Assessment of Stability of Embankments on Soft Ground Using Matsuo Chart and SLOPE/W

Increase in infrastructure development for rapid growth of population demands the construction of earth structures on soft compressible ground. A tendency exists in geotechnical practice for rapid construction of embankments to meet the stringent construction schedules. Embankments constructed on soft ground develop large settlements and deform laterally resulting in instability. The rates of increase of both settlement at the centre and the lateral displacement at the toe increase sharply with such rapid construction practice indicating embankment instability. Matsuo and Kawamura (Soils Found 17:37–52, 1977 [1]) proposed construction control chart based on field measurements of settlement at the centre of the embankment and the lateral deformations near to toe to predict the degree of safety or stability of an embankment during the construction itself. The present study analyses the stability of various embankments constructed using Matsuo stability charts for different embankment loading. Further, these embankments constructed on soft ground are modelled in SLOPE/W based on the limit equilibrium method and the factor of safety (FOS) estimated. Factor of safety obtained from the Matsuo charts accounts for deformations that occur during construction, whereas SLOPE/W software is based purely on limit equilibrium state and not on actual response of the ground. The analyses are carried out considering slope geometry, geotechnical properties of soils and of the ground, e.g. water table. Stability of embankments is evaluated using Bishop simplified and Janbu’s methods and the factors of safety compared. Reported case records of embankments that are stable are considered in this analysis and the field measurements reported are used for assessing the stability with increase in embankment loading. Results of the present study confirm that the Matsuo chart predicts the slope stability across different embankment conditions with a high degree accuracy. Janbu’s method predicts the FOS similar to the value obtained from Matsuo charts.