Gongbei tunnel is an important part of Hong Kong-Zhuhai-Macao Bridge cable; its foundation pit bottom is dealt with cemented soil. The aggressive ions of the sea will easily have an effect on the cemented soil as the underground pressure water is connected to the brine. Through the laboratory experiment and theoretical deduction

the mechanical properties and durability of cemented soil in the corrosion environment are studied as follows. Laboratory cemented soil and corrosion environment are made to test the unconfined compression strength of the samples soaked at 90 d

180 d and 270 d respectively. Result of this laboratory experiment indicates that: under the influence of erosion environment

the maximum value of uniaxial compressive strength of cement soil will be reached between 90 d and 270 d. After the soak period exceeds 90 d

the solution that contains MCN shows up an entirely negative effect on the compressive strength of cemented soil. Under low concentration (1.5 g/L and 4.5 g/L)

the chemical reaction between MSN and cemented soil achieves an optimum value; in comparative conditions the compression strength damage of cement soil is minimal. The effect of magnesium chloride on compressive strength of the cemented soil samples is much larger than that of magnesium sulfate. Based on the principle of chemical kinetics and the chemical equation between magnesium sulfate and the cement hydration products

combined with the assumptions

the relationship between ion concentration and corrosion time is deduced as (C1/C2)β=t2/t1; that is

when the soil samples are eroded to equivalent compression strength

the reaction order of concentration is inversely proportional to corrosion time. According to the formula

the strength of cemented soil soaking in low concentration solution for a long time is predicted by the strength of cemented soil soaking in high concentration solution for a short time. At last

the theoretical results are verified by experimental data.