| At present,many scholars have achieved remarkable results in grouting materials,theory and technology of underwater engineering.However,the research on the anti-dispersion,anti-scouring ability,fixed-point retention ability and micro-crack filling of slurry materials in wading conditions is not sufficient.Based on this,a new type of epoxy resin magnetic self-polymerization grouting material is developed.The material uses oily epoxy resin as the substrate and adds a certain amount of micron Fe3O4 magnetic powder to prepare an oily epoxy-based magnetic guiding slurry with guided flow,strong anti-scouring ability,good anti-dispersion effect,and overcoming self-weight to achieve anti-dip grouting.Based on the self-developed visual test device for underwater crack repair,the seepage diffusion law under the forward/reverse angle of single crack space of underwater bagged concrete is studied,which provides a new research idea and method for underwater crack repair.The research contents are as follows:1)Through orthogonal test and single factor（coupling agent）test,the performance of Oily Epoxy resin Magnetic self-polymerization Slurry（OEMS）substrate under different mix ratio design was studied.The results showed that the incorporation of fly ash improved the dispersion of magnetic powder in the slurry.The optimal parameters are determined by range analysis and single factor analysis,and the optimal mix design of OEMS is obtained.OEMS has significant magnetic adsorption advantages,which lays a foundation for the directional flow and fixed-point adsorption of fracture grouting.2)Scanning electron microscopy（SEM）analysis,X-ray photoelectron spectroscopy（XPS）analysis,X-ray diffraction（XRD）analysis,industrial CT scanning analysis and other micro-test methods were used to explore the mechanical properties,microstructure,micro-bonding mechanism of OEMS,composition distribution in different strength magnetic field regions,and pore size distribution in different strength magnetic field regions.It is concluded that:（1）Fe3O4 magnetic powder and fly ash act as aggregates and are wrapped by oily epoxy resin to form a continuous network structure,which reduces the porosity and crystallinity.A large number of pores inside the oily epoxy resin are filled with powder materials,and the structure is dense,which increases the volume density and greatly improves the mechanical properties of the oily epoxy resin.（2）The seepage diffusion law of OEMS underwater single fracture in bagged concrete under space forward/reverse angle is studied,and the mechanism of"layered magnetic adsorption and external extrusion diffusion"of OEMS underwater fracture is revealed.（3）OEMS forms coordination bonds with Ca or Si elements in old concrete,so it has good bonding properties.（4）From the weak magnetic field area to the medium magnetic field area and then to the strong magnetic field area,the pore area and pore area are significantly reduced,and the effect of OEMS exhaust is quantitatively described.3)A self-propelled hollow magnetic self-polymerization grouting bolt and underwater fracture repair visualization test device was developed.Based on this device,the visualization test of underwater fracture repair was carried out.The results show that:（1）The OEMS self-polymerization ability increases exponentially with the increase of magnetic field strength.（2）Based on the self-propelled hollow magnetic self-agglomerating grouting bolt,OEMS has a significant diffusion filling effect in underwater cracks,and the local crack filling rate is as high as 90%.（3）The seepage diffusion law of underwater mold bag concrete single crack OEMS under spatial forward/reverse angle is studied,and the mechanism of"layered magnetic adsorption bridging diffusion"of OEMS underwater crack is revealed.（4）The motion state and stress analysis of OEMS micro-magnetic particles are analyzed,and the OEMS micro-magnetic model is established to provide technical reference and theoretical support for the repair of underwater mold bag concrete cracks. |
