Abstract: In the process of deep excavation and tunnel design, soils of different sites may undergo different static stress paths. Under different stress paths, soils may behave different static characteristics. At the same time, in engineering practice, the work strain of soils is in the range of small strain; and in the range of small strain, the static characteristics of soils behave more nonlinear and depending the stress paths. In this paper, based on the soft clays which spread widely in the Eastern China and behave many bad engineering properties, a series of static stress paths tests were conducted under undrained condition and drained condition. Test results show that: under both undrained and drained conditions, the stress paths make great influences on the static strength; the stress paths with increasing confining pressure increase the static strength; while the stress paths with decreasing confining pressure decrease the static strength. Meanwhile, the stress paths make greater influences on the degradation of secant Young’s modulus; the stress paths with increasing confining pressure decrease the secant modulus; while the stress paths with decreasing confining pressure increase the secant modulus. The influence of stress paths on the secant modulus is more significant in the range of small strain; and it is due to the anisotropy induced by the change of stress path directions.

Key words: clay, stress-strain relationships, stress path, secant modulus