Consolidation constants should be defined by use of effective stress. However, because of no measurement of pore water pressure. the constants have not been determined in terms of effective stress as continuously changing indices. For the purpose to overcome this barrier, a new testing method artificially varying pore water pressures at the top and bottom surfaces of a specimen was developed in this study. By use of the new method, effective- stress analyses have been proved to be applicable even for step-loading type tests, arid compression behaviors represented by C_s and C_c have been precisely examined. Furthermore. a new type of constant-gradient consolidation test procedure was developed based on the idea of water pressure control, and the much more reliable compression constants as well as permeability behaviors represented by the coettiwent of permeability, k, have been determined in the terms of continuously changing effective stress.
Based on the results stated above, a firm foundation on which the latest constitutive equation could be constituted has been obtained.