Abstract: This paper investigates the compressibility properties of the soil samples at a large embedment depth on the site from ChangTai Yangtze River bridge site by using the consolidation tests and the unconfined compression tests. The compression curve characteristics of the undisturbed samples are mainly analyzed to reveal the compressive strength and the compression deformation of the deep structured soil. The test results show that the consolidation curves of the undisturbed samples exhibited essentially inverse sigmoid shape, which involve four distinct phrases with a dramatical dropdown segments. The results also indicated that the tested soil samples are of high void ratio, high saturation, and high sensitivity. Such observations suggested that the deformation of the soil sample caused by the unloading should be properly taken into consideration for the deep structural soil in the engineering practice. In addition, the actual structural yield stress of the deep soil is less than pc calculated by the Casagrand graphical method. As such, it is suggested to combine e~lgPand Es~P curves to collaboratively determine the structural yield stress of the deep soil.

Key words: Structured Soils, Consolidation Test, Compressibility, Structure Yield Stress