 7, the lower steel beam 8, the first pair of tie cables 9, the second pair of tie cables 11 and the thin rock layer 3 solidify into a solid whole, and the two side walls of the lower roadway 2 are supported by anchor net spraying.

[0036] This structure avoids and overcomes the problems existing in the current traditional large-span interchange structures, such as roadway penetration, adjustment system, impact on production, large workload, complex technology, high construction difficulty, long construction period, high cost, and potential safety hazards. It also avoids and overcomes the drawbacks that the current traditional large-span interchanges cannot leave a thin rock layer 3 and that the thin rock layer 3 cannot bear the load. By applying the slab theory to the large-span interchange and the reinforcement of the thin rock layer 3, through the slab reinforcement of the thin rock layer 3 of the interchange, a large-span rectangular plane rigid thin slab with four sides fixed on the solid rock is formed, realizing the retention and load-bearing of the large-span interchange in the thin rock layer 3, reducing the tunneling gradient and the amount of rock roadway work, avoiding the impact on the system and production caused by penetration. Compared with the traditional interchange, obvious effects have been achieved in terms of technology, construction period, cost, benefit, and safety. It is an effective large-span interchange technology proven by practice. At the same time, the large-span interchange technology with four-sided fixed slab reinforcement for the thin rock layer 3 applies the theory of the slab to the field of the thin rock layer 3, proposes the concept of the load-bearing of the thin rock layer 3, establishes the mechanical model of the four-sided fixed slab reinforcement for the thin rock layer 3, forms an anchor steel concrete-thin rock layer 3 with four sides fixed on the solid rock and integrated with the solid rock layer into a light and thin rectangular slab large-span load-bearing structure, advocates the method of retaining the thin rock layer 3 and the surrounding rock control technology, breaks through the traditional thinking, realizes the load-bearing of the thin rock layer 3, enriches the surrounding rock control theory, and has certain theoretical and practical significance.

Claims

1. The large-span roadway interchange structure in a coal mine includes an upper roadway (1) and a lower roadway (2). A thin rock layer (3) is left in the interchange area between the upper roadway (1) and the lower roadway (2). An upper anchor net (4) is laid on the top of the thin rock layer (3). Above the upper anchor net (4), a middle steel beam (5) arranged along the direction of the sidewall of the upper roadway (1) is provided at the middle position between the two sidewalls of the upper roadway (1). Above the upper anchor net (4), a plurality of upper steel beams (6) arranged along the direction of the sidewall of the upper roadway (1) are distributed on both sides of the middle steel beam (5). The lengths of the upper steel beams (6) and the middle steel beam (5) are both greater than the roadway width of the lower roadway (2), so that the two ends of the upper steel beams (6) and the middle steel beam (5) are respectively supported on the solid rock of the two sidewalls of the lower roadway; A lower anchor net (7) is laid on the bottom of the thin rock layer (3). Below the lower anchor net (7), a plurality of lower steel beams (8) are arranged along the direction perpendicular to the sidewall of the lower roadway (2) and along the direction of the sidewall of the lower roadway (2). The end faces of the two ends of the lower steel beam (8) are aligned with the two sidewalls of the upper roadway (1). A lower spacing is provided between adjacent lower steel beams (8); A first pair of tension anchor cables (9) passing through the thin rock layer (3) are anchored between each upper steel beam (6) and the lower spacing. Oblique tension anchor cables (10) are respectively anchored between the two ends of each lower steel beam (8) and the solid rock of the two sidewalls of the upper roadway (1). A second pair of tension anchor cables (11) passing through the thin rock layer (3) are anchored between the middle of each lower steel beam (8) and the corresponding position of the middle steel beam (5).

2. The large-span roadway interchange structure for coal mines according to claim 1, characterized in that Concrete is poured and grouted on the bottom plate of the upper roadway (1), so that the upper anchor net (4), the upper steel beam (6), the middle steel beam (5), the second pair of tension anchor cables (11), the first pair of tension anchor cables (9) and the thin rock layer (3) solidify into a solid whole; Shotcrete is applied to the roof of the lower roadway (2), so that the lower anchor net (7), the lower steel beam (8), the first pair of tension anchor cables (9), the second pair of tension anchor cables (11) and the thin rock layer (3) solidify into a solid whole, and the two sidewalls of the lower roadway (2) are supported by anchor net shotcrete.

3. The large-span roadway interchange structure for coal mines according to claim 2, wherein The thickness of the thin rock layer (3) is 2 - 3m.

4. The large-span roadway interchange structure in a coal mine according to claim 3, characterized in that, A steel beam spacing of 300 - 500mm is provided between two adjacent upper steel beams (6) on the same side of the middle steel beam (5), and the lower spacing is 300 - 500mm.

5. Construction method of large-span roadway interchange structure in coal mine, wherein, The upper roadway (1) 1) is an existing roadway, and the lower roadway (2) is an excavated roadway. It is characterized by the following steps: 1) Determine the thickness of the reserved thin rock layer (3) in the intersection area between the upper roadway (1) and the lower roadway (2), and level the floor of the upper roadway (1); 2) Lay an upper anchor net (4) at the intersection area between the floor of the upper roadway (1) and the lower roadway (2). Above the upper anchor net (4), lay a middle steel beam (5) arranged along the direction of the sidewall of the upper roadway (1) at the middle position between the two sidewalls of the upper roadway (1). Above the upper anchor net (4), lay a plurality of upper steel beams (6) arranged along the direction of the sidewall of the upper roadway (1) at both sides of the middle steel beam (5). The lengths of the upper steel beams (6) and the middle steel beam (5) are greater than the roadway width of the lower roadway (2) so that both ends of the upper steel beams (6) and the middle steel beam (5) are respectively supported on the solid rock of the lower two sidewalls; 3) Excavate the lower roadway (2) in a small cycle and leave a thin rock layer (3) at the intersection area between the lower roadway (2) and the upper roadway (1). During excavation, when the lower roadway (2) is excavated to the position corresponding to the upper steel beam (6) in each small cycle, first lay a lower anchor net (7), then drive the first pair of tension anchor cables (9) between the lower anchor net (7) and the corresponding upper steel beam (6), and then the next small cycle of excavation can be carried out until passing through the intersection area; 4) After the lower roadway (2) passes through the intersection area and all the first pair of tension anchor cables (9) are driven, lay lower steel beams (8) evenly arranged along the direction perpendicular to the sidewall of the lower roadway (2) and arranged along the direction of the sidewall of the lower roadway (2) below the lower anchor net (7). The end faces of both ends of the lower steel beams (8) are aligned with the two sidewalls of the upper roadway (1). The first pair of tension anchor cables (9) are located between two adjacent lower steel beams (8). Drive inclined tension anchor cables (10) in sequence between the two ends of each lower steel beam (8) and the solid rock of the two sidewalls of the upper roadway (1); 5) Drive the second pair of tension anchor cables (11) in sequence between the middle of each lower steel beam (8) and the corresponding position of the middle steel beam (5).

6. The construction method of the large-span roadway interchange structure in coal mines according to claim 5, characterized in that, It also includes step 6): Pour and grout concrete on the floor of the upper roadway (1) so that the upper anchor net (4), the upper steel beams (6), the middle steel beam (5), the second pair of tension anchor cables (11), the first pair of tension anchor cables (9) and the thin rock layer (3) solidify into a solid whole; Spray concrete on the roof of the lower roadway (2) so that the lower anchor net (7), the lower steel beams (8), the first pair of tension anchor cables (9), the second pair of tension anchor cables (11) and the thin rock layer (3) solidify into a solid whole, and carry out anchor net and shotcrete support on both sidewalls of the lower roadway (2).

7. The construction method of the large-span roadway interchange structure in coal mines according to claim 6, characterized in that, The thickness of the thin rock layer (3) is 2 - 3m.

8. Construction method of large-span roadway interchange structure in coal mine, wherein, The lower roadway (2) is an existing roadway, and the upper roadway (1) is an excavated roadway. It is characterized by the following steps: 1) Determine the thickness of the reserved thin rock layer (3) in the intersection area between the upper roadway (1) and the lower roadway (2), and spray mortar to level the roof of the lower roadway (2); 2) Lay a lower anchor net (7) at the intersection area of the roof of the lower roadway (2) and the upper roadway (1). Below the lower anchor net (7), lay a plurality of lower steel beams (8) evenly distributed along the direction perpendicular to the sidewall of the lower roadway (2) and arranged along the sidewall direction of the lower roadway (2). The end faces of both ends of the lower steel beam (8) are aligned with the sidewalls of both sides of the upper roadway (1). There is a lower spacing between adjacent lower steel beams (8). At both ends of each lower steel beam (8), drive diagonal stay cables (10) between the end parts and the solid rock of the sidewalls of both sides of the upper roadway (1); 3) Excavate the upper roadway (1) and leave a thin rock layer (3) at the intersection area between the lower roadway (2) and the upper roadway (1); 4) Level the floor of the upper roadway (1). Lay an upper anchor net (4) at the intersection area of the floor of the upper roadway (1) and the lower roadway (2). At the middle position between the sidewalls of both sides of the upper roadway (1) above the upper anchor net (4), lay a middle steel beam (5) arranged along the sidewall direction of the upper roadway (1). At both positions on both sides of the middle steel beam (5) above the upper anchor net (4), lay a plurality of upper steel beams (6) arranged along the sidewall direction of the upper roadway (1). The lengths of the upper steel beam (6) and the middle steel beam (5) are greater than the roadway width of the lower roadway (2) so that both ends of the upper steel beam (6) and the middle steel beam (5) are respectively supported on the solid rock of the sidewalls of both sides of the lower roadway (2); 5) Drive all the first pair of tension cables (9) passing through the thin rock layer (3) in sequence between each upper steel beam (6) and the lower spacing; 6) Drive all the second pair of tension cables (11) passing through the thin rock layer (3) in sequence between the middle position of each lower steel beam (8) and the corresponding position of the middle steel beam (5).

9. The construction method of the large-span roadway interchange structure in coal mines according to claim 8, characterized in that, It further includes step 7): Pour and grout concrete on the floor of the upper roadway (1) so that the upper anchor net (4), the upper steel beam (6), the middle steel beam (5), the second pair of tension cables (11), the first pair of tension cables (9) and the thin rock layer (3) solidify into a solid whole; Spray concrete on the roof of the lower roadway (2) so that the lower anchor net (7), the lower steel beam (8), the first pair of tension cables (9), the second pair of tension cables (11) and the thin rock layer (3) solidify into a solid whole, and carry out anchor net spraying support on both sidewalls of the lower roadway (2).

10. The construction method of the large-span roadway interchange structure in coal mines according to claim 9, characterized in that, The thickness of the thin rock layer (3) is 2 - 3m.

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