Undrained shear strength properties of organic harbor mud at low consolidation stress levels

2011 ◽  
Vol 48 (3) ◽  
pp. 388-398 ◽  
Author(s):  
Benjamin Friedrich Schlue ◽  
Tobias Mörz ◽  
Stefan Kreiter
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Strength Properties ◽  
Undrained Shear Strength ◽  
Ex Situ ◽  
High Plasticity ◽  
Compression Time ◽  
Stress Levels ◽  
Strong Surface ◽  
Undrained Shear

Dredging operations in European harbors for maintenance of navigable water depth produce vast amounts of harbor mud. Between 2005 and 2007, the second largest harbor construction project in Germany was designed as a pilot study, using dredged harbor mud as backfill material to avoid expensive deposition or ex situ treatment. During this project, strong surface deformations of the backfill highlighted the need for an improved assessment of undrained shear strength of naturally liquid harbor mud. The strength of harbor mud cannot be measured accurately under corresponding low in situ effective stress levels by standard laboratory tests. Therefore, a large-scale oedometer cell with a diameter of 22 cm was designed, providing the opportunity to perform vane shear measurements during consolidation. This study shows that East Harbor mud is a very sensitive, organogenic clay of extremely high plasticity, exhibiting very small undrained shear strength when compared with other cohesive soils. Both the peak and residual undrained shear strengths are shown to increase about 3%–4% per log-cycle increase in secondary compression time (days).

scholarly journals Experimental investigations of using deep mixing method to stabilise problematic clays in Ontario

2021 ◽  
Author(s):  
Shuihan Li
Keyword(s):  
Shear Strength ◽  
Strength Properties ◽  
Undrained Shear Strength ◽  
Experimental Investigations ◽  
Silty Clay ◽  
Slag Cement ◽  
Mixing Method ◽  
Sensitive Marine Clay ◽  
Strength Improvement ◽  
Undrained Shear

Champlain Sea clay is a sensitive marine clay which can lose more than 90% of its strength when disturbed. Organic silty clay, commonly found in Ontario, has a high compressibility and a low shear strength. In this experimental study, different binders were applied to Champlain Sea clay and organic silty clay to improve its strength properties. The results indicate that cement and slag/cement can significantly improve the strength of these problematic clays. A cement dosage ranging from 150 kg/m3 to 250 kg/m3 can consistently improve the undrained shear strength of Champlain Sea clay and organic silty clay with the maximum strength improvement ratio of 10 and 18 respectively. A slag/cement dosage of 290 kg/m3 with a mass ratio of 3:1 can improve the undrained shear strength of Champlain Sea clay for more than 50 times. Lime was found to be effective in treating organic silty clay as well.

Behavior of a Cemented Plastic Clay as an Embankment Foundation

1974 ◽  
Vol 11 (1) ◽  
pp. 46-58
Author(s):  
Guy Lefebvre ◽  
Liguori M. Lefebvre ◽  
Peter Rosenberg
Keyword(s):  
Shear Strength ◽  
Pore Pressure ◽  
Applied Pressure ◽  
Undrained Shear Strength ◽  
Glacial Lake ◽  
Triaxial Tests ◽  
High Plasticity ◽  
Degree Of Consolidation ◽  
Undrained Shear ◽  
Varved Clay

A 32 ft (10 m) high embankment has been built at Matagami, Quebec, on a varved clay deposit of the glacial lake Barlow–Ojibway. This paper reports on some aspects considered in the design, mainly the cementation and the high plasticity of the clay. The variation of settlements and pore pressure is presented and indicates that, 8 months after construction, the pore pressure dissipation is very small while the measured settlements reach 18 in. (45 cm).Triaxial tests, with various consolidation times, were carried out on specimens cut from undisturbed block samples obtained in the same area, in order to study the effect of consolidation on the shear strength of these cemented clays. Results indicate that the undrained shear strength decreases during consolidation until the degree of consolidation reaches 50%. This phenomenon together with the non-dissipation of pore pressure in the field is attributed to the collapse of the cemented structure when the applied pressure exceeds Pc.Similar behavior reported for two other cases of embankments built on deposits of the same origin, leads to the conclusion that the stage construction method is not suitable for embankment on cemented clays, at least those from the glacial lake Barlow–Ojibway, because no gain in shear strength is recorded over a normal consolidation period.

scholarly journals Strength Properties of Reinforced Peat Using Fiber-Polyester and Shredded Rubber-Crumb as Reinforcement Material

2018 ◽  
Vol 7 (3.18) ◽  
pp. 26
Author(s):  
Norazzlina M.Sa’don ◽  
Abdul Razak Abdul Karim ◽  
Siti Noor Linda Taib ◽  
Mahshuri Yusof
Keyword(s):  
Shear Strength ◽  
Waste Disposal ◽  
Strength Properties ◽  
Undrained Shear Strength ◽  
Engineering Properties ◽  
Rubber Crumb ◽  
Fiber Reinforced ◽  
Effective Contact ◽  
Strength Improvement ◽  
Undrained Shear

This paper presents an investigation of the strength improvement of reinforced peat by using the fiber reinforcement techniques of the lightweight waste material, i.e., tire-waste disposal. The fiber-polyester and shredded rubber crumb are extracted and process for the collected tire-waste disposal. In this study, the fiber-polyester and shredded rubber-crumb are mixed with peat (Pt), with undrained shear strength, cu of <10 kPa and 5 % cement content, which act as a binder. The peat samples are mixed at various percentages of fiber-polyester and shredded rubber-crumb. The compacted fiber-reinforced peat samples were prepared at optimum moisture content, mixes thoroughly to a uniform condition by laboratory mixer and air cured for 7 and 28 days in a single batch. The strength improvement of undrained shear strength, cu of >100 kPa is targeted at minimal percentages of cement added. The Unconfined Compression Strength (UCS) and California Bearing Ratio (CBR) tests are performed for determination of the engineering properties of fiber-reinforced peat. Based on the results obtained, one can be seen that both fiber-polyester and shredded rubber crumb shows an increment in unconfined compressive strength value of 214 kPa and 55 kPa, respectively. In summary, the study shown that, the inclusion of fiber-polyester and shredded rubber-crumb from tire-waste disposal increased the effective contact area between reinforced material and peat, which then improved the strength significantly, and the used of tire-waste disposal for the construction may not only provide the alternative mean of recycling and reusing, however, it also addressed economic and environmental concerns and reduce construction cost by making the best use of locally available materials.  

scholarly journals Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis

2016 ◽  
Vol 53 (7) ◽  
pp. 1138-1155 ◽  
Author(s):  
Rajib Dey ◽  
Bipul Hawlader ◽  
Ryan Phillips ◽  
Kenichi Soga
Keyword(s):  
Shear Strength ◽  
Shear Band ◽  
Large Scale ◽  
Critical Length ◽  
Undrained Shear Strength ◽  
Model Parameters ◽  
Submarine Landslides ◽  
Weakened Zone ◽  
Sensitive Clay ◽  
Undrained Shear

Post-slide investigations suggest that many large-scale submarine landslides occur through marine sensitive clay layers. A nonlinear mathematical model for post-peak degradation of undrained shear strength of sensitive clay is proposed based on experimental results. A method for estimation of model parameters is presented. Incorporating the model, an analytical solution is developed to examine possible mechanisms of large-scale submarine landslides. Analyses are performed for mild infinite slopes where the failure initiates from a “fully weakened zone” of soil having undrained shear strength lower than the shear stress acting parallel to the slope. The driving force, in excess of resistance, generated from the fully weakened zone is then transferred to the surrounding soil elements resulting in shear band formation due to strain-softening behaviour of sensitive clays. When the length of the fully weakened zone is greater than a critical length, catastrophic shear band propagation (self-driven without any additional external force) occurs, which could result in large-scale offshore landslides. A simple design chart is developed to calculate the critical length. Compared with a 2005 study by Puzrin and Germanovich based on a linear post-peak shear strength degradation model, the present study gives a conservative estimation of critical length for catastrophic shear band propagation.

scholarly journals Experimental investigations of using deep mixing method to stabilise problematic clays in Ontario

2021 ◽  
Author(s):  
Shuihan Li
Keyword(s):  
Shear Strength ◽  
Strength Properties ◽  
Undrained Shear Strength ◽  
Experimental Investigations ◽  
Silty Clay ◽  
Slag Cement ◽  
Mixing Method ◽  
Sensitive Marine Clay ◽  
Strength Improvement ◽  
Undrained Shear

Champlain Sea clay is a sensitive marine clay which can lose more than 90% of its strength when disturbed. Organic silty clay, commonly found in Ontario, has a high compressibility and a low shear strength. In this experimental study, different binders were applied to Champlain Sea clay and organic silty clay to improve its strength properties. The results indicate that cement and slag/cement can significantly improve the strength of these problematic clays. A cement dosage ranging from 150 kg/m3 to 250 kg/m3 can consistently improve the undrained shear strength of Champlain Sea clay and organic silty clay with the maximum strength improvement ratio of 10 and 18 respectively. A slag/cement dosage of 290 kg/m3 with a mass ratio of 3:1 can improve the undrained shear strength of Champlain Sea clay for more than 50 times. Lime was found to be effective in treating organic silty clay as well.

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