| The anchor rod is a commonly used support structure in the construction field,widely applied in engineering projects such as slopes,excavations,tunnels,and galleries.However,the current bonding-type anchor rod grouting technology has limitations,especially in the case of underwater construction,which makes it difficult to achieve complete filling of the anchor grout and thus affects the bearing capacity of the anchor rod support structure,increasing the risk of collapse.To solve this problem,our team independently developed a crack defect grouting technology based on the drilling-injection integrated self-propelled hollow magnetic suction anchor rod technology and conducted experimental research.This technology utilizes the characteristics of the magnetic field-induced directional movement of the grout to achieve efficient,accurate,and controllable anchor rod grouting,thereby improving the bearing capacity and stability of the anchor rod support structure.This article focuses on the theoretical and practical applications of the drilling-injection integrated magnetic suction anchor rod grouting repair technology,providing important reference for the study of new anchor rod grouting reinforcement methods.The main aspects include:(1)This study explores the selection of materials and methods for the magnetic suction end.1.Experimental results show that a black iron oxide film can be formed on the surface of the drill-injection integrated anchor rod after blackening treatment,but the magnetic field strength is too low to meet the requirements for the attraction of magnetic slurry.2.Although ferric oxide,aluminum-nickel-cobalt,and iron-nickel-cobalt can be magnetized,their magnetic field strength is weak.Therefore,except for neodymium iron boron,the magnetization effect of the other three materials cannot meet the requirements of the magnetic suction end.Therefore,this study chose neodymium iron boron as the magnetic powder material for the self-made special-shaped magnetic suction end.(2)This study explores the selection of materials and methods for the magnetic attraction end,as well as the optimal ratio of magnetic powder carrier liquid.1.three different molds were used to cast neodymium iron boron(Nd Fe B)magnetic solution,and a control experiment was conducted with a unified ratio of carrier liquid to magnetic powder(1:3)using magnetic field strength and cost as indicators to compare the differences between different ratios,quality,volume,weighted magnetic field strength,and cost.The results showed that the cost of a single self-made magnetic ring filled with Nd Fe B 13-9 magnetic powder was only 56% of the cost of a commercially available Nd Fe B magnetic ring,and its volume was larger,8.3 times that of a commercially available Nd Fe B magnetic ring.2.the long-term durability of the self-made magnetic attraction end was investigated,and the results showed that it only weakened by 2.5% to 4% over a period of three months,demonstrating good durability.3.the attraction experiment of ORE-MS repair material was carried out,and the results showed that under different ratios of 1:1,1:2,and 1:3,the attraction diameter using Nd Fe B 13-9 magnetic powder was 6.25%,1.942%,and 5.769% larger than that using Nd Fe B6-3 magnetic powder,respectively.The mold design for the optimized irregular magnetic attraction end and the best ratio of magnetic powder carrier liquid were also investigated.(3)Study on mechanical properties of ORE-MS repair material under different magnetic attraction.1.The magnetic attraction end without an embedded magnetic ring performs the best in terms of axial stress,and the Nd Fe B 13-9 magnetic powder with a ratio of 1:3 without threads has a higher axial stress than the magnetic attraction end with threads.2.Conducted research on the in-situ adhesion between ORE-MS repair material and the defect concrete.The results show that the peak load of the magnetic attraction end without threads is generally30% higher than that with threads.3.The arrangement of the magnetic rings also has an impact on the mechanical properties.The magnetic rings arranged at intervals of 50 mm can improve the ultimate pull-out force of the anchor body by 20%.(4)ORE-MS repair material has a good bonding effect when repairing the surface of the defect concrete,and its bonding force is greater than the bonding force between the anchor body and the anchor bar.(4)Study on the motion behavior of ORE-MS repair material under magnetic field.1.A series of motion equations were derived through frame-by-frame processing of high-definition cameras.2.The motion trajectories and the maximum affected distances of the material were investigated under magnetic field strengths of 5000 Gs,7000Gs,and 9000 Gs,which were found to be 1.81 cm,1.85 cm,and 1.89 cm,respectively.3.A set of motion equations in the x and y directions for ORE-MS repair material under known magnetic field strengths were determined,providing a reliable theoretical basis for injection repair.(5)Research on drilling-grouting integrated self-drilling magnetic anchor rod grouting repair process.1.Developed a self-drilling machine to achieve the integrated construction process from drilling to grouting repair for different defects in the concrete structure.2.Three types of grouting materials and five construction schemes were used to conduct comparative experiments based on the grouting filling rate index.The experimental results showed that cement-based slurry,regardless of its magnetic or magnetic attraction properties,failed to achieve the desired repair effect.On the contrary,the ORE-MS repair material could diffuse significantly in the crack,proving that epoxy resin as the main component of the magnetic slurry is the best choice.3.The compatibility between the ORE-MS repair material and the magnetic suction anchor rod is far superior to that of the underwater self-leveling cement magnetic slurry.The maximum slurry volume in schemes one,four,and five was 2.67 times,2.52 times,and 3.11 times that of scheme two.4.The construction method in scheme five had a significant diffusion effect with a diffusion distance of 38mm～44mm.The farthest end could diffuse to the edge of the entire crack at about 70mm～150mm.The slurry diffusion distance was 2.68 times that of 56 mm without lateral limitation.It was superior to the 1.21 times and 1.78 times in schemes one and four,achieving the desired repair effect.5.Increasing the opening distance between the grouting ports by 50 mm could achieve the best slurry repair effect,and its comprehensive slurry filling rate could reach 97.02%.6.The drilling-grouting integrated self-propelled magnetic bolt grouting technology basically fills the interior of the crack completely,and the repair effect is good.The crack filling density is high,and the slurry on the surface of the crack is closely bonded,indicating that the drillinggrouting integrated magnetic suction bolt can achieve the crack repair effect. |
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