Experimental Evaluation of Lateral Swelling Pressure of Expansive Soil Fill behind a Retaining Wall

Advances in Materials Science and Engineering

et al. 2021

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Evaluation of swelling behavior is important for designing structures in expansive soils areas, especially for highway that the swelling pressure generated upon pavement and retaining structures in both vertical and horizontal directions due to infiltration. In this study, modification was made on unsaturated consolidation oedometer to provide synchronized measurement of vertical swelling strain (VSS) and lateral pressure (LP) of expansive soil under constant net normal stress and controlled matric suction. Vertical swelling (VS) test and lateral swelling (LS) test were conducted to investigate the anisotropic swelling behavior. The influence of mean net stress and net stress ratio on VSS was investigated, and the anisotropic swelling behavior of unsaturated expansive soil was characterized using anisotropic swelling ratio. The results show that the VSS nonlinearly decreased as the mean net stress increased and increased as the net stress ratio increased. The expansive soil would rapidly enter the passive state due to lateral swelling pressure under relatively low surcharge, with major principal axis rotating from vertical direction to lateral direction, which advances the possibility of passive failure for light retaining structures. The anisotropic swelling behavior objectively exists and varies with matric suction and net normal stress, which should not be ignored for engineering application.

Section: Calibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Study on Swelling Behavior and Its Anisotropic Evaluation of Unsaturated Expansive Soil

Advances in Materials Science and Engineering

et al. 2021

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“…e gravel used in this study was taken from Danzhou City, Hainan Province, China. Its basic physical properties are as follows: density � 2.06 g/cm 3 , gravel (>4.75 mm) content � 57%, sand (0.075-4.75 mm) content � 41.9%, and silt and clay (<0.075 mm) content � 1.1%.…”

Section: Gravelmentioning

confidence: 99%

“…When high plasticity soil is directly used to fill road subgrades, the resilient modulus often could not satisfy the minimum requirement for pavement design [1,2]. us, high plasticity soil is generally not a qualified subgrade filler and should be discarded as construction and demolition waste (CDW) [3]. However, this would cause high construction costs and go against environmental protections.…”

Section: Introductionmentioning

confidence: 99%

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

Ren

Advances in Civil Engineering

et al. 2020

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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.

“…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

Advances in Civil Engineering

Zeng

et al. 2020

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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.