scholarly journals The effect of confinement in liquefaction tests carried out in a cyclic simple shear apparatus

2019 ◽  
Vol 92 ◽  
pp. 08002 ◽  
Author(s):  
Lucia Mele ◽  
Stefania Lirer ◽  
Alessandro Flora
Keyword(s):  
Simple Shear ◽  
Initial Conditions ◽  
Confining Pressure ◽  
Cyclic Stress ◽  
Shear Tests ◽  
Liquefaction Resistance ◽  
Pressurized Water ◽  
Cyclic Stress Ratio ◽  
Complex Behaviour ◽  
Continuous Rotation

The cyclic simple shear tests can be used to reproduce in laboratory the complex behaviour of the soil during an earthquake, simulating the continuous rotation of the principal stress axes. In this research a comparison of results between cyclic simple shear tests carried out with confining pressure or confining rings is reported. A cyclic simple shear apparatus is used to carry out tests with confining rings (the conventional way to carry out cyclic simple shear tests) and with a confining pressure applied to the specimen through pressurized water, where the K0 condition during consolidation is guaranteed by a sophisticated control system. The apparatus, in both the configurations, is described in detail. All tests were carried out on reconstituted specimens of an Italian sand with similar initial conditions, such as low relative density and confining pressure. All experimental results are reported in the plane cyclic stress ratio (CSR) and number of cycles where liquefaction occurs (Nliq) in order to evaluate the effect of confinement on the liquefaction resistance of the studied sand.

Laboratory study on subgrade fluidization under undrained cyclic triaxial loading

2020 ◽  
Vol 57 (11) ◽  
pp. 1767-1779 ◽  
Author(s):  
Buddhima Indraratna ◽  
Mandeep Singh ◽  
Thanh Trung Nguyen ◽  
Serge Leroueil ◽  
Aruni Abeywickrama ◽  
...  
Keyword(s):  
Stress Ratio ◽  
Confining Pressure ◽  
Cyclic Stress ◽  
Triaxial Tests ◽  
Loading Conditions ◽  
Cyclic Triaxial ◽  
Cyclic Stress Ratio ◽  
Upward Migration ◽  
Efficient Operation ◽  
Mud Pumping

A long-term issue that has hampered the efficient operation of heavy-haul tracks is the migration of fluidized fines from the shallow soft subgrade to the overlying ballast, i.e., mud pumping. This paper presents a series of undrained cyclic triaxial tests where realistic cyclic loading conditions were simulated at low confining pressure that is typical of shallow subgrade beneath a ballast track. Subgrade soil specimens with a low-plasticity index collected from a field site with recent history of mud pumping were tested at frequencies from 1.0 to 5.0 Hz and a cyclic stress ratio (CSR) from 0.1 to 1.0. The experimental results indicate that under adverse loading conditions of critical cyclic stress ratio (CSRc) and frequency, there is upward migration of moisture and the finest particles towards the specimen top and this causes the uppermost part of the soil specimen to soften and fluidize. Conversely, a smaller value of CSR tends to maintain stability of the specimen despite the increasing number of loading cycles. It is noteworthy that for any given combination of CSR and frequency, the relative compaction has a significant influence on the cyclic behaviour of the soil and its potential for fluidization.

Regression model for evaluating liquefaction potential by discriminant analysis of the SPT N value

2005 ◽  
Vol 42 (3) ◽  
pp. 856-875 ◽  
Author(s):  
Sheng-Yao Lai ◽  
Ping-Sien Lin ◽  
Ming-Jyh Hsieh ◽  
Hoi-Fung Jim
Keyword(s):  
Discriminant Analysis ◽  
Standard Penetration Test ◽  
Cyclic Stress ◽  
Soil Liquefaction ◽  
Liquefaction Resistance ◽  
Multivariate Statistical ◽  
Liquefaction Potential ◽  
Cyclic Stress Ratio ◽  
N Value ◽  
Spt N Value

Discriminant models are developed for evaluating soil liquefaction potential, using standard penetration test (SPT) data for 592 occurrences of liquefaction and nonliquefaction. The discriminant model used is a multivariate statistical method. The square root of the SPT N value, (N1)601/2, and the logarithm of the cyclic stress ratio, ln CSR7.5, are adopted as the major parameters for analyses. Two models measuring liquefaction resistance through the SPT N value are also established in this study, which allows calculated results to be compared with the empirical curves. Key words: liquefaction, discriminant analysis, misclassified probability.

scholarly journals Liquefaction and Reliquefaction Resistance of Saturated Sand Deposits Treated with Sand Compaction Piles

2021 ◽  
Author(s):  
Gowtham Padmanabhan ◽  
Ganesh Kumar
Keyword(s):  
Relative Density ◽  
Ground Improvement ◽  
Cyclic Stress ◽  
Shaking Table ◽  
Repeated Loading ◽  
Saturated Sand ◽  
Liquefaction Resistance ◽  
Cyclic Stress Ratio ◽  
Pore Water Pressures ◽  
Soil Densification

Abstract To mitigate liquefaction and its associated soil deformations, ground improvement techniques were adopted in field to reinforce saturated sand deposits. Sand Compaction Pile (SCP) is one such popular proven treatment to improve liquefaction resistance of sandy deposits. Installation of sand compaction piles improves soil density and rigidity which further enhance seismic resistance against liquefaction and this was well evident from past field observations. However, studies involving SCP performance during repeated shaking events were not available/limited. In this study, using 1-g uniaxial shaking table a series of shaking experiments were performed on SCP treated and untreated sand deposits having 40% and 60% relative density subjected to repeated incremental acceleration loading conditions(i.e. 0.1g – 0.4g at 5 Hz frequency).Parameters such as improvement in soil resistance and relative density, generation and dissipation of excess pore water pressures, maximum observed foundation settlement and soil displacement and variation in cyclic stress ratio were evaluated and compared. Seismic response of liquefiable sand deposits found to be improved significantly due to SCP installation together with occurrence of continuous soil densification under repeated loading. The experimental observations suggested that SCP can perform better even at repeated shaking events.

The Effect of Cyclic Loading of Liquefaction on Palu Sands 

2021 ◽  
Author(s):  
Muhammad Firas Andanawarih ◽  
Widjojo Adi Prakoso
Keyword(s):  
Relative Density ◽  
Cyclic Load ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Cyclic Triaxial ◽  
Liquefaction Resistance ◽  
Cyclic Stress Ratio ◽  
Factors Affecting ◽  
Earthquake Load ◽  
Central Sulawesi

<p>Liquefaction is a phenomenon where soil loses its strength. The phenomenon of liquefaction occurs on non-cohesive soils with medium to fine grains. The phenomenon of liquefaction occurs during an earthquake, the ground experiences shaking vibrations. Palu, Central Sulawesi, Indonesia is one of the areas affected by the liquefaction phenomenon which causes damage to infrastructure in the area. The Palu earthquake that occurred on September 28, 2018, at 18:02:44 WITA with a magnitude of M<sub>w</sub> = 7.4, centered on 26 km north of Donggala, Central Sulawesi. One aspect of the assessment for soil susceptibility to potential liquefaction is laboratory tests. One common laboratory test that can be performed is the cyclic triaxial test. The factors affecting the liquefaction resistance of saturated sand are the relative density and cyclic stress ratio (CSR). The susceptibility of each relative density (30%, 50% and 70%) of the soil experiencing liquefaction and the cyclic stress ratio (0.15, 0.20 and 0.25) will be varied to see the amount of cyclic load needed until the soil experiences liquefaction, the load frequency to represent the earthquake load is 1 Hz with sinusoidal waves. This study will test the fine sands from Palu, Central Sulawesi, Indonesia, to determine their respective behavior when the soil is given a cyclic load.</p><p>Keywords: Cyclic Triaxial, Liquefaction, Cyclic Stress Ratio, Relative Density, Fine Sands.</p>

Cyclic strength of a natural liquefiable sand stabilized with colloidal silica grout

2008 ◽  
Vol 45 (10) ◽  
pp. 1345-1355 ◽  
Author(s):  
J. A. Díaz-Rodríguez ◽  
V. M. Antonio-Izarraras ◽  
P. Bandini ◽  
J. A. López-Molina
Keyword(s):  
Cyclic Loading ◽  
Pore Pressure ◽  
Simple Shear ◽  
Colloidal Silica ◽  
Low Cost ◽  
Silty Sand ◽  
Experimental Program ◽  
Shear Tests ◽  
Liquefaction Resistance ◽  
Wide Range

This paper summarizes the experimental results of a series of cyclic simple shear tests on liquefiable silty sand with and without sample improvement with colloidal silica grout. The objective of the paper is to evaluate the effectiveness of colloidal silica grouting in reducing the liquefaction potential of natural silty sand. Colloidal silica was selected as a stabilizing material due to its low viscosity, wide range of gel times, nontoxicity, and low cost. The soil tested in this experimental program is a poorly graded sand with 11.5% of nonplastic silt from the Port of Lázaro Cárdenas, México. Colloidal silica treated and untreated sand specimens show different pore pressure response and deformation behavior under cyclic loading in simple shear tests. The results indicate that, for a given initial relative density and initial effective vertical stress, liquefiable silty sand specimens stabilized with colloidal silica grout generally exhibit significant gain in liquefaction resistance compared with untreated specimens. It was also found that the colloidal silica grout reduces considerably the rates of pore pressure generation and shear strain of the silty sand specimens subjected to cyclic loading.

A laboratory investigation of the dynamic properties of tailings

2011 ◽  
Vol 48 (11) ◽  
pp. 1587-1600 ◽  
Author(s):  
Michael James ◽  
Michel Aubertin ◽  
Dharma Wijewickreme ◽  
G. Ward Wilson
Keyword(s):  
Dynamic Properties ◽  
Cyclic Stress ◽  
Test Results ◽  
Liquefaction Resistance ◽  
Cyclic Stress Ratio ◽  
Cyclic Resistance ◽  
Direct Simple Shear ◽  
Cyclic Resistance Ratio ◽  
Modulus Reduction

The dynamic response of tailings from a gold mine located in western Quebec was evaluated using cyclic laboratory testing. These tailings are classified as nonplastic silt and sand. Specimens of the tailings were prepared as slurries, consolidated to vertical effective stresses of 100–400 kPa, and subjected to cyclic direct simple shear testing with cyclic stress ratio, CSR, values between 0.075 and 0.15. The shear modulus reduction of the tailings under cyclic loading was found to be fairly similar to that described for clean sands in the literature. The cyclic resistance ratio, CRR (which reflects the liquefaction resistance), of the samples was not significantly affected by the effective consolidation stress (in the range considered here). Analysis of test results with the simplified method of liquefaction evaluation indicates that this method may be applicable to these tailings. However, other factors, such as the possible effects of layering and ageing of the tailings in situ, should also be considered in such an assessment.

scholarly journals A parametric study on cyclic strength of coastal sand of Digha in West Bengal, India

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pinak Ray ◽  
Ramendu Bikas Sahu
Keyword(s):  
West Bengal ◽  
Confining Pressure ◽  
Cyclic Stress ◽  
Cyclic Strength ◽  
Triaxial Tests ◽  
Cyclic Stress Ratio ◽  
Confining Pressures ◽  
Coastal Sand ◽  
Number Of Cycles

AbstractStress controlled cyclic triaxial tests have been carried out on coastal sand of Digha, West Bengal, India at different frequencies, confining pressures, relative densities and number of loading cycles for determination of influence of these parameters on cyclic strength (expressed in terms of cyclic stress ratio) and initial liquefaction of Digha sand. The test results provide evidence that increasing density of sand increases liquefaction potential, though it has been found that increase in effective confining pressure reduces cyclic strength of sand. Cyclic strength of sand decreases with increase of number of loading cycles at a specific density and a particular confining pressure. It has been observed that frequency of loading cycles does have any significant influence on the number of cycles for initial liquefaction of Digha sand. An empirical correlation has been developed on cyclic strength of sand based on these parameters and it has been found that this correlation fits quite well with the observed experimental results.

scholarly journals Liquefaction resistance of christchurch sandy soils from direct simple shear tests

2021 ◽  
Vol 141 ◽  
pp. 106489
Author(s):  
Claudio Cappellaro ◽  
Misko Cubrinovski ◽  
Jonathan D. Bray ◽  
Gabriele Chiaro ◽  
Michael F. Riemer ◽  
...  
Keyword(s):  
Simple Shear ◽  
Sandy Soils ◽  
Shear Tests ◽  
Liquefaction Resistance ◽  
Direct Simple Shear

scholarly journals Effect of Cyclic Loading Frequency on Liquefaction Prediction of Sand

2020 ◽  
Vol 10 (13) ◽  
pp. 4502
Author(s):  
Zhenzhen Nong ◽  
Sung-Sik Park ◽  
Sueng-Won Jeong ◽  
Dong-Eun Lee
Keyword(s):  
Cyclic Loading ◽  
Relative Density ◽  
Effective Stress ◽  
Simple Shear ◽  
Loading Frequency ◽  
Shear Tests ◽  
Liquefaction Resistance ◽  
Dense Sand ◽  
Direct Simple Shear ◽  
Vertical Effective Stress

The frequency of ground motions during earthquakes is typically in the order of a few hertz. As the earthquake-induced liquefaction of soils is widely assessed by performing laboratory tests, it is necessary to consider various loading frequencies generated by real earthquakes. The effect of loading frequency has been studied by cyclic triaxial tests; however, it has rarely been investigated by cyclic direct simple shear tests, which are more similar to the cyclic loading conditions associated with earthquakes. In this study, a series of cyclic direct simple shear tests were performed on clean sand with a relative density (Dr) of 40% (loose sand) and 80% (dense sand), obtained from Nakdong River. The parameters considered are the initial vertical effective stresses (σv0′ = 50, 100, and 200 kPa) and the loading frequencies (f = 0.05, 0.1, 0.5, and 1 Hz) to evaluate the effect of the loading frequency on the liquefaction prediction of clean sand. The results showed that the liquefaction resistance of the sand increases with the increase in the loading frequency, regardless of the initial vertical effective stress and relative density. When the loading frequency increased from 0.1 to 0.5 or 1 Hz, the maximum increase in the cyclic resistances were 15%, and 19% for loose and dense sand, respectively. For a given loading frequency, the liquefaction resistance of the sand decreased when the initial vertical effective stress increased.

scholarly journals Experimental Investigation of the Liquefaction Properties and Post-Liquefaction Volumetric Strain of Calcareous Sand in Dredger Fill Site

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Shenghua Zhao ◽  
Yanlin Zhao ◽  
Jiang He ◽  
Zhenzhong Cao ◽  
Lei Wang
Keyword(s):  
Relative Density ◽  
Pore Pressure ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Cyclic Stress ◽  
Calcareous Sand ◽  
Liquefaction Resistance ◽  
Modified Method ◽  
Pressure Development ◽  
Dredger Fill

In this study, dynamic triaxial cyclic tests were conducted to examine the liquefaction properties and post-liquefaction volumetric strain of calcareous sand from a dredger fill site in the midst of the islands and reefs of the South China Sea. The test results indicated that there were some differences in micromorphology and composition between the calcareous sand obtained via dredging and natural calcareous sand. Axial cyclic stress attenuation can lead to higher cyclic vibration than actual liquefaction vibration, and the modified method can eliminate the effect of axial cyclic stress attenuation. Saturated calcareous sand liquefies under undrained and cyclic loading conditions, and the liquefaction resistance of the calcareous sand decreases with an increase of the effective confining pressure in the dense state. Calcareous sand obtained via dredging exhibited a higher liquefaction resistance compared with other types of calcareous sand. Furthermore, the proposed pore pressure development modified model better describes the pore pressure growth of the calcareous sand from the filling site. The fitting parameters of this model exhibited a high correlation with the relative density. Moreover, the post-liquefaction volumetric strain of the calcareous sand is larger than that of quartz sand, exhibiting a linear relationship with relative density.

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