ABSTRACT
The existing empirical methods of seepage coefficient for clay are difficult in parameter acquisition and poor in calculation accuracy, so it’s possible to find reasonable ones based on the mature empirical methods of coarse-grained soil. Firstly, the permeation mechanism of clay was analysed including influencing factors, spatial process and parameter calculation, and the ineffective and effective voids were defined, then the empirical methods of clay and coarse-grained soil were summarized and listed; Secondly, clay was put equivalent to coarse-grained soil according to bound water consolidation, and the parameter “equivalent void ratio” was introduced to establish the equivalent calculation methods; Finally, liquid-plastic limit method to determine the volume of ineffective void was explained, and the feasibility of equivalent calculation methods was evaluated by three examples. The results show: seepage, permeation and effective permeation are three different concepts, groundwater permeates in clay via the effective void. For certain soil, the increasing sequence of permeability coefficient is seepage coefficient, permeation coefficient and effective permeation coefficient; Introduction of “equivalent void ratio” unifies calculation of seepage coefficient for clay and coarse-grained soil; The maximum of bound water content is about 0.9 time the size of liquid-limit; Equation Mesri of clay and the equivalent calculation methods of Terzaghi or Curson-Karman are suitable for calculating seepage coefficient of clay for the closest results to experimental values.
