Laboratory testing and analysis of dynamic and static resilient modulus of subgrade soil under various influencing factors

Liu, Xiaolan; Zhang, Xianmin; Wang, Hao; Jiang, Baiyu

doi:10.1016/j.conbuildmat.2018.11.061

Cited by 58 publications

(14 citation statements)

References 14 publications

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“…To avoid no convergence when the deviator stress is dynamic, the minimum bulk stress was proposed as the factor in characterizing the confining effect and defined as the bulk stress under no deviator stress [5,25]. Meanwhile, to integrate the moisture-dependent factor, a developed predicted model of the Mr is displayed in equation (6), which incorporates the soil suction and minimum bulk stress into the MEPDG model.…”

Section: Developed Model Considering Moisturementioning

confidence: 99%

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Numerical Method of Flexible Pavement considering Moisture and Stress Sensitivity of Subgrade Soils

Zheng

Yao

et al. 2019

Advances in Civil Engineering

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Weaknesses of the subgrade structure induce the asphalt surface diseases and shorten the service life of flexible pavement. However, the resilient modulus (Mr) of subgrade soils is difficult to be evaluated directly since the subgrade is hidden and covered by the granular or asphalt layer. This study aimed to establish a numerical approach to predict the dynamic behavior of flexible pavements considering the stress sensitivity and moisture variation of subgrade soils. Firstly, 2D FEM simulations of flexible pavements were performed with half-sine loadings. A constitutive model of subgrade soils was proposed to incorporate soil suction and octahedral shear stress. It was validated using the laboratory triaxial test data of 3 selected soils. Then, the developed model was programmed by the user-defined material subroutine (UMAT) in the software ABAQUS. Subsequently, the validity of FEM model was verified by the laboratory tank model. Finally, the effect of moisture contents on the dynamic response of pavement structures was studied by tensile stress and vertical compressive strain. Results show that the surface deflection of the FEM model is similar to that of the actual pavement structure with the R2 of 98.44%. The developed UMAT program is reliable since the distribution of Mr in the FEM model is influenced by the stress and moisture condition of subgrade soils. When the moisture content is increased by 63%, the average Mr of subgrade soils is decreased by 18.7%. Meanwhile, the stiffness softening of subgrade soils increases vertical compressive strain at the top of the subgrade and the tensile stress at the bottom of the surface layer. It is interesting that the developed model can be applied to analyze the fatigue cracking of both subgrade and surface layers in the future.

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Section: Developed Model Considering Moisturementioning

confidence: 99%

“…e balanced moisture content of the subgrade is up to 71% higher than the maximum moisture content of the initial design in the south China area [5]. e stiffness of the subgrade decreases significantly and the deformation increases continuously due to the effect of humidity and cumulative load [6].…”

Section: Introductionmentioning

confidence: 95%

Numerical Method of Flexible Pavement considering Moisture and Stress Sensitivity of Subgrade Soils

Zheng

Yao

et al. 2019

Advances in Civil Engineering

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“…Last decade brought attention to cohesive soils tested in drained and undrained conditions. The test results have shown non-cohesive soils' different responses to cyclic loading [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Undrained Pore Pressure Development on Cohesive Soil in Triaxial Cyclic Loading

et al. 2019

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Cohesive soils subjected to cyclic loading in undrained conditions respond with pore pressure generation and plastic strain accumulation. The article focus on the pore pressure development of soils tested in isotropic and anisotropic consolidation conditions. Due to the consolidation differences, soil response to cyclic loading is also different. Analysis of the cyclic triaxial test results in terms of pore pressure development produces some indication of the relevant mechanisms at the particulate level. Test results show that the greater susceptibility to accumulate the plastic strain of cohesive soil during cyclic loading is connected with the pore pressure generation pattern. The value of excess pore pressure required to soil sample failure differs as a consequence of different consolidation pressure and anisotropic stress state. Effective stresses and pore pressures are the main factors that govern the soil behavior in undrained conditions. Therefore, the pore pressure generated in the first few cycles plays a key role in the accumulation of plastic strains and constitutes the major amount of excess pore water pressure. Soil samples consolidated in the anisotropic and isotropic stress state behave differently responding differently to cyclic loading. This difference may impact on test results analysis and hence may change the view on soil behavior. The results of tests on isotropically and anisotropically consolidated soil samples are discussed in this paper in order to point out the main features of the cohesive soil behavior.

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“…ere are many indexes, such as the liquid limit, plastic limit, CBR value, and compression index, for evaluating the improvement effect of high plasticity soils [5][6][7][8]. Additionally, the resilient modulus is a comprehensive property that can reflect the above indexes and is also a basic index for pavement design [21][22][23][24][25]. erefore, it is appropriate to use resilient modulus to evaluate the improvement effect of high plasticity soils [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Influence of Gradation on Resilient Modulus of High Plasticity Soil‐Gravel Mixture

Liu

Ren

Zhang

et al. 2020

Advances in Civil Engineering

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Because of low resilient modulus, high plasticity soil is often not allowed to fill road subgrades and is discarded as construction and demolition waste (CDW). To make use of the CDW, this study explored the possibility of improving high plasticity soil with gravel and examined the effect of gravel gradation on the resilient modulus of the soil-gravel mixture. A series of dynamic triaxial tests, tests of voids in coarse aggregate, and X-ray CT scans were carried out on high plasticity soil-gravel mixtures of different gravel contents and gravel gradation types. The test results show that there is a critical gravel content, that is, 44.1%. When the gravel content is less than 44.1%, the mixture shows a dense suspended structure and its modulus increases slowly with increasing gravel content. When the gravel content is greater than 44.1%, the mixture exhibits a dense skeleton structure and the modulus increases rapidly as the gravel content rises. Moreover, as the gravel gradation tends to the lower type, coarse aggregates increase in quantity and contact each other to form a dense skeleton; thus, the modulus increases accordingly. As the gravel gradation approaches the upper type, coarse aggregates decrease in quantity and tend to suspend in the soil, so the modulus decreases. With the increase in contact number, the skeleton structure is continuously improved, and thus the modulus is enhanced progressively. The results indicate that the gravel mixing method with a gravel content of 40%–45% can effectively improve high plasticity soil and shows great environmental and economic benefits.

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Laboratory testing and analysis of dynamic and static resilient modulus of subgrade soil under various influencing factors

Cited by 58 publications

References 14 publications

Numerical Method of Flexible Pavement considering Moisture and Stress Sensitivity of Subgrade Soils

Numerical Method of Flexible Pavement considering Moisture and Stress Sensitivity of Subgrade Soils

Undrained Pore Pressure Development on Cohesive Soil in Triaxial Cyclic Loading

Influence of Gradation on Resilient Modulus of High Plasticity Soil‐Gravel Mixture

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