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

Abstract

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.

Stability Analysis of Plant-Root-Reinforced Shallow Slopes along Mountainous Road Corridors Based on Numerical Modeling

“…The effect of plant roots on slope stability can be divided into hydrological and mechanical factors, which can be valuable to ensure slope stability [1,2,5,21,[25][26][27][28][29][30][31][32][33][34][35][36][37]. With regards to the hydrological effects, plants intercept rainfall allowing it to slowly infiltrate into the soil by reducing the runoff velocity and, thus, reduces soil erosion [7,8,38].…”

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

“…Khan et al [20] studied the impact of WDC on the HPYCS shear strength variations based on several tests. During this study, tests were conducted on the samples of HPYCS collected from a highway slope site borehole in Jackson, Mississippi.…”

“…The effect of WDC in a controlled environment in the laboratory was investigated on the HPYCS samples with 76.2 mm diameter and 25.4 mm height, which were subjected to three, five, and seven repeats of the WDC and then tested for the void ratio, microstructure, volumetric deformation, and shear strength. Khan et al [20] reported the axial deformation of HPYCS under different WDCs. Furthermore, the fully-coupled flow and stability analysis with consideration of the soil unsaturated matric suction and moisture variation was also conducted.…”

Determination of Geotechnical Properties and Stability of Expansive Soil using Fly Ash

“…Black cotton soil is composed of fine-grained soil or decomposed rocks that show huge volume changes when subjected to variability in moisture content. Expansive soil shows swell-shrink behavior near the ground surface due to the land covered by expansive soil [6,7]. These soils occupy approximately 8.9×10 km 2 in India; approximately one-fifth of their surface area covers the states of Maharashtra, Gujarat, Uttar Pradesh, Madhya Pradesh, Rajasthan, Andhra Pradesh, Geotechnical Properties and Stability of Expansive Soil using Fly Ash Farhan KHAN et al http://wjst.wu.ac.th and Tamil Nadu [8,9].…”