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With climate change frequency of extreme disasters is increasing day by day. Excessive rainfall causes shallow landslides during such extreme events, very commonly on highway slopes containing highly plastic clay. Mississippi results in a perfect area to study the Vetiver System (VS) performance for shallow slope failure under excessive rainfall, with an average annual rainfall intensity higher than other neighboring states in the south. A highway slope in Mississippi containing high-plastic clay is explored throughout the year 2019, where time-dependent slope movement along the depth is monitored with rainfall variation. A 9.1 m slope inclinometer along with a rain gauge and an air temperature sensor have been installed at that section. The slope has experienced a shallow movement at the slope surface with a depth of 1.9 m with already observed rainfall intensity. A 6 m2 area of the slope is selected and reinforced with Vetiver grass. Nevertheless, quantitative studies of how much contribution the VS provides to slope stabilization in the field are still relatively scarce. The current paper presents a comparative study of the VS performance on the shallow slope movement in expansive soil observed from inclinometer data for the last two years. It is observed that due to Vetiver grass, the slope movement rate has reduced to 2% since plantation of Vetiver grass from that of 10% before Vetiver grass. Later, this result is further verified through a numerical investigation where Vetiver grass is simulated by changing soil properties. Numerical analysis indicates root reinforcement from the root dimensions increases slope stability up to 30%. This study outlines an approach for the study of VS in terms of contribution to slope stabilization, including field observation and numerical analysis.
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This content will become publicly available on February 27, 2026
Vetiver Influence Zone Detection Using Geophysical Methods
Soil bioengineering using Vetiver is a widely used vegetation-based slope failure mitigation technique. Though Sunshine Vetiver grass, also known as Chrysopogon zizanioides, grows 3 m in length inside the soil in tropical and subtropical climate conditions, the depth up to which Vetiver impacts the soil property has remained undetected. This study has investigated the subsurface influence zone of Vetiver grass based on nondestructive geophysical investigations Electrical Resistivity Imaging (ERI) and Multichannel Analysis of Surface Waves (MASW) in a high plasticity expansive clay soil slope in Mississippi, United States. ERI data collected on the slope revealed that the top 2 m of the high plasticity clay soil had a higher resistivity value with Vetiver (ranging from 4 to 60 m) compared to the soil without Vetiver (ranging from 2 to 28 m). MASW investigation results at the same slope have indicated a similar increase in shear wave velocity with Vetiver up to 2 m indicating enhanced soil stiffness while compared to the section without it. The combined geophysical approach using ERI and MASW reveals that the root system of the Vetiver grass enhanced the moisture content and increased the stiffness of soil within the top layers. Though the grass roots can grow more than 3 m inside the soil, the major influence was observed within the top 2 m from the slope surface.
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- Award ID(s):
- 2046054
- PAR ID:
- 10584453
- Editor(s):
- Beauregard, Melissa S; Budge, Aaron S
- Publisher / Repository:
- American Society of Civil Engineers
- Date Published:
- ISBN:
- 9780784485989
- Format(s):
- Medium: X
- Location:
- Louisville, Kentucky
- Sponsoring Org:
- National Science Foundation
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