透水係数の不均質分布構造同定における非適切問題の克服法

Abstract

本研究では、区域単位に不均質な透水係数分布下の地下水流動に対して、観測水位から分布を同定する際の非適切性を克服する手法を提案した。数値実験では同条件下の仮想地下水流動に対して、区域毎の分布同定結果と地盤統計モデル化による一括の同定結果とで比較検討した。前者の同定精度は非適切条件のため低下したのに対し、後者は非常に高くなった。以上により、本提案手法は逆問題の非適切性を克服し、同定の精度向上にも寄与するとわかった。

This study shows that the distributed pareter modeled herein can improve the effectiveness of solving inverse and ill-posed problems through the numerical experiments. A model structure of distributed permeability to be identified is formed with a geostatistical-based model. A hypothetical aquifer divided into twenty constant-permeability zones is designed. The attempts that twenty permeabilities are piecewisely identified, and that geostatistical-based parameters are identified, are carried out. The former solution is described with part inaccuracy. The latter one is accurately represented. It can be proven that the proposed approach to overcome an ill-posed problem is highly successful in identifying a distributed permeability.