Investigation of a shallow slope failure on expansive clay in Texas

Khan, Mohammad Sadik; Hossain, Sahadat; Ahmed, Asif; Faysal, Mohammad

doi:10.1016/j.enggeo.2016.10.004

Cited by 118 publications

(48 citation statements)

References 11 publications

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“…During the dry period, the highly plastic clay soil developed desiccation cracks, which might have significantly increased the permeability vertically at the active zone. However, due to the desiccation crack, the permeability in the horizontal direction might not have any effect and could have remained unchanged [44][45][46]. The Yazoo clay usually has significant cracks, which have been observed in the laboratory as well as in the field.…”

Section: Effect Of Rainfall On Slope Failurementioning

confidence: 99%

Coupled Effect of Wet-Dry Cycles and Rainfall on Highway Slope Made of Yazoo Clay

2019

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Expansive Yazoo clay soil is susceptible to volumetric deformation and is dominant in central Mississippi and other neighboring southern states of the United States. Recurring shrink-swell behavior causes a significant problem to infrastructures in the area. Although Yazoo clay causes a significant problem in the deep southern states, limited study has been conducted on the behavior of Yazoo clay, especially in the presence of rainfall. The objective of this current study is to investigate the coupled effect of changes in void ratio due to wet-dry cycles and rainfall on the stability of highway slopes made of Yazoo clay. The finite element method in Plaxis 2D by Bentley System (https://www.plaxis.com/) has been utilized to investigate the coupled effect of changes in mechanical properties and rainfall using flow-deformation and stability analysis. Reconstituted expansive clay soil samples were used for the laboratory experiment. The reconstituted Yazoo clay samples were subjected to 3, 5, and 7 wetting and drying cycles in an enclosed chamber for a 24-h period. The axial deformation of the samples and the change in void ratios at each number of the cycle was closely monitored. The strength change at each wet and dry cycle was also investigated and used for slope stability analysis in the presence of rainfall. The test results indicate that the void ratio increases with the increasing number of wet-dry cycles. A continuous increment in void ratios from 0.99 in an undisturbed state with no wet-dry cycle to 1.49 at the 7th wet-dry cycle, indicating a 48.9% increase, as the wetting and drying cycle increases was recorded; in turn, decreasing the cohesion of the soil by 77%. The factor of safety considering the effect of two total rainfall periods of Rv = 126.2 mm (2 h) and Rv = 271.7 mm (3 days) reduced from 1.7 to 1.2 and 1.68 to 1.02, considering the effect of the 7th wet-dry cycle at the topsoil. The changes in the void ratio due to the wetting and drying cycle of Yazoo clay soil reduces the shear strength to a fully softened condition, increasing the possibility of slope failure. This condition further worsens in the presence of a perched water condition due to the infiltration of rain water.

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Section: Effect Of Rainfall On Slope Failurementioning

confidence: 99%

Coupled Effect of Wet-Dry Cycles and Rainfall on Highway Slope Made of Yazoo Clay

2019

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“…Based on the Geologic Atlas Map of Texas, North Texas consists of sedimentary rock with smectite clay minerals and sulfates [6]. Researchers reported overburden residual soils linked with this formation usually consist of clay having high plasticity indices [19][20][21].…”

Section: Subsurface Resultsmentioning

confidence: 99%

“…The generated model could find its application in predicting pavement deformation with respect to rainfall at any time of the year.Geosciences 2019, 9, 446 2 of 22 high plasticity [5]. These characteristics impart high swelling and shrinkage with moisture gain and dissipation, respectively, in such soil [6]. A significant amount of montmorillonite is reported in mid-zone of the USA [7].…”

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confidence: 99%

“…Research by References [8] and [9] reported the presence of montmorillonite clayey soil in Dallas -Fort Worth area. This results in the volume expansion in wet season and shrinkage in dry season [6].Volume change phenomenon in the expansive clayey subgrade leads to distresses in the pavement. The distresses are released in the form of cracking, heaving, and settlement of the pavement [1].…”

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Deformation Modeling of Flexible Pavement in Expansive Subgrade in Texas

et al. 2019

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The tendency of expansive subgrade soil to undergo swelling and shrinkage with the change in moisture has a significant impact on the performance of the pavement. The repeated cycles of wet and dry periods throughout a year lead to considerable stress concentration in the pavement subgrade soil. Such stress concentrations leads to the formation of severe pavement cracks. The objective of the research is to develop a prediction model to estimate the deformation of pavement over expansive subgrade. Two pavement sites—one farm to market road and one state highway—were monitored regularly using moisture and temperature sensors along with rain gauges. Additionally, geophysical testing was performed to obtain a continuous profile of the subgrade soil over time. Topographical surveying and horizontal inclinometer readings were taken to determine pavement deformation. The field monitoring data resulted in a maximum movement up to 80 mm in the farm to market road, and almost 38 mm in the state highway. The field data were statistically evaluated to develop a deformation prediction model. The validation of the model indicated that only a fraction of the deformation was reflected by seasonal variation, while inclusion of rainfall events in the equation significantly improved the model. Furthermore, the prediction model also incorporated the effects of change in temperature and resistivity values. The generated model could find its application in predicting pavement deformation with respect to rainfall at any time of the year.

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