Abstract: The compressive strength of the fiber-lime-fly ash-saline soil is affected by the salt contents and reinforcement modes. Unconfined compressive tests are conducted on lime-fly ash-saline soil and fiber-lime-fly ash-saline soil in the condition of nine salt contents(0.5%, 1.5%, 2.5%, 3.5%, 4.5%, 5.5%, 7.0%, 8.5% and 10%) and six reinforcement modes (the whole sample, the top1/3, the top 1/2, the middle 1/3, the bottom 1/2 and the bottom 1/3 of sample). The results show that both the compressive strength and the failure strain increase with increasing salt content which is less than 7%, and decreases with increasing salt content which is more than 7%. When the fibers are added to the middle 1/3 of the sample, the compressive strength is the largest, which is reduced to the whole, the bottom 1/2, the top 1/2, the bottom 1/3 and the top 1/3 of sample. The compressive strength is basically the same when the reinforcement mode is the bottom 1/2 and the top 1/2, and that of the reinforcement modes is the bottom 1/3 and the top 1/3. The All stress-strain curves of lime-fly ash-saline soil and fiber-lime-fly ash-saline soil are strain softening. The soil has the best deformation resistance when the sample is reinforced entirely. Fiber reinforcement can counteract the damage caused by salt expansion and moisture absorption softening of solidified soil due to high salt content. The deformation resistance of fiber-lime-fly ash-saline soil is best when the whole sample is reinforced fibers.

Key words: reinforced soil, polypropylene fiber, compressive strength, salt content, reinforcement modes