Research And Application Study Of Magnetorial Self-Expanding Anchorage Materials

The 14th“Five-Year Plan”has embarked on a new journey of my country’s comprehensive construction of a modern socialist country.It has further promoted the development and utilization of infrastructure such as hydro-power energy,mining and transportation.In 2020alone,the country’s total investment in water conservancy construction reached 769.5 billion yuan,which held a record high.And grouting and anchoring technology will also be widely used in infrastructure construction.Grouting and anchoring often occur in complex geological environments,such as the filling of the grouting in the upward hole project is not dense,the micro-fracture grout is not easy to fill,and the underwater grouting Engineering problems such as easy dispersion of pulp.This not only seriously affects the safe operation of the project and the display of economic benefits,but also leads to the development and application of this technology has been severely restricted.Compared with ordinary grouting anchoring materials,this paper has developed the magnetic-convergence self-expanding anchoring material,which has the characteristics of underwater anti-dispersion,anti-gravity directional convergence,self-expanding compaction,etc.The strength improvement test,long-term durability test,anchor pullout test and magnetic induction repair test of magnetic-convergence self-expanding anchoring material were carried out,which systematically studied the physical and mechanical properties and reinforcement mechanism of magnetic-convergence self-expanding anchoring materials.The main research contents and results are as follows:(1)Magnetic-convergence self-expanding slurry proportioning test and performance research.(1)Based on the optimal ratio of cement-based underwater self-compacting anchoring slurry,the research and development idea of magnetic-convergence self-expanding anchoring material of"magnetic powder exchange for sand and carrier-based packaging"was proposed,and it was pointed out that the best magnetic powder carrier was water glass,and cement-based magnetic convergent anchoring material ratio is 0.4,4%of flocculant,1%of water reducing agent,0.1%of defoamer,45%of magnetic powder,21%of water glass,1.5%of PVP,and the strength can reach 30.92MPa in 7 days.(2)The strength can be as high as 46.4MPa in 7 days after adding 30%expansion agent,and the compressive strength prediction formula of magnetic-convergence self-expanding anchorage material has been established.(2)Magnetic convergence research on the long-term durability of self-expanding anchoring materials.(1)Seawater erosion strength test pointed out that 21%water glass content of magnetic-convergence self-expanding anchoring material strength can still reach42.45MPa,equivalent to C40 concrete,indicating that a large amount of water glass has better resistance to seawater erosion.(2)The electric flux test showed that the maximum electric flux of the magnetic converging self-expanding anchoring material with sodium silicate base was only 375C,which had good resistance to chloride ion penetration.The mathematical model of electric flux under the influence of the magnetic powder content of sodium silicate was established.(3)Through the long-term real-time monitoring of the expansion stress,it was pointed out that the expansion stress had good stability,which can provide a guarantee for the safe operation of the project.(3)Research on application of magnetic-convergence self-expanding anchorage.(1)The evolution process of the expansion stress under the effect of magnetic convergence was divided into stages.And the spatial evolution law of expansion stress under different water-rich conditions and different expansion agent content were obtained.Based on the expansion theory of circular hole,the distribution prediction analytical model of the expansion stress in the anchorage medium was established.(2)It was pointed out that the ultimate pull-out force of concrete medium and calcareous sand under the induction of magnetic field strength of12000GS are respectively increased to 2.43 times and 1.31 times.And an exponential function prediction model of the change of the ultimate pull-out force with the magnetic field was established,which showed that the increment of magnetic field could significantly improve the ultimate pull resistance.(3)At the same time,it was pointed out that excessive addition of expansion agent would lead to the concrete cracking of calcareous sand with significant pore reaming effect,resulting in the decrease of ultimate tensile strength,which indicated that the optimal amount of expansion agent should be designed according to the strength parameters of the medium in practical application.(4)Magnetic-convergence self-expanding anchorage performance improvement mechanism analysis.(1)The force mechanism diagram of the magnetic-convergence self-expanding grout under the action of gravity and magnetic field coupling in the process of grouting was drawn.It was pointed out that the grout could overcome the gravity convergence and realized anti-gravity grouting by the action of friction resistance f,and the relationship between friction resistance f and magnetic volume force F_mand the motion equation of the grout were deduced.(2)The mechanism of self-expansion and expansion under the effect of magnetic convergence was described.It was pointed out that the upper end resistance F_p of the anchor was proportional to the square of the diameter of the expansion and expansion under the effect of magnetic-convergence.(5)Research on the magnetic induction repair and reinforcement performance of fractured rock mass.(1)Through the uniaxial compression and shear tests of sandstone restoration samples,it was pointed out that the compressive strength of the samples after the restoration of the unsaturated polyester resin-based magnetic-convergent slurry could be restored to27.7MPa,and the shear strength could be restored to the highest 0.9MPa,which were better than that of the vulcanized silicone rubber based grout.Moreover,there were obvious peak strength and residual peak strength,and the samples had obvious plastic deformation energy absorption characteristics.(2)By comparison,it was pointed out that the filling rate of magnetic-induced remediation could reach 100%,and the filling effect was obviously better than that of pure cement remediation,which can solve the engineering problem that the conventional technology grout was not easy to diffuse filling in micro-cracks.