Effect of rod friction on vane shear tests in very soft organic harbour mud

Schlue, Benjamin Friedrich; Mörz, Tobias; Kreiter, Stefan

doi:10.1007/s11440-007-0047-7

Cited by 9 publications

(2 citation statements)

References 5 publications

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“…Rod friction [76] and shear rate [3] effects were neglected due to the small penetration depth of 30 mm and the low peripheral velocity of 1.1 mm/min.…”

Section: Laboratory Vane Shear Testsmentioning

confidence: 99%

Shear strength behavior and parameters of microbial gellan gum-treated soils: from sand to clay

2018

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Microbial biopolymers have recently been introduced as a new material for soil treatment and improvement. Biopolymers provide significant strengthening to soil, even in small quantities (i.e., at 1/10th or less of the required amount of conventional binders, such as cement). In particular, thermo-gelating biopolymers, including agar gum, gellan gum, and xanthan gum, are known to strengthen soils noticeably, even under water-saturated conditions. However, an explicitly detailed examination of the microscopic interactions and strengthening characteristics between gellan gum and soil particles has not yet been performed. In this study, a series of laboratory experiments were performed to evaluate the effect of soil-gellan gum interactions on the strengthening behavior of gellan gum-treated soil mixtures (from sand to clay). The experimental results showed that the strengths of sand-clay mixtures were effectively increased by gellan gum treatment over those of pure sand or clay. The strengthening behavior is attributed to the conglomeration of fine particles as well as to the interconnection of fine and coarse particles, by gellan gum. Gellan gum treatment significantly improved not only interparticle cohesion but also the friction angle of clay-containing soils.

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“…Rod friction [76] and shear rate [3] effects were neglected due to the small penetration depth of 30 mm and the low peripheral velocity of 1.1 mm/min.…”

Section: Laboratory Vane Shear Testsmentioning

confidence: 99%

Shear strength behavior and parameters of microbial gellan gum-treated soils: from sand to clay

2018

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“…It is widely used for its simplicity, speed and relative cost, and it is the only method commonly used in both laboratory and field settings in contrast to other soft soil test methods such as fall cone penetrometers or full-flow penetrometers ͑Zreik et al 1995; Stewart and Randolph 1994͒. However, the results of vane shear tests are affected by many factors such as shear rate, strength anisotropy or rod friction effects ͑Aas 1965; Flaate 1966;Wiesel 1973;Menzies and Mailey 1976;Torstensson 1977;Biscontin and Pestana 2001;Schlue et al 2007͒. Shear rate or peripheral velocity is among the most important factors affecting vane shear test results but there is currently no common international standard for peripheral velocity or rotation rate in vane shear tests ͑Leroueil and Marques 1996͒.…”

Section: Introductionmentioning

confidence: 99%

Influence of Shear Rate on Undrained Vane Shear Strength of Organic Harbor Mud

Schlue

Moerz

Kreiter

2010

J. Geotech. Geoenviron. Eng.

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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 to use dredged harbor mud as backfill material to avoid expensive disposal or ex situ treatment. During this project, a partial collapse of the backfill highlighted the need for an improved assessment of undrained shear strength of naturally occurring liquid harbor mud. Using vane shear testing, this study evaluates the effect of shear rate on the undrained shear strength of harbor mud. It is shown that measured values for both peak and residual shear strength are significantly influenced by shear rate effects. Furthermore, the influence of shear rate on the peak shear strength is found to be independent of water content while the influence of the shear rate on the residual shear strength strongly depends on water content. New shear rate dependent correction factors are proposed using the test results and the observed time to failure in the harbor basin. The proposed correction leads to significant lower design undrained shear strengths than the classical Bjerrum correction and would have predicted the failure during the construction.

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