Abstract: The soft soil in coastal area will be affected by the long-term immersion of the brine, in order to obtain the evolution law of mechanical properties with time, on the basis of the main composition of the brine content and preparation of the brine solution. Selection of Tianjin binhai new area of soft soil, mixed with 15% cement for maintenance. In order to illustrate the effect of salt solution immersion, the salt water and fresh water soaking two way contrast test are carried out. Unconfined compressive strength test results show that the improvement of soft clay after fresh water solution and salt solution immersion in 3 days, reached its maximum intensity difference; 7 d and 28 d curing age sample are respectively 0.40, 1.28 MPa. Then, using the Seep/W and GEOSTUDIO CTRAN module to simulate the process of salt ion in brine immersed specimens, it is found that salt solution ion in sample 2-3 days after, internal migration into the 5 mm under sample surface area, tends to steady. The results of numerical calculation is consistent with the experimental phenomena.

Key words: improved soil, erosion effect, unconfined compressive strength, ion concentration, brine soaking