堤防基礎地盤における透水係数と粒度特性の関係

抄録

Permeability of substrata is the essential property which controls the seepage safety of levee systems. Permeability of unconsolidated porous sediment is obtained generally by laboratory test, pumping test and in- situ permeability test in single borehole. In contrast, estimation from the grain size characteristics has been widely adopted as an alternative way, due to the difficulty and cost expensiveness of permeability tests. Creager’s equation, whereas old-fashioned, is one the most usual methods for estimating permeability from grain size parameters. The equation input D20 diameter value and output the permeability range in the order of power. Kozeny-Carman equation and Timur equation are also well known equations to estimate permeability from them. Appropriateness of each equation is practically important issue because they are used in safety assessment of levee systems without any constraints. We then collected in-situ permeability test data and grain size analysis data, and analyzed them statistically with special reference to the bimodal grain mixture model.