Shallow Slides in Compacted High Plasticity Clay Slopes

Author(s):  
C. P. Aubeny ◽  
R. L. Lytton
2020 ◽  
Vol 57 (9) ◽  
pp. 1265-1279
Author(s):  
H. Postill ◽  
N. Dixon ◽  
G. Fowmes ◽  
A. El-Hamalawi ◽  
W.A. Take

Seasonal wetting and drying stress cycles can lead to long-term deterioration of high-plasticity clay slopes through the accumulation of outward and downward deformations leading to plastic strain accumulation, progressive failure, and first-time failures due to seasonal ratcheting. Using recent advances in hydromechanical coupling for the numerical modelling of unsaturated soil behaviour and development of nonlocal strain-softening regulatory models to reduce mesh dependency of localization problems, the mechanism of seasonal ratcheting has been replicated within a numerical model. Hydrogeological and mechanical behaviours of the numerical model have been compared and validated against physical measurements of seasonal ratcheting from centrifuge experimentation. Following validation, the mechanism of seasonal ratcheting was explored in a parametric study investigating the role of stiffness and long-term behaviour of repeated stress cycling extrapolated to failure. Material stiffness has a controlling influence on the rate of strength deterioration for these slopes; the stiffer the material, the smaller the seasonal movement and therefore the more gradual the accumulation of irrecoverable strains and material softening. The validation presented provides confidence that the numerical modelling approach developed can capture near-surface behaviour of high-plasticity, overconsolidated clay slopes subject to cyclic wetting and drying. The approach provides a tool to further investigate the effects of weather-driven stress cycles and the implication of climate change on high-plasticity clay infrastructure slopes.


Author(s):  
Ömür Çimen ◽  
Mehmet Saltan ◽  
S. Nilay Keskin

AbstractHigh-plasticity clayey subgrade, which is unsuitable for road construction, may sometimes occur along highway routes. In such cases, engineers need to change the route of a highway project, resulting in an increase in road length and project costs. In this study, waste pumice was examined for stabilization of high-plasticity clayey subgrade, which is inappropriate for road construction. For this purpose, the physical and index properties of clay and pumice were determined. Then, the pumice was mixed with high plasticity clay at different ratios by weight. By performing standard Proctor compaction tests on the mixtures, the effects of adding pumice on compaction were also studied. Unconfined compression tests and California bearing ratio (CBR) tests were performed on all pumice-clay mixtures, and the test results and the CBR ratios were compared for each sample, respectively. The results showed that pumice stabilization improved the mechanical properties and reduced the swelling potential of high plasticity clayey subgrade.


2014 ◽  
Vol 998-999 ◽  
pp. 522-525
Author(s):  
Juan Juan Jin ◽  
Min He ◽  
Peng Liu

As the future highest dam in the world, Shuang Jiang Kou rock-fill dam was the water retaining structure of homonymous hydropower station, a controlling engineering on Da Du River hydropower development, which is under design now. This dam is a central earth core dam with a height of 312 meters. A type of gravel soil stiffer than clay, which is made by artificial compounding of clay and gravel, is introduced to reduce the difference in displacement of earth core and rock filled shell zone. Because of the introduced less flexible central core, a more remarkable arching effect of the abutment on earth core might occur simultaneously. A three dimensional coupled nonlinear finite element analysis is carried out to study the three dimensional arching effect of Shuang Jiang Kou rock-fill dam. Computation results show that the arching effect is much notable. Then an innovation is proposed in design, in which a contact high-plasticity clay layer is introduced. It is verified that this innovation is effective and necessary.


2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Frederick Nai Charkley ◽  
Kunyong Zhang ◽  
Guoxiong Mei

The behaviors of high-plasticity clays depend largely on the clay mineral content. Recently, it has been observed that sudden slope failures of most clay slopes occur in regions pronounced with repeated rainfall and sunny climate. The reason for this is still unclear. Examining the effect of clay minerals and drastic weather changes on shear strength will be useful in predicting the performance of structures built in such soils and to take precautionary measures to improve the properties before failure. Therefore, a series of quick direct shearing tests were conducted on 11 artificial clay mixtures. The cohesion and frictional strength properties were determined and linked to the proportion of clay minerals and the number of wetting and drying cycles. The results show a significant reduction in shear strength after exposure to wetting and drying. Generally, montmorillonite-dominated mixtures were less susceptible to the changes in cohesion strength than kaolin-dominated mixtures, and the reduction in frictional strength was relatively insignificant.


2013 ◽  
Vol 31 (4) ◽  
pp. 1171-1185 ◽  
Author(s):  
Maria Mavroulidou ◽  
Xiwei Zhang ◽  
Michael J. Gunn ◽  
Zeljko Cabarkapa

ASTONJADRO ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 301
Author(s):  
Soewignjo Agus Nugroho ◽  
Ferry Fatnanta ◽  
Muhammad Faizal Alridho

<p>Cement and lime are widely used as stabilizing agents for soft clays. Some pozzolanic materials have also been used as additives such as asphalt, geosta, fly ash (geopolymer), base ash, salt. Industrial waste such as rice husk ash, coal burning ash (geopolymer) is also used as an alternative for stabilization materials. This research aims to study the effect of sawdust ash, as wood waste, to replace cement and lime on the stabilization of high plasticity clay. The effectiveness of sawdust ash, in this study, was evaluated from the CBR value. The test samples were also reviewed under conditions with and without immersion and with and without curing. Based on the test results, lime is very effective as an additive because it increases the CBR value of more than 100 at a level of 10%. Wood husk ash also increases the CBR value by 100%. The use of cement, lime and wood husk ash requires curing time so that there is a strong bond between the clay and additives. The use of additives without curing did not increase the CBR value. In the stabilization of clay with 10% lime, replacement of lime with wood husk ash by 4%-6%, can be used as a road sub-grade with good quality.</p>


2020 ◽  
Vol 236 ◽  
pp. 117567
Author(s):  
Qian Guo ◽  
Mingli Wei ◽  
Haoliang Wu ◽  
Yizhong Gu

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