Method of guniting support process

Abstract

The invention relates to a method of a guniting support process, which comprises the following steps: step 1, preparation before construction: cleaning the surface of surrounding rock to be supported, preparing cement, yellow sand and water granulated slag micro powder according to a mass ratio of 1: 0.5: 0.1, and debugging guniting equipment, an anchor rod trolley with a net hanging mechanism and detection equipment; 2, primary guniting is conducted, specifically, cement, yellow sand and water granulated slag micro powder are mixed according to the ratio of 1: 0.5: 0.1, water is added, stirring is conducted, guniting is conducted on the surface of the surrounding rock, and the thickness ranges from 50 mm to 80 mm; 3, the anchor rod trolley fully covers a hanging net, a reinforcing mesh is attached to the first-time guniting layer through a mechanical arm and a laser positioning system of the anchor rod trolley, the mesh fully covers the section to be supported, and a temporary anchor rod is adopted for fixing; 4, secondary guniting is conducted, specifically, a mixture is prepared by adopting the same material proportion as that in the step 2, guniting is conducted on the guniting layer after net hanging, the thickness ranges from 80 mm to 120 mm, and it is ensured that the net piece is completely wrapped; and 5, maintenance and detection are carried out, spraying and moisturizing film maintenance are carried out on the supporting structure subjected to secondary guniting for more than or equal to 7 days, and the appearance, the thickness and the compressive strength are detected.

Description

Technical Field

[0001] This invention relates to a method, specifically a shotcrete support process, belonging to the technical field of underground mine support and tunnel engineering support. Background Technology

[0002] In underground engineering projects such as mining and tunnel excavation, shotcrete support is a key technology for ensuring the stability of surrounding rock and preventing collapse. However, existing shotcrete support technologies have the following problems:

[0003] Unreasonable material ratio: Traditional shotcrete often uses a binary ratio of "cement-sand-gravel" or "cement-sand", which results in low material density, slow strength growth in the later stage, and easy cracking and spalling due to long-term exposure to the damp underground environment, leading to insufficient support durability; although some processes add admixtures, the types of admixtures, such as fly ash and slag powder, lack specificity in selection and proportion design, making it impossible to balance strength and cost.

[0004] The efficiency of the wire mesh installation process is low: existing wire mesh installation operations mostly rely on manual hand tools or simple mechanical assistance, resulting in incomplete wire mesh coverage, loose mesh adhesion to the surrounding rock, and slow construction speed, which cannot meet the rapid support requirements of large-section roadways or tunnels; some anchor bolt trolleys are only used for anchor bolt installation and are not combined with the wire mesh installation process, resulting in low equipment utilization.

[0005] Poor connection between shotcrete processes: Traditional "one-time shotcrete + mesh" or "mesh + one-time shotcrete" processes suffer from insufficient bonding strength between the shotcrete layer and the mesh / surrounding rock, easily leading to delamination between the shotcrete layer and the mesh. While secondary shotcrete processes exist, inconsistent material ratios compared to the first shotcrete result in significant differences in shrinkage rates between the two layers, causing interface cracks and affecting the overall support effect. To address these problems, this invention proposes a shotcrete support process with optimized material ratios and efficient process coordination, solving the defects of low support strength, poor construction efficiency, and insufficient durability in existing technologies. Summary of the Invention: The purpose of this invention is to provide a method for shotcrete support processes that improves the overall performance and construction efficiency of the support structure by optimizing the shotcrete material ratio, combining it with an anchor bolt trolley to achieve full-coverage mesh, and using secondary shotcrete with the same ratio. Therefore, a new solution is urgently needed to address this technical problem. Summary of the Invention

[0006] This invention addresses the technical problems existing in the prior art by providing a method for shotcrete support. This technical solution optimizes the proportion of shotcrete cement materials, thereby improving the support strength and durability.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a method for shotcrete support, the method comprising the following steps:

[0008] Step 1: Preparation before construction: Clean the surface of the surrounding rock to be supported, prepare cement, yellow sand, and water slag powder in a mass ratio of 1:0.5:0.1, and debug the shotcrete equipment, the anchor trolley with the netting mechanism, and the testing equipment.

[0009] Step 2: First spraying: Mix cement, yellow sand, and water slag powder in a ratio of 1:0.5:0.1 and add water to stir. Spray the mixture onto the surface of the surrounding rock to a thickness of 50-80mm.

[0010] Step 3: The anchor bolt trolley fully covers the mesh. Using the mechanical arm and laser positioning system of the anchor bolt trolley, the steel mesh is attached to the first shotcrete layer. The mesh fully covers the section to be supported and is fixed with temporary anchor bolts.

[0011] Step 4: Secondary spraying. Prepare a mixture using the same material ratio as in Step 2, and spray the mixture onto the sprayed layer after the mesh is attached.

[0012] Thickness 80-120mm, ensuring the mesh completely covers the area;

[0013] Step 5: Curing and Inspection. Spray and moisturize the support structure after secondary spraying for ≥7 days, and inspect its appearance, thickness and compressive strength.

[0014] Step 1 is as follows:

[0015] 1.1 Surrounding Rock Cleaning: Clean the surface of the surrounding rock to be supported in the underground roadway or tunnel, removing loose rocks, loose rock fragments, and surface dust to ensure that the surrounding rock surface is flat and free of impurities; if there is water accumulation on the surrounding rock surface, use drainage equipment to remove it or lay waterproof membrane to isolate the moisture.

[0016] 1.2 Material Preparation: Prepare cement, yellow sand, and water slag powder in a mass ratio of 1:0.5:0.1; among which, the cement should be 42.5 grade ordinary Portland cement, the yellow sand should be medium sand with a fineness modulus of 2.3-3.0, and the water slag powder should have a specific surface area ≥400m². 2 / kg, activity index ≥95% after 28 days; the three materials are stored separately in sealed storage silos, each equipped with a humidity sensor to monitor humidity ≤5% to prevent moisture absorption and clumping.

[0017] 1.3 Equipment Commissioning: Shotcrete Equipment: Inspect the shotcrete machine. Select a rotor-type shotcrete machine. Check the material conveying pipeline and nozzles with a rated working pressure of 0.4-0.6MPa for blockages. Adjust the material feeding speed of the shotcrete machine, controlling it at 3-5m / s. 3 / h; Anchor bolt trolley: Select a multi-functional anchor bolt trolley with a net hanging mechanism, adjust the mechanical arm stroke of the trolley to ensure coverage of the top, sides and bottom of the section to be supported, and control the net clamping force at 5-8kN to avoid net deformation; Testing equipment: Calibrate the humidity sensor with a measurement accuracy of ±2% RH and the compressive strength tester with an error of ≤1% to ensure data accuracy.

[0018] Step 2: The initial shotcrete application is as follows:

[0019] 2.1 Material Mixing: Add cement, yellow sand, and water slag powder to a forced mixer at a mass ratio of 1:0.5:0.1, and add water at the same time (water-binder ratio 0.4-0.45). Mix for ≥3 minutes to form a uniform spray slurry mixture. During the mixing process, check the state of the mixture through the observation window of the mixer to ensure that there are no lumps, good fluidity, and a slump of 120-150mm.

[0020] 2.2 Shotcrete Operation: Start the shotcrete machine and have the operator hold the nozzle to perform the first shotcrete on the cleaned surrounding rock surface; during shotcreting, the angle between the nozzle and the surrounding rock surface should be controlled at 75°-90°, and the distance between the nozzle and the surrounding rock surface should be 0.8-1.2m. The shotcrete sequence should be "from bottom to top and from left to right" to avoid missed areas; the thickness of the first shotcrete should be controlled at 50-80mm. After shotcreting, use a scraper to smooth the surface of the shotcrete layer to ensure that the surface is flat and free of depressions.

[0021] Step 3 involves fully covering the anchor bolt trolley with netting, as detailed below.

[0022] 3.1 Reinforcing mesh preparation: Select steel mesh with a diameter of 6-8mm and a mesh size of 100mm×100mm-150mm×150mm. Cut the mesh into a suitable shape according to the size of the cross-section to be supported. If the cross-section is large, multiple mesh pieces are connected by welding, with the welding point spacing ≤200mm, to ensure a firm connection.

[0023] 3.2 Anchor Bolt Trolley Netting Installation: Start the anchor bolt trolley and adjust the netting mechanism to the support position using the trolley's robotic arm; the clamping device of the netting mechanism clamps the edge of the netting, attaching the netting to the surface of the shotcrete layer after the first shotcrete application; calibrate the netting position using the trolley's laser positioning system to ensure that the netting covers the entire section to be supported, with no gaps, and the overlap width between netting sections is ≥100mm; after the netting is fixed, use temporary anchor bolts with a diameter of 20mm and a length of 500mm to fix the netting to the shotcrete layer and surrounding rock, with a temporary anchor bolt spacing ≤1500mm to ensure that the netting is not loose.

[0024] Step 4: Secondary shotcreting is as follows:

[0025] 4.1 Material Mixing: Using the same proportions as in step 2.1, cement: yellow sand: water slag powder = 1:0.5:0.1, and the same mixing parameters, prepare the spraying grout mixture to ensure that the composition and properties of the secondary spraying grout material are consistent with those of the primary spraying grout material.

[0026] 4.2 Shotcrete Operation: Start the shotcrete machine and perform secondary shotcrete on the shotcrete layer after the mesh is installed; during shotcrete, the nozzle should avoid the temporary anchor bolt position to prevent the anchor bolt from being covered by too much shotcrete; the thickness of the secondary shotcrete should be controlled at 80-120mm to ensure that the mesh is completely wrapped by the shotcrete layer, and the distance between the mesh and the surface of the shotcrete layer should be ≥30mm; during the shotcrete process, check the bonding status between the shotcrete layer and the mesh in real time. If air bubbles or voids appear, stop shotcrete in time, clean and then re-shot.

[0027] Step 5: Maintenance and Inspection, specifically as follows:

[0028] 5.1 Curing: After the secondary shotcrete is completed, the shotcrete support structure shall be cured; the curing method is "spray curing and covering with a moisturizing film", the curing temperature is ≥5℃, and the curing time is ≥7 days; during the curing period, the surface humidity of the shotcrete layer shall be monitored daily and maintained at ≥90%RH. If the humidity is insufficient, spray should be added in time.

[0029] 5.2 Inspection: After curing, the support structure shall be inspected for performance: Appearance inspection: Check whether there are cracks or peeling on the surface of the shotcrete layer, and whether the mesh is exposed. If defects are found, repair them with the same mix proportion material; Thickness inspection: Use an ultrasonic thickness gauge to select no less than 5 test points on the support section to measure the total thickness of the shotcrete layer. The first and second measurements shall be taken to ensure that the total thickness is ≥130mm and the error is ≤5mm; Strength inspection: Drill a core sample with a diameter of 50mm and a height of 50mm on the shotcrete layer and use a compressive strength tester to test the compressive strength after 28 days. The strength shall be ≥25MPa. If the strength does not meet the standard, analyze the cause and repeat the shotcrete operation.

[0030] Compared to existing technologies, the advantages of this invention are as follows: Optimized material ratio, improving support strength and durability: This invention uses a ratio of cement: yellow sand: water slag powder = 1:0.5:0.1. The active components of the water slag powder can react with cement hydration products to generate more gel, improving the density of the shotcrete. Testing shows a 28-day compressive strength ≥25MPa, which is 30%-40% higher than the traditional "cement-yellow sand" ratio. It also exhibits excellent long-term moisture resistance, showing no cracking or peeling even after one year of use in a damp underground environment. Full-coverage netting using an anchor bolt trolley improves construction efficiency and coverage quality: Netting operations are achieved through an anchor bolt trolley with a netting mechanism. The robotic arm's stroke can cover large-section tunnels with a cross-sectional area ≤20m². 2The efficiency of mesh installation is 5-8 times higher than manual installation. Combined with a laser positioning system, the mesh covers all areas without gaps, and the overlap width and fixed spacing meet the specifications, avoiding the deviation problems of manual mesh installation. Secondary shotcreting with the same mix ratio enhances overall bonding performance: the first and second shotcreting use the same material ratio, eliminating shrinkage differences caused by different ratios and avoiding interface cracks; the second shotcreting completely wraps the mesh, and the bonding strength between the shotcrete layer and the mesh is ≥1.5MPa, which is 25%-30% higher than secondary shotcreting with different mix ratios, significantly enhancing the overall deformation resistance of the support structure. The process is closely integrated to meet the needs of rapid support in underground engineering: from surrounding rock cleaning, first shotcreting, mesh installation to secondary shotcreting, each process is coordinated through equipment debugging and parameter control, achieving a single-cycle support time of 10m length and 10m... 2 For example, the tunnel section takes ≤8 hours, which is 30% shorter than the traditional process, meeting the need for simultaneous rapid underground tunneling and support. Attached Figure Description

[0031] Figure 1 The process flow diagram of the shotcrete support technology of this invention is as follows:

[0032] Figure 2 : Schematic diagram of anchor bolt trolley netting installation

[0033] Figure 3 Schematic diagram of the cross-section of the shotcrete layer.

[0034] Explanation of reference numerals in the attached drawings: 1-Anchor bolt trolley, 2-Mechanical arm, 3-Network hanging mechanism, 4-Laser positioning transmitter, 5-Reinforcing mesh, 6-Temporary anchor bolt, 7-First shotcrete layer, 8-Second shotcrete layer, 9-Surrounding rock;

[0035] 10-Laser positioning system, 11-Robotic arm. Detailed Implementation

[0036] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0037] Example 1: See Figures 1-3 A method for shotcrete support, the method comprising the following steps:

[0038] Step 1: Preparation before construction: Clean the surface of the surrounding rock to be supported, prepare cement, yellow sand, and water slag powder in a mass ratio of 1:0.5:0.1, and debug the shotcrete equipment, the anchor trolley with the netting mechanism, and the testing equipment.

[0039] Step 2: First spraying: Mix cement, yellow sand, and water slag powder in a ratio of 1:0.5:0.1 and add water to stir. Spray the mixture onto the surface of the surrounding rock to a thickness of 50-80mm.

[0040] Step 3: The anchor bolt trolley fully covers the mesh. Using the mechanical arm and laser positioning system of the anchor bolt trolley, the steel mesh is attached to the first shotcrete layer. The mesh fully covers the section to be supported and is fixed with temporary anchor bolts.

[0041] Step 4: Secondary spraying. Prepare a mixture using the same material ratio as in Step 2, and spray the mixture onto the sprayed layer after the mesh is attached.

[0042] Thickness 80-120mm, ensuring the mesh completely covers the area;

[0043] Step 5: Curing and Inspection. Spray and moisturize the support structure after secondary spraying for ≥7 days, and inspect its appearance, thickness and compressive strength.

[0044] Step 1 is as follows:

[0045] 1.1 Surrounding Rock Cleaning: Clean the surface of the surrounding rock to be supported in the underground roadway or tunnel, removing loose rocks, loose rock fragments, and surface dust to ensure that the surrounding rock surface is flat and free of impurities; if there is water accumulation on the surrounding rock surface, use drainage equipment to remove it or lay waterproof membrane to isolate the moisture.

[0046] 1.2 Material Preparation: Prepare cement, yellow sand, and water slag powder in a mass ratio of 1:0.5:0.1; among which, the cement should be 42.5 grade ordinary Portland cement, the yellow sand should be medium sand with a fineness modulus of 2.3-3.0, and the water slag powder should have a specific surface area ≥400m². 2 / kg, activity index, ≥95% after 28 days; store the three materials separately in sealed storage silos, with humidity sensors installed inside the silos to monitor humidity ≤5% to prevent the materials from becoming damp and clumping.

[0047] 1.3 Equipment Commissioning: Shotcrete Equipment: Inspect the shotcrete machine. Select a rotor-type shotcrete machine. Check the material conveying pipeline and nozzles with a rated working pressure of 0.4-0.6MPa for blockages. Adjust the material feeding speed of the shotcrete machine, controlling it at 3-5m / s. 3 / h; Anchor bolt trolley: Select a multi-functional anchor bolt trolley with a net hanging mechanism, adjust the mechanical arm stroke of the trolley to ensure coverage of the top, sides and bottom of the section to be supported, and control the net clamping force at 5-8kN to avoid net deformation; Testing equipment: Calibrate the humidity sensor with a measurement accuracy of ±2% RH and the compressive strength tester with an error of ≤1% to ensure data accuracy.

[0048] Step 2: The initial shotcrete application is as follows:

[0049] 2.1 Material Mixing: Add cement, yellow sand, and water slag powder to a forced mixer at a mass ratio of 1:0.5:0.1, and add water at the same time, with a water-cement ratio of 0.4-0.45. Mix for ≥3 minutes to form a uniform spray slurry mixture. During the mixing process, check the state of the mixture through the observation window of the mixer to ensure that there are no lumps, good fluidity, and a slump of 120-150mm.

[0050] 2.2 Shotcrete Operation: Start the shotcrete machine, and the operator holds the nozzle to perform the initial shotcrete application on the cleaned surrounding rock surface. During shotcreting, the angle between the nozzle and the surrounding rock surface should be controlled at 75°-90°, and the distance between the nozzle and the surrounding rock surface should be 0.8-1.2m. The shotcrete sequence should be "from bottom to top, from left to right" to avoid missed areas. The initial shotcrete thickness should be controlled at 50-80mm. After shotcreting, use a scraper to smooth the surface of the shotcrete layer, ensuring a flat surface without depressions. See also... Figure 3 , Figure 3 : Schematic diagram of the shotcrete layer cross section, indicating the structural and dimensional relationships of the first shotcrete layer (50-80mm), the mesh (6-8mm steel reinforcement), the grid (100-150mm), and the second shotcrete layer (80-120mm).

[0051] Step 3 involves fully covering the anchor bolt trolley with netting, as detailed below.

[0052] 3.1 Mesh Preparation: Select steel mesh with a diameter of 6-8mm and a mesh size of 100mm×100mm-150mm×150mm. Cut the mesh into a suitable shape according to the dimensions of the section to be supported. If the section size is large, multiple mesh pieces are connected by welding, with a weld spacing of ≤200mm, to ensure a firm connection.

[0053] 3.2 Anchor Bolt Trolley Netting Installation: Start the anchor bolt trolley and adjust the netting mechanism to the support position using the trolley's robotic arm; the clamping device of the netting mechanism clamps the edge of the netting, attaching the netting to the surface of the shotcrete layer after the first shotcrete application; calibrate the netting position using the trolley's laser positioning system to ensure that the netting covers the entire section to be supported, with no gaps, and the overlap width between netting sections is ≥100mm; after the netting is fixed, use temporary anchor bolts with a diameter of 20mm and a length of 500mm to fix the netting to the shotcrete layer and surrounding rock, with a temporary anchor bolt spacing of ≤1500mm to ensure that the netting is not loose.

[0054] Step 4: Secondary shotcreting is as follows:

[0055] 4.1 Material Mixing: Using the same proportions as in step 2.1, cement: yellow sand: water slag powder = 1:0.5:0.1, and the same mixing parameters, prepare the spraying grout mixture to ensure that the composition and properties of the secondary spraying grout material are consistent with those of the primary spraying grout material.

[0056] 4.2 Shotcrete Operation: Start the shotcrete machine and perform secondary shotcrete on the shotcrete layer after the mesh is installed; during shotcrete, the nozzle should avoid the temporary anchor bolt position to prevent the anchor bolt from being covered by too much shotcrete; the thickness of the secondary shotcrete should be controlled at 80-120mm to ensure that the mesh is completely wrapped by the shotcrete layer, and the distance between the mesh and the surface of the shotcrete layer should be ≥30mm; during the shotcrete process, check the bonding status between the shotcrete layer and the mesh in real time. If air bubbles or voids appear, stop shotcrete in time, clean and then re-shot.

[0057] Step 5: Maintenance and Inspection, specifically as follows:

[0058] 5.1 Curing: After the secondary shotcrete is completed, the shotcrete support structure shall be cured; the curing method is "spray curing and covering with a moisturizing film", the curing temperature is ≥5℃, and the curing time is ≥7 days; during the curing period, the surface humidity of the shotcrete layer shall be monitored daily and maintained at ≥90%RH. If the humidity is insufficient, spray should be added in time.

[0059] 5.2 Inspection: After curing, performance testing of the support structure shall be carried out: Appearance inspection: Check whether there are cracks or peeling on the surface of the shotcrete layer, and whether the mesh is exposed. If defects are found, repair them with materials of the same mix ratio; Thickness inspection: Use an ultrasonic thickness gauge to select no less than 5 test points on the support section to measure the total thickness of the shotcrete layer for the first and second measurements to ensure the total thickness.

[0060] ≥130mm, error ≤5mm; Strength test: Drill a core sample 50mm in diameter and 50mm in height on the shotcrete layer, and use a compressive strength tester to test the compressive strength after 28 days. The required strength is ≥25MPa; If the strength does not meet the standard, analyze the cause and repeat the shotcrete operation.

[0061] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A method of a shotcrete process, characterized in that, The method comprises the following steps: Step 1: preparation before construction, cleaning the surface of the surrounding rock to be supported, preparing cement, yellow sand, and water slag powder in a mass ratio of 1:0.5:0.1, debugging the shotcreting equipment, the anchor rod trolley with a mesh hanging mechanism, and the detection equipment; Step 2: first shotcreting, mixing cement, yellow sand, and water slag powder in a mass ratio of 1:0.5:0.1 and adding water to stir, shotcreting the surface of the surrounding rock, with a thickness of 50-80 mm; Step 3: full coverage of the anchor rod trolley with a mesh, through the mechanical arm of the anchor rod trolley and the laser positioning system, the steel mesh is attached to the first shotcreting layer, the mesh fully covers the section to be supported, and temporary anchor rods are used for fixation; Step 4: second shotcreting, using the same material ratio as step 2 to prepare the mixture, shotcreting the shotcreting layer after mesh hanging, with a thickness of 80-120 mm, to ensure that the mesh is completely wrapped; Step 5: maintenance and detection, the support structure after the second shotcreting is maintained by spraying and moisture film for more than 7 days, and the appearance, thickness, and compressive strength are detected.

2. A method of the gunite process according to claim 1, characterized in that, Step 1 is specifically as follows: 1.1 surrounding rock cleaning: cleaning the surface of the surrounding rock to be supported in the underground roadway or tunnel, removing floating stones, loose rock blocks, and surface dust, and ensuring that the surface of the surrounding rock is flat and free of impurities; if there is water on the surface of the surrounding rock, drainage equipment is used to remove or waterproof coiled material is laid to isolate water, 1.2 Material preparation: prepare cement, yellow sand, water slag powder in the mass ratio of 1:0.5:0.1; wherein, the cement selects 42.5 grade ordinary portland cement, the yellow sand is medium sand, the fineness modulus is 2.3-3.0, the water slag powder needs to meet the specific surface area ≥400m 2 / kg, the activity index 28 days ≥95%; store the three materials in sealed storage bins respectively, set humidity sensors in the storage bins, monitor the humidity ≤5%, prevent the materials from being damp and caked, 1.3 equipment debugging: shotcreting equipment: checking whether the feeding pipe and the nozzle of the shotcreting machine are unobstructed, and debugging the feeding speed of the shotcreting machine; anchor rod trolley: selecting a multifunctional anchor rod trolley with a mesh hanging mechanism, debugging the stroke of the mechanical arm of the trolley, and ensuring that the top, side, and bottom of the section to be supported are covered, and the mesh clamping device; detection equipment: calibrating the humidity sensor and the compressive strength detector to ensure accurate data.

3. A method of the gunite process according to claim 2, wherein, Step 2: first shotcreting is specifically as follows: 2.1 material mixing: putting cement, yellow sand, and water slag powder into a forced mixer in a mass ratio of 1:0.5:0.1, adding water at the same time, with a water-binder ratio of 0.4-0.45, stirring for more than 3 min to form a uniform shotcreting mixture; during the stirring process, the mixture state is checked through the observation window of the mixer to ensure that there are no lumps and good fluidity, with a slump of 120-150 mm; 2.2 shotcreting operation: starting the shotcreting machine, and the operator holds the nozzle to first shotcrete the cleaned surface of the surrounding rock; the angle between the nozzle and the surface of the surrounding rock is controlled at 75°-90°, the distance between the nozzle and the surface of the surrounding rock is 0.8-1.2 m, the shotcreting sequence is "from bottom to top, from left to right", and missed shotcreting is avoided; the first shotcreting thickness is controlled at 50-80 mm, and the shotcreting layer is scraped flat after shotcreting to ensure that the surface is flat and free of depressions.

4. The method of the gunite process according to claim 3, wherein, Step 3: full coverage of the anchor rod trolley with a mesh is specifically as follows, 3.1 mesh preparation: selecting a steel mesh with a diameter of 6-8 mm, cutting the mesh into an adaptive shape according to the size of the section to be supported; if the size of the section is large, multiple meshes are connected by welding, with a welding point spacing of ≤200 mm, to ensure that the mesh is firmly connected, 3.2 Anchor rod trolley net hanging: start the anchor rod trolley, adjust the net hanging mechanism to the position to be supported through the mechanical arm of the trolley; the clamping device of the net hanging mechanism clamps the edge of the mesh, and the mesh is attached to the surface of the shotcrete layer after the first shotcrete; the position of the mesh is calibrated through the laser positioning system of the trolley to ensure that the mesh covers the entire section to be supported without any empty area, and the overlap width between the meshes is ≥100mm; after the mesh is fixed, temporary anchor rods with a diameter of 20mm and a length of 500mm are used to fix the mesh with the shotcrete layer and surrounding rock, and the spacing between the temporary anchor rods is ≤1500mm to ensure that the mesh does not loosen.

5. The method of the gunite process according to claim 2, wherein, Step 4: The second shotcrete is as follows, 4.1 Material mixing: the same proportion as step 2.1 is used, cement: yellow sand: water slag powder = 1:0.5:0.1, and the same mixing parameters are used to prepare the shotcrete mixture to ensure that the composition and performance of the second shotcrete material are consistent with those of the first shotcrete material, 4.2 Shotcrete operation: start the shotcrete machine to perform the second shotcrete on the shotcrete layer after the net is hung; avoid the position of the temporary anchor rod when spraying to avoid excessive coverage of the anchor rod by the shotcrete; the thickness of the second shotcrete is controlled at 80-120mm to ensure that the mesh is completely wrapped by the shotcrete layer, and the distance between the mesh and the surface of the shotcrete layer is ≥30mm; check the bonding state of the shotcrete layer and the mesh in real time during the shotcrete process, and if there are air bubbles or hollows, stop the shotcrete in time and clean up before re-spraying.

6. The method of the gunite process according to claim 2, wherein, Step 5: Curing and detection, as follows: 5.1 Curing: after the second shotcrete is completed, the shotcrete support structure is cured; the curing method is "spray curing and covering moisture film", the curing temperature is ≥5℃, and the curing time is ≥7 days; monitor the surface humidity of the shotcrete layer every day during the curing period to maintain ≥90%RH, and if the humidity is insufficient, spray in time; 5.2 Detection: after the curing is completed, the performance of the support structure is detected: appearance detection: check whether there are cracks, peeling on the surface of the shotcrete layer, and whether the mesh is exposed, if there are defects, use the same proportion of materials for repair; thickness detection: use an ultrasonic thickness gauge to select not less than 5 detection points on the support section to measure the total thickness of the shotcrete layer, ensuring that the total thickness is ≥130mm with an error of ≤5mm; strength detection: drill a core sample on the shotcrete layer with a diameter of 50mm and a height of 50mm, and use a compressive strength detector to detect the 28-day compressive strength, which is required to be ≥25MPa; if the strength is not up to standard, analyze the reasons and perform the shotcrete operation again.

Images