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本論文は，兵庫県内の県道の線形改良事業で建設された約 20m のジオテキスタイル補強土壁を含む高 さ約 45m の高盛土に発生した工事中の変形原因とその対策について述べている．当該補強土壁は施工中 に壁面のはらみ出し量が 15cm を超える大変形が発生した。変状の原因解明のため実施した表面波探査お よびボーリング調査と，盛土材を用いた室内試験により，補強土壁および背面盛土の現況を詳細に調査し た．次に施工履歴および調査結果を反映した変形解析を実施し，原位置挙動を再現し得る数値モデルを作 成し，高盛土の変形量を予測したところ，嵩上げ盛土工事によりジオテキスタイルの破断が予測された． そこで，安全に高盛土を築造するため対策工の検討を行い，工事再開のための施工管理基準を提示した．

When a geotextile as filter is set in a ground for drainage, a decreasing of cross-plane flow performance of geotextile is expected due to a clogging associated with a intrusion and capture of soil particle. The objective of this paper is to consider a suitable geotextile filter to be hard to arise a clogging for fine-grained soils at a field site. This study was performed to focusing on a change of coefficient of permeability normal to plane on a kind of geotextile filter. A series of constant head permeability test on various geotextile filter was performed sandwiching in a geotextile filter between fine-grained geomaterial and gravel layer. This paper is discussed on a test method for an evaluation of the clogging property of getxtile filter, apparent opening size tests of geotextile and clogging properties of geotextile filters based on test resultes of a series of constant head permeability test on various geotextile filter.

The apparent opening size (O95) of geotextile is a physical parameter closely related to the permeability property and/or amount of clogging of geotextile. In this paper, the various methods for apparent opening size of geotextile are discussed. The apparent opening size tests of geotextile on the wet and hydrodynamic method were performed, and the apparent opening size of each test method was evaluated. Based on test results, an improvement of each test method was proposed. It was found that the value of apparent opening size of geotextile obtained from wet and hydrodynamic methods were near to a theory value proposed by J.P. Giroud.

A series of constant head permeability test was performed by putting in a geotextile between a geomaterial layer and a gravel layer in order to evaluate an effect of geomaterial on the cross-plane flow performance of geotextile filter. As the geomaterials for this study, Ataka loam, Kanto loam, Rokunohe sand with fine-grained and Muroran sand with fine-grained were prepared. Based on test results, it was found that the cross-plane flow performance of geotextile depended on the relationship between an amount of clogging per unit volume on each geotextile and a percentage passing by mass of soil particle size less than an opening size of geotextile. It is expected that a clogging mass and an amount of clogging per unit volume are affected by a fiber structure of geotextile.

The apparent opening size (O95) of geotextile is a physical parameter closely related to the permeability property and/or amount of clogging of geotextile. In this study, since the apparent opening size is an important parameter, the apparent opening size test of geotextile on the wet method was performed and verified the adequacy of that test method. The apparent opening size of geotextile obtained from that test is discussed. Based on a series of constant head permeability test results on the various geomaterials carried out in the past, the effect of the apparent opening size on the permeability of the geotextile is also discussed.

In this paper, the evaluation methods of slope stability of the embankment constructed by the geo-textile-reinforced method for soft soil materials ware considered. In the proposed stability analysis method, the constitutive equation of the embankment material which consists of the reinforced materials and the soft soil has formulated as a macroscopic composite material model based on microscopic consideration. Furthermore, distribution of equivalent plastic strain in a dam body on which the seepage force and effective weight was loaded was estimated by the numerical analysis using the proposed material model. The stability of the slope was evaluated as an average safety factor by divided it by the slip surface length, after integrating a local safety factor along the sliding surface. The proposed analysis method was applied to the stability analysis of the slope of the earth fill dam reinforced by the geo-textile material when the water level gone down in a reservoir. Those analysis results ware compared with the analysis results by the classical slice method which assumed the circular slip, and was considered.