報告書番号

U99079

タイトル（和文）

地盤の電気化学特性を利用した電気探査法の適用性の検討 --石炭灰地盤の電気特性--

タイトル（英文）

Feasibility study on electrical exploration based on electric chemical properties of layers － Resistivity and induced polarization characteristics of reclaimed ground with coal ash －

概要 （図表や脚注は「報告書全文」に掲載しております）

石炭灰埋立地盤のような不均質な地盤の物理特性を物理探査法により評価することは従来困難であった。そこで，電気探査法の地盤物性評価への適用性を検討するため，石炭灰埋め立て地盤を模擬した不飽和地盤モデルの電気化学特性を測定した。その結果，比抵抗比(比抵抗/間隙水比抵抗)と飽和度(20～100%)にはArchieの式に従うことが認められ，灰種によらず比抵抗比から飽和度が求められることがわかった。しかし，飽和度が小さい条件(20%以下)では細粒な灰粒子による表面伝導現象が影響することが推定された。また，電気探査IP法により広い周波数帯域の電気特性を計測した結果，強熱減量分が多い灰はそれが少ない灰よりも大きいIPが発生し，飽和度に影響されることが認められた。さらに，供試体の物理試験結果より間隙率･含水比と一軸圧縮強度との間には強熱減量分により異なる相関性が認められ，比抵抗とIPから灰地盤の強度特性の分布を推定できる可能性があることがわかった。

概要 （英文）

It has been conventionally difficult to estimate the physical and mechanical properties of an inhomogeneous ground such as reclaimed ground which consists of various kinds of coal ash by means of geophysical surveys. Electric-chemical properties of unsaturated artificial grounds composed of various kinds of coal ash were measured in the laboratory. The result indicates that the relationship between the ratio of resistivities (artificial ground/ pore water) and saturation rate is according to Archie's law in the case of higher saturation rate (20-100%). This empirical relationship may be used to estimate saturation rate of unsaturated grounds from this ratio. However, at the condition of lower saturation rate (<20%), it was inferred that the electrical resistivity was mainly reflected by "surface conductivity phenomena" which occurred at the surface of fine particles contained in coal ash. Then, we measured other electrical properties such as induced polarization (IP) for wide band frequency using IP method. The result showed that the "IP effect" was measured higher at artificial grounds composed of much ignition loss rate than that of less ignition loss rate, and that it was reflected by saturation rate. Finally, porosity and water content were related to unconfined compressive strength due to ignition loss rate from the physical tests using samples made by coal ash. These results indicate that estimates of physical properties derived using these relationships can help obtain the distribution of compressional strength at reclaimed ground area with coal ash.

報告者

キーワード