Combined Effect of Rainfall and Shear Strength on the Stability of Highway Embankments Made of Yazoo Clay in Mississippi

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

doi:10.1007/s10706-020-01187-8

Cited by 16 publications

(9 citation statements)

References 26 publications

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“…According to the test results, it can be concluded that the slope after the seventh WDC (4.31 kPa and frictional angle of 18.42 deg) experiences its first-time slide. Furthermore, according to the shear strength test results, Nobahar et al [17] investigated the change in shear strength of HPYCS, and from the peak, FSSS, and the residual tests, the Mohr-Coulomb failure envelop was developed. It was observed that the peak shear strength test (c = 18.4 kPa and phi = 20.2 degrees) resulted in the highest shear strength, whereas the residual shear strength test (c = 5.45 kPa and phi = 12.8 degrees) resulted in the lowest shear strength.…”

Section: Site Locationmentioning

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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Section: Site Locationmentioning

confidence: 99%

“…The hydraulic model was selected to be the Van Genuchten model. The HPYCS Water Retention Curve (SWRC) curve was developed by Nobahar et al [17] in Mississippi. During the numerical analysis, the Van Genuchten fitting parameters of the HPYCS were employed.…”

Section: Finite Element Modelingmentioning

confidence: 99%

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

2021

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“…In recent decades, greater emphasis has been placed on the micro-and mesostructural levels. Several studies have reported that the shear strength of the expansive soil primarily depends on the original cracks and weak structural plane (Mehta and Sachan 2017;Nobahar et al 2020;Ye et al 2010). The research on the meso-crack properties of expansive soils is more focused on the evolution of the geometrical natures and fractal characteristics in the drying phase (DeCarlo and Shokri 2014;Peron et al 2009;Tang et al 2008), but there are few reports on the meso-crack characteristics under repeated WD cycles (Huang et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Shear strength and damage characteristics of compacted expansive soil subjected to wet–dry cycles: a multi-scale study

Liu

Jing

2021

Arab J Geosci

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In expansive soil regions, engineering geological disasters frequently occur in wet-dry (WD) environments, which are inseparable from the degradation of soil shear strength and structural damage. This study attempts to assess the underlying mechanisms of shear strength degradation and micro-and mesoscale damage to expansive soil under WD cycles. Recompacted specimens were subjected to several WD cycles, then triaxial shear, nuclear magnetic resonance, and scanning electron microscopy tests were performed. Moreover, the influence of the WD cycles on the shear strength of expansive soil was evaluated. The state-of-the-art image processing and analysis techniques were combined to quantitatively investigate the evolution of the soil micro-and mesostructural characteristics. The results reveal that the deterioration of soil shear strength is primarily embodied in the initial 3 WD cycles, and is mainly due to the severe loss of cohesion (about 51.69%) during this period. Soil meso-cracks were formed under the combined effects of swelling potential and tensile stress, which mainly occurred in three stages: initiation stage (1-2 cycles); propagation stage (3-4 cycles); equilibrium stable stage (5-6 cycles). Indeed, the strength and average width of cracks were increased to varying degrees, which degraded the structural integrity of the soil. In addition, the microstructure of the soil was deeply affected by WD cycles; the total volume of pores increased significantly, the particles roundness decreased marginally, and an isotropic particles orientation was achieved as a whole with local preferential orientation (depolarization). The deterioration of shear strength of the expansive soil may be attributed to alterations in humidity, which causes the clay minerals in the soil to swell and shrink repeatedly, thereby yielding the irreversible fatigue damage of microstructure and propagation of meso-cracks. This work sheds light on the properties of shear strength evolution and mechanisms of structural damage in expansive soils in semi-arid regions.

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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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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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Combined Effect of Rainfall and Shear Strength on the Stability of Highway Embankments Made of Yazoo Clay in Mississippi

Cited by 16 publications

References 26 publications

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

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

Shear strength and damage characteristics of compacted expansive soil subjected to wet–dry cycles: a multi-scale study

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

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