Teacher

Ing. Marco DEL FABBRO

Credits

6 CFU

Objectives

The course provides the theoretical and practical knowledge about the different analytical methods useful to evaluate stability and safety conditions of natural slopes and earth works. Valuation methods are presented for choosing the correct shear strength parameters to perform static and seismic stability analysis also in seepage conditions. Concepts for the slope stabilization methods and design elements for remedial works are also given.

Acquired skills

- The students will be able to know and apply:
- analysis criteria of natural and artificial slopes in static, dynamic and seepage conditions.
- deterministic and probabilistic slope stability analysis methods.
- design criteria of stabilization and remedial works.

Contents

Introduction: presentation of the Course, detailed contents and general objectives (2 hours).

Soil mechanics summary:  geotechnical properties, failure criteria and shear strength of soils, drained and undrained mechanical behaviour; stress path; partial saturation; shear strength and permeability tests (2 hours).

Geotechnical model: landslides classification; geometry and stratigraphy; influence of the groundwater regime; influence of weak and strong layers; slope movements and type of failure; selection of the slip surfaces (4 hours).

Shear strength of slopes: Definition of the shear zone, weak zone and failure surface; selection of shear strength parameters; suction contribution, discontinuities in rock slopes (4 hours).

Laboratory of soil mechanics: peak and residual shear tests in drained and undrained conditions (4 hours). 

Permeability of slopes: Hydraulic conductivity in saturated and partially saturated soils; influence of seepage and drainage; water table variations and their variability. Hydraulic gradient and critical values. Evaluation of permeability by laboratory and in situ tests (4 hours).

Limit equilibrium methods and limit analysis methods: Limit equilibrium conditions of finite and indefinite slopes. Taylor’s methods and abacus design; generalised equilibrium method and derived methods: Fellenius, Bishop, Janbu, Spencer, Morgenstern e Price; GLE; comparison and limitation of LE methods; Limit analysis theorems and methods (4 hours).

Stability of natural slopes in static conditions: Global and partial safety factors; stability analysis in drained/undrained conditions or totally/partially saturated conditions; deterministic, probabilistic and sensitivity analysis of slopes (6 hours).

Stability of natural slopes in seismic conditions: Dynamic soil properties recall and seismic actions; pseudostatic analysis; slope stability analysis in pre-seismic, dynamic and post-seismic conditions; evaluation of pore water pressures (6 hours).

Stability of cuts: Hydraulic limit states and design against uplift and heave; critical height and vertical cut stability in undrained conditions (2 hours).

Slope stabilization methods: Design concepts; re-profiling, drainage trenches, horizontal drains, anchors, nailing, piles, geosynthetics, naturalistic engineering techniques (6 hours).

Finite element stability analysis: Introduction to FEM in geotechnical stability analysis; comparison of FE and LE methods; application cases (2 hours).

Code and regulation references: The stability of natural and artificial slopes for Italian code NTC08. (2 hours).

Numerical examples and case histories: Numerical exercises of ideal and real case history modelled with LE and FE stability analysis software (12 hours).

References

Evaluation methods

Oral exam and practical written exercises