Abstract：The mechanical characteristics of natural soils are significantly affected by their structure. The special mechanical characteristics of natural soils and the influence of stress path on natural soils are disclosed through the comparison of results of tests on natural soils and manipulated soils with multiple stress paths. The structural and underconsolidation behaviors of natural soils are shown in the normal consolidation experiment. The structure damage of the natural underconsolidated soils caused by the increment of volumetric strain is more significant than that caused by the increment of shearing strain. The influence of the structure on natural soils is mainly embodied as the increase of internal friction angle. At small strain，natural soils are of high stiffness，obvious nonlinearity and are markedly different from the manipulated soils. Through the comparison of test results of natural soil samples cut from different direction，the anisotropy of natural soils which becomes obvious as strain decreases is illustrated.
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2004, Vol. 23 
