Advanced grouting reinforcement method for driving working face to pass through tectonic fracture zone

Abstract

The invention discloses an advanced grouting reinforcement method for a driving face to pass through a tectonic fracture zone, which comprises the following steps of: 1, identifying the tectonic fracture zone, and determining a grouting reinforcement range; 2, top plate advance grouting holes and coal side advance grouting holes which are arranged in a staggered mode are formed in a top plate and a coal side of the driving working face correspondingly, and a drill bit of a preset specification is adopted for drilling; 3, nano-modified single-liquid or double-liquid grouting materials are selected according to different parts, and slurry is prepared according to the preset water cement ratio; 4, after hole sealing is completed in a composite hole sealing mode, grouting is conducted according to a segmented grouting mode, graded grouting pressure and a corresponding preset grouting sequence; 5, after the grouting pressure and the grouting amount reach the standard, grout is stopped, equipment is cleaned, and grouting of the next hole is conducted; and 6, after the slurry reaches the design strength, tunneling operation is carried out. According to the advanced grouting reinforcement method for the tunneling working face passing through the tectonic fracture zone, the problems that in traditional grouting, the grouting efficiency conflicts with the tunneling efficiency, the reinforcement effect is uneven, and the stability of surrounding rock is insufficient are solved.

Description

Technical Field

[0001] This invention belongs to the field of tunnel support technology, specifically relating to a method for pre-grouting reinforcement of tunnel faces passing through structural fracture zones. Background Technology

[0002] When the tunneling face passes through a fractured geological zone, the advanced grouting reinforcement technology has several key shortcomings in practical applications: Traditional grouting methods often involve grouting at the tunneling face, leading to a conflict between grouting operations and tunneling construction, severely restricting construction efficiency; grouting materials have poor compatibility. Ordinary inorganic materials (such as ordinary silicate cement) have large particle sizes, weak injectability, difficulty in penetrating micro-cracks, low bonding strength, and slow solidification. Organic polymer materials, on the other hand, have drawbacks such as toxicity, high reaction temperatures, and insufficient safety, making it impossible to balance reinforcement effectiveness with construction efficiency. Safety issues include: a lack of targeted grouting hole layout, with hole positions, angles, and spacing not adequately matching the differentiated reinforcement needs of the roof and sides, easily creating reinforcement blind spots; fixed sealing parameters not dynamically adjusted according to geological conditions and reinforcement effects, often causing grout bypass and leakage, resulting in ineffective coverage of the target area; uneven grouting effect, with reinforcement failures easily occurring in some sides or roof areas, failing to form a complete load-bearing structure, leading to risks such as roof delamination and coal seam spalling, making it difficult to ensure the stability of the surrounding rock during tunneling and mining. Summary of the Invention

[0003] The purpose of this invention is to provide a method for advanced grouting reinforcement of tunneling faces through structurally fractured zones, which solves the problems of conflict between grouting and tunneling efficiency, uneven reinforcement effect and insufficient surrounding rock stability in traditional grouting.

[0004] The technical solution adopted in this invention is a method for pre-grouting reinforcement of tunneling faces through structurally fractured zones, comprising the following steps: Step 1: Identify the structural fracture zone based on previous geological data and determine the grouting reinforcement range; Step 2: Arrange staggered pre-grouting holes for the roof and pre-grouting holes for the coal face on the roof and coal face respectively, and drill the holes using a drill bit of a preset specification. Step 3: Select nano-modified single-component or double-component grouting materials for different parts and prepare the grout according to the preset water-cement ratio; Step 4: After sealing the holes using a composite sealing method, grout according to the segmented grouting method, graded grouting pressure, and corresponding preset grouting sequence; Step 5: After the grouting pressure and grouting volume reach the standard, stop grouting, clean the equipment, and proceed with grouting the next hole; Step 6: After the grout reaches the designed strength, tunneling operations will commence.

[0005] The invention is further characterized by: In step 2, several pre-grouting holes are arranged in each cycle. All pre-grouting holes are perpendicular to the tunneling face and staggered in height. The elevation angle of the odd-numbered grouting holes is 9~11°, and the elevation angle of the even-numbered grouting holes is 4~6°. The pre-grouting holes are 4700~4900mm away from the bottom plate. The middle hole is located in the middle of the top plate, and the holes on both sides are 600~800mm away from the side wall. The hole spacing is 1100~1300mm, and the hole depth is 9000~11000mm.

[0006] In step 2, several coal face advance grouting holes are arranged in each cycle. These advance grouting holes are parallel to the bottom plate and staggered inside and outside. They are arranged parallel to each other from the top plate to the bottom plate. Among these advance grouting holes, the odd-numbered holes are deflected inward by 9-11° from the vertical excavation face, and the even-numbered holes are deflected inward by 4-6° from the vertical excavation face. The advance grouting holes are 4000-1600mm away from the bottom plate, and the first advance grouting hole is 500-700mm away from the top plate, with a hole depth of 9000-11000mm.

[0007] In step 3, the nano-modified two-component grouting material is a two-component powder consisting of components A and B. Over 95% of the nano-modified two-component grouting material is inorganic. The particle size D of the nano-modified two-component grouting material is... 90 The nano-modified two-component grouting material has a diameter of no more than 10µm, a maximum reaction temperature of no more than 55℃, and is non-toxic. It sets in 3~10min, has a compressive strength of no more than 50MPa after 28 days, and a bond strength with the coal body of no more than 1.7MPa after 28 days.

[0008] In step 3, the nano-modified single-component grouting material is in powder form, and more than 90% of it is inorganic. The particle size D of the nano-modified single-component grouting material is... 90 The nanometer diameter is no larger than 10µm, the maximum reaction temperature is no larger than 30℃, and it is non-toxic. The nano-modified single-liquid grouting material initially sets in 28~32min, has a compressive strength of no more than 50MPa after 28 days, and a bonding strength with the coal body of no more than 1.8MPa after 28 days.

[0009] In step 3, the preset water-cement ratio is the mass ratio of clean water to grouting material. The water-cement ratio of nano-modified two-component grouting material is 0.6~1.0, and the water-cement ratio of nano-modified single-component grouting material is 0.8~1.0.

[0010] In step 4, the graded grouting pressure is as follows: 3~5MPa for shallow surrounding rock within 2m, 5~15MPa for medium-deep surrounding rock within 2~5m, and 15~25MPa for deep surrounding rock within 5~10m.

[0011] In step 4, the segmented grouting is as follows: the first segment is 5-10m away from the borehole, and the second segment is 1-5m away from the borehole. The grout penetration pattern is explored through the first grouting cycle, and the grouting hole parameters are adjusted.

[0012] In step 4, the composite sealing method is as follows: a one-way high-pressure sealing device is used to seal the hole 1m from the hole opening, and "cotton yarn + double liquid material" is used to seal the section from 1m to the hole opening. The sealing depth is increased when the hole opening is broken.

[0013] In step 2, drilling and in step 4, grouting are carried out using a synchronous dual-liquid grouting pump. The rated grouting pressure of the synchronous dual-liquid grouting pump is not less than 30 MPa and the rated discharge is not less than 50 L / min. In step 3, when preparing the nano-modified dual-liquid grout, components A and B are stirred separately, and the stirring time is not more than 10 min. During grouting, it is forbidden to change the mixing tank containing components A and B or the grouting pump suction pipe.

[0014] The beneficial effects of this invention are: The method for pre-grouting reinforcement of tunneling faces through structural fracture zones provided by this invention effectively solves the problems of conflict between grouting and tunneling efficiency, uneven reinforcement effect and insufficient surrounding rock stability in traditional grouting. By accurately locating the fractured zone using preliminary geological data and combining it with a staggered grouting hole design between the roof and coal face, the reinforced area is fully covered without any blind spots, avoiding the problem of weak local reinforcement caused by unreasonable hole layout in traditional methods. Nano-modified single / double-liquid grouting materials are selected, which have the characteristics of being non-toxic and environmentally friendly, highly permeable, high-strength, highly adhesive, and having an adjustable setting time. This solves the pain points of poor injectability of traditional cement grout and the toxicity of organic grouts. Its high early strength performance can also shorten the curing cycle. Combined with segmented grouting, graded pressure control, and targeted grouting sequence (alternating repositioning of the roof and bottom-up grouting of the face), the waiting time for grouting and tunneling is reduced, improving the efficiency of construction coordination. A composite sealing process is adopted to prevent grout leakage, ensuring that the grout fully fills the cracks and compacts the surrounding rock, firmly cementing the fractured roof coal and coal face to form a complete load-bearing structure. This significantly improves the shear bearing capacity and long-term stability of the surrounding rock, avoids the risk of roof coal collapse, and ensures the normal operation of the roadheader. Meanwhile, the grouting parameters can be dynamically optimized through the first cycle to adapt to different geological conditions, further enhancing the reinforcement effect and construction flexibility, providing a reliable guarantee for the integrity of the coal body during tunneling and mining, and possessing multiple advantages such as safety, environmental protection, efficiency, and stability. Attached Figure Description

[0015] Figure 1 This is a diagram showing the arrangement of grouting holes in Embodiment 6 of the method for pre-grouting reinforcement of the tunneling face through the fractured zone of the present invention. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0017] Example 1 The method for pre-grouting reinforcement of the tunneling face through a fractured structural zone proposed in this embodiment includes the following steps: Step 1: Identify the structural fracture zone based on previous geological data and determine the grouting reinforcement range; Step 2: Arrange staggered pre-grouting holes for the roof and pre-grouting holes for the coal face on the roof and coal face respectively, and drill the holes using a drill bit of a preset specification. Step 3: Select nano-modified single-component or double-component grouting materials for different parts and prepare the grout according to the preset water-cement ratio; Step 4: After sealing the holes using a composite sealing method, grout according to the segmented grouting method, graded grouting pressure, and corresponding preset grouting sequence; Step 5: After the grouting pressure and grouting volume reach the standard, stop grouting, clean the equipment, and proceed with grouting the next hole; Step 6: After the grout reaches the designed strength, tunneling operations will commence.

[0018] Example 2 The method for pre-grouting reinforcement of the tunneling face through a fractured structural zone proposed in this embodiment includes the following steps: Step 1: Identify the structural fracture zone based on previous geological data and determine the grouting reinforcement range; Step 2: Arrange staggered pre-grouting holes for the roof and pre-grouting holes for the coal face on the roof and coal face respectively, and drill the holes using a drill bit of a preset specification. Several pre-grouting holes are arranged in each cycle of the roof slab. All the pre-grouting holes are perpendicular to the tunneling face and staggered in height. The elevation angle of the odd-numbered grouting holes is 9~11°, and the elevation angle of the even-numbered grouting holes is 4~6°. The pre-grouting holes are 4700~4900mm away from the bottom plate. The middle hole is located in the middle of the roof slab, and the holes on both sides are 600~800mm away from the side wall. The hole spacing is 1100~1300mm, and the hole depth is 9000~11000mm. Several coal face grouting holes are arranged in each cycle. All the coal face grouting holes are parallel to the bottom plate and staggered inside and outside. The coal face grouting holes are arranged in parallel from the top plate to the bottom plate. Among the coal face grouting holes, the odd-numbered grouting holes are deflected inward by 9~11° from the vertical excavation face, and the even-numbered grouting holes are deflected inward by 4~6° from the vertical excavation face. The coal face grouting holes are 4000~1600mm away from the bottom plate, the first coal face grouting hole is 500~700mm away from the top plate, and the hole depth is 9000~11000mm. Step 3: Select nano-modified single-component or double-component grouting materials for different parts and prepare the grout according to the preset water-cement ratio; Step 4: After sealing the holes using a composite sealing method, grout according to the segmented grouting method, graded grouting pressure, and corresponding preset grouting sequence; Step 5: After the grouting pressure and grouting volume reach the standard, stop grouting, clean the equipment, and proceed with grouting the next hole; Step 6: After the grout reaches the designed strength, tunneling operations will commence.

[0019] Example 3 The method for pre-grouting reinforcement of the tunneling face through a fractured structural zone proposed in this embodiment includes the following steps: Step 1: Identify the structural fracture zone based on previous geological data and determine the grouting reinforcement range; Step 2: Arrange staggered pre-grouting holes for the roof and pre-grouting holes for the coal face on the roof and coal face respectively, and drill the holes using a drill bit of a preset specification. Several pre-grouting holes are arranged in each cycle of the roof slab. All the pre-grouting holes are perpendicular to the tunneling face and staggered in height. The elevation angle of the odd-numbered grouting holes is 9~11°, and the elevation angle of the even-numbered grouting holes is 4~6°. The pre-grouting holes are 4700~4900mm away from the bottom plate. The middle hole is located in the middle of the roof slab, and the holes on both sides are 600~800mm away from the side wall. The hole spacing is 1100~1300mm, and the hole depth is 9000~11000mm. Several coal face grouting holes are arranged in each cycle. All the coal face grouting holes are parallel to the bottom plate and staggered inside and outside. The coal face grouting holes are arranged in parallel from the top plate to the bottom plate. Among the coal face grouting holes, the odd-numbered grouting holes are deflected inward by 9~11° from the vertical excavation face, and the even-numbered grouting holes are deflected inward by 4~6° from the vertical excavation face. The coal face grouting holes are 4000~1600mm away from the bottom plate, the first coal face grouting hole is 500~700mm away from the top plate, and the hole depth is 9000~11000mm. Step 3: Select nano-modified single-component or double-component grouting materials for different parts and prepare the grout according to the preset water-cement ratio; The nano-modified two-component grouting material is a two-component powder consisting of components A and B. Over 95% of the nano-modified two-component grouting material is inorganic. The particle size D of the nano-modified two-component grouting material is... 90 The nano-modified two-component grouting material has a particle size of no more than 10µm, a maximum reaction temperature of no more than 55℃, and is non-toxic. It sets in 3~10min, has a compressive strength of no more than 50MPa after 28 days, and a bond strength with the coal body of no more than 1.7MPa after 28 days. The nano-modified single-component grouting material is in powder form, with over 90% being inorganic components. The particle size D of the nano-modified single-component grouting material is... 90The nano-modified single-liquid grouting material has a particle size of no more than 10µm, a maximum reaction temperature of no more than 30℃, and is non-toxic. It sets in 28~32min, has a compressive strength of no more than 50MPa after 28 days, and a bond strength with the coal body of no more than 1.8MPa after 28 days. The preset water-cement ratio is the mass ratio of clean water to grouting material. The water-cement ratio of nano-modified two-component grouting material is 0.6~1.0, and the water-cement ratio of nano-modified single-component grouting material is 0.8~1.0. Step 4: After sealing the holes using a composite sealing method, grout according to the segmented grouting method, graded grouting pressure, and corresponding preset grouting sequence; Step 5: After the grouting pressure and grouting volume reach the standard, stop grouting, clean the equipment, and proceed with grouting the next hole; Step 6: After the grout reaches the designed strength, tunneling operations will commence.

[0020] Example 4 The method for pre-grouting reinforcement of the tunneling face through a fractured structural zone proposed in this embodiment includes the following steps: Step 1: Identify the structural fracture zone based on previous geological data and determine the grouting reinforcement range; Step 2: Arrange staggered pre-grouting holes for the roof and pre-grouting holes for the coal face on the roof and coal face respectively, and drill the holes using a drill bit of a preset specification. Several pre-grouting holes are arranged in each cycle of the roof slab. All the pre-grouting holes are perpendicular to the tunneling face and staggered in height. The elevation angle of the odd-numbered grouting holes is 9~11°, and the elevation angle of the even-numbered grouting holes is 4~6°. The pre-grouting holes are 4700~4900mm away from the bottom plate. The middle hole is located in the middle of the roof slab, and the holes on both sides are 600~800mm away from the side wall. The hole spacing is 1100~1300mm, and the hole depth is 9000~11000mm. Several coal face grouting holes are arranged in each cycle. All the coal face grouting holes are parallel to the bottom plate and staggered inside and outside. The coal face grouting holes are arranged in parallel from the top plate to the bottom plate. Among the coal face grouting holes, the odd-numbered grouting holes are deflected inward by 9~11° from the vertical excavation face, and the even-numbered grouting holes are deflected inward by 4~6° from the vertical excavation face. The coal face grouting holes are 4000~1600mm away from the bottom plate, the first coal face grouting hole is 500~700mm away from the top plate, and the hole depth is 9000~11000mm. Step 3: Select nano-modified single-component or double-component grouting materials for different parts and prepare the grout according to the preset water-cement ratio; The nano-modified two-component grouting material is a two-component powder consisting of components A and B. Over 95% of the nano-modified two-component grouting material is inorganic. The particle size D of the nano-modified two-component grouting material is... 90The nano-modified two-component grouting material has a particle size of no more than 10µm, a maximum reaction temperature of no more than 55℃, and is non-toxic. It sets in 3~10min, has a compressive strength of no more than 50MPa after 28 days, and a bond strength with the coal body of no more than 1.7MPa after 28 days. The nano-modified single-component grouting material is in powder form, with over 90% being inorganic components. The particle size D of the nano-modified single-component grouting material is... 90 The nano-modified single-liquid grouting material has a particle size of no more than 10µm, a maximum reaction temperature of no more than 30℃, and is non-toxic. It sets in 28~32min, has a compressive strength of no more than 50MPa after 28 days, and a bond strength with the coal body of no more than 1.8MPa after 28 days. The preset water-cement ratio is the mass ratio of clean water to grouting material. The water-cement ratio of nano-modified two-component grouting material is 0.6~1.0, and the water-cement ratio of nano-modified single-component grouting material is 0.8~1.0. Step 4: After sealing the holes using a composite sealing method, grout according to the segmented grouting method, graded grouting pressure, and corresponding preset grouting sequence; The graded grouting pressure is as follows: 3~5MPa for shallow surrounding rock within 2m, 5~15MPa for medium-deep surrounding rock within 2~5m, and 15~25MPa for deep surrounding rock within 5~10m. The segmented grouting process is as follows: the first segment is 5-10m away from the borehole, and the second segment is 1-5m away from the borehole. The grout penetration pattern is explored through the first grouting cycle, and the parameters of the grouting hole are adjusted accordingly. The composite sealing method is as follows: a one-way high-pressure sealing device is used to seal the hole 1m from the hole opening, and "cotton yarn + double liquid material" is used to seal the section from 1m to the hole opening. The sealing depth is increased when the hole opening is broken. Step 5: After the grouting pressure and grouting volume reach the standard, stop grouting, clean the equipment, and proceed with grouting the next hole; Step 6: After the grout reaches the designed strength, tunneling operations will commence.

[0021] Example 5 The method for pre-grouting reinforcement of the tunneling face through a fractured structural zone proposed in this embodiment includes the following steps: Step 1: Identify the structural fracture zone based on previous geological data and determine the grouting reinforcement range; Step 2: Arrange staggered pre-grouting holes for the roof and pre-grouting holes for the coal face on the roof and coal face respectively, and drill the holes using a drill bit of a preset specification. Several pre-grouting holes are arranged in each cycle of the roof slab. All the pre-grouting holes are perpendicular to the tunneling face and staggered in height. The elevation angle of the odd-numbered grouting holes is 9~11°, and the elevation angle of the even-numbered grouting holes is 4~6°. The pre-grouting holes are 4700~4900mm away from the bottom plate. The middle hole is located in the middle of the roof slab, and the holes on both sides are 600~800mm away from the side wall. The hole spacing is 1100~1300mm, and the hole depth is 9000~11000mm. Several coal face grouting holes are arranged in each cycle. All the coal face grouting holes are parallel to the bottom plate and staggered inside and outside. The coal face grouting holes are arranged in parallel from the top plate to the bottom plate. Among the coal face grouting holes, the odd-numbered grouting holes are deflected inward by 9~11° from the vertical excavation face, and the even-numbered grouting holes are deflected inward by 4~6° from the vertical excavation face. The coal face grouting holes are 4000~1600mm away from the bottom plate, the first coal face grouting hole is 500~700mm away from the top plate, and the hole depth is 9000~11000mm. Step 3: Select nano-modified single-component or double-component grouting materials for different parts and prepare the grout according to the preset water-cement ratio; The nano-modified two-component grouting material is a two-component powder consisting of components A and B. Over 95% of the nano-modified two-component grouting material is inorganic. The particle size D of the nano-modified two-component grouting material is... 90 The nano-modified two-component grouting material has a particle size of no more than 10µm, a maximum reaction temperature of no more than 55℃, and is non-toxic. It sets in 3~10min, has a compressive strength of no more than 50MPa after 28 days, and a bond strength with the coal body of no more than 1.7MPa after 28 days. The nano-modified single-component grouting material is in powder form, with over 90% being inorganic components. The particle size D of the nano-modified single-component grouting material is... 90 The nano-modified single-liquid grouting material has a particle size of no more than 10µm, a maximum reaction temperature of no more than 30℃, and is non-toxic. It sets in 28~32min, has a compressive strength of no more than 50MPa after 28 days, and a bond strength with the coal body of no more than 1.8MPa after 28 days. The preset water-cement ratio is the mass ratio of clean water to grouting material. The water-cement ratio of nano-modified two-component grouting material is 0.6~1.0, and the water-cement ratio of nano-modified single-component grouting material is 0.8~1.0. Step 4: After sealing the holes using a composite sealing method, grout according to the segmented grouting method, graded grouting pressure, and corresponding preset grouting sequence; The graded grouting pressure is as follows: 3~5MPa for shallow surrounding rock within 2m, 5~15MPa for medium-deep surrounding rock within 2~5m, and 15~25MPa for deep surrounding rock within 5~10m. The segmented grouting process is as follows: the first segment is 5-10m away from the borehole, and the second segment is 1-5m away from the borehole. The grout penetration pattern is explored through the first grouting cycle, and the parameters of the grouting hole are adjusted accordingly. The composite sealing method is as follows: a one-way high-pressure sealing device is used to seal the hole 1m from the hole opening, and "cotton yarn + double liquid material" is used to seal the section from 1m to the hole opening. The sealing depth is increased when the hole opening is broken. Step 5: After the grouting pressure and grouting volume reach the standard, stop grouting, clean the equipment, and proceed with grouting the next hole; Step 6: After the grout reaches the designed strength, tunneling operations will commence; In step 2, drilling and in step 4, grouting are carried out using a synchronous dual-liquid grouting pump. The rated grouting pressure of the synchronous dual-liquid grouting pump is not less than 30 MPa and the rated discharge is not less than 50 L / min. In step 3, when preparing the nano-modified dual-liquid grout, components A and B are stirred separately, and the stirring time is not more than 10 min. During grouting, it is forbidden to change the mixing tank containing components A and B or the grouting pump suction pipe.

[0022] Example 6 The method for pre-grouting reinforcement of tunneling faces passing through structurally fractured zones proposed in this embodiment, taking the 20203 main haulage roadway tunneling face of Sunjiacha Longhua Coal Mine as an example, includes the following steps: Step 1: Geological identification and determination of reinforcement scope; Geological data from the early excavation of auxiliary transport roadways 20202 and 20203 were collected. It was found that sections 3400-3750m in both roadways traversed geological structural zones, where the roof coal was severely fractured, with a maximum collapse height of 0.8m, leading to over-extension use of the roadheader and failure of temporary supports. Based on this, the grouting reinforcement section for the 20203 main transport roadway was determined to be 3300-3750m (100m ahead of schedule), with a total grouting length of 500m. The roof reinforcement range was 10m above the working face, and the left and right coal face reinforcement ranges were each 5m to the side of the working face. Step 2: Grouting hole layout and drilling construction; Pre-grouting holes are staggered and arranged on the roof and coal face of the tunneling face according to the design, such as... Figure 1 As shown, a 42mm diameter alloy steel drill bit is used in conjunction with a drilling rig for drilling; Grouting holes in the roof: 5 holes are arranged in each cycle, all perpendicular to the tunneling face and staggered in height. Holes #1, #3, and #5 are 4800mm from the bottom plate and at an elevation angle of 10°; holes #2 and #4 are 4800mm from the bottom plate and at an elevation angle of 5°; hole #3 is located in the middle of the roof; holes #1 and #5 are 700mm from the side wall, with a hole spacing of 1200mm and a hole depth of 10000mm. Grouting holes in the coal face: 3 holes are arranged in each cycle, all parallel to the bottom plate and staggered inside and outside. Hole #6 is 4000mm from the bottom plate and deflected inward by 10° from the working face; Hole #7 is 2800mm from the bottom plate and deflected inward by 5° from the working face; Hole #8 is 1600mm from the bottom plate and deflected inward by 10° from the working face. The depth of each hole is 10000mm. After drilling is completed, use air pressure to test the smoothness of the borehole to ensure that there is no collapse or blockage, and the hole position deviation is controlled within ±50mm; Step 3: Selection of grouting materials and preparation of grout; Specialized nano-modified grouting materials were selected for different sections, and the grout was prepared according to the preset water-cement ratio: The top slab uses a nano-modified two-component grouting material (component A: yellow, component B: white), with over 95% inorganic components and a particle size D. 90 =8μm, maximum reaction temperature 52℃. Prepare according to water-cement ratio of 0.8 (mass ratio of water to grouting material). Take 50kg of component A and 50kg of component B (equal mass ratio), add 80kg of water, and stir separately in two mixing tanks for 15min to ensure that the grout is uniform and free of lumps, and has a fluidity ≥300mm / 30s; The coal seam uses nano-modified single-component grouting material, with over 90% inorganic components and a particle size D. 90 =9μm, maximum reaction temperature 28℃. Prepare according to water-cement ratio of 0.9 (mass ratio of water to grouting material). Take 100kg of grouting material, add 90kg of clean water, stir for 12min until the grout is fine and free of sediment, let stand for 5min and there is no segregation before use; Step 4: Composite sealing and segmented grouting; Sealing treatment: A composite sealing method is adopted. The unidirectional high-pressure sealing device is sent to a distance of 1m from the hole opening through the grouting pipe at the hole opening. The grouting pump is started to inject a small amount of two-component grout, and the sealing is automatically completed. Cotton yarn is filled in the section from 1m to the hole opening, and then two-component grout is injected and compacted. Due to the hole opening being broken, the sealing depth of two holes is adjusted to 1.2m. Segmented grouting: Following the principle of "deep first, then shallow," the first grouting segment should be 5-10m away from the borehole opening, and the second segment should be 1-5m away from the borehole opening. Graded pressure control: 4MPa for shallow surrounding rock within 2m, 10MPa for medium-deep surrounding rock between 2-5m, and 20MPa for deep surrounding rock between 5-10m. The pressure is controlled by the flow valve of the grouting pump to rise slowly and avoid impacting the surrounding rock. Grouting sequence: The top plate adopts alternating grouting (1#→2#→3#→4#→5#), and the side plate adopts sequential grouting from bottom to top (8#→7#→6#). When grouting the first grouting hole (3# top plate hole), record the grout penetration time and diffusion range, and adjust the grouting parameters of subsequent holes. Step 5: Grouting compliance assessment and equipment cleaning; During the grouting process of each grouting hole, the pressure and grouting volume are monitored simultaneously: when the grouting pressure reaches the corresponding grade final pressure and remains stable for 3 minutes, and the grouting volume reaches the design value (90L for a single hole in the top plate and 85L for a single hole in the side plate), the grouting is deemed to have met the standard, and the grouting pump valve is closed to stop grouting. After the grouting is stopped, add clean water to the mixing tank and start the grouting pump to clean the pipeline, pump body and mixer. Continue cleaning for 5 minutes until clean water flows out and there is no grout residue. Then remove the grouting pipe at the hole and connect to the next grouting hole to repeat the grouting operation. Complete 3 cycles of grouting per shift. Step 6: Grout curing and tunneling operations; After grouting is completed, the reinforced area is sealed and cured: the double-liquid grout for the roof sets in 3 minutes and reaches a compressive strength of 9.8 MPa in 2 hours; the single-liquid grout for the coal face sets in 30 minutes; after 24 hours of curing, the solid strength of the grout is tested and found to be above 35 MPa. The integrity of the surrounding rock is detected by ground-penetrating radar, confirming that the broken coal body has formed a continuous load-bearing structure. Subsequently, the roadheader was started for tunneling operations, with the tunneling speed controlled at 5m / d. During the tunneling process, the deformation of the roof and coal face was monitored in real time, and the deformation was controlled within 20mm, which met the normal operation requirements of the roadheader. No roof coal collapse occurred.

Claims

1. A method for pre-grouting reinforcement of a tunneling face passing through a fractured structural zone, characterized in that, Includes the following steps: Step 1: Identify the structural fracture zone based on previous geological data and determine the grouting reinforcement range; Step 2: Arrange staggered pre-grouting holes for the roof and pre-grouting holes for the coal face on the roof and coal face respectively, and drill the holes using a drill bit of a preset specification. Step 3: Select nano-modified single-component or double-component grouting materials for different parts and prepare the grout according to the preset water-cement ratio; Step 4: After sealing the holes using a composite sealing method, grout according to the segmented grouting method, graded grouting pressure, and corresponding preset grouting sequence; Step 5: After the grouting pressure and grouting volume reach the standard, stop grouting, clean the equipment, and proceed with grouting the next hole; Step 6: After the grout reaches the designed strength, tunneling operations will commence.

2. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, In step 2, several pre-grouting holes for the roof are arranged in each cycle. All of these pre-grouting holes are perpendicular to the tunneling face and staggered in height. The elevation angle of the odd-numbered grouting holes is 9~11°, and the elevation angle of the even-numbered grouting holes is 4~6°. The pre-grouting holes are 4700~4900mm away from the bottom plate. The middle hole is located in the middle of the roof plate, and the holes on both sides are 600~800mm away from the side wall. The hole spacing is 1100~1300mm, and the hole depth is 9000~11000mm.

3. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, In step 2, several coal face advance grouting holes are arranged in each cycle. All of these coal face advance grouting holes are parallel to the bottom plate and staggered inside and outside. The coal face advance grouting holes are arranged in parallel from the top plate to the bottom plate. Among the coal face advance grouting holes, the odd-numbered grouting holes are deflected inward by 9~11° perpendicular to the working face, and the even-numbered grouting holes are deflected inward by 4~6° perpendicular to the working face. The coal face advance grouting holes are 4000~1600mm away from the bottom plate, the first coal face advance grouting hole is 500~700mm away from the top plate, and the hole depth is 9000~11000mm.

4. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, In step 3, the nano-modified two-component grouting material is a two-component powder consisting of components A and B. More than 95% of the nano-modified two-component grouting material is inorganic, and the particle size D of the nano-modified two-component grouting material is... 90 The nano-modified two-liquid grouting material has a particle size not exceeding 10µm, a maximum reaction temperature not exceeding 55℃, and is non-toxic. The nano-modified two-liquid grouting material initially sets in 3~10min, has a compressive strength of not exceeding 50MPa after 28 days, and a bonding strength with the coal body of not exceeding 1.7MPa after 28 days.

5. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, In step 3, the nano-modified single-component grouting material is in powder form, and more than 90% of the nano-modified single-component grouting material is inorganic. The particle size D of the nano-modified single-component grouting material is... 90 The nano-modified single-liquid grouting material has a particle size not exceeding 10µm, a maximum reaction temperature not exceeding 30℃, and is non-toxic. It initially sets in 28~32min, has a compressive strength of not exceeding 50MPa after 28d, and a bonding strength with the coal body of not exceeding 1.8MPa after 28d.

6. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, The preset water-cement ratio mentioned in step 3 is the mass ratio of clean water to grouting material. The water-cement ratio of nano-modified two-component grouting material is 0.6~1.0, and the water-cement ratio of nano-modified single-component grouting material is 0.8~1.

0.

7. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, The graded grouting pressures mentioned in step 4 are: 3~5MPa for shallow surrounding rock within 2m, 5~15MPa for medium-deep surrounding rock within 2~5m, and 15~25MPa for deep surrounding rock within 5~10m.

8. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, The segmented grouting described in step 4 is as follows: the first segment is 5-10m away from the borehole, and the second segment is 1-5m away from the borehole. The grout penetration pattern is explored through the first grouting cycle, and the grouting hole parameters are adjusted.

9. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, The composite sealing method described in step 4 is as follows: a one-way high-pressure sealing device is used to seal the hole 1m from the hole opening, and "cotton yarn + double liquid material" is used to seal the section from 1m to the hole opening. The sealing depth is increased when the hole opening is broken.

10. The method for pre-grouting reinforcement of a tunneling face through a fractured structural zone according to claim 1, characterized in that, In step 2, drilling and in step 4, grouting are carried out using a synchronous dual-liquid grouting pump. The rated grouting pressure of the synchronous dual-liquid grouting pump is not less than 30 MPa and the rated discharge is not less than 50 L / min. In step 3, when preparing the nano-modified dual-liquid grout, components A and B are stirred separately, and the stirring time is not more than 10 min. During grouting, it is forbidden to change the mixing tank containing components A and B or the grouting pump suction pipe.

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