Abstract: Surcharge preloading, as an effective foundation treatment method, is usually adopted to reduce the large settlement of pavement constructed in soft clay subgrade caused by long-term traffic loading. After surcharge preloading, the soft clay performs apparent over-consolidated characteristics. Cyclic torsional shear tests are conduct on soft clay under different over-consolidation ratio through GDS hollow cylinder apparatus to study the effects of over-consolidation ratio on the development of axial cumulative strain, hysteretic-curve of stress-strain, and modulus of resilience. Test results suggest that over-consolidation restrains the development of cumulative strain of soft clay under cyclic loading. At given load, as over-consolidation ratio increases, the cumulative strain reduces, and the cycle number which stabilizes pore pressure and cumulative strain is smaller; and moreover, the hysteretic-curve of stress-strain changes less obviously with the proceeding of load cycle. In addition, larger modulus of resilience would give rise to a more explicit characteristic of elasticity.

Key words: over-consolidated, soft clay, deformation behavior, GDS hollow cylinder apparatus, traffic load, cumulative strain