In this paper, experimental results of the relation among compressive stress, pore pressure and volumetric strain at the undrained condition and the relation between pore pressure and consolidation time at the drained process of compacted partially saturated decomposed granite soil and Fujinomori clayey soil are shown. The applicability of Hilf's equation between pore pressure and compression stress at undrained condition is examined with experimental results. From these results, following results are obtained.
(1) In the case of sandy decomposed granite soil, the pore pressure by comrpessive stress at undrained condition is rapidly increased as the compacted moisture content is greater than two or three percents wet side of optimum moisture content. On the other hand, in the case of Fujinomori clayey soil, pore pressure increased gradually with the increment of compacted moisture content.
(2) The relation curves between pore pressure and drained time are similar with the curve of Terzaghi's consolidation theory, but the dissipation of pore pressure is delayed in comparison with the theory. The cause of this phenomemon is considered the decrease of permeability of soils with decrease of degree of saturation by dessipaiton of pore pressure.
(3) In comparison with pore pressure at undrained condition and Hilf's equation, this gives greater pore pressure than that. The part of this cause is on the method of experiment but Hilf's equation has also defect. From this, Hilf's equation gives excessive pore pressure at undrained condition.