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.

DEGRADATION EFFECT OF SEAWATER ON THE LONG-TERM DYNAMIC BEHAVIOR OF ARTIFICIALLY CEMENTED SAND

2013 ◽  
Vol 07 (04) ◽  
pp. 1350031 ◽  
Author(s):  
BO LI ◽  
YUANQIANG CAI ◽  
XIANGWU ZENG ◽  
LINYOU PAN
Keyword(s):  
Shear Modulus ◽  
Dynamic Behavior ◽  
Tap Water ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Resonant Column ◽  
Cyclic Triaxial Tests ◽  
Cemented Sand

The dynamic behavior of lightly cemented sand under long-term seawater attack was evaluated in this study. Resonant column and cyclic triaxial tests were employed to investigate the evolution of the shear modulus and damping ratio of cemented sand with respect to soaking period (SP), confining pressure, and cement content (CC). The results of this study show that the cementation of the sand is affected by soaking in seawater to a greater extent than by soaking in tap water. The shear modulus of the cemented sand soaked in seawater was smaller than that of the cemented sand soaked in tap water. The damping ratio increased significantly, as the SP increased and was greater for the cemented sand soaked in seawater than for the cemented sand soaked in tap water. The dynamic behavior of nonhomogenous specimens was examined. Crystallization of salts could be clearly observed and probably explains the evolution of the dynamic behavior of the cemented sand. Finally, the shear modulus was fitted using Rollins' Law [Rollins et al., 1998], which demonstrates that the parameters used in the equation can be reasonably fitted linearly over a range of SPs.

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 Laboratory Characterization of a Compacted–Unsaturated Silty Sand with Special Attention to Dynamic Behavior

2020 ◽  
Vol 10 (7) ◽  
pp. 2559
Author(s):  
Andrzej Głuchowski ◽  
Zdzisław Skutnik ◽  
Marcin Biliniak ◽  
Wojciech Sas ◽  
Diego Lo Presti
Keyword(s):  
Shear Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Bender Element ◽  
State Dependent ◽  
Laboratory Characterization ◽  
Dynamic Excitations

The dynamic properties of compacted non-cohesive soils are desired not only because of the risk of natural sources of dynamic excitations such as earthquakes, but mostly because of the anthropogenic impact of machines that are working on such soils. These soils are often unsaturated, which positively affects the soil’s mechanical properties. The information about the values of these parameters is highly desirable for engineers. In this article, we performed a series of tests, including oedometric tests, resonant column tests, bender element tests, and unsaturated triaxial tests, to evaluate those characteristic parameters. The results showed that sandy silt soil has a typical reaction to dynamic loading in terms of shear modulus degradation and the damping ratio curves’ characteristics, which can be modeled by using empirical equations. We found that the compaction procedure caused an over-consolidation state dependent on the moisture content during compaction effort. The article analyzed the soil properties that impact the maximum shear modulus G0 value. Those properties were suction s, confining pressure σ3, and compaction degree represented by the void ratio function f(e).

scholarly journals Effect of Sand Fouling on the Dynamic Properties and Volume Change of Gravel During Cyclic Loadings

2020 ◽  
Author(s):  
Meysam Bayat
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Dynamic Behavior ◽  
Volume Change ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Practical Applications ◽  
Large Shear Strain

Understanding the factors that influence the dynamic behavior of granular soils during cyclic loading is critical to infrastructure design. Previous research has lacked quantitative study of the effects of fouling index (FI), mean effective confining pressure, relative density, shear strain level and anisotropic consolidation, especially when the effective vertical stress is lower than the effective horizontal stress on the dynamic behavior of gravelly soils. The objective of the present study was to evaluate the dynamic behavior and volume change of both clean and fouled specimens for practical applications. To this end, cyclic triaxial tests with local strain measurements under both isotropic and anisotropic confining conditions were conducted. It is found that the fouled specimen with 50 % sand (i.e. the specimen which contains 50 % gravel and 50 % sand) has the highest shear modulus at low shear strain levels and the largest volume reduction and damping ratio at large shear strain levels. The results of tests indicate that the effect of fouling index on the shear modulus is reduced at large shear strain levels. Volumetric contraction due to the increase in mean effective confining pressure is more significant at large shear strain levels. The results also indicate that the stiffness of the specimens under anisotropic compression mode are larger than those in extension or isotropic mode.

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.

scholarly journals Effect of High-Stress Equal Amplitude Cyclic Loading on Mechanical and Deformation Characteristics of Rubber Concrete

2019 ◽  
Vol 3 (5) ◽  
Author(s):  
Xin Huang ◽  
Yu Chen
Keyword(s):  
Cyclic Loading ◽  
High Stress ◽  
Peak Stress ◽  
Repeated Loading ◽  
Peak Strain ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Degradation Degree ◽  
Rubber Concrete ◽  
Equal Amplitude

In order to study the mechanical and deformation characteristics of rubber concrete under repeated loading, 50 cycles of high-stress equal amplitude cyclic loading and uniaxial compression tests were carried out on 30 concrete specimens of 5 groups. The change of uniaxial mechanical properties and the deformation during cyclic loading of normal concrete (NC) and rubber concrete (RC) with 5%, 10%, 15%, and 20% content were analysed. The results show that the peak stress and modulus of elasticity decrease and the peak strain increases with the increase of rubber content. After cyclic loading, the degradation degree of NC peak stress and elastic modulus reached 11.0% and 36.8% respectively. This study can provide a basis for the application of rubber concrete.

Stability threshold for cyclic loading of saturated clay

1989 ◽  
Vol 26 (1) ◽  
pp. 122-131 ◽  
Author(s):  
Guy Lefebvre ◽  
Denis LeBoeuf ◽  
Benoît Demers
Keyword(s):  
Shear Strength ◽  
Cyclic Loading ◽  
Strain Rate ◽  
Undrained Shear Strength ◽  
Triaxial Tests ◽  
Repeated Loading ◽  
Loading Test ◽  
Stability Threshold ◽  
The Stability ◽  
Undrained Shear

This paper presents the results of an experimental investigation performed to study the stability threshold under cyclic (repeated) loading, and the postcyclic static strength of a sensitive clay from the Hudson Bay region. The strain rate and structure effects were also studied by carrying out monotonic and cyclic triaxial tests at both slow and rapid strain rates or frequencies, and at confining pressures above and below the apparent preconsolidation pressure. The stability threshold for both structured and normally consolidated Grande Baleine clay is about 60–65% of the original undrained shear strength measured at the same strain rate as that used in the repeated loading test. The undrained shear strength and the failure envelope remain essentially unchanged if the repeated preloading is kept below the threshold. The clay structure remains unaltered by this preloading. Key words: clay, stability threshold, cyclic loading, earthquake, postcyclic strength.

scholarly journals Dynamic Properties of Sand-Sawdust Mixture for Modeling Deposit Soil

2019 ◽  
Vol 9 (18) ◽  
pp. 3863
Author(s):  
Pan ◽  
Li ◽  
Lu ◽  
Chen
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Shaking Table Test ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Strain Range ◽  
Confining Pressure ◽  
Shaking Table ◽  
Triaxial Tests ◽  
Hysteresis Curve

Soil mixtures with various materials such as scraps of rubber tire, iron powder, and synthetic fibers have been widely used in civil engineering for experimental research or infrastructure construction and maintenance. However, these materials are not only expensive, but may also result in environmental concerns. In recent years, sawdust, because of its light-weight, inexpensive, and environmental friendly characteristics, has frequently been used in the shaking table test to adjust the dynamic properties of experimental soil. However, the dynamic properties of a sand-sawdust mixture for the shaking table test are still unclear. In this paper, the dynamic properties and the hysteresis curve characteristics of the sand-sawdust mixture as well as the influence of the sawdust content and confining pressure on the dynamic properties were studied using a series of consolidated drained dynamic triaxial tests. The test results show that, with the increase of the shear strain, the shape of the hysteresis loops changes from symmetrical willow-leaf to asymmetry sharp-leaf. For a given confining pressure, both the shear modulus and damping ratio decreases as the sawdust percentage increases. It was observed that, with an increase in confining pressure, the shear modulus increased while the damping ratio decreased slightly in the shear strain range of 10−3 to 7×10−3. It was also observed that the maximum shear modulus increased as the confining pressure increased, while the maximum damping ratio remained nearly constant. In addition, both the maximum shear modulus and the maximum damping ratio decreased as the sawdust content increased. Finally, the normalized shear modulus and damping ratio were established, which can be used in simulations using the shaking table test.

Experimental Study on Dynamic Characteristics of Tailings

2014 ◽  
Vol 580-583 ◽  
pp. 455-459
Author(s):  
Jian Bin Zhao ◽  
Ying Chun Ji ◽  
Xiao Liu ◽  
Di Li
Keyword(s):  
Elastic Modulus ◽  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Coarse Grain ◽  
Test Results ◽  
Cyclic Triaxial Tests ◽  
Copper Tailings ◽  
Fine Grain

In this paper, the dynamic characteristics for three different kinds of copper tailings are studied through a series of cyclic triaxial tests. It is found that under confining pressure 200 and 300 kPa, elastic modulus raises with the increasement of coarse grain content to a certain degree and then declines, and the maximum elastic modulus corresponds to good gradation. While, as for confining pressure 100 kPa, elastic modulus raises with the increasement of fine grain content. It is also found that elastic modulus raises with the increasement of confning pressure. And, damping ratio raises with the increasement of shear strain and finally to a stable value. Finally, the fitting Gd/Gdmax~ curve for three kinds of tailings shows the reasonableness of test results.

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.

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