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Residual strength of slip zones of large landslides in the Three Gorges area, China
Residual strength of slip zones of existing landslides is the most important parameter to evaluate their stability (or reactivation potential) and is crucial for understanding reactivation mechanisms. The materials making up slip zones of existing landslides, such as old or ancient landslides, essentially behave like soils and their residual strength is commonly determined by laboratory reversal direct shear and ring shear, or in-situ direct shear tests. These tests are time-consuming and costly. Therefore it is most desirable to find a more practical means of estimating residual strength of the slip zones. Slip zones of the large landslides in the Three Gorges area are commonly composed of fine grained soils with substantial amount of coarse-grained particles, particularly gravel-sized particles. In this study, residual strength of the soils from slip zones of these landslides were examined in relation to their index properties based on a survey of 170 landslides. It was found that laboratory determined residual friction angle using gravel-free fraction of the disturbed soils from the slip zones was closely related to clay content, liquid limit and plasticity index. On the other hand, in-situ residual friction angle of these soils (i.e. including gravel fraction) showed very weak correlations with clay content and Atterberg limits, but was largely dependent on gravel and fines (clays+silts) contents, increasing with gravels and decreasing with fines, and displayed strong linear correlation with the ratio of gravel to fines contents. These observations indicate that among the index properties, clay content and Atterberg limits can be used to estimate residual strength of the soils finer than 2 mm, but they are not appropriate to evaluate the residual strength of the soils containing considerable amount of gravel-sized particles. For the latter, particle size distribution (particularly the ratio of gravel to fines contents) appears to be a useful index. Additionally, it was found that there was no identifiable correlation between relative abundance of individual major clay minerals and residual friction angles of both gravel-free fraction of disturbed and in-situ soils, suggesting that influence of clay minerals on residual strength of these soils can not be simply evaluated based on their abundance.
Residual strength of slip zones of large landslides in the Three Gorges area, China
Residual strength of slip zones of existing landslides is the most important parameter to evaluate their stability (or reactivation potential) and is crucial for understanding reactivation mechanisms. The materials making up slip zones of existing landslides, such as old or ancient landslides, essentially behave like soils and their residual strength is commonly determined by laboratory reversal direct shear and ring shear, or in-situ direct shear tests. These tests are time-consuming and costly. Therefore it is most desirable to find a more practical means of estimating residual strength of the slip zones. Slip zones of the large landslides in the Three Gorges area are commonly composed of fine grained soils with substantial amount of coarse-grained particles, particularly gravel-sized particles. In this study, residual strength of the soils from slip zones of these landslides were examined in relation to their index properties based on a survey of 170 landslides. It was found that laboratory determined residual friction angle using gravel-free fraction of the disturbed soils from the slip zones was closely related to clay content, liquid limit and plasticity index. On the other hand, in-situ residual friction angle of these soils (i.e. including gravel fraction) showed very weak correlations with clay content and Atterberg limits, but was largely dependent on gravel and fines (clays+silts) contents, increasing with gravels and decreasing with fines, and displayed strong linear correlation with the ratio of gravel to fines contents. These observations indicate that among the index properties, clay content and Atterberg limits can be used to estimate residual strength of the soils finer than 2 mm, but they are not appropriate to evaluate the residual strength of the soils containing considerable amount of gravel-sized particles. For the latter, particle size distribution (particularly the ratio of gravel to fines contents) appears to be a useful index. Additionally, it was found that there was no identifiable correlation between relative abundance of individual major clay minerals and residual friction angles of both gravel-free fraction of disturbed and in-situ soils, suggesting that influence of clay minerals on residual strength of these soils can not be simply evaluated based on their abundance.
Residual strength of slip zones of large landslides in the Three Gorges area, China
Restfestigkeit von Gleitzonen großer Hangrutschungen im Gebiet der Drei Schluchten, China
Wen, B.P. (author) / Aydin, A. (author) / Duzgoren-Aydin, N.S. (author) / Li, Y.R. (author) / Chen, H.Y. (author) / Xiao, S.D. (author)
Engineering Geology ; 93 ; 82-98
2007
17 Seiten, 15 Bilder, 2 Tabellen, 30 Quellen
Article (Journal)
English
Bergbau , Bautechnik , Ingenieurwesen , Erdbau , Dammbau , Geologie , geologische Messung , Tektonik , Staudamm , Festigkeit , mechanische Festigkeit , Korngrößenverteilung , Sand , Kies , Ton (Mineral) , Boden (Erde) , Bodeneigenschaft , Bodenmechanik , China
Residual strength of slip zones of large landslides in the Three Gorges area, China
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