Prediction of permanent deformation for subgrade soils under traffic loading in Southern China

Self Cite

To better control the strength and deformation of the roadbed, a constitutive model of rockfill was established based on property-dependent plastic potential theory for geomaterials. The effect of the particle gradation on the anisotropy was described in the model. According to the effect of the particle grading and crushing on the fractal dimension, the fractal theory and fabric tensor were introduced to establish the yield and failure criteria of the rockfill. By combining the property-dependent concepts of the materials and the results of the rockfill strength test, a critical state line considering the microstructure, fractal dimension, particle breakage, and stress state of the rockfill was established. The dilatancy equation was derived based on the novel potential theory and the hardening criterion affected by the critical state was established. A constitutive model of the rockfill in the general stress space was established under the framework of the novel potential theory. The 3D strength and its intensity change in the π plane were simulated through the drainage strength test results, which verified the description of the critical state under various stress paths. By simulating the stress-strain relationship, the validity and rationality of the model were verified.

“…When g(− π/6) was equal to c, g(π/6) was equal to 1. M f is the peak failure stress ratio, which stands for equation (8) with the peak internal friction angle φ f :…”

Section: Yield Surfacementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Constitutive Model of Rockfill Based on Property‐Dependent Plastic Potential Theory for Geomaterials

Zhang

et al. 2020

Self Cite

“…where N is the loading number, ε a is the axial strain after N times of repeated loading, σ d is the dynamic deviator stress, σ f is the static failure stress, and a 1 and a 2 are the coefficients. Zhang et al [23] developed an improved deformation model considering the origin octahedral shear stress, as shown in the following equation:…”

Section: Prediction Equation Of the Deformation Behaviour For The Vvcmmentioning

confidence: 99%

“…Saberian et al [20] investigated the permanent deformation of unbound granular materials with crumb rubber and crushed glass. Zhang et al [21][22][23] established a series of improved prediction models to evaluate the permanent deformation and resilient modulus for highway subgrade soils, and revealed the effect of compaction, matric suction, and traffic loads. ese require a proper understanding of the deformation behaviour under various influencing factors such as loading conditions (e.g., loading stress, loading time, and confining pressure), aggregate gradation, and compaction density.…”

Section: Introductionmentioning

confidence: 99%

Combined Effect of Compaction Methods and Loading Conditions on the Deformation Behaviour of Unbound Granular Material

Ren

Wang

2020

Unbound granular material is an important construction material that is used for flexible pavement. As one of the most important indices used for describing the properties of unbound granular material, the deformation characteristic is significantly influenced by the compaction method used. However, the effects of the compaction method on the deformation behaviour are neglected in the existing studies. Hence, we investigate the deformation characteristics of unbound granular material produced by the vertical vibration compaction method (VVCM) and the modified Proctor compaction method (MPCM) via repeated triaxial load tests and reveal the effect of loading conditions and aggregate gradations. The results show that (a) the deformation of unbound granular material decreases as the stress level and confining pressure are increased; (b) the deformation resistance of unbound granular material produced by the VVCM is superior to that produced by the MPCM; (c) the difference of deformation resistance arising between using the VVCM and MPCM decreases as confining pressure increases and is not significant with changes in the stress level; (d) the extent of various factors on deformation characteristics from greatest to least is as follows: stress level > aggregate gradation > compaction method > confining pressure; and (e) increasing the content of coarse aggregates is conducive to enhancing the deformation resistance of unbound granular material, particularly for the VVCM. Finally, a simple approach for modelling and predicting deformation is established.

“…en, the moisture will migrate between the existing and new embankment owing to their moisture content difference. is is helpful to a series of performance deteriorations of the new embankment, such as a loss of the structural bearing capacity [8,9], an increase of lateral pressure [10], a reduction of the resilient modulus [11,12], and an increase of permanent deformation [13,14]. erefore, it is extremely important to reveal the moisture migration process between the existing and new embankment.…”

Section: Introductionmentioning

confidence: 99%

Moisture Migration and Control of New Embankment for Reconstruction and Expansion Project in Southern China

Zhang

Zeng

et al. 2020

Self Cite

In hot and humid regions of southern China, the volumetric moisture content of the embankment after opening to traffic for a period of time reaches a stable state, and it is higher than the design value. When it was widened, the humidity gradient and exchange were formed due to the difference in moisture content between the existing and new embankment. To reveal the moisture migration of the existing and new embankment and control the rise of volumetric moisture content in new embankment, six frequency domain reflectometry sensors were installed in existing and new embankment to monitor the volumetric moisture content. A finite element model for the embankment was established and verified with the measured data. And seven numerical analyses of transient seepage in the new embankment of the cushion, cover, and partition using capillary barrier by sand were simulated. The results show that the volumetric moisture contents of the new embankment in southern China gradually increase and eventually reach an equilibrium state. The increase in water comes from the slope, the foundation, and the existing embankment. Early in the first 1∼2 years, the water mainly comes from the foundation and the existing embankment. After that, as time goes by, the water comes mostly from the slope infiltration and gradually migrates to the foundation and the existing embankment. Finally, the volumetric moisture content and the water storage gradually reach equilibrium. The volumetric moisture content of the new embankment using capillary barrier by sand at the cushion, the cover, and the partition is maintained as the construction volumetric moisture content. This combination is a very effective method to control the humidity stability of the new embankment in southern China.