| Clay foundation is often difficult to meet the requirements of modern engineering construction on the bearing capacity of the foundation,and developing new soil improvement technology is always a hot research topic in engineering,geotechnical engineering and road engineering.As a new soil improvement technology,adding nano-bentonite can effectively enhance the engineering mechanical properties of the soil.With the wide application of nano-materials,the cost of the nano-materials is greatly reduced,technology process and construction are simple.Meanwhile nano-bentonite itself is a soil,will not produce secondary pollution of the soil.So master the characteristics of nano-bentonite modified soil has important significance for the promotion and application of the technology.In order to study the effect of nano-bentonite reinforcement on clay properties,a series of tests are conducted on clay with different nano-bentonite contents(0.5%,1%,1.5%and 2%).The main results obtained were as followed:1.Through carrying out unconfined compressive strength tests and CBR tests,the mechanical properties of nano-bentonite,effects of nano-bentonite content,rate of water content,dry density on the unconfined compressive strength were studied.The results indicate that the addition of nano-bentonite can effectively improve the compressive properties and bearing capacity of clay,and the compressive strength increases with nano-bentonite content and dry density,while it first decreases and then increases with the increases of water content.Inclusion of nano-bentonite fills the pores,so the effective contact area increase,and strength increases.Meanwhile,water plays a role of lubrication.2.The effect of nano-bentonite addition on the coefficient of consolidation and permeability is analyzed.The results show that adding few nano-bentonite does not affect the original consolidation characteristics,but it shows a better effect.When the nano-bentonite content is 0.5%,the deformation of clay reaches the maximum and void ratio of clay reaches the minimum.While the coefficient of consolidation and permeability increase with increasing nano-bentonite content under high stress state.The analysis shows that nano-bentonite can provide new cementations,resulting in significant improvement to solidification effect.3.Through comparing the effect of the incorporation of nano-bentonite on the destructive characteristics of soil samples,we can found that when adding nano-bentonite,the crack on the surface of the soil were continuous,and the toughness of the soil were strengthened,the brittle failure were improved obviously.4.The effect of nano-bentonite and organic bentonite incorporation on the clay properties was studied.It found that variation of final compression ratio,final void ratio,consolidation coefficient and permeability coefficient of nano-bentonite were more significant than organic bentonite.And the effect of modified clay is better than that of the organic bentonite modified clay,which can effectively improve the compressibility,accelerate the consolidation rate and reduce the pores between the soils.5.The finding of nano-bentonite modified clay has great potential because it is significant for improving the strength,bearing capacity and deformation performance of foundation soil,and it can be used as a new idea of clay modification. |
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