Case Study Method: Relationship between Fully Softened and Residual Shear Angle and Liquid Limit in Problematic Clay Soil

Kukuh Mahi Sudrajat; Sri Prabandiyani Retno Wardani; Kresno Wikan Sadono

Kukuh Mahi Sudrajat Department of Civil Engineering, Universitas Mercu Buana Jakarta, Indonesia; Doctoral Programme in Civil Engineering, Faculty of Engineering, Diponegoro University, Semarang, Indonesia
Sri Prabandiyani Retno Wardani Doctoral Programme in Civil Engineering, Faculty of Engineering, Diponegoro University, Semarang, Indonesia
Kresno Wikan Sadono Doctoral Programme in Civil Engineering, Faculty of Engineering, Diponegoro University, Semarang, Indonesia

Keywords: clay soil, fully softened shear strength, residual shear strength, liquid limit, landslide

Abstract

Problem clay soils often experience a significant decrease in shear strength from peak strength to residual strength, which greatly affects slope stability and geotechnical structures. This study examines the empirical relationship between the angle of repose in fully softened and residual conditions and the liquid limit in various types of problem clay soils through a methodological case study approach. This research method is based on the need to comprehend how to operate clay soils under critical conditions, especially on slopes that have experienced movement or are in a remolded condition. The fully softened condition represents the strength of soil that has been loaded to a considerable displacement but has not yet reached the residual condition, while the residual condition represents the minimum strength that can be achieved after a very large displacement. This case study method aims to identify and analyse the mathematical correlation between shear strength parameters (fully softened and residual angles of repose) and the liquid limit as an index of plasticity that can be easily determined in the laboratory. This case study method aims to identify and analyse the mathematical correlation between shear strength parameters (fully softened and residual shear angles) and the liquid limit as an index of plasticity that can be easily determined in the laboratory. The methods used include a comprehensive literature review of previous research, secondary data collection from various geotechnical projects, and statistical analysis to determine trends in the relationship between these parameters. A case study approach was used to validate the empirical correlations found in the literature with local soil conditions. Linear and nonlinear regression analyses were applied to develop prediction equations that can be used in geotechnical engineering practice.

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