Experimental Study On Residual Strength Of Fly Ash Mixed With Loess

Fly ash as a secondary product of coal fired power plant is of great potential for use. But it products huge emissions increased year by year, not only occupy a large amount of arable land, but also pollute the environment. A large number of ash emissions caused great pressure on the construction of national economy and ecological environment. How to use ash effectively has become a common concern off all countries. Therefore, it is necessary and significant to speed up the comprehensive utilization of fly ash. In this paper, HJ-1 type ring shear apparatus is used for the experiment study of two aspects of the ash loess. Firstly, exploring the shear strength characteristics of pure fly ash under different shear rate, water content and normal stress. Secondly, exploring the strength and deformation characteristics of fly ash with different shear rate, water content, normal stress and loess content. The main conclusions are as follows:(1)With the increase of the amount of loess content, the optimum water content of fly ash with soil is approximately linearly decreased, maximum dry density approximately linearly increased. The project can account for the fly- ash by mixing loess, improving the cohesive strength of fly ash.(2)Under low normal stress, shear rate does not affect the shear strength of pure fly ash; Under higher normal stress, with the increase of shear rate, the shear strength of pure fly ash is reduced. Shear rate has the opposite effect on peak strength and residual strength of fly ash mixed with soil, with the increase of shear rate, the peak strength of fly ash mixed with soil increases, while the residual strength decreases.(3)With the increase of normal stress, the shear strength of pure fly ash showed a significant increase; Before the peak intensity of fly ash mixed with soil shear stress increases rapidly with the increase of shear strain, and the higher the normal stress, the faster the growth of the stress. After peak intensity, almost appear softening of strength, but the performance is not obvious. With the increase of normal stress, the peak strength of the fly ash mixed with soil is gradually increased, so does residual strength.(4)With the increase of water content, the shear stress of pure fly ash increased gradually. The more close to the optimal water content, the greater the shear strength; For the fly ash with soil under different water content, with the increase of water content, the residual strength of soil sample decreases, the residual friction angle and the residual cohesion are both reduced. Finally, the vertical settlement is gradually increasing with the increase of water content.(5) The pure fly ash is a strain hardening type under low water content, strain softening at high water content. The strain softening model is shown in the fly ash with soil under different water content. When the water content is 27%, 32%, the residual strength o f pure fly ash is minimum, the residual strength of fly ash with ten percent soil is maximum. When the water content is 37%, the residual strength of fly ash with twenty percent soil is minimum, the residual strength of pure fly ash and fly ash with thirty percent soil are maximum; when the water content is 42%, with the increase of the content of loess, the residual strength increases gradually.