| The silt used as roadbed filling in the flooded area of the Yellow River often causes a lot of engineering problems and can only be used after stabilization.In practical engineering,the stabilized silt filling is not only in unsaturated state,but also under the action of environmental factors such as dry-wet cycle for a long time.In this paper,the unsaturated mechanical properties of nano-silica-lime stabilized silt in the flooded area of the Yellow River were studied by means of laboratory test,theoretical analysis and numerical simulation.The main research contents and results are as follows:(1)The domestic and foreign research status of soil-water characteristic curve,unsaturated soil shear strength and,dry-wet cycle and were systematically summarized and analyzed,and the limitations and main research contents of this paper were pointed out.(2)Through soil-water characteristic curve tests,the soil-water characteristic curve of nano-silica-lime stabilized silt and the influence of dry-wet cycle on soil-water characteristic curve were studied.It was found that the addition of nano silica and lime significantly increased the air intake value,residual water content,saturated water content and fractal dimension of soil.The number of feature points in soil-water characteristic curve of stabilized silt increased after one dry-wet cycle,and then decreased with the increase of dry-wet cycle times.(3)Based on the statistical damage theory,the unsaturated statistical damage softening model of nano-silica-lime stabilized silt was established.Unconfined compressive strength test and unsaturated triaxial test were used to study unsaturated damage evolution of stabilized silt.The results show that the increase of matric suction and net confining pressure can inhibit the damage propagation in the silt.After one dry-wet cycle,the "reverse damage" occurreds in stabilized silt.Then the damage degree increased with the increase of dry-wet cycle times,and gradually stabilized after five cycles.(4)The two-dimensional ballastless track subgrade model was established by using finite element software,and the dynamic response of nano-silica-lime stabilized silt subgrade under long-term cyclic load was analyzed.It was found that there is no plastic deformation of nano-silica-lime stabilized silt subgrade filling before and after the dry-wet cycle.The nano-silica-lime stabilized silt has high dynamic stability and resistance to the dry-wet cycle. |
