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Showing 8 results for Cyclic Triaxial Test

Baziar M.h., Asna Ashari M.,
Volume 2, Issue 3 (9-2004)
Abstract

An experimental study was carried out to evaluate the liquefaction resistance of silty sand utilizing laboratory techniques. In this study, liquefaction potential of silty sand by using cyclic triaxial tests on frozen samples retrieved from calibration chamber and constructed samples by dry pouring method were investigated. Correlation between cone penetration resistance and cyclic strength of undisturbed silty sand samples are also examined using CPT calibration chamber and cyclic triaxial tests. The cone penetration tests were performed on silty sand samples with fine contents ranging from 0% to 50% and overburden stresses in the range of 100-300 kPa. Then the soil sample in calibration chamber, in the same way that soil samples were prepared during CPT sounding, was frozen and undisturbed soil specimen retrieved from frozen soil sample were tested using cyclic triaxial tests. Analysis of results indicates that the quality of frozen samples is affected by fine content and overburden pressures. Also, using data obtained in this research, the relationship between cone tip resistance and cyclic resistance ratio (CRR) for silty sand soils will be presented. These correlations are in relatively good agreement with field case history data. Also increasing confining pressure in silty sand material increases the cone tip resistance and generally, cyclic resistance ratio increases by increasing silt content.
Saleh Zadeh H., Procter D.c., Merrifield C.m.,
Volume 3, Issue 3 (9-2005)
Abstract

The unique behaviour of carbonate materials under shear loading has stimulated in investigating of their geological and engineering properties.Carbonate soils composed of calcium or other carbonates and most abundant in tropical marine environments are of interest from geotechnical view, especially for offshore engineers engaged with Fossil-based fuel exploitation. This was initiated in the early 1960's, when the first offshore borings in the Persian Gulf identified layers of calcarenite and thick layers of sand containing visible shell fragments.For the purpose of exploiting gas and oil resources in hot and temperate climates (e.g. Persian Gulf) off-shore structures have been placed on carbonate soils. The carbonate sediments are high crushable compared with low crushable sediments such as quartzic soils.To examine the crushability of these problematic sediments a series of monotonic compression, extension and post-cyclic triaxial tests under different densities and confining pressures was carried out to study the crushing behaviour of "Rock" carbonate sand obtained from Cornwall, England.It was shown that crushing coefficient decreases with increasing in maximum principal effective stress ratio for both loose and dense states. It seems that for skeletal carbonate sand maximum and minimum dry densities will be changed during shearing loading. In other words, even though the sample has experienced an increase in density, it may also have experienced a reduction in relative density.
H. Soltani-Jigheh, A. Soroush,
Volume 4, Issue 3 (9-2006)
Abstract

This paper presents the results of a series of monotonic and post-cyclic triaxial tests carried out on a clay specimen and three types of clay-sand mixed specimens. The focus of the paper is on the post-cyclic mechanical behavior of the mixed specimens, as compared to their monotonic behavior. Analyses of the tests results show that cyclic loading degrade undrained shear strength and deformation modulus of the specimens during the post-cyclic monotonic loading. The degradation depends on the sand content, the cyclic strain level and to some degrees to the consolidation pressure.
H. Soltani-Jigheh, A. Soroush,
Volume 8, Issue 2 (6-2010)
Abstract

Mixed clayey soils occur as mixtures of sand (or gravel) and clay in widely varying proportions. Their

engineering behavior has not been comprehensively studied yet. An experimental program, comprising monotonic,

cyclic, and post-cyclic triaxial tests was undertaken on compacted clay-granular material mixtures, having different

proportions of clay and sand or gravel. This paper presents the results of cyclic triaxial tests and explains the behavior

of the mixtures based on number of loading cycles, cyclic strain amplitude, granular material content, grain size, and

effective confining pressure. The results indicate an increase in degree of degradation and cyclic loading-induced pore

water pressure as the number of loading cycles, cyclic strain and granular material content increase. Also the results

show that the grain size has no significant effect on the degree of degradation and cyclic loading-induced pore water

pressure in the specimens. The effect of granular material content on pore water pressure during cyclic loading in

equal-stress-level was also examined. The pore water pressure increases with the increase of granular material

content.


S.m. Mir Mohammad Hosseini, A.a. Hajimohammadi, A. R. Hajimohammadi,
Volume 8, Issue 2 (6-2010)
Abstract

Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are

employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran.

A large area of southern regions of Iran is formed from clay, silt and sand. In this study, maximum shear modulus that

is derived from both field (by seismic piezocone) and laboratory (by Resonant Column and Cyclic Triaxial) tests on

soil samples from the southern region, indicated a meaningful effect of sample disturbance. Results show that in

laboratory tests, loose samples tend to become denser and therefore exhibit greater stiffness whereas dense samples

tend to become looser, showing a reduction in stiffness. According to the results of the present study, there are narrow

limits of soils shear moduli for which the laboratory tests and the field measurements yield approximately the same

amounts. This limit of shear moduli is about 30-50(MPa) for clay deposits and 70-100 (MPa) for sandy deposits. Since

the shear moduli of soils in small strains can also be computed from the shear wave velocity, also correlations based

on parameters derived from SCPTu test for shear wave velocity determination of sandy and clayey soils of the studied

area are presented. This study shows that shear wave velocity can be related to both corrected tip resistance and total

normal stress. The measurements of the damping ratio and shear module, because of a great disturbance of stiff

deposits during the sampling process and also due to considerable differences between the laboratory and field

results, by the laboratory approaches are not reliable and advised.


Rouzbeh Dabiri, Faradjollah Askari, Ali Shafiee, Mohammad Kazem Jafari,
Volume 9, Issue 2 (6-2011)
Abstract

Laboratory data, which relate the liquefaction resistance of Firoozkooh sand and non-plastic silt mixtures to shear wave velocity are

presented and compared to liquefaction criteria derived from seismic field measurements by Andrus and Stokoe [1]. In the work

described herein, cyclic triaxial and resonant column tests were conducted on specimens of clean sand and sand-silt mixtures with silt

content up to 60%, prepared at different densities. Cyclic undrained strength and small strain shear wave velocity were determined

for identical specimens formed by undercompaction method. It was found that silt content affects cyclic resistance and shear wave

velocity. In addition, the laboratory results indicated that using the existing field-based correlations will overestimate the cyclic

resistance of the Firoozkooh sand-silt mixtures when silt content is 60%. For clean sand and the specimens containing up to 30% fines,

results of this study on cyclic resistance are fairly consistent with Andrus and Stokoe correlations. These findings suggest the need for

further evaluation of the effects of non-plastic fines content upon liquefaction criteria derived from seismic field measurements.


S.h.r. Kargar, H. Shahnazari, H. Salehzadeh,
Volume 12, Issue 4 (12-2014)
Abstract

In this study, a researching program is conducted by cyclic triaxial test to determine the post-cyclic behavior of Bushehr carbonate sand retrieved from the north of the Persian Gulf, under anisotropic consolidation at 200 kPa confining pressure. The article compares the post-cyclic monotonic strength and excess pore water pressures generated after the test with the pre-cyclic monotonic results. The results attest to the existence of a relationship between CSR (Cyclic Stress Ratio) and the frequency of failure cycles. The article also investigates the relationship between the amount of excess pore pressures generated during both the cyclic and post-cyclic loading, revealing an increase in the post-cyclic strength and stiffness of sand retrieved from Bushehr. Also the effect of multi stages cyclic loading, density, pore pressure and stain history in post cyclic strength and stiffness is evaluated. The increasing in post cyclic strength and stiffness depends on excess pore pressure generated during cyclic loading and stain history. This article also reveals that a distinct trend in the relation between post cyclic behavior and crushing value does not exist at lower confining pressure.


M. Alibolandi, Dr. R. Ziaie Moayed,
Volume 13, Issue 3 (12-2015)
Abstract

In this study a series of cyclic triaxial tests were performed to examine the undrained dynamic resistance of silty sand reinforced with various arrangements of geotextile layers. The silt content of samples varies in percentage from 0, 10, 20, 30, 40 and 50%. A total of 32 laboratory cyclic triaxial tests have been performed on silty sand samples reinforced with geotextile layers in different depths. All tests were performed with 100 kPa confining pressure, subjected to an isotropic consolidated undrained (CIU) condition. The tests were conducted at a frequency of 2 Hz. Results indicate that both the geotextile arrangement and the silt content were most essential in the liquefaction potential of reinforced sands. An increase in the number of geotextile layers enhanced the cyclic resistance of reinforced samples against the liquefaction potential. It was also found that when the geotextile layer was posited near the top of the specimen (load application part) the liquefaction resistance would increase (e.g. for clean sands, the improvement of liquefaction resistance caused by the geotextile layer had a 0.2 depth, and the sample height was 5.5 times greater than the geotextile layer inserted in mid height of sample H). Based on the obtained results, effects of geotextile on liquefaction resistance decreased as fines content increased to about 33%. Further increase in the fines content however, would lead to higher in reinforcement advantages. The liquefaction improvement is more effective with a higher number of geotextile layers. The results also revealed that the reinforcement effect in FC≈33 % is at its lowest amount. 



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