Abstract:

Salt heaving is the main disease of sulphate saline soil; and the key point of ground treatment for airport engineering is to eliminate salt heaving. Experiments about salt heaving under different loads were carried out to study the restraining effect of load on sulphate saline soil with different compaction degrees and saltnesses; and salt heaving formula which can calculate salt heaving rate was deduced. Control guideline of ground treatment by heavy cover replacement technique was discussed: compaction degree shouldn’t be too high, the suggested value can be picked from 90% to 95% when ground carrying capacity is adequate; feeble sulphate saline soil can be used for filling 2 meters below pavement, the suggested saltness is lower than 0.5%; water dangerous point produces the worst danger, so drainage design should be taken into consideration seriously. The method and flow chart for calculating the least load and the least thickness was given. Calculation indicates that 50 kPa is almost enough to control salt heaving; the least thickness is about 2 meters with grit stone for cover. Heavy cover replacement technique will be used widely in ground treatment in airport engineering with sulphate saline soil in Northwest China.

Key words: ground treatment, heavy cover replacement technique, dangerous point, sulphate saline soil, salt heaving, airport