Stability of lime-fly ash loess under action of water immersion

The strength tests and mercury injection tests on lime-fly ash loess under 2 actions of water immersion with different times of wetting-drying cycle and different saturation times were conducted, and the stability of lime-fly ash loess was analyzed.Analysis result shows that the unconfined compressive strength of lime-fly ash loess at 7 dis higher and about 1.33 MPa.With the increase of the times of wetting-drying cycle, the strength of lime-fly ash loess decays.After2 times of wetting-drying cycle, the strength falls drastically and tends to be stable.After10 times of wetting-drying cycle, the unconfined compressive strength and shear strength of limefly ash loess decrease by 42.8% and 47.4%, respectively.With the increase of the times of drying-wetting cycle, the total void volume of lime-fly ash loess increases linearly.After 10 times of wetting-drying cycle, the total pore volume of lime-fly ash loess increases from 0.200 1 mL·g^-1 to 0.238 3 mL·g^-1, which is equivalent to 19%.During drying-wetting cycle, the pore diameter variation rules are different, the large void volume increases linearly, but the small and micro void volumes do not change basically.With the increase of saturation time, the strength of limefly ash loess decays, decreases significantly after 2 dwater immersion, and gradually stabilizes with the continuous immersion.After 4 dwater immersion, the unconfined compressive strength and shear strength of lime-fly ash loess decrease by 33.6% and 54.7%, respectively.The result indicates that when the contents of lime and fly ash are less, the water can weaken the strength of lime-fly ash loess obviously, the action of water immersion can lead to the decrease of strength, the dry density slightly decreases, and the total pore volume increases.But compared with the unmodified loess, the lime-fly ash loess has higher strength and better water stability, and can be used as road subgrade in loess area.