| Water-quenched nickel-iron slag is an industrial waste slag formed by melting water after quenching of molten metals with FeO,SiO2 and MgO as the main components in the process of smelting nickel and its alloys.In tecent years,with the increasing demand for nickel metal in China,the nickel iron slag produced by smelting nickel metal is also increasing.Because of its low activity,poor stability,fewer channels for comprehensive utilization and high cost of utilization,a large number of nickel iron slag are idle stacked or deep-sea landfill,occupying land and polluting the environment.Therefore,it is urgent to develop a reasonable and effective comprehensive utilization method of nickel-iron slag to turn waste into treasure and produce greater economic value,environmental protection value and social value.At present,the main research on the treatment methods of nickel-iron ore slag includes:extracting useful metal elements such as Fe,Co,Ni and Cu;producing building glass-ceramics;producing building materials and products;and using nickel-iron slag as underground filling material,these methods can not treat water-quenched nickel-iron ore slag well.At the same time,because the water quenched nickel-iron slag smelting area is often distributed in the coastal soft soil area,the filling of embankment in this area often needs to be transported to borrow soil from abroad,resulting in greater economic burden.In this paper,the applicability of water-quenched nickel-iron slag as filling material for embankment slope is discussed through laboratory tests.The reinforced soil structure of water-quenched nickel-iron slag geogrid and the key technology of water sinking pressure are developed.The following work is carried out around it:(1)The chemical composition,morphology,particle size,compaction and expansion characteristics of water-quenched nickel-iron slag were analyzed through indoor chemical composition test,appearance observation test,screening test,light compaction test and free expansion test.The physicochemical properties and road engineering properties of water-quenched nickel-iron slag were discussed.(2)Large-scale repeated direct shear tests of water-quenched nickel-iron slag under dry-wet cycling were carried out to simulate the effect of surface weathering on nickel-iron slag,and to explore the trend of shear strength decline and the limited influence of water content of water-quenched nickel-iron slag under the influence of dry-wet cycling.(3)Model pull-out test of nickel-iron slag-reinforcement structure was carried out to simulate the stress state of nickel-iron slag-reinforcement structure roadbed slope under different water content(0%,2%,6%,27%(saturation)and different normal stress conditions(25kPa,50kPa,100kPa).Based on this,the relationship between cohesion and water content,friction angle and water content of water-quenched nickel-iron slag-reinforcement structure was obtained.Relation,and drawing strength at different water content.(4)In this paper,a structural design scheme for the application of water quenched nickel-iron slag in geogrid reinforced soil structure is developed.Mohr—Coulomb model in ABAQUS software is used to simulate the stability of geogrid reinforced soil slope structure.The site monitoring shows that the slope structure has the characteristics of stability,reliability,good environmental benefits,high economic benefits,simple and fast construction,and is very suitable for the scientific and effective comprehensive application of nickel iron ore slag in geotechnical engineering.(5)This paper puts forward the construction technology and technical points of water-sinking compaction,and solves the problem that the compaction degree of the embankment filled with water-quenched nickel-iron slag is difficult to meet the design requirement due to the conventional mechanical compaction.The water-quenched nickel-iron slag is compacted by water-sinking compaction method,and then the artificial hard shell with geogrid reinforced structure can be formed by two-way enclosure of geogrid.This method improves the overall stifness and lateral restraint of cushion,and effectively improves the compaction of water quenched nickel iron slag. |
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