Preparation Of Magnetic-sensitive Lunar Regolith Simulant And Experimental Study On Its Basic Properties

Since the beginning of the 21 st century,the global "lunar fever" has been heating up rapidly again.Many countries around the world have begun to deploy plans for lunar exploration and development.The construction of lunar base and mineral resources development have become important tasks and inevitable trends of deep space exploration at this stage.Systematic study of the properties of lunar regolith,especially the mechanical and engineering properties of lunar regolith in the environment of small gravity field on the lunar surface,is an urgent task for lunar development.Limited by the lack of in-situ lunar regolith,the present study on mechanical behavior of lunar regoliths is mainly based on the simulation of lunar regoliths.Based on the geotechnical magnetic-similitude-gravity model testing method proposed by the team earlier,this paper focuses on the physical and mechanical properties of in-situ lunar regolith,such as special particle shape,and develops a magnetic-sensitive lunar regolith simulant which can not only effectively simulate the basic physical and mechanical properties of in-situ lunar regolith,but also can effectively simulate the magnetic sensitivity of lunar small gravity field environment with geotechnical magnetic-similitude-gravity model testing method.Firstly,the basic principle and test system of geotechnical magneticsimilitude-gravity model testing method are briefly introduced,and the requirements of magnetization and magneto-gravity characteristics of the magnetic-sensitive lunar regolith simulant are given in detail.At the same time,the basic physical and mechanical properties of in-situ lunar regolith are summarized in detail by collecting and collating a large number of domestic and foreign literatures,mainly including the geometry characteristics of lunar regolith,density,compressibility and shear resistance,and the target parameters and quantitative evaluation indexes of the lunar regolith simulant were determined.Secondly,combined with the formation process of in-situ lunar regolith,a magnetic-sensitive lunar regolith simulant technology roadmap based on "high temperature sintering" and "impact crushing" is proposed,which corresponds to the geological process of the formation of original lunar bedrock and the formation of lunar regolith by dynamic crushing such as meteorite impact.Specifically,magnetic-sensitive remolded volcanic rocks are prepared from pozzolanic ash and ferric oxide powder by pre-pressing,high-temperature sintering and pore-forming with ammonium bicarbonate,and magnetic-sensitive lunar regolith are prepared by dynamic crushing,screening,drying and mixing of magnetic-sensitive remolded volcanic rocks.The effects of ammonium bicarbonate content,sintering temperature and crushing method on the preparation of magnetic-sensitive lunar regolith simulant were discussed emphatically,and the reasonable range of sample preparation parameters was given.Finally,the basic physical and mechanical properties of magnetic-sensitive lunar regolith simulant were systematically tested and compared with in situ lunar regolith.Specifically,based on the geotechnical magnetic-similitude-gravity testing system,the magnetization characteristics of the magnetic-sensitive lunar regolith simulant were tested;the specific gravity and the maximum and minimum dry density were tested by referring to the geotechnical test standard method;the particle size and its distribution were tested by sieving method and laser particle size analyzer;the particle shape parameters were obtained by microphotography technology and graphics analysis software;and the resistance was studied by triaxial test,by which the peak value and critical shear strength index are obtained,and the compressibility is studied by consolidation test,by thich the compression index is obtained.The results show that the magnetic-sensitive lunar regolith simulant can simulate the special physical and mechanical properties of the in-situ lunar regolith,such as the special particle morphology,high shear strength and weak cohesion,and can effectively simulate the environment of the small gravity field of the moon in combination with the geotechnical magnetic-similitude-gravity model testing method.There are 55 figures,26 tables and 112 references in this paper.