To describe nonlinear shear rheological properties and establish shear rheological model for soft clay,the shear creep experiential formula suggested by Singh-Mitchell was modified to be valid in low corrected stress level condition. The functional expression of viscoplastic shear strain rate in terms of shear stress and viscoplastic shear strain was derived from the relationship equation among viscoplastic shear strain, dissipative shear stress and equivalent time. After combining this expression with shear elastic model, a shear elasto-viscoplastic model was formulated. Based on this model,analytical solutions of shear rheology were not only obtained for single-stage and multi-stage loading under constant effective confining stress, but integral solution of shear rheology was also obtained for both effective confining and shear stresses to vary with time.The results show that the rheological model can numerically simulate relatively well the shear creep development under multi-stages loading in drained triaxial test,and describe the rheological rules that shear strain changes with effect factors such as corrected stress level(or shear stress),effective confining stress and loading duration.%为反映软土剪切流变的非线性特性,建立剪切流变模型,修正了Singh-Mitchell提出的指数型剪切蠕变经验公式,使之适用于低修正应力水平工况.根据黏塑性剪应变-耗散剪应力-等效时间之间的关系方程推导出黏塑性剪应变速率与剪应力和黏塑性剪应变之间的函数表达式.把该表达式和剪切弹性模型相结合,建立了剪切弹黏塑性模型.以此模型为基础,不但获得了有效围压恒定时单级和多级荷载作用下的剪切流变解析解,而且还获得了有效围压和剪应力均随时间变化时的剪切流变积分解答.结果表明,流变模型能够较好地定量模拟三轴固结排水试验中多级加载作用下的剪切蠕变发展过程,合理地反映剪应变随修正应力水平(或剪应力)、有效围压和持续时间等影响因素变化的流变规律.
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