Abstract: The deformation and failure process of natural soil under loading can be obtained by research on structured clay ,on which the design of construction and soil improvement can be based when the structural influence is considered. With the construction of high, deep and great buildings, the research on the structured soil has recently become more and more important. Natural soils are structured and anisotropic. A new method is developed here to prepare artificially structured soils with initial stress-induced anisotropy. Silty clays are mixed with cements, salt grains and kaolin soils to form structured soil samples with initial stress-induced anisotropy. The bonding between soil particles can be formed by the hydration of cement, the big pore distribution can be produced by the dissolution of salt grains, and the initial stress-induced anisotropy can be developed by applying external forces on the ends of the samples with confining pressure states during the process of hydration. Triaxial shear tests under drained conditions are performed on initial uniform structured soil samples, initial stress-induced anisotropic structured soil samples and reconstituted soil samples. The influence of initial stress on the stress-strain properties of structured soils are analyzed and the breakage mechanism of structured soils with initial stress-induced anisotropy is also investigated.

Key words: initial stress-induced anisotropy, triaxial test, artificially structured soil