A Study on the Effect of a Dyke Reinforced by Geotextile-Encased Sand Columns

2014 ◽  
Vol 919-921 ◽  
pp. 7-9
Author(s):  
Fang Ouyang ◽  
Jun Wei Bi ◽  
Jian Wei Han ◽  
Wei Ming Liao
Keyword(s):  
Shear Strength ◽  
Soft Soil ◽  
Undrained Shear Strength ◽  
Settlement Rate ◽  
Soft Soils ◽  
Three Stages ◽  
Undrained Shear

A dyke construction was dealed with geotextile-encased sand columns. The dyke was used to enclose a polder in Hamburg-Finkenwerder, Germany. With the help of geotextile, the columns can be used in very soft soils , even undrained shear strength cu < 15 kN/m2, without excessive bulging. After the system is installed, the dike can be filled immediately. To analysis observed data of the long-term settlements in the dyke, three stages can be gotten i.e. "Primary settlements" - "Secondary settlements" - "Creep settlements". Most settlements occurred during the primary filling, while, only little settlements appeared after that construction was accomplished. The settlement rate decreases from the first settlement stage to the last one. No jump takes place when unloading soft soil. Furthermore, the method shorten time and saved a lot of money.

The 2nd Hanrahan Lecture: Geotechnical properties of Irish compressible soils

2020 ◽  
Vol 53 (4) ◽  
pp. 475-522
Author(s):  
Michael Long
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Geotechnical Properties ◽  
Rapid Rate ◽  
Soft Soils ◽  
Micro Scale ◽  
Ground Investigation ◽  
The Future ◽  
Work Done ◽  
Undrained Shear

The objectives of this paper are to provide an update on work done and the development of knowledge on Irish compressible soils since Eamon Hanrahan's book on the topic. Eamon subdivided these soils into three categories; namely, alluvial, estuarine and lake-bed deposits, and he termed them ‘troublesome soils’. A brief background geology will initially be presented. The complexity of the deposits both on a macro- and micro-scale will be highlighted. Sites that have been well studied will be summarized and the engineering solutions used to construct on these sites will be reviewed. Although work on these sites presents a significant engineering achievement, some important lessons were learned. The remainder of the paper deals with how these lessons might be addressed in the future; for example, how to use modern ground investigation techniques to best characterize these complex deposits and what are the best techniques for examining important detailed aspects of 1D consolidation behaviour such as the identification of the apparent preconsolidation stress, the sometimes rapid rate of consolidation and creep, and also how to characterize the undrained shear strength of the soils. The work will be benchmarked against experience of the behaviour of Scandinavian soft soils.

Undrained Shear Strength of K0 Consolidated Soft Soils

2008 ◽  
Vol 8 (2) ◽  
pp. 105-113 ◽  
Author(s):  
Li-Zhong Wang ◽  
Kai-lun Shen ◽  
Sheng-Hua Ye
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Soft Soils ◽  
Undrained Shear

scholarly journals Slope Stability of Embankments on Soft Soil Improved with Vertical Drains

2020 ◽  
Vol 6 (1) ◽  
pp. 164-173 ◽  
Author(s):  
F. Kassou ◽  
J. Ben Bouziyane ◽  
A. Ghafiri ◽  
A. Sabihi
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Factor Of Safety ◽  
Field Measurements ◽  
Undrained Shear Strength ◽  
Slope Stability Analysis ◽  
Soft Ground ◽  
Soft Soils ◽  
Undrained Shear

The overloads of structures or embankments built on clayey soft ground are generally applied gradually, respecting a specific phasing. This phasing on construction allows the undrained shear strength of clay increasing over consolidation in order to avoid the risk of collapse during loading. In this work, the undrained shear strength of clay over the consolidation was estimated following SHANSEP method of which parameters proposed by eight researchers have been employed, as well as the slope stability analysis of embankments on soft soils during staged construction. Assessment of factor of safety for slope stability was conducted basing on the Bishop method. Additionally, the variations of undrained shear strength and factor of safety were presented. In order to validate the methods discussed in this study, slope stability analysis of five embankments constructed on clayey soft soils improved by the vertical drain technique in a high-speed railway construction project in Morocco was performed. For these embankments, field measurements about lateral displacement are presented.  It was found that some of the adopted methods is in a good agreement with field measurements. Hence, generalization of these methods to many soft ground cases can be proposed.

Study on the Variation Regularity of Shear Strength of Saturated Soft Clay under Cyclic Loading

2011 ◽  
Vol 250-253 ◽  
pp. 2388-2391 ◽  
Author(s):  
Xiao Ping Wang ◽  
Jian Qi Wu
Keyword(s):  
Shear Strength ◽  
Cyclic Loading ◽  
Bearing Capacity ◽  
Triaxial Test ◽  
Soft Clay ◽  
Undrained Shear Strength ◽  
Saturated Soft Clay ◽  
Undrained Shear

The stiffness and shear strength of soft clay attenuate under long-term cyclic loading, resulting in reduced foundation bearing capacity of road. The variation regularity of undrained shear strength of saturated soft clay which is normally consolidated or over consolidated under cyclic loading was studied with two-way vibration triaxial test, and some useful results are obtained.

Effect of the Time on the Undrained Shear Strength and Permeability of Clay-Wooden Sawdust Mixtures Used to Improve Landfills Liner

2020 ◽  
Vol 857 ◽  
pp. 311-318
Author(s):  
Omar Hamdi Jasim ◽  
Doğan Çetin
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Unconfined Compression Test ◽  
Remarkable Effect ◽  
The Impact ◽  
Undrained Shear

This study aims to assess the impact of time on sawdust usage to enhance the behavior of the clay used in landfills. The soil used in this paper was brought from Büyükçekmece region / Istanbul. Four proportions (1, 2, 3 and 5) of the sawdust were added as a percentage of the dry weight of the soil. Soil-sawdust mixtures were compacted with the optimum water content corresponding to each percentage and samples were extracted. The extracted samples were divided into two groups, the immediate tests were performed on the first group while the second group was kept in special containers for long-term tests after 90 days. A series of undrained unconsolidated triaxial tests (UU) and unconfined compression tests (UCS) were performed on the specimens and compared with the row soil, in the immediate tests, the results from the UU triaxial test showed that the undrained shear strength was increased as the sawdust content increased and then decreased, it was conducted that the optimum sawdust content was 3%, it was increased the undrained shear strength by (39.5%) and (41.44%) for UU triaxial and Unconfined compression tests respectively. After 90 days of the curing period, it found that 2% is the optimum sawdust content, it was increased the undrained shear strength by (202.51%) and (176.64%) for UU triaxial and unconfined compression test respectively. In the immediate and long-term tests, the coefficient of permeability increased by (66.66) and (94.44%) as the sawdust increased from 0 to 5 % respectively. Sawdust increases the hydraulic conductivity of the clay. It can be concluded that the sawdust usage has a remarkable effect on the shear strength of the clay for both immediate and long-term tests.

scholarly journals Post-Cyclic Mechanical Behaviors of Undisturbed Soft Clay with Different Degrees of Reconsolidation

2021 ◽  
Vol 11 (16) ◽  
pp. 7612
Author(s):  
Yuan Lu ◽  
Jian Chen ◽  
Juehao Huang ◽  
Libo Feng ◽  
Song Yu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Undrained Shear Strength ◽  
Excess Pore Water Pressure ◽  
Undrained Shear ◽  
Excess Pore

Soft soil is often subjected to cyclic loading such as that imposed during storms, under traffic, or in an earthquake. Furthermore, the cyclic-loading-induced excess pore water pressure can be partially dissipated after cyclic loading. Thus, different reconsolidation processes should be considered. A series of static and dynamic triaxial tests were conducted on undisturbed soft soil to determine the post-cyclic mechanical behavior thereof, such as the variation of undrained shear strength, the development of excess pore water pressure, and the evolution of effective stress path. The effects of consolidated confining pressure, cyclic stress ratio, and degree of reconsolidation were analyzed. Results show that the trend of all stress–strain curves is similar under different conditions. The effect of the degree of reconsolidation is such that, with increasing the degree of reconsolidation, the shear strength is enhanced. Meanwhile, compared with undrained shear strength without cyclic loading, the shear strength after cyclic loading with full reconsolidation is increased. These factors also have a significant effect on the undrained shear strength: the greater both the confining pressure and cyclic stress ratio are, the higher the undrained shear strength. A positive excess pore water pressure is always observed during post-cyclic shearing process, irrespective of different factors. The S-shaped effective stress paths under different test conditions are observed and cross the critical state line. The microstructures of undisturbed soil and post-cyclic specimens with different degrees of reconsolidation were quantitatively investigated. Besides that, the degree of influence of different factors on the post-cyclic undrained strength was analyzed. Based on the test results, the undrained shear strength with cyclic load-history was well predicted by existing models.

scholarly journals Determination of bearing capacity of bored pile using SPT number N and undrained shear strength Su

2014 ◽  
Vol 17 (3) ◽  
pp. 86-93
Author(s):  
Nhat Dai Vo
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Skin Friction ◽  
Undrained Shear Strength ◽  
Soft Soils ◽  
Bored Pile ◽  
Undrained Shear

In this paper, the determination of bearing capacity of bored pile using the SPT number and undrained shear strength is presented. The advantages of this method are simple and always feasible, especially for bridge and pier designing in case of expressway projects constructed on soft soils. The 22TCN 272-05 standard is used to calculate bearing capacity of bored pile including skin friction and end bearing capacities. An applicable form for calculating the bearing capacity of bored pile is made. An example is presented and the applied result is shown.

scholarly journals Improvement of Geotechnical Properties of Cohesive Soil Using Crushed Concrete

2019 ◽  
Vol 5 (10) ◽  
pp. 2110-2119 ◽  
Author(s):  
Mahdi O. Karkush ◽  
Sarah Yassin
Keyword(s):  
Shear Strength ◽  
Soft Soil ◽  
Deformation Modulus ◽  
Cohesive Soil ◽  
Undrained Shear Strength ◽  
Geotechnical Properties ◽  
Crushed Concrete ◽  
Waste Concrete ◽  
Natural Aggregates ◽  
Undrained Shear

Some natural resources such as gravel are not renewable, therefore, it is necessary to reduce the use of such resources and replace them with other recycled, economic, and environmentally friendly materials. Recycled crushed concrete aggregates demolished from old buildings and blocks of waste concrete can be used to replace the natural aggregates. The present study focused on using recycled crushed concrete in improvement the chemical and geotechnical properties of soft soil having undrained shear strength of 6.78 kPa. The soft soil samples were mixed with 5, 10, and 15% of crushed concrete. The blocks of waste concrete are grinded by mills to get crushed concrete which passing sieve no. 4. Such aggregates are lighter than natural aggregates and provide a good deformation modulus when mixed with soil. In Iraq, there are hundred thousand tons of concrete blocks used as fences and now considered wastes after removing these security fences, so it’s important to interest from recycling of such materials to be used in the improvement wide region of soft soils in Iraq. The results of tests showed increasing the undrained shear strength of soft soil by 175-193.5% and reduced the compressibility of soft by 25-31% measured in terms of compression index.

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