固結したフィルダム基礎地盤の動的強度特性と地震時安定性の評価

Abstract

Fundamental characteristics of the dynamic shear strength of cemented sands, which are often encountered in the diluvial deposits, were investigated through series of cyclic triaxial tests on artificially cemented sands with different contents of Portland cement. By using presented experimental formulae together with some simple elastic stress calculation, a practically useful method of evaluating seismic stability of cemented sand foundations was proposed. Validity of the method was examined for an actual dam foudation. Main results were summarized as follows : 1) Characteristics of the dynamic shear strength of cemented sands are similar as those of the static undrained strength of overconsolidated clays. 2) The unconfined compressive strength can be a practically useful measure to represent pseudo-overconsolidation effect of cemented sands. 3) Applicability of the proposed evaluating method of seismic stability was confirmed for an actual dam foundation. 4) Seismic shear failure in a dam foundation tends to develop under the toe of an earthfill slope, which is likely to cause an overall sliding failure of the fill.