An approximate solution of consolidation for double-layered ground with different smear radii by vertical drains

An analytical solution for consolidation of double-layered ground by vertical drains is proposed, in which only the radial seepage is taken into consideration and the smear radius varies with soil layers. To improve the computing efficiency, a simplified method for selecting serious solutions is presented. The approximate solution is illustrated by Tang's solution (Tang and Onitsuka, 2001) and a large radial consolidation test. The error caused by the forbiddance of vertical drainage can be ignored when the ratio of vertical time factor to radial time factor is small enough, for example, 1/200; and which is easy to satisfy in the field. Through adjusting the control precision of series solutions, the consolidation behavior at any soil layer can be calculated. Horizontal permeability coefficient and smear radius affect the consolidation rate, especially when changing them in the layer which has smaller consolidation coefficient. Moreover, the orthogonal relation for the double-layered and mutilayered system is demonstrated. Using the proposed method, analytical solution for consolidation of double- layered ground by vertical drains can be more acceptable to engineers.