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.

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.

scholarly journals Some Geotechnical Properties of Plastic Soil Enhanced with Cement Dust

2021 ◽  
Vol 27 (10) ◽  
pp. 20-33
Author(s):  
Abeer F. Hussein ◽  
Ahmed S. Ali ◽  
Abbas J. Al-Taie
Keyword(s):  
Shear Strength ◽  
Dry Weight ◽  
Undrained Shear Strength ◽  
Geotechnical Properties ◽  
Cement Kiln ◽  
Compression Tests ◽  
Cement Dust ◽  
Engineering Structures ◽  
Soil Cement ◽  
Undrained Shear

Plastic soil exhibits unfavorited geotechnical properties (when saturation), which causes negative defects to engineering structures. Different attempts (included various materials) were conducted to proffer solutions to such defects by experimenting in practical ways. On one hand, these attempts aimed to improve the engineering characteristics of plastic soil, and on the other hand, to use problematic waste materials as a stabilizer, like cement kiln dust, and to reduce environmental hazards. This paper explored the shrinkage, plasticity, and strength behavior of plastic soil enhanced with cement dust. The cement dust contents were 0%, 5%, 10%, 15% and 20% by dry weight of soil. An experimental series of shrinkage and plasticity tests and unconfined compression tests were carried out to explore the effects of cement dust on the quantitative amount of shrinkage, plasticity characteristics, and shear strength experienced by plastic soil. The effects of curing on soil strength were also investigated. The finding of this paper showed that the critical behavior and plasticity of plastic soil could be reduced by mixing the soil with 15% or 20% of cement dust. The undrained shear strength, cu, of plastic soil-cement dust mixtures increased with the increasing dust content up to 20%. In fact, this strength was affected by the curing period. The best enhancement was attained when the content of cement dust was 20%, and the undrained shear strength was increased more than three times at this content.

Geotechnical properties of soft clays from the Witch Ground Basin, central North Sea

1991 ◽  
Vol 7 (1) ◽  
pp. 151-156 ◽  
Author(s):  
M. A. Paul ◽  
L. M. Jobson
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Geotechnical Properties ◽  
Seismic Surveys ◽  
Soft Clays ◽  
Fine Grained ◽  
Acoustic Signatures ◽  
The Witch ◽  
Central North Sea ◽  
Undrained Shear

AbstractThe Witch Ground Basin to the northeast of Peterhead is occupied by Late to Postglacial clays which reach a maximum thickness of over forty metres. High resolution seismic surveys have shown that the Sediments can be divided into two stratigraphic units on the basis of their acoustic signatures: the upper Witch Ground Formation shows in its lower part a finely detailed pattern of laterally continuous multiple reflectors, whereas the lower Swatchway and Coal Pit Formations present a disorganised signature in which few reflectors are continuous.Profiles of bulk density, water content and undrained shear strength have been obtained from two continuously sampled, adjacent boreholes which penetrated the sediments to a depth of forty metres. These show that the deposits of the Witch Ground Basin comprise a single geotechnical unit with the properties expected of a fine grained sediment of glaciomarine origin. The principal geotechnical properties change gradationally as a result of changes in composition and from selfweight compression. The different seismic signatures on which the basin stratigraphy is based are not reflected by major geotechnical changes within the sediment, but may well result from secondary features of the geotechnical profile.

scholarly journals Improving geotechnical properties of clayey soil using polymer material

2018 ◽  
Vol 162 ◽  
pp. 01002 ◽  
Author(s):  
Hussein Karim ◽  
Kawther Al-Soudany
Keyword(s):  
Shear Strength ◽  
Polymer Material ◽  
Clayey Soil ◽  
Undrained Shear Strength ◽  
Geotechnical Properties ◽  
Fiber Content ◽  
Strength Parameter ◽  
Polymer Content ◽  
Polymer Fiber ◽  
Undrained Shear

This study illustrates the application of polymer material for clayey soil stabilization. The article will focus on studying the strength behavior of the clayey soils reinforced with homogenously polymer fiber. In the current research, “polypropylene” was selected as polymer material to reinforce the natural clay soil. This polymer fiber was added to the clayey soil with four different percentages of (0, 1.5, 3, and 5%) by weight of soil. Various tests with different polymer contents were performed to study the effect of using such a polymer as a stabilizing agent on geotechnical properties of clay. As the fiber content increases, the optimum moisture content (OMC) is increased while the specific gravity decreases. For Atterberg’s limits, the results indicated increasing liquid limit and plasticity index while decreasing plastic limit with increase in polymer content. The outcomes of the tests also reflected a considerable improvement in the unconfined compressive strength with noticeable improvement in the shear strength parameter (undrained shear strength, cu) of the treated soils. The undrained shear strength obtained from treated soil with 5% polymer addition is more than three times that of the untreated soil. With an increase in polymer content, the consolidation parameters (Compression index Cc and recompression index Cr) decreases. Finally, the benefit of the reinforcement is increased with increasing polymer fiber content.

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.

scholarly journals Influence of the rotation of principal stress directions on undrained shear strength

2013 ◽  
Vol 45 (2) ◽  
pp. 183-192 ◽  
Author(s):  
Grzegorz Wrzesiński ◽  
Zbigniew Lechowicz
Keyword(s):  
Shear Strength ◽  
Principal Stress ◽  
Laboratory Tests ◽  
Cohesive Soil ◽  
Undrained Shear Strength ◽  
Hollow Cylinder Apparatus ◽  
Stress Directions ◽  
Anisotropic Consolidation ◽  
Undrained Conditions ◽  
Undrained Shear

Abstract Influence of the rotation of principal stress directions on undrained shear strength. The paper presents the results of research on natural cohesive soil carried out in the Hollow Cylinder Apparatus (HCA). The main goal of this study was to determine the values of undrained shear strength at different angle of the rotation of principal stress directions. The research were carried out with anisotropic consolidation and shearing in undrained conditions (CAU) on cohesive soil with overconsolidation ratio (OCR) equals 4 and plasticity index (Ip) about 77%. The results of laboratory tests allow to assess the influence of the rotation of principal stress directions on undrained shear strength

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.

Investigating performance of micropiled raft in foundation of power transmission line towers in cohesive soil: experimental and numerical study

2018 ◽  
Vol 55 (3) ◽  
pp. 312-328 ◽  
Author(s):  
Ali-Asghar Zekavati ◽  
Alireza Khodaverdian ◽  
Mohammad-Ali Jafari ◽  
Ahmad Hosseini
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Transmission Line ◽  
Power Transmission ◽  
Cohesive Soil ◽  
Undrained Shear Strength ◽  
Sensitivity Analyses ◽  
Power Transmission Line ◽  
Efficiency Coefficient ◽  
Undrained Shear

This paper captures the behavior of micropiled rafts in power transmission line tower foundations in cohesive soil, concentrating on their uplift performance whether due to the tower position along the line or under wind loading conditions. In this regard, first a number of micropiles were driven into the ground of a project site at the ParehSar power plant, Gilan, Iran. Compression and uplift loading tests were conducted according to relevant standards. On the basis of the field data, a three-dimensional finite element model was developed and subsequently calibrated and verified. The behavior of micropiled rafts subjected to uplift, which is a typical type of loading in foundations of 230 kV four-circuit lattice towers, was then studied by means of this model in terms of a wide-ranging parametric study. In the sensitivity analyses, the impacts of various parameters, such as micropile spacing-to-diameter (s/d) and length-to-diameter (l/d) ratios along with undrained shear strength of the soil, on the uplift capacity of an individual micropile within and out of the group were investigated. Furthermore, interaction factors were computed based on diverse values for undrained shear strength of the soil, s/d ratio, l/d ratio, and grout–soil adhesion. From design and analysis perspectives, the finite element method (FEM) outputs revealed that the efficiency coefficient of micropiled rafts during uplift can be considered equal to one. Moreover, it was found that not only does the behavior of micropiles affect the neighboring micropiles immediately adjacent to the loaded one, but it also influences those in further rows, the result of which would be considering their significance as well.

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