Impact of Rainfall Variation on Slope Made of Expansive Yazoo Clay Soil in Mississippi

Nobahar, Masoud; Khan, Mohammad Sadik; Ivoke, John; Amini, Farshad

doi:10.1007/s40515-019-00083-w

Cited by 12 publications

(13 citation statements)

References 8 publications

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“…Nobahar et al [33] developed the Soil Water Retention Curve (SWRC) curve for the Yazoo clay soil in Mississippi, shown in Figure 3. Nobahar et al, 2019 developed the SWRC curve based on the filter paper method proposed by [32]. The Van Genuchten (1980) model is presented in Equations (1) and (2):…”

Section: Methodsmentioning

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: Methodsmentioning

confidence: 99%

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

2019

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“…The geometry of the slope is developed based on the existing borehole log and soil test results. The physical and engineering properties and characteristics of HPYCS were determined by lab testing [16,19]. Moreover, the FSSSs, as determined from the soil test results are utilized for the uppermost soil.…”

Section: Finite Element Modelingmentioning

confidence: 99%

“…Finite element flow analysis conducted by Nobahar et al [19] was utilized to evaluate the effect of rainfall on a slope constructed using HPYCS in Mississippi. During this study, representative HPYCS samples from a Mississippi highway slope were collected and tested.…”

Section: Finite Element Modelingmentioning

confidence: 99%

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Numerical Investigation of Slope Stabilization Using Recycled Plastic Pins in Yazoo Clay

2021

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Geographically, at the center of Mississippi is a concentration of High Plastic Yazoo Clay Soil (HPYCS). Shallow landslides frequently occur in embankments constructed with HPYCS caused by rainfall-induced saturation of the embankment slope. The traditional methods are becoming expensive to repair the shallow slope failure. The use of Recycled Plastic Pins (RPPs) to stabilize shallow slope failures offers a significant cost and construction benefit and can be a useful remedial measure for these types of failures. The current study investigates the effectiveness of RPP in slopes constructed with HPYCS, using the Finite Element Method (FEM). The FEM analysis was conducted with the PLAXIS 2D software package. Three uniform and varied RPP spacings were investigated to reinforce 2–4H:1V slopes. Reinforced slope stability analyses were performed to investigate the applicability of RPP in HPYCS. The FEM analysis results indicated that RPP provides shear resistance for the sloping embankment constructed of HPYCS. Uniform spacing of RPP provides sufficient resistance that increases the Factor of Safety (FS) to 1.68 in 2H:1V slopes with deformation of RPP less than 15 mm. The uniform spacing and varied spacing combination of RPP increase the FS to 2.0 with the deformation of RPP less 7 mm.

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“…Slope failure is widespread on highway slopes, which causes damage to the pavement and requires a significant maintenance budget each year. Rainfall-induced slope failures reportedly occur during or immediately following periods of intense or prolonged heavy rainfall onto fine-grained soil ( 6–15 ). The unsaturated state of the soil plays a significant role in protecting natural slopes from failure.…”

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confidence: 99%

Progressive Development of the Perched Water Zone in Highway Slopes Made of Highly Plastic Clay

Nobahar

Khan

Stroud³

et al. 2021

Transportation Research Record

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Based on National Oceanic and Atmospheric Administration data, after Hawaii and Louisiana, Mississippi is the rainiest state in the United States, having the most peak precipitation that occurs mainly in late winter. Development of perched water (DPW) has had a remarkable effect on the service life of highway slopes constructed on expansive clay. The objective of the current study is to map the DPW condition at highway slopes made of highly plastic clay (HPC) in Mississippi. Several highway slopes that are made of HPC in Jackson, MS, were instrumented using moisture sensors, water potential probes, and rain gauges. Based on the field investigations, it has been observed that a perched water condition exists in all the slopes constructed of Yazoo clay. To investigate the DPW condition and map the accumulation of the water within the slopes, a series of flow analyses have been conducted using the finite element method in Plaxis. The flow analysis is conducted considering the shrink/swell behavior of the Yazoo clay with the real-time rainfall events, as observed in the rain gauges. The numerical analysis was in good agreement with field monitoring results. Based on the analysis, it is observed that rainwater accumulated during the summer to fall season because of a high infiltration rate with the presence of desiccation cracks. On the other hand, the low permeability situation during the spring held the percolated water within the slopes. Repeated events of infiltration and water hold-up condition progressively develop the perched water zone in the slopes made of Yazoo clay.

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Impact of Rainfall Variation on Slope Made of Expansive Yazoo Clay Soil in Mississippi

Cited by 12 publications

References 8 publications

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

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

Numerical Investigation of Slope Stabilization Using Recycled Plastic Pins in Yazoo Clay

Progressive Development of the Perched Water Zone in Highway Slopes Made of Highly Plastic Clay

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