All these methods are based on the comparison of forces, moments, or stresses resisting movement of the mass with those that can cause unstable motion (disturbing forces). In rock slope engineering, methods may be highly significant to simple block failure along distinct discontinuities. Translational or rotational movement is considered on an assumed or known potential slip surface below the soil or rock mass. Limit equilibrium methods investigate the equilibrium of a soil mass tending to slide down under the influence of gravity. Stability analyses of two-dimensional slope geometries using simple analytical approaches can provide important insights into the initial design and risk assessment of slopes. Two-dimensional sections are analyzed assuming plane strain conditions. Most slope stability analysis computer programs are based on the limit equilibrium concept for a two- or three-dimensional model.
Also, even for very simple slopes, the results obtained with typical limit equilibrium methods currently in use (Bishop, Spencer, etc.) may differ considerably. In these cases more sophisticated numerical modelling techniques should be utilised. internal deformation and brittle fracture, progressive creep, liquefaction of weaker soil layers, etc.). For example, limit equilibrium is most commonly used and simple solution method, but it can become inadequate if the slope fails by complex mechanisms (e.g. The engineer must fully understand limitations of each technique. Finite element limit analysis, Discontinuity layout optimization) to complex and sophisticated numerical solutions (finite-/distinct-element codes). Today engineers have a lot of possibilities to use analysis software, ranges from simple limit equilibrium techniques through to computational limit analysis approaches (e.g. īefore the computer age stability analysis was performed graphically or by using a hand-held calculator. Choice of correct analysis technique depends on both site conditions and the potential mode of failure, with careful consideration being given to the varying strengths, weaknesses and limitations inherent in each methodology. Water pressure acting in the pore spaces, fractures or other discontinuities in the materials that make up the pit slope will reduce the strength of those materials. The presence of water has a detrimental effect on slope stability. properties of soil/rock mass, slope geometry, groundwater conditions, alternation of materials by faulting, joint or discontinuity systems, movements and tension in joints, earthquake activity etc.
Successful design of the slope requires geological information and site characteristics, e.g. The main objectives of slope stability analysis are finding endangered areas, investigation of potential failure mechanisms, determination of the slope sensitivity to different triggering mechanisms, designing of optimal slopes with regard to safety, reliability and economics, designing possible remedial measures, e.g. Slope stability is the resistance of inclined surface to failure by sliding or collapsing. embankments, road cuts, open-pit mining, excavations, landfills etc.) and the equilibrium conditions. Slope stability analysis is performed to assess the safe design of a human-made or natural slopes (e.g. Figure 1: Rotational failure of slope on circular slip surface