Three-soft coal seam bottom plate supporting structure and construction method thereof

Abstract

The invention relates to the technical field of mining construction, in particular to a three-soft-coal-seam bottom plate supporting structure and a construction method thereof.The three-soft-coal-seam bottom plate supporting structure comprises pipe piles, a top beam assembly and a terrace layer, and the pipe piles comprise the two pipe piles arranged in a splayed shape in the section of a roadway; the pipe pile comprises a grouting pipe and a pile body formed through pouring of the grouting pipe, the grouting pipe comprises a first section inserted into a roadway bottom plate and a second section exposed out of the bottom plate, and the two pile bodies arranged adjacently in the trend of a roadway are partially overlapped. The crown beam assembly is connected with the second section of the grouting pipe; according to the three-soft coal seam bottom plate supporting structure, the reinforcing effect of the bottom plate is guaranteed, meanwhile, the supporting structure can be parallel to a driving working face, the supporting process is simple, and the supporting operation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mining construction, and particularly relates to a floor support structure for a three-soft coal seam and a construction method thereof. Background Art

[0002] In recent years, the focus of coal resource exploitation has gradually shifted to the central and western regions. The roof and floor rock strata of the working faces in this area are mainly weakly cemented soft rocks, with poor cementation degree, and significant water-induced sandification, mudification and disintegration. Coupled with the influence of "three highs and one disturbance", the problem of large deformation of the surrounding rock of the three-soft coal seam and strong mine pressure roadway is prominent.

[0003] Currently, the method of "inverted arch + full-section grouting" is commonly used to control the large deformation of the floor, which has achieved certain effects. However, this method has the following disadvantages: the construction process is complex, 6 bottom anchor cables need to be constructed and grouted in one section, which has an intersecting influence on the production of the driving working face, the driving efficiency is low, and the mining and excavation replacement is tense. Summary of the Invention

[0004] The present invention provides a floor support structure for a three-soft coal seam and a construction method thereof. While ensuring the floor reinforcement effect, the floor support structure for the three-soft coal seam can be carried out in parallel with the driving working face, the support process is simple, and the support operation efficiency is improved.

[0005] In a first aspect, an embodiment of the present invention provides a floor support structure for a three-soft coal seam, including: pipe piles, including two pipe piles arranged in an "eight" shape within the cross-section of the roadway. The pipe pile includes a grouting pipe and a pile body formed by pouring through the grouting pipe. The grouting pipe includes a first section inserted into the roadway floor and a second section exposed outside the floor. Two adjacent pile bodies along the roadway alignment partially overlap; a capping beam assembly, connecting the second section of the grouting pipe; and a floor layer, arranged on the floor.

[0006] In a possible implementation manner, the length of the first section is greater than 4500 mm, and the length of the second section is less than 400 mm.

[0007] In a possible implementation manner, the first section includes a first region 1111 adjacent to the second section and a second region far from the second section. The second region is provided with grouting holes for forming the pile body.

[0008] In a possible implementation manner, drill holes for installing the grouting pipe are opened on the floor. Two drill holes in the same cross-section are respectively located on both sides of the roadway center line. The distance between the drill hole adjacent to the belt conveyor and the roadway center line is 400 mm - 800 mm, and the distance between the drill hole adjacent to the pedestrian side and the roadway center line is 700 mm - 1100 mm.

[0009] In a possible implementation manner, an angle a is formed between the grouting pipe and the horizontal line, where the angle a satisfies: 60° ≤ a ≤ 80°.

[0010] In a possible implementation, the capping beam assembly includes: a mesh sheet laid on the bottom plate; a steel strip laid on the mesh sheet, and the steel strip is used to connect two grouting pipes within the same cross-section; a pressing plate arranged along the roadway direction for connecting at least two continuously arranged grouting pipes.

[0011] In a possible implementation, the thickness of the floor layer is t, where t satisfies: 150 mm ≤ t ≤ 250 mm.

[0012] In a second aspect, the present invention provides a construction method for the above-mentioned support structure for the floor of the three-soft coal seam, including the following steps: Drilling: Drilling in an "eight" shape along the same cross-section on the bottom plate of the roadway; Installing grouting pipes: Installing grouting pipes in the drilled holes so that the grouting pipes have a first section inserted into the bottom plate and a second section exposed outside the bottom plate; Grouting: Grouting through the grouting pipes to form pile bodies in the bottom plate, and two adjacent pile bodies along the roadway direction partially overlap; Capping beam assembly construction: Connecting and fixing the first section of the grouting pipe through the capping beam assembly; Floor layer pouring: After the capping beam assembly construction is completed, pouring concrete on the bottom plate to form a floor layer.

[0013] In a possible implementation, drilling includes: Drilling on both sides of the roadway center line. Among the two drilled holes within the same cross-section, the distance between one drilled hole adjacent to the belt conveyor and the roadway center line is 400 mm - 800 mm, and the distance between the drilled hole adjacent to the pedestrian side and the roadway center line is 700 mm - 1100 mm.

[0014] In a possible implementation, grouting includes: Grouting adjacent grouting pipes under pressure so that adjacent pile bodies partially overlap; Each grouting pipe is subjected to at least one supplementary grouting.

[0015] The support structure for the floor of the three-soft coal seam and its construction method provided by the present invention form a stable support foundation through the deep anchoring and grouting reinforcement of the "eight"-shaped pipe piles. The inclined arrangement of the pipe piles not only provides vertical support force but also effectively resists the deformation force in the horizontal direction, preventing the bottom plate from bulging. The partial overlap design of adjacent pile bodies forms a continuous support curtain, effectively blocking the propagation path of the bottom plate deformation. The setting of the capping beam assembly connects the independent pipe piles into a whole, significantly improving the integrity and cooperative working ability of the support system. The setting of the floor layer provides a flat foundation for equipment operation and at the same time plays a role in dispersing stress and protecting the bottom plate. This structural design breaks through the limitations of the traditional "inverted arch + full-section grouting" method. While ensuring the bottom plate reinforcement effect, it can be carried out in parallel with the tunneling face, with a simple support process and improved support operation efficiency. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic structural diagram of a support structure for the floor of a triple-soft coal seam provided by the present invention within a cross-section.

[0018] Figure 2 It is a schematic side view structural diagram of a support structure for the floor of a triple-soft coal seam provided by the present invention.

[0019] Figure 3 It is a schematic structural diagram of another support structure for the floor of a triple-soft coal seam provided by the present invention.

[0020] Figure 4 It is a schematic structural diagram when a grouting pipe, a steel strip, and a pressing plate are connected provided by the present invention.

[0021] Figure 5 It is a schematic structural diagram when a grouting pipe and a crown beam assembly are connected provided by the present invention.

[0022] Figure 6 It is a schematic structural diagram when a grouting pipe and a pressing plate are connected provided by the present invention.

[0023] Figure 7 It is a schematic structural diagram of another connection between a grouting pipe and a pressing plate provided by the present invention.

[0024] Figure 8 It is a schematic structural diagram of a grouting pipe provided by the present invention.

[0025] Figure 9 It is a flow block diagram of a construction method for a support structure for the floor of a triple-soft coal seam provided by the present invention.

[0026] Reference numerals: 1, pipe pile; 11, grouting pipe; 111, first section; 1111, first area; 1112, second area; 112, second section; 113, perforated steel pipe; 114, hollow grouting bolt; 12, pile body; 2, roadway; 21, roadway center line; 3, crown beam assembly; 31, mesh; 32, steel strip; 33, pressing plate; 4, floor layer. Detailed implementation manners

[0027] To make the objectives, technical solutions, and advantages of the present invention more clear, the following will, in conjunction with the accompanying drawings in the present invention, clearly and completely describe the technical solutions in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts fall within the scope of protection of the present invention.

[0028] The following will, in conjunction with Figures 1-8 describe a support structure for the floor of a triple-soft coal seam provided by an embodiment of the present invention, including: pipe piles 1, a capping beam assembly 3, and a floor layer 4. Among them: The pipe piles 1 include two pipe piles 1 arranged in an "eight" shape within the cross-section of the roadway 2. The pipe piles 1 include grouting pipes 11 and pile bodies 12 formed by pouring through the grouting pipes 11. The grouting pipes 11 include a first section 111 inserted into the floor of the roadway 2 and a second section 112 exposed outside the floor. Two adjacent pile bodies 12 along the trend of the roadway 2 partially overlap.

[0029] The capping beam assembly 3 is connected to the second section 112 of the grouting pipe 11.

[0030] The floor layer 4 is arranged on the floor.

[0031] In the present invention, through the deep anchoring and grouting reinforcement of the "eight"-shaped pipe piles 1, a stable support foundation is formed. The inclined arrangement of the pipe piles 1 not only provides vertical support force but also effectively resists horizontal deformation force, preventing the floor from heaving. The partial overlap design of adjacent pile bodies 12 forms a continuous support curtain, effectively blocking the propagation path of floor deformation. The setting of the capping beam assembly 3 connects the independent pipe piles 1 into a whole, significantly improving the integrity and cooperative working ability of the support system. The setting of the floor layer 4 provides a flat foundation for equipment operation, and at the same time plays a role in dispersing stress and protecting the floor. This structural design breaks through the limitations of the traditional method of "inverted arch + full-section grouting", and while ensuring the floor reinforcement effect, it can be carried out in parallel with the tunneling face, with simple support technology and improved support operation efficiency.

[0032] In the related art, currently, the method of "inverted arch + full-section grouting" is commonly used to control large floor deformation, which has achieved certain effects. However, this method has three disadvantages: 1. The construction process is complex. Six floor anchor cables need to be constructed and grouted in one cross-section, which has an intersection impact on the production of the tunneling face, resulting in low tunneling efficiency and tight mining and excavation replacement; 2. The aperture of the floor anchor cables is small, which has a reinforcement effect on the small-range rock mass around the drilling holes. The number of construction drilling holes is large, the engineering quantity is large, and the number of construction personnel is large, and the problem of over-limit personnel in the working face is prominent; 3. The drilling aperture is small, and the grouting volume and grouting range of this method are small, and the reinforcement effect is poor.

[0033] In the embodiments of the present invention, two pipe piles 1 are arranged in a "V"-shape on the cross-section to form a stable support foundation. Compared with the prior art in which 6 anchor cables are arranged and grouted in one cross-section, the number of drilling operations is reduced by more than half, thereby improving the operation efficiency. Moreover, the pipe piles 1 arranged in a "V"-shape make the second section 112 exposed outside the floor inclined, which can effectively reduce the cross influence on the production of the driving face. Then, the crown beam assembly 3 is used to reinforce the second section 112 of the grouting pipe 11 exposed outside the floor, so that multiple pipe piles 1 form a whole. Not only are the two pipe piles 1 in the same cross-section connected as a whole, but also the pipe piles 1 adjacent along the roadway 2 are connected as a whole.

[0034] In some embodiments, the length of the first section 111 is greater than 4500 mm, and the length of the second section 112 is less than 400 mm.

[0035] In the embodiments of the present invention, the length requirements of the first section 111 and the second section 112 of the pipe pile 1 are clearly defined, that is, the first section 111 is greater than 4500 mm and the second section 112 is less than 400 mm. This size design has important significance in practical applications: the length of the first section 111 exceeding 4500 mm ensures that the pipe pile 1 can penetrate the soft floor layer and reach the stable bedrock layer, providing reliable anchoring force. At the same time, this depth is also beneficial to the full diffusion of the grouting liquid, forming a larger reinforcement area. The design of controlling the length of the second section 112 within 400 mm can not only meet the connection requirements of the crown beam assembly 3, but also does not affect the normal operation of equipment and the passage of personnel in the roadway 2. This length design is particularly suitable for the support of the roadway 2 under deep mining and strong mine pressure conditions, and can effectively cope with the floor deformation problem. In the water-bearing stratum, sufficient anchoring depth is also beneficial to form an effective waterproof barrier to prevent groundwater from eroding and softening the floor.

[0036] In a specific embodiment, the length of the first section 111 of the grouting pipe 11 is 5000 mm, and the length of the second section 112 is 300 mm. Compared with the current grouting pipe 11 with a small aperture and shallow depth, the present invention can form a larger pile body 12 by increasing the diameter of the grouting pipe 11 and increasing the length inserted into the floor, thereby ensuring the support strength. Moreover, compared with the current inverted arch floor support, the amount of bottom excavation is reduced by 80%, the amount of concrete pouring is reduced by 80%, the driving efficiency is increased by 30%, and the cost of floor treatment is reduced by 70%. It has significance in terms of economy, technology, reliability, etc.

[0037] In some embodiments, the first section 111 includes a first region 1111 adjacent to the second section 112 and a second region 1112 away from the second section 112. The second region 1112 is provided with grouting holes for forming the pile body 12.

[0038] In the embodiments of the present invention, the structural details of the first-section 111 pipe pile 1 are clarified. It is divided into a first region 1111 adjacent to the second section 112 and a second region 1112 far from the second section 112, and grouting holes are arranged in the second region 1112. This design shows unique advantages in practical applications: the reasonable arrangement of the grouting holes makes the grouting process more controllable and efficient. The design of not arranging grouting holes in the first region 1111 prevents the backflow of the grouting liquid along the outer wall of the pipe pile 1, ensuring the grouting pressure and grouting effect. The grouting holes in the second region 1112 can make full use of the grouting pressure to evenly disperse the grouting liquid into the surrounding rock mass. This zoning design is particularly suitable for the reinforcement of soft and broken strata and can form a uniform and continuous reinforcement area. Under strong mine pressure conditions, this grouting method can effectively improve the rock mass strength and enhance the overall stability of the support system.

[0039] Specifically, the grouting pipe 11 includes an extendable steel flower pipe 113 and a hollow grouting bolt 114. In the ground machine repair workshop, the steel flower pipe 113 (the second section) is welded and fixed to the hollow grouting bolt 114 (φ21.8×2000mm) and sealed. That is, the bolt is inserted 1700mm into the steel flower pipe, with 300mm exposed outside. The extendable steel flower pipe (DN76, inner diameter 76mm, wall thickness 4mm, length 2.5m / section, and the last two sections are connected by a pipe pile coupling to form a 5000mm-long pipe) is installed in the borehole. The head of the first-section steel flower pipe is designed to be conical for easy installation; the grouting holes of the steel flower pipe are arranged in a "three-flower" pattern, with a hole diameter of 10mm and a spacing of 200mm. No grouting holes are arranged in the last 1000mm of the tail of the steel flower pipe.

[0040] In some embodiments, boreholes for installing the grouting pipe 11 are drilled on the floor. The two boreholes in the same cross-section are respectively located on both sides of the roadway center line 21. The distance between the borehole adjacent to the belt conveyor and the roadway center line 21 is 400mm - 800mm, and the distance between the borehole adjacent to the pedestrian side and the roadway center line 21 is 700mm - 1100mm.

[0041] In the embodiments of the present invention, the specific position parameters of the boreholes are specified, and the distance ranges between the boreholes on the belt conveyor side and the pedestrian side and the roadway center line 21 are clarified. This spatial layout design fully considers the actual production requirements: on the belt conveyor side, the distance of 400 - 800mm not only ensures the support effect but also avoids interference with the transportation equipment. The distance of 700 - 1100mm on the pedestrian side reserves enough space for personnel passage. This asymmetric layout fully adapts to the different functional requirements of the roadway 2. In the fully mechanized mining face and the transportation roadway 2, this layout scheme can ensure the safety of equipment operation and personnel passage, while ensuring the support effect. For areas that require frequent maintenance, this layout is also convenient for construction and later maintenance.

[0042] In a specific embodiment, the distance between the borehole adjacent to the belt conveyor and the roadway centerline 21 is 600 mm, and the distance between the borehole adjacent to the pedestrian side and the roadway centerline 21 is 900 mm.

[0043] In some embodiments, an angle a is formed between the grouting pipe 11 and the horizontal line, where the angle a satisfies: 60° ≤ a ≤ 80°.

[0044] In the embodiments of the present invention, the angle range between the grouting pipe 11 and the horizontal line is specified (60° ≤ a ≤ 80°). This angle requirement has important technical significance in practical applications: the inclination range of 60° - 80° is determined comprehensively based on the characteristics of rock stratum stress distribution and construction operability. Within this angle range, the pipe pile 1 can effectively resist the deformation force generated by the floor heave, while ensuring the grouting effect. This inclination design shows unique advantages under the condition of weak floor: the inclined arrangement of the pipe pile 1 increases the contact area with the rock stratum, improving the anchoring force; during grouting, this angle range is conducive to the full diffusion of the slurry under the action of gravity, forming a continuous solidified body. In high-stress areas, this inclination design can better withstand and transfer complex stress states. At the same time, this angle range is also convenient for the construction of the drilling rig and the installation of the grouting pipe 11, improving the construction efficiency and reducing the construction difficulty.

[0045] In a specific embodiment, an angle a is formed between the grouting pipe 11 and the horizontal line, where the angle a is equal to 75°.

[0046] In some embodiments, the crown beam assembly 3 includes: a mesh 31 laid on the floor; a steel strip 32 laid on the mesh 31, and the steel strip 32 is used to connect two grouting pipes 11 within the same cross-section; a pressing plate 33 arranged along the trend of the roadway 2, and the pressing plate 33 is used to connect at least two continuously arranged grouting pipes 11.

[0047] In the embodiments of the present invention, the structural composition of the crown beam assembly 3 is described, including three key components: the floor mesh 31, the steel strip 32, and the pressing plate 33. This hierarchical support structure plays an important role in practical applications: the mesh 31 laid at the bottom as the basic support layer can effectively prevent the peeling of scattered rock blocks and provide initial support; the setting of the steel strip 32 realizes the effective connection of two grouting pipes 11 within the same cross-section, forming an overall stress system; the pressing plate 33 enhances the longitudinal integrity of the support structure by connecting multiple grouting pipes 11 in the trend. Under large deformation conditions, this multi-level support structure shows excellent adaptability: the mesh 31 can limit the falling of fragmented rock blocks, protecting the safety of operators and equipment; the steel strip 32 system is stressed to prevent excessive stress on a single pipe pile 1; the connection function of the pressing plate 33 enables the support structure to deform synergistically, avoiding stress concentration. For soft rock conditions, this support structure can also effectively prevent rock mass weathering and fragmentation, prolonging the support effect.

[0048] Specifically, the pressing plate is made of mining I-beams. A layer of φ6.5mm wire mesh 31 is laid on the floor. The adjacent wire meshes 31 overlap by no less than 100mm, and the overlapping parts are connected by 14# steel wire, with no less than 3 strands. After the floor wire mesh 31 is laid, 2000mm long round steel strips 32 (hole spacing 1800mm) are used to connect the grouting pipes 11 along the dip direction. Along the strike direction, the mining I-beams are sleeved into the pipe pile 1 anchor rods, 150×150mm anchor trays are installed, and a pre-tightening force of ≮100kN is applied. The length of the mining I-beam is 2500mm, and holes with a size of 50×40mm (length × width) are processed at 500mm from both ends respectively for sleeving into the hollow grouting anchor rod 14 along the strike direction.

[0049] In some embodiments, the thickness of the floor layer 4 is t, where t satisfies: 150mm ≤ t ≤ 250mm.

[0050] In the embodiments of the present invention, the thickness range of the floor layer 4 is specified (150mm ≤ t ≤ 250mm). This thickness design has clear technical basis in practical applications: the minimum thickness of 150mm ensures that the floor layer 4 has sufficient bearing capacity and durability to withstand the dynamic loads generated by equipment operation and personnel passage; the maximum limit of 250mm is considered for material economy and construction convenience. Under strong mining pressure conditions, the floor layer 4 with this thickness range can effectively disperse and transfer loads, preventing local damage. For water-bearing strata, the appropriate thickness can also provide good waterproof and anti-seepage effects. At the same time, this thickness design is also convenient for cooperating with other support structures of the roadway 2 to form a complete support system. In actual construction, the thickness within this range is convenient for on-site pouring and vibration, ensuring the construction quality.

[0051] In a specific embodiment, the floor layer 4 is a 200mm thick concrete floor, and the concrete strength grade is C30.

[0052] The support structure for the floor of the soft coal seam with three soft characteristics forms a stable support foundation through the deep anchoring and grouting reinforcement of the "eight"-shaped pipe piles 1. The inclined arrangement of the pipe piles 1 not only provides vertical support force but also effectively resists the deformation force in the horizontal direction, preventing the floor from heaving. The partial overlap design of the adjacent pile bodies 12 forms a continuous support curtain, effectively blocking the propagation path of the floor deformation. The setting of the capping beam assembly 3 connects the independent pipe piles 1 into a whole, significantly improving the integrity and collaborative working ability of the support system. The setting of the floor layer 4 provides a flat foundation for equipment operation and at the same time plays a role in dispersing stress and protecting the floor. This structural design breaks through the limitations of the traditional "inverted arch + full-section grouting" method. While ensuring the floor reinforcement effect, it can be carried out parallel to the tunneling face, with a simple support process and improved support operation efficiency.

[0053] Such as Figure 9As shown in the figure, the present invention provides a construction method for the above-mentioned supporting structure for the floor of the three soft coal seams, which includes the following steps: S1. Drilling: Drill holes in the shape of an "eight" on the floor of the roadway 2 along the same cross-section; S2. Installing the grouting pipe 11: Install the grouting pipe 11 in the drilled hole, so that the grouting pipe 11 has a first section 111 inserted into the floor and a second section 112 exposed outside the floor; S3. Grouting: Grout through the grouting pipe 11 to form a pile body 12 in the floor, and two adjacent pile bodies 12 along the trend of the roadway 2 partially overlap; S4. Construction of the capping beam assembly: Connect and fix the first section 111 of the grouting pipe 11 through the capping beam assembly; S5. Pouring the floor layer 4: After the construction of the capping beam assembly is completed, pour concrete on the floor to form the floor layer 4.

[0054] The embodiments of the present invention describe the specific construction method of the supporting structure for the floor of the three soft coal seams, including five key steps: drilling, installing the grouting pipe 11, grouting, construction of the capping beam assembly, and pouring the floor layer 4. This construction method shows significant advantages in practical applications: First, the entire construction process can be carried out in parallel with the tunneling face, significantly improving the construction efficiency; Second, each construction step is closely connected, avoiding dead construction time; Third, the construction process is simple and clear, facilitating on-site operation and quality control. In actual projects, this construction method also shows good adaptability: During the drilling process, parameters can be appropriately adjusted according to the on-site geological conditions; During the grouting process, the grouting pressure and grouting volume can be adjusted according to the rock formation conditions; The construction of the capping beam assembly and the pouring of the floor layer 4 can be coordinated with other supporting works. At the same time, this construction method greatly reduces the engineering quantity and construction difficulty required for traditional inverted arch support.

[0055] Specifically, before drilling, it is also necessary to carry out bottom excavation on the floor of the roadway. To reduce the bottom excavation construction operation, only the bottom excavation work of the 200mm concrete floor needs to be considered during normal tunneling.

[0056] In some embodiments, the drilling includes: S11. Drill holes on both sides of the roadway center line 21. Among the two drill holes in the same cross-section, the distance between one drill hole adjacent to the belt conveyor and the roadway center line 21 is 400mm - 800mm, and the distance between the drill hole adjacent to the pedestrian side and the roadway center line 21 is 700mm - 1100mm.

[0057] In the embodiments of the present invention, the specific parameters of the drilling construction are further refined, and the specific distance range between the drill hole and the roadway center line 21 is specified. Such precise construction parameter design fully considers the actual production requirements: the distance range of 400 - 800 mm on the side of the belt conveyor not only ensures the support effect but also avoids interference with the transportation equipment; the distance of 700 - 1100 mm on the pedestrian side fully considers the safety of personnel passage. In actual construction, such parameter design is also convenient for construction positioning and quality control: construction personnel can select the best drilling position within the specified range according to specific conditions; at the same time, such layout is also convenient for later inspection and maintenance. For roadways 2 with different cross-sectional sizes, such parameter range provides sufficient adjustment space, enhancing the adaptability of the construction method.

[0058] Specifically, the distance between a drill hole adjacent to the belt conveyor and the roadway center line 21 is 600 mm, and the distance between the drill hole adjacent to the pedestrian side and the roadway center line 21 is 900 mm.

[0059] In some embodiments, the grouting includes: S31. Grouting adjacent grouting pipes 11 under pressure to make adjacent pile bodies 12 partially overlap; S32. Each grouting pipe 11 is subjected to at least one supplementary grouting.

[0060] The embodiments of the present invention put forward specific requirements for the grouting process, including two key links: grouting under pressure and supplementary grouting. Such grouting process has important significance in practical applications: grouting under pressure can ensure that the slurry fully penetrates into the surrounding rock mass to form a continuous solidified body; supplementary grouting can make up for the possible deficiencies in the primary grouting and improve the grouting quality. In soft and fractured strata, such grouting process is particularly effective: pressure grouting can overcome the formation resistance and ensure the full diffusion of the slurry; multiple groutings can form a more dense solidified body. For water-bearing strata, such grouting process can also form an effective waterproof barrier. In actual construction, such grouting process also has good operability and controllability, which is convenient for on-site adjustment and quality control.

[0061] Specifically, after the foundation pit is poured, the pipe piles 1 can be grouted. The core of the floor treatment is floor grouting. Utilizing the characteristics of the surrounding rock being easy to soften and having large expansibility, the slurry penetration range is expanded through grouting under pressure to improve the overall stability of the floor. The grouting construction process is: prepare grouting tools and equipment → connect the air and water pipes → mix the slurry → connect the 11th grouting pipe path with the hollow grouting bolt → grout under pressure → grout adjacent drill holes → supplementary grouting → clean the grouting pump. The grouting material is selected as a grouting material with rapid setting, high compressive strength, and high anchoring force and is grouted according to the corresponding ratio. The grouting equipment uses a 2ZBQ30 / 6 type mine pneumatic grouting pump as the grouting equipment for the pipe piles 1.

[0062] The present invention adopts the support method of "prestressed grouting pipe pile curtain + capping beam" to control the large deformation of the floor slab. High anti-pulling anchoring force and high anti-shearing force are achieved by large-diameter steel pipe cast-in-place piles in the soft floor slab. High-pressure and large-displacement grouting is used to form a curtain-like wall that cuts off the horizontal stress between the piles and at the bottom corners of the roadway. The capping beam connects the pile groups into one body to achieve the goals of strengthening the floor slab in the roadway, reducing roof fall and increasing stiffness, laminating the floor rock strata, and cutting off the stress flow. This effectively controls the large deformation of the roadway during tunneling, thus solving the problems of slow tunneling speed, low efficiency, high cost of the inverted arch construction process, and tight mining and excavation connection.

[0063] Compared with the inverted arch support, this technology reduces the bottom excavation volume by 80%, reduces the concrete pouring volume by 80%, increases the tunneling efficiency by 30%, and reduces the floor treatment cost by 70%. It is significant in terms of economy, technology, reliability, etc.

[0064] This method is not only applicable to soft rock roadways but also to deep mining mines and strong mine pressure roadways. It has significant economic and social benefits.

[0065] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-soft coal seam floor support structure, characterized in that: include: A pipe pile (1) comprising two pipe piles (1) arranged in an "eight" shape in the cross section of a tunnel (2), the pipe pile (1) comprising a grouting pipe (11) and a pile body (12) formed by pouring the grouting pipe (11), the grouting pipe (11) comprising a first section (111) inserted into a bottom plate of the tunnel (2) and a second section (112) exposed outside the bottom plate, and two adjacent pile bodies (12) arranged along the direction of the tunnel (2) partially overlap; A crown beam assembly (3) connected to the second section (112) of the grouting pipe (11); The floor layer (4) is arranged on the base plate.

2. The three-soft coal seam floor support structure according to claim 1 is characterized in that: The length of the first section (111) is greater than 4500 mm, and the length of the second section (112) is less than 400 mm.

3. The three-soft coal seam floor support structure according to claim 2 is characterized in that: The first section (111) comprises a first area (1111) adjacent to the second section (112) and a second area (1112) away from the second section (112); the second area (1112) is provided with grouting holes for forming the pile body (12).

4. The three-soft coal seam floor support structure according to any one of claims 1 to 3, characterized in that: The bottom plate is provided with a borehole for installing the grouting pipe (11), and the two boreholes located in the same section are respectively located on both sides of the center line (21) of the tunnel, the distance between the borehole adjacent to the belt conveyor and the center line (21) of the tunnel is 400mm-800mm, and the distance between the borehole adjacent to the pedestrian side and the center line (21) of the tunnel is 700mm-1100mm.

5. The three-soft coal seam floor support structure according to any one of claims 1 to 3, characterized in that: An angle a is formed between the grouting pipe (11) and the horizontal line, wherein the angle a satisfies: 60°≤a≤80°.

6. The three-soft coal seam floor support structure according to claim 1 is characterized in that: The crown beam assembly (3) comprises: A mesh sheet (31) is laid on the bottom plate; A steel belt (32) is laid on the mesh (31), and the steel belt (32) is used to connect two grouting pipes (11) in the same section; A pressure plate (33) is arranged along the direction of the tunnel (2) and is used to connect at least two grouting pipes (11) that are arranged continuously.

7. The three-soft coal seam floor support structure according to claim 1 or 6, characterized in that: The thickness of the floor layer (4) is t, wherein t satisfies: 150 mm ≤ t ≤ 250 mm.

8. A construction method of the three-soft coal seam floor support structure according to any one of claims 1 to 7, characterized in that: The steps include: Drilling: Drill holes in the shape of an "eight" on the bottom plate of the tunnel (2) along the same section; Installing a grouting pipe (11), installing the grouting pipe (11) in the drilled hole so that the grouting pipe (11) has a first section (111) inserted into the bottom plate and a second section (112) exposed outside the bottom plate; Grouting: grouting is performed through a grouting pipe (11) to form a pile body (12) in the bottom plate, and two adjacent pile bodies (12) along the direction of the tunnel (2) partially overlap; Construction of the crown beam assembly: connecting and fixing the first section (111) of the grouting pipe (11) through the crown beam assembly; Pouring of the floor layer (4): After the construction of the crown beam assembly is completed, concrete is poured on the base plate to form the floor layer (4).

9. The construction method according to claim 8, characterized in that: The drilling comprises: drilling holes on both sides of the lane centerline (21); of the two holes in the same section, the distance between the hole adjacent to the belt conveyor and the lane centerline (21) is 400 mm-800 mm, and the distance between the hole adjacent to the pedestrian side and the lane centerline (21) is 700 mm-1100 mm.

10. The construction method according to claim 8, characterized in that: The grouting comprises: Adjacent grouting pipes (11) are subjected to pressure grouting to allow adjacent pile bodies (12) to partially overlap; Each grouting pipe (11) is subjected to at least one supplementary grouting.

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