The quick lime pile method is widely used in Japan to improve soft soil grounds. Utilizing chemical reaction in which quick lime changes into slake lime, the method reduces water content of the soil and increases its strength. In this paper properties of soils treated by the method are preseted by analizing the data obtained at the construction site of the development of the Tokyo International Airport. The main conclusions are as follows:
1) By the investigation of the lime piles, the method to estimate the reduction of the water contents is proposed using the specific gravity of the lime pile after the reaction.
2) In the present design method, the shear strength after the treastment is estimated by the same manner as the preloading method with consolidation pressure equivalent to the reduction of the water content. The study makes its apllicability clear. However, the certain safety factor is required due to the disturbance of the soil during the reaction of lime which rapidly expands and compresses the surrounding soil with high pressure.