A method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions

Abstract

The present invention is a method for constructing a coal mine return air shaft wind tunnel under the condition of a high static water level impact layer, which belongs to the field of mine ventilation technology. It adopts a coal mine return air shaft shaft wind tunnel construction method that combines enclosure and dewatering, adopts a drilling jet grouting method to form a water-stop curtain, and provides a water absorption well in the foundation pit for dewatering operations, so as to construct the wind tunnel safely and quickly, and combines dewatering inside and outside the foundation pit to isolate the construction impact caused by external water gushing during the wind tunnel construction. At the same time, reinforced concrete cast-in-place piles are used for primary slope support to reinforce the surrounding rocks on both sides of the wind tunnel, so that the working environment is relatively safe, and the wind tunnel is constructed under the premise of ensuring safety.

Description

Technical Field

[0001] The invention belongs to the technical field of mine ventilation, and relates to a construction method, in particular to a coal mine return air shaft wind tunnel construction method under the condition of a high static water level impact layer. Background Art

[0002] The wind tunnel of the return air shaft of a coal mine is a key part connecting the shaft and the main ventilation fan of the mine. It is usually at a 45° angle with the shaft, and the bottom plate can be buried up to 12-15m. It is usually constructed by open excavation, and in order to meet the needs of shaft drilling construction, it can usually be constructed only after the shaft reaches the bottom. When the stratum where the wind tunnel is located is an alluvial layer, and the static water level in the construction area is high, when it is above the bottom plate of the shaft wind tunnel, the construction working surface is below the static water level, and water gushing during construction will cause great difficulties and hidden dangers to the construction. In order to ensure the safety of excavation, the freezing method can be used to form a freezing curtain, but the construction of a freezing station to form a freezing system is expensive and takes a long time. Summary of the invention

[0003] The present invention adopts a coal mine return air shaft wind tunnel construction method combining enclosure and lowering, and performs construction under the condition of high static water level impact layer, thereby shortening the construction period and ensuring the construction quality.

[0004] The technical solution adopted by the present invention is:

[0005] A method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions, the construction method comprising the following steps:

[0006] A. Construct jet grouting holes 2m outward from the shaft wall of the return air shaft and 3m outward from the outer wall of the wind tunnel, and use the drilling jet grouting method to form a water-stop curtain, and the area inside the water-stop curtain forms a foundation pit;

[0007] B. Construct observation holes around the water-stop curtain to observe the water gushing around the foundation pit;

[0008] C. Construct a water absorption well in the foundation pit, place a drainage pump in the water absorption well, and use the water absorption well to carry out dewatering operations during the construction of the wind tunnel;

[0009] D. On the outside of the wind tunnel and inside the water-stop curtain, two rows of reinforced concrete piles are constructed to form a support structure. A crown beam is constructed on the top of the reinforced concrete piles. Support anchor cables and mortar anchors are constructed in three layers along the reinforced concrete piles downwards, and steel mesh is hung for spraying.

[0010] E. Excavate reinforced concrete piles to the bottom of the wind tunnel, lay concrete bottom, and lay 100mm thick C20 concrete;

[0011] F. Carry out the construction of the return air shaft. After reaching the bottom, prepare for the measurement and layout of the wind tunnel and determine the excavation range of the wind tunnel;

[0012] G. Carry out the construction of wind tunnel.

[0013] The drilling jet grouting method used in step A has a drilling diameter of 500 mm, a hole depth of 15.5 m, a horizontal spacing of 300 mm, a vertical spacing of 250 mm, and uses P·S32.5 cement with a water-cement ratio of 0.45-0.5.

[0014] The number of observation holes in step B is 4, one each being arranged around the water-stop curtain.

[0015] In step C, two rows of water absorption wells are arranged crosswise on the left and right sides of the foundation pit.

[0016] The cast-in-place concrete pile includes a steel cage and concrete. The steel cage includes steel bars arranged in a circular shape transversely and steel rings arranged longitudinally along the steel bars. A reinforcement mechanism is provided on the steel cage. The reinforcement mechanism includes reinforcement bars. The reinforcement bars are arranged in a barb-like shape on the side of the steel cage. The steel cage enhances its fit with the concrete with the help of the reinforcement bars.

[0017] The reinforcement mechanism also includes a connecting seat, the end of which is connected to the reinforcement strip, and the reinforcement strip is arranged on the side of the steel cage with the help of the connecting seat.

[0018] The connection seat is provided with a clamp structure distributed in a T shape, and the connection seat is connected with the steel bar and the steel ring by means of the clamp structure.

[0019] The connection seat is provided with a surrounding component in a T-shaped distribution, and the surrounding component is a spiral spring structure. The connection seat is wound and connected with the steel bar and the steel ring by means of the surrounding component.

[0020] The reinforcement mechanism is arranged at one third of the lower part of the steel cage.

[0021] The beneficial effects of the present invention are:

[0022] 1. Social benefits

[0023] (1) A new design concept and construction method were proposed for the construction of return air shafts in coal mines.

[0024] (2) This construction method solves the construction difficulties such as the return air shaft wind tunnel being located in the alluvial layer, with a high static water level and a large amount of water gushing out.

[0025] (3) The drilling jet grouting method is used to form a water-stop curtain, which can quickly stop and reduce water in a safe precipitation space, and the wind tunnel can be constructed safely and quickly.

[0026] (4) Reinforced concrete bored piles are used for primary slope support to reinforce the surrounding rock on both sides of the wind tunnel. The working environment is relatively safe, and the wind tunnel is constructed under the premise of ensuring safety.

[0027] (5) The combination of precipitation inside and outside the foundation pit isolates the construction impact caused by external water gushing during the construction of the wind tunnel.

[0028] 2. Safety benefits

[0029] (1) The drilling jet grouting method forms a water-stop curtain, which isolates the water and sand gushing during the construction of the wind tunnel and avoids accidents.

[0030] (2) Before the construction of the wind tunnel, reinforced concrete cast-in-place piles were used for primary support, which achieved advanced support and carried out construction in the supported safe construction area, ensuring the construction safety during the excavation process.

[0031] (3) After adopting a series of technologies, the construction of the return air shaft wind tunnel was completed safely and quickly, and full negative pressure ventilation of the mine was formed as soon as possible, meeting the needs of underground construction and production.

[0032] 3. Economic benefits

[0033] (1) It reduces the high cost and long construction period caused by the ground freezing method.

[0034] (2) The mine was fully negative-pressure ventilated as soon as possible, which accelerated the mine construction process and shortened the construction period, allowing the mine to be put into production as soon as possible.

[0035] (3) Shortened process time, saved construction period, and reduced labor costs and machinery equipment usage fees.

[0036] The present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a plan layout diagram of the return air shaft wind tunnel construction method of the present invention;

[0038] Figure 2 This is a partial enlarged view of the water-stop curtain of the present invention;

[0039] Figure 3 It is a schematic diagram of the wind tunnel support structure of the return air shaft of the present invention;

[0040] Figure 4 It is a schematic diagram of the structure of the steel cage in the reinforced concrete cast-in-place pile of the present invention;

[0041] Figure 5 is a schematic diagram of the clamp structure of the present invention;

[0042] Figure 6 is a schematic diagram of a surrounding component in the present invention;

[0043] In the attached drawings, 1. return air shaft, 2. air tunnel, 3. jet grouting hole, 4. observation hole, 5. water suction well, 6. reinforced concrete bored piles, 7. supporting anchor cables, 8. mortar anchoring, 9. steel mesh, 10. steel cage, 11. steel bar, 12. steel ring, 13. reinforcement bar, 14. connecting seat, 15. clamp structure, 16. surrounding parts. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings, but the protection scope and implementation methods of the present invention are not limited thereto.

[0045] Specific embodiment, the present invention is a method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions, the construction method comprising the following steps:

[0046] A. Construct jet grouting holes 3 2m outward from the shaft wall of the return air shaft 1 and 3m outward from the outer wall of the wind tunnel 2, and use the drilling jet grouting method to form a water-stop curtain, and the area inside the water-stop curtain forms a foundation pit;

[0047] B. Construct observation holes 4 around the water-stop curtain to observe the water gushing around the foundation pit;

[0048] C. Construct a water absorption well 5 in the foundation pit, place a drainage pump in the water absorption well 5, and use the water absorption well 5 to perform dewatering operations during the construction of the wind tunnel 2;

[0049] D. On the outside of the wind tunnel 2 and inside the water-stop curtain, two rows of reinforced concrete piles 6 are constructed to form a support structure. A crown beam is constructed on the top of the reinforced concrete piles 6. Support anchor cables 7 and mortar anchors 8 are constructed in three layers downward along the reinforced concrete piles 6, and steel plate mesh 9 is hung for spraying;

[0050] E. Excavate reinforced concrete piles 6 to the bottom of the wind tunnel 2, lay concrete bottom, and lay 100mm thick C20 concrete;

[0051] F. Carry out the construction of the return air shaft 1. After reaching the bottom, prepare for the survey and layout of the wind tunnel 2 and determine the excavation range of the wind tunnel 2;

[0052] G. Carry out the construction of air tunnel 2.

[0053] Among them, the drilling jet grouting method is to use a drilling rig to drill a hole, insert the grouting pipe with a nozzle to the predetermined position of the soil layer, and use high-pressure equipment to make the slurry into a high-pressure jet of more than 20Mpa, which is ejected from the nozzle to impact and destroy the soil. Some fine soil materials emerge from the water with the slurry, and the remaining soil particles are mixed with the slurry under the impact force of the jet flow, centrifugal force and gravity, and are rearranged regularly according to a certain slurry-soil ratio. After the slurry solidifies, a water-stop curtain is formed in the soil.

[0054] Among them, the staff can use the set observation holes to observe the water gushing around the foundation pit in real time. When there is a lot of water gushing around the foundation pit, the drainage pump can be turned on to carry out precipitation operations.

[0055] Furthermore, in step A, the drilling jet grouting method is used, wherein the borehole diameter is 500 mm, the hole depth is 15.5 m, the horizontal spacing is 300 mm, the vertical spacing is 250 mm, P·S32.5 cement is used, and the water-cement ratio is 0.45-0.5; in step B, the number of observation holes 4 is 4, each of which is arranged around the water-stop curtain; in step C, two rows of water absorption wells 5 are arranged crosswise on the left and right sides of the foundation pit.

[0056] like Figure 1 to Figure 3 As shown, the present invention uses a water-stop curtain formed by jet grouting holes 3 to retain water on the periphery of the foundation pit, provides a water suction well 5 in the foundation pit for dewatering operations, and forms a primary support through reinforced concrete bored piles 6 to prevent accidents such as slope instability, sliding, cracking, and collapse during construction. Dewatering inside and outside the foundation pit is combined to isolate the construction impact caused by external water gushing during the construction of the wind tunnel 2.

[0057] After the shaft of the return air shaft 1 is constructed to the bottom, the surveying and laying out of the wind tunnel 2 is completed, the excavation range of the wind tunnel 2 is determined, and the mechanical equipment and materials required during the construction of the wind tunnel 2 are prepared.

[0058] Further, if Figure 4 As shown, the present invention is a support structure for excavation of a foundation pit of a return air shaft 1 and a wind tunnel 2 in a coal mine, including concrete cast-in-place piles, wherein the concrete cast-in-place piles include a steel cage 10 and concrete, wherein the steel cage 10 includes steel bars 11 arranged transversely in a ring shape and steel rings 12 arranged longitudinally along the steel bars 11, wherein a reinforcement mechanism is provided on the steel cage 10, wherein the reinforcement mechanism includes a reinforcement bar 13, wherein the reinforcement bar 13 is arranged in a barb shape on the side of the steel cage 10, and the steel cage 10 enhances the fit with the concrete by means of the reinforcement bar 13. When preparing the reinforced concrete pile 6, due to reasons such as uneven concrete pouring or a certain fluidity of concrete, when the steel casing is pulled out, it is easy to lift a part of the steel cage 10, causing the steel cage 10 to deviate from the set position. Now, a reinforcement strip 13 structure is added around the steel cage 10. The barbed reinforcement strip 13 structure can increase the resistance between the steel cage 10 and the concrete when the steel casing is pulled out, which ensures the fixation of the position of the steel cage 10 to a certain extent, further enhances the stability and bearing capacity of the reinforced concrete pile 6, and solves the safety hazard caused by the defects of the support structure during the excavation of the wind tunnel 2 of the coal mine return air shaft 1. At the same time, when preparing the reinforced concrete pile 6, the barbed reinforcement strip 13 affects the process of putting the steel cage 10 into the steel pipe sleeve.

[0059] Furthermore, the reinforcement mechanism further includes a connection seat 14, the end of which is connected to the reinforcement bar 13, and the reinforcement bar 13 is arranged on the side of the steel cage 10 by means of the connection seat 14. The connection seat 14 increases the contact area between the reinforcement bar 13 and the steel cage 10, so that the reinforcement bar 13 can be more firmly connected to the steel cage 10, preventing the reinforcement bar 13 from falling off during operation and causing loss of effect, further ensuring the feasibility of the solution.

[0060] Further, if Figure 5 As shown, the connection seat 14 is provided with a T-shaped clamp structure 15, and the connection seat 14 is connected with the reinforcing bar 11 and the reinforcing ring 12 by means of the clamp structure 15. The added clamp structure 15 can easily complete the connection between the reinforcement mechanism and the reinforcing cage 10, and when in use, it can be directly clamped with the side wall of the reinforcing cage 10, saving work flow.

[0061] Further, if Figure 6 As shown, the connection seat 14 is provided with a surrounding component 16 in a T-shaped distribution, and the surrounding component 16 is a spiral spring structure. The connection seat 14 is connected to the steel bar 11 and the steel ring 12 by winding with the surrounding component 16. The added surrounding component 16 can easily complete the connection between the reinforcement mechanism and the steel cage 10. When in use, the reinforcement mechanism is directly screwed to the side wall of the steel cage 10 in a surrounding manner, which is convenient and stable.

[0062] Further, as a better improvement of the present invention, the reinforcement mechanism is arranged at one-third of the lower part of the steel cage 10. The reinforcement mechanism includes four reinforcement bars 13, which are evenly distributed at the same level of the steel cage 10. The reinforcement structure is arranged at one-third of the lower part of the steel cage 10, which increases the load-bearing capacity of the reinforcement mechanism, can better increase the resistance between the steel cage 10 and the concrete, and the position is not easy to move; four reinforcement bars 13 are arranged on the side wall of the steel cage 10, which can save materials to the maximum extent and make the four reinforcement bars 13 evenly stressed, thereby achieving the corresponding effect.

Claims

1. A method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions, characterized in that: The construction method comprises the following steps: A. Construct a jet grouting hole (3) 2 m outward from the shaft wall of the return air shaft (1) and 3 m outward from the outer wall of the wind tunnel (2), and use the drilling jet grouting method to form a water-stop curtain, and the area inside the water-stop curtain forms a foundation pit; B. Construct observation holes (4) around the water-stop curtain to observe the water gushing around the foundation pit; C. constructing a water absorption well (5) in the foundation pit, placing a drainage pump in the water absorption well, and using the water absorption well (5) to perform dewatering operations during the construction of the wind tunnel; D. On the outside of the wind tunnel (2) and inside the water-stop curtain, two rows of reinforced concrete piles (6) are constructed to form a support structure. A crown beam is constructed on the top of the reinforced concrete piles (6). Support anchor cables (7) and mortar anchors (8) are constructed in three layers downward along the reinforced concrete piles (6) and steel mesh (9) are hung for spraying. E. Excavate reinforced concrete piles (6) to the bottom of the wind tunnel (2) and lay concrete foundation with 100 mm thick C20 concrete; F. Carry out the construction of the return air shaft (1). After reaching the bottom, prepare for the survey and layout of the wind tunnel (2) and determine the excavation range of the wind tunnel (2); G. Carry out the construction of the wind tunnel (2).

2. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 1, characterized in that: The drilling jet grouting method used in step A has a drilling diameter of 500 mm, a hole depth of 15.5 m, a horizontal spacing of 300 mm, a vertical spacing of 250 mm, and uses P·S32.5 cement with a water-cement ratio of 0.45-0.

5.

3. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 1, characterized in that: In step B, the number of observation holes (4) is 4, one each being arranged around the water-stop curtain.

4. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 1, characterized in that: In step C, two rows of water absorption wells (5) are arranged crosswise on the left and right sides of the foundation pit.

5. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 1, characterized in that: The reinforced concrete cast-in-place pile (6) comprises a steel cage (10) and concrete, the steel cage (10) comprising steel bars (11) arranged transversely in a ring shape and steel rings (12) arranged longitudinally along the steel bars (11), the steel cage (10) being provided with a reinforcement mechanism, the reinforcement mechanism comprising a reinforcement bar (13), the reinforcement bar (13) being arranged in a barb-like shape on a side surface of the steel cage (10), the steel cage (10) enhancing its fit with the concrete by means of the reinforcement bar (13).

6. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 5, characterized in that: The reinforcement mechanism further comprises a connecting seat (14), the end of the connecting seat (14) being connected to the reinforcement strip (13), and the reinforcement strip (13) being arranged on the side of the steel cage by means of the connecting seat (14).

7. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 6, characterized in that: The connection seat (14) is provided with a clamp structure (15) distributed in a T-shape, and the connection seat (14) is connected to the steel bar (11) and the steel ring (12) by means of the clamp structure (15).

8. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 6, characterized in that: The connection seat (14) is provided with a T-shaped surrounding component (16), the surrounding component (16) is a helical spring structure, and the connection seat (14) is connected to the steel bar (11) and the steel ring (12) by winding with the surrounding component (16).

9. The method for constructing a coal mine return air shaft wind tunnel under high static water level impact layer conditions according to claim 5, characterized in that: The reinforcement mechanism is arranged at one third of the lower part of the steel cage (10).

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