Research Article
Effects of Shearing Rate on the Stress-strain Response and Shear Strength of Red Clay: A Case Study of Wolaita Sodo City, Ethiopia
Issue:
Volume 11, Issue 3, September 2026
Pages:
59-68
Received:
12 October 2026
Accepted:
26 October 2026
Published:
9 November 2026
DOI:
10.11648/j.es.20261103.11
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Abstract: Rapid infrastructure development in Wolaita Sodo City, Ethiopia, relies extensively on locally available tropical red clay, whose high plasticity and compressibility result in complex mechanical behavior. However, the sensitivity of this residual soil to shearing rate under rapid and transient loading conditions remains poorly understood. This study investigates the effects of shearing rate on the stress-strain response, peak deviator stress, and shear strength of Wolaita Sodo red clay. Disturbed and undisturbed samples were collected from eight test pits distributed across four sub-cities at depths of 2.5-3.0 m. The experimental program included index-property characterization, Modified Proctor compaction, and Unconsolidated Undrained (UU) and Consolidated Undrained (CU) triaxial compression tests conducted at axial displacement rates of 0.01, 0.1, and 1.0 mm/min. The results demonstrate pronounced rate-dependent behavior. Increasing the displacement rate from 0.01 to 1.0 mm/min increased the peak deviator stress and undrained shear strength, while reducing the axial strain at failure, indicating a transition from more ductile to more brittle deformation. The CU tests also showed increases in the derived effective strength parameters, (c') and ϕ', with increasing shearing rate, although the magnitude of this response varied among test pits and confining pressures. Higher confining pressures generally increased the overall shear resistance. These findings provide site-specific experimental parameters for evaluating foundations, slopes, and other geotechnical structures constructed on tropical red clay deposits.
Abstract: Rapid infrastructure development in Wolaita Sodo City, Ethiopia, relies extensively on locally available tropical red clay, whose high plasticity and compressibility result in complex mechanical behavior. However, the sensitivity of this residual soil to shearing rate under rapid and transient loading conditions remains poorly understood. This stud...
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Eyob Shanka Koyra*
