Abstract: To study the behavior of soft clay under cyclic train loads, a series of non-destructive tests on remolding hollow cylinder samples is conducted using hollow cylindrical apparatus. Most of the tests are in the heart-shaped stress path and some are in the round stress path as assistant. The strain characteristics of non-coaxiality under the two kinds of stress path are compared with each other. The effects of vibration cycle times N on non-coaxiality and the influence of frequency f on the shape of curves between non-coaxial angle ? and major principal stress directional angle ?? are studied. The analysis of mechanism is carried out and the test results under the other dynamic stress level are compared with the former tests. In addition, a simplified model of relation between ? and ?? taking no account of f is established. The research shows that during any cycle of ?? , the relations between ? and ?? under the two stress paths have their own characteristics. And unit deviator strain increments caused by deviator stress increments (d? /ds) under the two stress paths at the same dynamic stress level are different from each other. However, during some section of ?? , the d?/ ds under the two stress paths are close to each other. The impacts of N on ? and d?/ds under the heart-shaped stress path are slight. d?/ds is much larger in the angle section [30°, 40°] of ?? than the other section during any vibration cycle time. The curves between ? and ?? fluctuate violently with the f increasing.

Key words: train loads, non-coaxial, vibration cycle times, frequency