Comparisons of deformation characteristics of rockfill materials using monotonic and cyclic loading laboratory tests and in situ tests

1994 ◽  
Vol 31 (2) ◽  
pp. 162-174 ◽  
Author(s):  
Nario Yasuda ◽  
Norihisa Matsumoto
Keyword(s):  
Cyclic Loading ◽  
Laboratory Test ◽  
Laboratory Tests ◽  
Shear Test ◽  
Triaxial Tests ◽  
Deformation Characteristics ◽  
Simple Shear Test ◽  
Small Strains ◽  
Rockfill Materials

The deformation characteristics of rockfill materials at very small strains were investigated by comparing the results of monotonic and cyclic loading laboratory tests with geophysical P- and S-wave logging data from the field. Using a precision linear variable differential transformer for displacement, the elastic moduli of rockfill materials at very small strains were measured in monotonic and cyclic loading triaxial tests. The laboratory test results agreed well with the field results. The shear moduli of rockfill materials from both a monotonic loading torsional simple shear test and a cyclic loading torsional simple shear test also showed good correspondence. Furthermore, the shear modulus predicted from the in situ shear wave tests in rockfill dams corresponded reasonably well with the modulus in the large-scale triaxial tests in the laboratory. Key words : deformation characteristics, embankment dams, rockfill materials, laboratory test, in situ test.

Experimental Study on the Deformation Characteristics of Rockfill Materials under Cyclic Loading of Spherical Stress

2017 ◽  
Vol 86 (2) ◽  
pp. 367-379
Author(s):  
Yanyi Zhang ◽  
Gang Deng ◽  
Yanfeng Wen ◽  
Zeping Xu ◽  
Shu Yu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Cyclic Loading ◽  
Deformation Characteristics ◽  
Rockfill Materials

Measurement of soil strength in simple shear tests

1991 ◽  
Vol 28 (2) ◽  
pp. 255-262 ◽  
Author(s):  
J. H. Atkinson ◽  
W. H. W. Lau ◽  
J. J. M. Powell
Keyword(s):  
Simple Shear ◽  
Shear Test ◽  
Triaxial Tests ◽  
Shear Stresses ◽  
Shear Tests ◽  
Laboratory Equipment ◽  
Simple Shear Test ◽  
Failure Envelopes ◽  
London Clay ◽  
Normal And Shear Stresses

During a simple shear test the axes of stress rotate and, in a conventional apparatus in which the only stresses measured are the normal and shear stresses on horizontal planes, it is not possible to define the stress state completely. As a result, the measured failure stresses may not represent the true strength of the soil. Examination of possible Mohr's circles for soils at failure in simple shear tests demonstrates that the measured strength for a given soil depends on, among other things, the ratio of the horizontal and vertical effective stresses at failure. Results of laboratory tests on Cowden Till and on blue London Clay show the differences between strengths measured in simple shear and triaxial tests. A consequence of the conventional interpretation of the simple shear test is that effective stress failure envelopes have a false cohesion intercept with friction angles smaller than those measured in triaxial tests. Key words: clays, laboratory equipment, shear strength, shear tests, triaxial tests.

scholarly journals Deformation Characteristics of Soft Marine Soil Tested under Cyclic Loading with Low Frequency

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yu Lu ◽  
Wenbin Fu ◽  
Danxuan Xue
Keyword(s):  
Cyclic Loading ◽  
Pore Pressure ◽  
High Stress ◽  
Low Frequency ◽  
Load Level ◽  
Triaxial Tests ◽  
Deformation Characteristics ◽  
Confining Stress ◽  
The Difference ◽  
Marine Soil

Soft marine soil which could be found widely at the coastal and offshore areas is usually associated with high settlement and instability, especially under cyclic loading. Many research studies have been conducted on its deformation characteristics under the cyclic loading with high frequency, whereas few works have been reported on that under the low-frequency cyclic loading which largely existed in engineering. In this work, a comprehensive series of undrained triaxial tests under cyclic loading with low frequency was conducted to investigate the deformation characteristics of soft marine soil. The results demonstrate that soil specimens accumulate plastic deformation and pore pressure under cyclic loading. Specimens tested under conditions such as high confining stress, high-stress ratio, and long cyclic period generally reveal higher deformation and pore pressure. Meanwhile, the rectangular wave presents the largest contribution to plastic strain and pore pressure, followed by the trapezoidal and triangular waves, respectively, whereas the difference between the various waves decreased gradually with the increasing load level and cyclic period. The undisturbed specimens displayed lower deformations and pore pressures than the reconstructed specimens, whereas the differences are not significant when the confining stress is much higher than the structural yield stress. Furthermore, an empirical model for predicting the evolution of pore pressure is proposed and then validated against the experimental data in both this work and the literature.

scholarly journals Undrained Cyclic Laboratory Behavior of Sandy Soils

Geosciences ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 512 ◽  
Author(s):  
Francesco Castelli ◽  
Antonio Cavallaro ◽  
Salvatore Grasso ◽  
Valentina Lentini
Keyword(s):  
Cyclic Loading ◽  
Seismic Retrofitting ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Residual Performance ◽  
Definition Of

The complex cyclic shear stress path experienced by the soil during an earthquake, which could also induce liquefaction phenomena, can be approximated in the laboratory only by using sophisticated testing apparatuses. Cyclic triaxial tests have been widely used, especially for coarse grained soils, as in this study. In the framework of the design for the seismic retrofitting of the ‘‘Ritiro viaduct’’ foundations along the A20 motorway connecting Messina with Palermo (Italy), a soil liquefaction study was also carried out. With this aim, a detailed geological and geotechnical characterization of the area was performed by in situ and laboratory tests, including seismic dilatometer Marchetti tests (SDMTs), the combined resonant column (RCT) and cyclic loading torsional shear tests (CLTSTs), and undrained cyclic loading triaxial tests (CLTxTs). In particular, the paper presents the results of cyclic triaxial tests carried out on isotropically consolidated specimens of a sandy soil. The seismic retrofitting works include the reinforcement of the foundation and replacement of the decks with newly designed type and structural schemes, mixed steel, and concrete with continuous girder. During the investigation, data were acquired for the characterization of materials, for the definition of degradation phenomena with the relative identification of possible causes, and for the estimation of the residual performance characteristics of the building. The structural campaign of investigations necessary to determine all of the key parameters useful for a correct definition of the residual performance capabilities of the work was divided into two phases: One in situ and one in the laboratory.

Damping at Small Strains in Cyclic Simple Shear Test

1998 ◽  
Vol 124 (7) ◽  
pp. 585-594 ◽  
Author(s):  
Mladen Vucetic ◽  
Giuseppe Lanzo ◽  
Macan Doroudian
Keyword(s):  
Simple Shear ◽  
Shear Test ◽  
Simple Shear Test ◽  
Small Strains

scholarly journals Impact of Cyclic Loading on Shakedown in Cohesive Soils—Simple Hysteresis Loop Model

2020 ◽  
Vol 10 (6) ◽  
pp. 2029 ◽  
Author(s):  
Andrzej Głuchowski ◽  
Wojciech Sas
Keyword(s):  
Cyclic Loading ◽  
Hysteresis Loop ◽  
Permanent Deformation ◽  
Triaxial Tests ◽  
Engineering Practice ◽  
Cohesive Soils ◽  
Loop Model ◽  
Deformation Characteristics ◽  
Cyclic Triaxial ◽  
Permanent Strain

The objective of this study is to characterize the permanent deformations and to present a mathematical model that enables the prediction of permanent strain during cyclic loading. First, laboratory cyclic triaxial tests are conducted on sandy silty clay samples to gather the data concerning the permanent deformation characteristics. The article discusses the shakedown theory and abation phenomena, and we present the Simple Hysteresis Loop Model (SHLM) based on the stress-controlled test results. The determined permanent deformation properties are a base for the development of SHLM parameters. The presented model is capable of accurately predicting the permanent deformation characteristics based on the derived parameters from the static tests. The SHLM connects the stress–strain and stiffness properties of cohesive soil, which gives it a great advantage to use it in engineering practice. The derived model was verified based on ex–post comparison to performed cyclic triaxial test. The developed SHLM mean absolute percentage error is equal to 12.18%, which indicates that the developed SHLM has desirable accuracy in the prediction of permanent strain properties in compacted cohesive soils.

scholarly journals Air Filters for Ventilating Systems — Laboratory and in Situ Testing

1999 ◽  
Vol os-8 (2) ◽  
pp. 1558925099OS-80
Author(s):  
Jan Gustavvson
Keyword(s):  
Air Pollution ◽  
Laboratory Test ◽  
Indoor Air ◽  
Laboratory Tests ◽  
Test Methods ◽  
In Situ Testing ◽  
Air Filters ◽  
The Past ◽  
Real World Applications

Over the past few decades, many laboratory test methods have been developed to measure and characterize air filters using different synthetic dusts. Today, with concern about indoor air quality (IAQ) and air pollution on the rise, new standards are being developed to test the ability of air filters to remove particles in the laboratory as well as in situ. Still, laboratory tests that use coarse dusts can give very misleading results, and the rated efficiency for a filter can decrease dramatically in real-world applications. For better understanding and prevention of IAQ problems, test methods should be extended to include particle shape, type, and properties.

Deformation characteristics of two cemented calcareous soils

2004 ◽  
Vol 41 (6) ◽  
pp. 1139-1151 ◽  
Author(s):  
Shambhu S Sharma ◽  
Martin Fahey
Keyword(s):  
Cyclic Loading ◽  
Damping Ratio ◽  
Calcareous Soils ◽  
Confining Pressure ◽  
Stiffness Degradation ◽  
Triaxial Tests ◽  
Repeated Loading ◽  
Deformation Characteristics ◽  
Initial Stiffness ◽  
Strain Threshold

The effect of cementation on the deformation characteristics of two cemented calcareous soils was investigated through a series of undrained triaxial tests performed under both monotonic and cyclic loading conditions. Increasing the level of cementation significantly increased the initial stiffness, resulting in the stiffness being more independent of the confining pressure. The curves of stiffness degradation with strain obtained from both cemented and uncemented calcareous soils compared with those of other noncalcareous soils revealed that calcareous soil attains a faster rate of modulus reduction with a higher strain threshold. It was also observed that the pattern of stiffness degradation is very similar in both cemented and uncemented samples. The stiffness degradation curves obtained from cyclic tests were found to lie within the range defined by the corresponding monotonic tests. The effect of number of cycles on the stiffness during cyclic loading was also examined and is found to depend on whether the postyield behaviour is controlled by the cohesive or the frictional response. Examination of the variation of damping ratio with strain revealed that the observed difference in the stiffness degradation curves between calcareous and noncalcareous soils was also reflected in the damping ratio, with the damping ratio of calcareous soils being below the range defined for noncalcareous soils.Key words: calcareous soils, triaxial test, shear modulus, damping ratio, repeated loading.

Dynamics of Nanoparticle Chain Aggregates of Carbon Under Tension

2003 ◽  
Vol 778 ◽  
Author(s):  
Rajdip Bandyopadhyaya ◽  
Weizhi Rong ◽  
Yong J. Suh ◽  
Sheldon K. Friedlander
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Polymer Film ◽  
Elastic Behavior ◽  
Small Strains ◽  
Transmission Electron ◽  
Chain Aggregates ◽  
Nanoparticle Chains ◽  
Reinforcing Filler

AbstractCarbon black in the form of nanoparticle chains is used as a reinforcing filler in elastomers. However, the dynamics of the filler particles under tension and their role in the improvement of the mechanical properties of rubber are not well understood. We have studied experimentally the dynamics of isolated nanoparticle chain aggregates (NCAs) of carbon made by laser ablation, and also that of carbon black embedded in a polymer film. In situ studies of stretching and contraction of such chains in the transmission electron microscope (TEM) were conducted under different maximum values of strain. Stretching causes initially folded NCA to reorganize into a straight, taut configuration. Further stretching leads to either plastic deformation and breakage (at 37.4% strain) or to a partial elastic behavior of the chain at small strains (e.g. 2.3% strain). For all cases the chains were very flexible under tension. Similar reorientation and stretching was observed for carbon black chains embedded in a polymer film. Such flexible and elastic nature of NCAs point towards a possible mechanism of reinforcement of rubber by carbon black fillers.

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