Advanced hydraulic fracturing pressure relief and full-length anchoring integrated process for stoping roadway bottom plate

Abstract

The invention relates to an advanced hydraulic fracturing pressure relief and full-length anchoring integrated technology for a mining roadway bottom plate. The technology comprises the steps that a bottom plate drilling machine is used for constructing and drilling a hole perpendicular to the roadway bottom plate; the pipeline is communicated with the emulsification pump station, the booster pump, the pressure gauge and the flowmeter; a high-pressure fracturing packer set is installed, the high-pressure fracturing packer set is conveyed to a preset fracturing position through an instrument, and a high-pressure pipeline is connected with a high-pressure sealing drill rod; opening a stop valve to pressurize and inject water, and performing high-pressure hydraulic fracturing on the fine sandstone area of the roof; when the pressure of the pressure gauge is suddenly reduced, and the water outlet time of the bottom plate exceeds 5-7 minutes or the fracturing time exceeds 30 minutes, the stop valve is closed, and fracturing is ended; after fracturing is finished, the pressure relief valve is opened to drain water, and after no pressure is released, the hole packer is recycled; recording hole sealing data, and finishing single-hole water injection. The method has the advantages that an advanced pressure relief fissure zone-grouting body-full-length anchor cable cooperative bearing system is adopted, the advanced pressure relief effect is reserved, and the overall bearing capacity of the bottom plate rock mass is improved through full-length anchoring.

Description

Technical Field

[0001] This invention belongs to the field of roadway management technology, specifically involving an integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the bottom plate of a mining roadway. Background Technology

[0002] During coal seam tunneling or mining, as the working face advances, severe roadway deformation occurs, typically manifesting as roof subsidence, localized roof rupture, anchor bolt failure, and individual anchor bolt breakage. This is often accompanied by water seepage, water spraying, severe inward squeezing of the roadway sides, and intense floor heave, posing significant safety hazards to roadway maintenance and use. Floor heave is the most difficult aspect of surrounding rock deformation to control; deformation and damage to the roadway floor frequently lead to a reduction in roadway cross-section or even support failure, seriously affecting the safety of pedestrians and transport in the coal mine.

[0003] Currently, most mining roadways adopt the method of allowing floor heave during mining and then passively excavating the floor later. This not only wastes time but also affects the normal use of the roadway and delays production. Although some existing technologies for treating floor heave involve direct grouting, this method does not consider the specific stress conditions of the roadway floor, resulting in poor actual treatment effects. Multiple excavations and repairs of the roadway floor are then required to meet the actual needs of safe production and use, which is time-consuming, labor-intensive, and costly.

[0004] In summary, current methods for treating floor heave caused by mining in longwall roadways face the technical challenge of unsustainable treatment. Summary of the Invention

[0005] The present invention aims to solve the problem of the lack of sustainability of existing methods for treating floor heave under the influence of mining in longwall roadways.

[0006] The present invention solves the above-mentioned technical problems through the following technical means: An integrated process for advanced hydraulic fracturing and pressure relief of the floor of a mining roadway and full-length anchoring includes the following steps: S1. Use a floor drilling rig to drill holes vertically into the tunnel floor. S2. According to the design plan, the high-pressure pipeline is connected to the emulsification pump station (or clean water pump), booster pump, pressure gauge and flow meter at the working face. S3. Install the high-pressure fracturing packer assembly. Use manual labor or a crawler drilling rig and a high-pressure sealing drill rod to send the high-pressure fracturing packer assembly to the predetermined fracturing position in the hole, and connect the high-pressure pipeline to the high-pressure sealing drill rod through an adapter. S4. Slowly open the shut-off valve to pressurize and inject water to perform high-pressure hydraulic fracturing on the fine sandstone area of ​​the roof. S5. When the pressure gauge pressure suddenly decreases (no longer rises significantly), water flows out of the bottom plate (adjacent borehole) for more than 5 to 7 minutes, or the fracturing time exceeds 30 minutes, close the shut-off valve and end the fracturing. S6. After fracturing is completed, slowly open the pressure relief valve to drain the water. After the water in the hole is drained and there is no pressure, retrieve the sealing device. S7. Record the sealing data; single-hole water injection is complete.

[0007] The method of this invention first forms a deep stress-relief fracture zone through hydraulic fracturing, releasing shallow high stress in advance and weakening the superimposed effect of mining pressure. Then, it directly utilizes the existing fracturing holes as anchor cable installation channels and adopts a full-length anchoring grouting process to fill the gaps between the hole wall and the anchor cable, as well as various fractures, with grout filling the gaps and various fractures, forming a collaborative bearing system of "advanced stress-relief fracture zone - grouting body - full-length anchor cable". This not only retains the advanced stress relief effect, but also improves the overall bearing capacity of the floor rock mass through full-length anchoring, achieving "advanced stress relief, multiple uses of one hole, and full-length stabilization", solving the technical problem of unsustainable floor heave treatment under the influence of mining in the retreat roadway.

[0008] Preferably, geological surveys are conducted before construction to determine the lithology, fissures, and water content of the area 300m ahead.

[0009] Preferably, after fracturing, the hole cleaning, anchor cable placement, and grouting should be carried out after an interval of 24-48 hours.

[0010] Preferably, in step S1, the construction distance is more than 300m away from the working surface.

[0011] Preferably, in step S1, the base plate is constructed using a ground anchor drilling rig with a drilling diameter of 42mm or 94mm. The drilling depth is determined based on the calculation of the key layer of the plate, numerical analysis, and comprehensive information from drilling inspection. Holes are drilled perpendicular to the base plate in the middle of the tunnel, with a spacing of 5-10m along the tunnel direction. The drilling distance is adjusted according to the specific fracturing effect.

[0012] Preferably, in step S3, the fracturing holes are arranged at intervals of 5-10m along the roadway direction.

[0013] Preferably, in step S3, the hole depth penetrates 3-5m into the shallow weak rock layer and enters the stable rock layer, which is suitable for the range of mining pressure propagation in the mining roadway. The diameter is selected as 21.8mm and the anchor cable hole diameter is 42mm.

[0014] Preferably, the anchor cable has a diameter of 21.8 mm, and the anchoring material is cement grout, grade 42.5 ordinary Portland cement, with a water-cement ratio of about 1:2. The anchor cable is inserted into the hole in the bottom plate, and the upper end of the anchor cable is required to be about 1 m below the hole opening. After being secured with wire, the grouting begins.

[0015] Preferably, by controlling the grouting pressure and the grout diffusion radius, it is ensured that the grout only fills the periphery of the fracturing hole and the shallow secondary fractures, without penetrating into the deep main pressure relief fracture zone, thus ensuring that the channel for the transfer of mining pressure to the deeper part is unobstructed. Preferably, after the fracturing of the fracturing hole is completed, the base plate is fully anchored and reinforced with "anchor cable + anchoring material".

[0016] The advantages of this invention are: Hydraulic fracturing creates deep stress relief fracture zones, releasing shallow high stress in advance and weakening the cumulative effect of mining pressure. Existing fracturing holes are then used directly as anchor cable installation channels. A full-length anchoring grouting process is adopted, filling the gaps between the hole wall and the anchor cable, as well as various fractures, with grout filling the gaps and various fractures. This forms a collaborative bearing system of "advanced stress relief fracture zone - grouting body - full-length anchor cable". This retains the advanced stress relief effect and enhances the overall bearing capacity of the floor rock mass through full-length anchoring, achieving "advanced stress relief, multiple uses of one hole, and full-length stabilization". This solves the technical problem of unsustainable treatment of floor heave under the influence of mining in the retreat roadway. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the construction process of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Combination Figure 1 As shown, geological surveys are first conducted to clarify the lithology, fissures, and water content distribution in the area 300m ahead of the work surface, thus accurately understanding the geological conditions surrounding the area to be constructed. The advance construction distance is limited to more than 300m from the working face. This is to avoid damage from mining disturbances during early construction and to ensure sufficient stress release period for the rock mass after decompression.

[0020] S1. Use a floor drilling rig to drill holes vertically into the tunnel floor. S2. According to the design plan, the high-pressure pipeline is connected to the emulsification pump station (or clean water pump), booster pump, pressure gauge and flow meter at the working face. S3. Install the high-pressure fracturing packer assembly. Use manual labor or a crawler drilling rig and a high-pressure sealing drill rod to send the high-pressure fracturing packer assembly to the predetermined fracturing position in the hole, and connect the high-pressure pipeline to the high-pressure sealing drill rod through an adapter. S4. Slowly open the shut-off valve to pressurize and inject water to perform high-pressure hydraulic fracturing on the fine sandstone area of ​​the roof. S5. When the pressure gauge pressure suddenly decreases (no longer rises significantly), water flows out of the bottom plate (adjacent borehole) for more than 5 to 7 minutes, or the fracturing time exceeds 30 minutes, close the shut-off valve and end the fracturing. S6. After fracturing is completed, slowly open the pressure relief valve to drain the water. After the water in the hole is drained and there is no pressure, retrieve the sealing device. S7. Record the sealing data; single-hole water injection ends.

[0021] It is important to note that in step S1, the fracturing holes are arranged at 5-10m intervals along the roadway direction, and the hole depth penetrates 3-5m into the shallow weak rock layer to reach the stable rock layer. Furthermore, to adapt to the range of mining pressure propagation in the mining roadway, the anchor cable diameter is selected as 21.8mm, the anchor cable hole diameter as 42mm, and the anchoring material is cement grout with grade 42.5 ordinary Portland cement and a water-cement ratio of approximately 1:2. The anchor cable is inserted into the bottom plate hole, requiring the upper end of the anchor cable to be about 1m below the hole opening. After securing it with wire, grouting begins. By controlling the grouting pressure and the grout diffusion radius, it is ensured that the grout only fills the area around the fracturing holes and shallow secondary fractures, without penetrating into the deep main pressure relief fracture zone, thus ensuring the smooth flow of mining pressure to deeper layers.

[0022] For fracturing holes in the base plate, a ground-anchored drilling rig is used. The hole diameter is 42mm or 94mm. The drilling depth is based on calculations of the key layers of the base plate, numerical analysis, and comprehensive information from borehole inspection. Holes are drilled perpendicular to the base plate in the middle of the roadway, with a spacing of 5-10m along the roadway direction. The drilling spacing is adjusted according to the specific fracturing effect. After fracturing, the base plate is fully anchored and reinforced using "anchor cables + anchoring material". After fracturing, an interval of 24-48 hours is allowed (until the fracturing fracture stabilizes and the stress is initially released) before cleaning the holes, removing the anchor cables, and grouting.

[0023] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Terms such as "upper," "lower," "left," "right," "front," and "rear" used in the invention are merely for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0024] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions 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 process for integrated hydraulic fracturing and pressure relief of the floor slab in a mining roadway and full-length anchoring, characterized in that, Includes the following steps: S1. Use a floor drilling rig to drill holes vertically into the tunnel floor. S2. According to the design plan, the high-pressure pipeline is connected to the emulsification pump station (or clean water pump), booster pump, pressure gauge and flow meter at the working face. S3. Install the high-pressure fracturing packer assembly. Use manual labor or a crawler drilling rig and a high-pressure sealing drill rod to send the high-pressure fracturing packer assembly to the predetermined fracturing position in the hole, and connect the high-pressure pipeline to the high-pressure sealing drill rod through an adapter. S4. Slowly open the shut-off valve to pressurize and inject water to perform high-pressure hydraulic fracturing on the fine sandstone area of ​​the roof. S5. When the pressure gauge pressure suddenly decreases (no longer rises significantly), water flows out of the bottom plate (adjacent borehole) for more than 5 to 7 minutes, or the fracturing time exceeds 30 minutes, close the shut-off valve and end the fracturing. S6. After fracturing is completed, slowly open the pressure relief valve to drain the water. After the water in the hole is drained and there is no pressure, retrieve the sealing device. S7. Record the sealing data; single-hole water injection ends.

2. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, Before construction, a geological survey was conducted to determine the lithology, fissures, and water content of the area 300m ahead.

3. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, After fracturing is completed, wait 24-48 hours before cleaning the hole, placing anchor cables, and grouting.

4. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, In step S1, the construction distance is more than 300m away from the working surface.

5. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, In step S1, the base plate is constructed using a ground anchor drilling rig with a drilling diameter of 42mm or 94mm. The drilling depth is determined based on the calculation of the key layer of the plate, numerical analysis, and comprehensive information from drilling inspection. Holes are drilled perpendicular to the base plate in the middle of the roadway, with a spacing of 5-10m along the roadway direction. The drilling spacing is adjusted according to the specific fracturing effect.

6. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, In step S3, the fracturing holes are arranged at intervals of 5-10m along the roadway.

7. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 4, characterized in that, In step S3, the hole depth penetrates the shallow weak rock layer by 3-5m to enter the stable rock layer, adapting to the range of mining pressure propagation in the mining roadway. A diameter of 21.8mm and an anchor cable hole diameter of 42mm are selected.

8. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, The anchor cable has a diameter of 21.8 mm. The anchoring material is cement grout, grade 42.5 ordinary Portland cement, with a water-cement ratio of about 1:

2. The anchor cable is inserted into the hole in the bottom plate, and the upper end of the anchor cable is required to be about 1 m below the hole opening. After securing it with wire, the grouting process begins.

9. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, By controlling the grouting pressure and the grout diffusion radius, it is ensured that the grout only fills the periphery of the fracturing hole and the shallow secondary fractures, without penetrating into the deep main pressure relief fracture zone, thus ensuring that the channel for the transfer of mining pressure to the deeper parts is unobstructed.

10. The integrated process of advanced hydraulic fracturing and pressure relief and full-length anchoring of the floor of a mining roadway according to claim 1, characterized in that, After the fracturing of the fracturing hole is completed, the base plate is fully anchored and reinforced with "anchor cable + anchoring material".

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