Abstract: In situ test methods have advantages in testing different soil parameters of soft soils. The accuracy and effectiveness of these in-situ testing methods are related to their structural characteristics; geological conditions, and testing experience of the operator. In Dongting Lake soft soil area, the insitu testing methods are very important tools for the soil property characterization, and it is also equally important to select the appropriate testing device for the certain soil parameter. This paper presents the comparative study results of wo soft soil with different deposition origin using different insitu testing devices. The results indicate that, the cone penetration test (CPT) results are repetitive and more accurate. Diverse results are obtained in using vane shear testing device; the empirical formula for flat dilatometer in Dongting soft soil has scattered results and are not reliable. It is concluded that the CPT should be mainly used for the soft soil characterization and compensated by vane shear device. Plat dilatometer should be used for the purpose of experience accumulation.

Key words: Dongting Lake, Soft Soil Characteristics, In-situ Tests, Comparative Studies