scholarly journals Influence of Humidity State on Dynamic Resilient Modulus of Subgrade Soils: Considering Repeated Wetting-Drying Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Gongfeng Xin ◽  
Anshun Zhang ◽  
Zijian Wang ◽  
Quanjun Shen ◽  
Minghao Mu
Keyword(s):  
Resilient Modulus ◽  
Confining Pressure ◽  
Service Performance ◽  
Triaxial Tests ◽  
Road Engineering ◽  
Groundwater Level Fluctuations ◽  
Subgrade Soils ◽  
Deviator Stress ◽  
Complicated Conditions ◽  
Satisfactory Prediction

The service performance of subgrade depends on the dynamic resilient modulus (MR) of subgrade soils. Meanwhile, due to complicated conditions such as rainfall infiltration, high temperature evaporation, and groundwater level fluctuations, it can be safely said that the humidity state and repeated wetting-drying (WD) cycles affect the MR of subgrade soils. The object of this study is to conduct a series of dynamic triaxial tests after WD cycles to investigate the characteristics of the MR under various factors. The main results are as follows: (i) the MR decreased with the increase of deviator stress and rose with the growth of confining pressure; (ii) the humidification effect caused by the increase in moisture content attenuated the MR; (iii) the accumulation of WD cycles damaged the MR; however the decline rate was gradually retarded until it was stable with WD cycles 5 times; (iv) the satisfactory prediction model for the MR of subgrade soils considering WD cycles was proposed and verified. It is expected that the findings can provide valuable contributions for road engineering.

Soil behavior during freezing and thawing using variable and constant confining pressure triaxial tests

2001 ◽  
Vol 38 (4) ◽  
pp. 863-875 ◽  
Author(s):  
Erik Simonsen ◽  
Ulf Isacsson
Keyword(s):  
Resilient Modulus ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Soil Behavior ◽  
Freezing And Thawing ◽  
Mean Values ◽  
Freeze Thaw ◽  
Subgrade Soils ◽  
Thaw Cycle ◽  
Significant Difference

Although variable confining pressure (VCP) triaxial tests are generally preferred to constant confining pressure (CCP) triaxial tests due to the more realistic stress application, VCP tests have never been utilized when investigating freeze–thaw effects on unbound road materials. In this study, three soils were investigated for resilient behavior during freezing and thawing utilizing both VCP and CCP triaxial testing. The soils were tested at selected temperatures between +20 and –10°C during one full freeze–thaw cycle. The results were analyzed in terms of the traditionally used resilient modulus and Poisson's ratio, as well as volumetric and shear components, and indicate a significant difference in moduli computed from CCP and VCP data. However, resilient moduli display compatible values when interpreted in terms of mean values of deviator stress and mean normal stress. With regard to freezevthaw effects on resilient moduli, the results are inconsistent with previous findings. However, this can be explained by the different test conditions applied.Key words: freeze–thaw, triaxial tests, unbound pavement materials, subgrade soils, resilient modulus.

scholarly journals Resilient modulus and cumulative plastic strain of frozen silty clay under dynamic aircraft loading

2021 ◽  
Vol 3 (10) ◽  
Author(s):  
Xiaolan Liu ◽  
Xianmin Zhang ◽  
Xiaojiang Wang
Keyword(s):  
Plastic Strain ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Research Findings ◽  
Cumulative Plastic Strain ◽  
Construction Operation ◽  
Compaction Degree

AbstractThis paper describes an investigation into the factors influencing the resilient modulus and cumulative plastic strain of frozen silty clay. A series of dynamic triaxial tests are conducted to analyze the influence of the temperature, confining pressure, frequency, and compaction degree on the resilient modulus and cumulative plastic strain of frozen silty clay samples. The results show that when the temperature is below − 5 °C, the resilient modulus decreases linearly, whereas when the temperature is above − 5 °C, the resilient modulus decreases according to a power function. The resilient modulus increases logarithmically when the frequency is less than 2 Hz and increases linearly once the frequency exceeds 2 Hz. The resilient modulus increases as the confining pressure and compaction degree increase. The cumulative plastic strain decreases as the temperature decreases and as the confining pressure, frequency, and compaction degree increase. The research findings provide valuable information for the design, construction, operation, maintenance, safety, and management of airport engineering in frozen soil regions.

scholarly journals Experimental Study on Dynamic Resilient Modulus of Lime-Treated Expansive Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zheng Lu ◽  
Yang Zhao ◽  
Shaohua Xian ◽  
Hailin Yao
Keyword(s):  
Moisture Content ◽  
Environmental Changes ◽  
Resilient Modulus ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
The Stability ◽  
Compaction Degree

Dynamic resilient modulus is the design index of highway subgrade design code in China, which is significantly affected by the traffic loads and environmental changes. In this study, dynamic triaxial tests were conducted to investigate the influence of moisture content, compaction degree, cyclic deviator stress, and confining pressure on lime-treated expansive soil. The suitability of UT-Austin model to lime-treated expansive soils was verified. The results indicate that the dynamic resilient modulus of lime-treated expansive soils increases nonlinearly with the increase of compaction degree, while decreases nonlinearly with the increase of dynamic stress level. The dynamic resilient modulus decreases linearly with the increase of moisture content and increases linearly with the increase of confining pressure. Moreover, the moisture content has a more significant effect on the dynamic resilient modulus of lime-treated expansive soil. Therefore, it is necessary to ensure the stability of soil humidity state and its excellent mechanical properties under long-term cyclic loading for the course of subgrade filling and service. Finally, the calculated results of the UT-Austin model for dynamic resilient modulus show a good agreement with the test results.

Study on Prediction Model of Dynamic Resilient Modulus of Cohesive Subgrade Soils Considering Moisture Variation

2014 ◽  
Vol 488-489 ◽  
pp. 411-416 ◽  
Author(s):  
Zhi Yong Li ◽  
Jing Rong Zou ◽  
Cheng Dong
Keyword(s):  
Moisture Content ◽  
Prediction Model ◽  
Filter Paper ◽  
Resilient Modulus ◽  
Subgrade Soils ◽  
Deviator Stress ◽  
Filter Paper Method ◽  
Bulk Stress ◽  
Effect Of Moisture ◽  
Paper Method

The matric suctions were measured by the filter paper method, and the parameters of soil-water characteristic curve were obtained. In order to investigate the effect of moisture content on cohesive subgrade soils dynamic resilient modulus, a series of dynamic-triaxial test were carried out. Based on the matric suctions measured by the filter paper method, the relationship between dynamic resilient modulus and matric suctions were analyzed. The study demonstrated that the dynamic resilient modulus values decrease with the increase of circular deviator stress and moisture content, in reverse of matric suctions. Considering that the dynamic resilient modulus is a function of deviator stress and bulk stress, based on the present three parameters compound constitutive model which reflects the effect of bulk stress and deviator stress, the effect of matric suctions which could indirectly reflect the effect of moisture content was introduced. And then the prediction model incorporating the effect of stress and moisture for cohesive subgrade soils was established. The model was utilized for experimental data regression analysis, a high coefficient of determination shows that the model is accurate and credible. The prediction models not only can evaluate the long-term performance of subgrade soil in Southern China's rainy areas, but also can provide parameters for the pavement design based on dynamic method.

Effects of inclusion contents on resilient modulus and damping ratio of unsaturated track-bed materials

2017 ◽  
Vol 54 (12) ◽  
pp. 1672-1681 ◽  
Author(s):  
Han-Lin Wang ◽  
Yu-Jun Cui ◽  
Francisco Lamas-Lopez ◽  
Jean-Claude Dupla ◽  
Jean Canou ◽  
...  
Keyword(s):  
Resilient Modulus ◽  
Damping Ratio ◽  
Triaxial Tests ◽  
Dynamic Parameters ◽  
Subgrade Soils ◽  
In Situ Investigation ◽  
Coarse Grains ◽  
The Matrix ◽  
Variation Rate ◽  
Number Of Cycles

For the French conventional railway lines, a layer, namely interlayer, was created in the substructure mainly by the interpenetration of ballast grains and subgrade soils. The in situ investigation indicated that the content of coarse grains decreases over depth. In this study, the resilient modulus and damping ratio of the unsaturated lower part of the interlayer soil were investigated at six different volumetric inclusion contents fv (volumetric ratio of dry coarse grains to the whole sample) by carrying out cyclic triaxial tests following a multi-step loading procedure. The results show that the two dynamic parameters (resilient modulus and damping ratio) change significantly at the beginning of loading and the variation rate decreases as the number of cycles increases. Besides, a mean characteristic volumetric inclusion content fv–cha ranging from 27.8% to 28.9% was identified, separating two zones with different inclusion effects. To verify this observation, X-ray microcomputed tomography (μCT) scans were conducted on as-compacted samples. The results obtained strongly support the existence of fv–cha: when fv ≤ fv–cha, the matrix of fines constitutes the skeleton of the sample with inclusions floating in it, leading to slight changes of the two dynamic parameters with fv. By contrast, when fv > fv–cha, the inclusions dominate the skeleton of the sample, giving rise to significant changes of the two dynamic parameters with fv.

Study on Static Strength of Aeolian Sand before and after Cyclic Loading

2014 ◽  
Vol 580-583 ◽  
pp. 191-194
Author(s):  
Da Peng Liu ◽  
Xiao Hua Yang ◽  
Jing Wang ◽  
Zheng Jun Mao
Keyword(s):  
Cyclic Loading ◽  
Confining Pressure ◽  
Static Strength ◽  
Triaxial Tests ◽  
Aeolian Sand ◽  
Desert Region ◽  
Deviator Stress ◽  
Before And After ◽  
The Stability ◽  
Engineering Practices

Aeolian sand is one commonly used subgrade filling in Xinjiang Oasis-desert region, engineering practices also proved its applicability as subgrade filling. In order to find the law of Aeolian sand subgrade static strength after cyclic loading, the paper studied the static strength of Aeolian sand before and after cyclic loading through the dynamic and static triaxial tests. It is concluded that the greater cyclic loading is, the more Aeolian sand static strength peak decreases. When cyclic loading is small, the bigger confining pressure and consolidation ratio are, the static strength peak increases more after cyclic loading. The bigger initial static deviator stress is, the more Aeolian sand static strength peak reduces. The frequency of cyclic loading has little effect on static strength. In order to keep the stability of low embankment, we should restrict overload , ensure subgrade and foundation consolidation adequately, at the same time using gravel or geosynthetic materials to package edge of roadbed, so as to increase confining pressure. The research results can provide reference for the design and construction of Aeolian sand low subgrade in Xinjiang Oasis-desert region.

Characterization of granular materials for pavements

1989 ◽  
Vol 26 (4) ◽  
pp. 725-730 ◽  
Author(s):  
A. Nataatmadja ◽  
A. K. Parkin
Keyword(s):  
Granular Materials ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Elastic Model ◽  
Deviator Stress ◽  
Repeated Load Triaxial Test ◽  
Materials Modelling ◽  
Repeated Load ◽  
Repeated Load Triaxial

For design and analysis of flexible pavements, a simple elastic model that does not require cumbersome calculation and also can rank materials according to their performance is clearly desirable. Early studies indicated that the resilient modulus of a granular material can be taken to be a function of the first invariant of stress, θ, although there is evidence that it is also dependent on the repeated deviator stress, qr. The limitations of some earlier models are discussed herein and a simple model for granular materials is proposed. The model is empirical in nature and based on repeated load triaxial testing with constant confining pressure. The application of this model in situations where the confining pressure is pulsed in phase with the deviator stress is also discussed. Key words: repeated load, triaxial test, resilient modulus, granular materials, modelling, pavement.

scholarly journals A Methodology for Determination of Resilient Modulus of Asphaltic Concrete

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
A. Patel ◽  
M. P. Kulkarni ◽  
S. D. Gumaste ◽  
P. P. Bartake ◽  
K. V. K. Rao ◽  
...  
Keyword(s):  
Resilient Modulus ◽  
Triaxial Tests ◽  
Asphaltic Concrete ◽  
Empirical Relationships ◽  
Cyclic Triaxial Tests ◽  
Electronic Circuitry ◽  
Quality Check ◽  
R Value ◽  
Vast Variation

Resilient modulus, , is an important parameter for designing pavements. However, its determination by resorting to cyclic triaxial tests is tedious and time consuming. Moreover, empirical relationships, correlating to various other material properties (namely, California Bearing Ratio, CBR; Limerock Bearing Ratio, LBR; R-value and the Soil Support Value, SSV), give vast variation in the estimated results. With this in view, an electronic circuitry, which employs bender and extender elements (i.e., piezo-ceramic elements), was developed. Details of the circuitry and the testing methodology adopted for this purpose are presented in this paper. This methodology helps in determining the resilient modulus of the material quite precisely. Further, it is believed that this methodology would be quite useful to engineers and technologists for conducting quality check of the pavements, quite rapidly and easily.

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