The consolidation problem of double-layered ground with impeded boundaries using vertical drains for soil improvement is studied based on the existing consolidation theory of double-layered ground with vertical drains. The corresponding solutions are presented and it is coded into a program. An engineering case is analyzed using the program and parametric studies are conducted to study the consolidation characteristics of the double-layered ground with impeded boundaries improved by vertical drains. The results lead to the following conclusions: The greater the values of impeded parameters (Rt and Rb) are

the faster the pore pressure of the system dissipate. Impeded parameters have greater influence on the stratum close to the impeded boundaries than that stratum far away from the impeded boundaries. The difference between the average consolidation defined by pore pressure and that defined by settlement is influenced by impeded parameters.