沈下要因を総合評価した長崎県諌早干拓地の地盤沈下予測

概要

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Naturally speaking, the land subsidence has been caused due to dead load (for example, embankment, building and polder dyke), repeated load (for example, traffic and ocianic tide) and over-pumping grandwater. In the Isahaya polder in Nagasaki prefecture, the land subsidence has been observed since in 1970s. This paper completes an iterative quasi-three-dimensional finite element model for heterogeneous multi aquifer systems and evaluates the land subsidence due to only over-pumping grandwater using one-dimensional consolidation finite element model for the Isahaya polder. The calculated values of land subsidence have been sufficiently agreed with the observed values in inland. However, the difference has been apparent especially near the shore. Therefore, this paper proposes a prediction model of land subsidence synthetically evaluated all, factors mensionded avove except of traffic load. It has been clarified that the proposed model reasonably predicts the land subsidence in the Isahaya polder, as the result of the comparison with calculated and observed values.