Effect of Toe Cutting on Hillslope Stability

This paper reports about the numerical analyses conducted to investigate the instability induced due to toe cutting of simple homogeneous slopes during possible construction and widening of roads. A simple homogeneous hill slope made up of c-φ soil and overlying a rigid bedrock foundation material has been analyzed using Morgenstren-Price limit equilibrium method (Morgenstern and Price 1965) with the aid of Geostudio SLOPE/W 2007. Toe cutting analyses have been conducted for a wide variation of geotechnical, hydraulic and seismic parameters. The stability of the slope is assessed by the evaluated factor of safety which defines the mobilization of the shear strength along a particular slip line. Analyses are done in three stages. In the first stage, simplified hill slopes are analyzed solely under self-weight of the slope. In the second stage, pseudo-static analysis has been conducted. In third stage, water table variation is incorporated in the toe cutting analysis. Results are presented in graphical form and based on present study discussions are made regarding the critical horizontal extent of vertical toe cutting of hill slopes depending upon the slope type and different geotechnical parameters.