Abstract
It has been pointed out that the maximum depth of the Plastic Board Drain (PD), which is used for accelerating the dissipation of the pore water pressure in soft clay, is about 20m because of the small sectional area and low rigidity. The authors have developed the cross shaped drain (CSD) in order to be applied for the improvement of deeper soil. This cross shaped drain is composed of four band shaped drains, and the dissipation of pore water pressure is expected to be uniform. Triaxial Ko-consolidation tests were carried out. It was found that the equivalent diameter of CSD is about 1.5 times that of band shaped drain for the same width. A simple analytical method to estimate the equivalent diameter has been proposed.
