Unsupported browser

For a better experience, please update your browser to its latest version.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Technical paper: Stability coefficients for highway cutting slope design

by G E Barnes, senior lecturer, Geotechnical Engineering, School of Civil Engineering and Building, Bolton Institute.

This paper was first published in GE’s May 1992 issue


A new method is presented which gives the minimum factor of safety for long-term stability of a homogeneous slope of height H using effective stress parameters in the form F = a + b tanφ. The stability coefficients a and b are presented in tabular and graphical form for slope inclinations of 1:1, 2:1, 3:1 and 4:1and have been found to be related to the cohesion soil parameter, c’/γH, and the water table level parameter, hw/H. Pore pressures are represented as a quasi steady state condition by a water table at toe level beyond the toe and then inclined at various angles within the slope given by the depth below crest level, hw. This is considered to be of more practical use than the arbitrary pore pressure coefficient, ru, which has been used previously in slope stability charts. When the critical circle lies below the water table the slope is considered ‘wet’. The situation when the critical circle lies above the water table and the slope can be considered ‘dry’ has been determined. This enables the assessment of whether the presence of a water table is important or not. The coefficient a was found to depend on slope inclination, c’/yH, and whether the slope is ‘wet’ or ‘dry’. The coefficient b was found to depend on slope inclination, c’/yH, and water table level, h„. The location of the critical slip circle in terms of depth factor, D, is also presented for the case when φ30’. An example calculation is given on the use of the coefficients. 

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Links may be included in your comments but HTML is not permitted.