ABSTRACT The provisions of European (EC7 and EC8) and Italian (NTC-08) building codes for stability analyses of man-made slopes (i.e. embankments and cut slopes) are discussed in the paper and the major criticalities and uncertainties are identified. These relate to: 1. The values of the reduction coefficient of the expected horizontal peak ground acceleration for the pseudo-static analyses; 2. The use of the partial coefficients for the ultimate limit state (ULS) and the serviceability limit state (SLS) analyses; 3. The selection of recorded and/or artificial acceleration time histories in the Newmark sliding block procedures; 4. Reference requirements for a judgment on the stability of slopes given that the permanent displacement increases exponentially as the critical seismic coefficient decreases. For each of the four points listed above is proposed an interpretation of the examined Codes,where the rules are unclear,or an integration,where the rules are absent. The safety verifications of an actual artificial slope,the embankments of a reservoir basin for flood reduction of the Parma stream,a tributary on the right side of the Po River (Italy),are considered to exemplify concretely the proposed suggestions. The aforementioned basin has recently been the object of a detailed study performed in order to evaluate its safety conditions following the new national seismic classification. An in-depth survey was carried out within the study and the necessary information needed to define a reliable geotechnical modelling of the embankment and soil foundation was obtained. Seismic stability analyses of the embankment of the reservoir basin were performed on a number of representative sections using both pseudo-static and Newmark displacement methods. The peak ground acceleration values and the acceleration time histories at the base of the embankment were assessed by means of one-dimensional ground response analyses. Reference input motions for ground response analyses were obtained from the recent Italian seismic hazard estimates in accordance with NTC-08 requirements. Return periods of the seismic event of 50,475,and 975 years were considered. Stability analyses discussed in the present paper were performed referring to the 475-year return period of the earthquake and relate to the internal side of the embankment of the most critical section in the reservoir conditions of rapid water drawdown.

Discussion and suggestions on design code provisions for seismic stability analyses of artificial slopes / C. MADIAI; G. VANNUCCHI. - ELETTRONICO. - (2011), pp. 1-12. (Intervento presentato al convegno ERTC-12 workshop on evaluation of EC8 tenutosi a Atene nel 11 settembre 2011).

Discussion and suggestions on design code provisions for seismic stability analyses of artificial slopes

MADIAI, CLAUDIA;VANNUCCHI, GIOVANNI
2011

Abstract

ABSTRACT The provisions of European (EC7 and EC8) and Italian (NTC-08) building codes for stability analyses of man-made slopes (i.e. embankments and cut slopes) are discussed in the paper and the major criticalities and uncertainties are identified. These relate to: 1. The values of the reduction coefficient of the expected horizontal peak ground acceleration for the pseudo-static analyses; 2. The use of the partial coefficients for the ultimate limit state (ULS) and the serviceability limit state (SLS) analyses; 3. The selection of recorded and/or artificial acceleration time histories in the Newmark sliding block procedures; 4. Reference requirements for a judgment on the stability of slopes given that the permanent displacement increases exponentially as the critical seismic coefficient decreases. For each of the four points listed above is proposed an interpretation of the examined Codes,where the rules are unclear,or an integration,where the rules are absent. The safety verifications of an actual artificial slope,the embankments of a reservoir basin for flood reduction of the Parma stream,a tributary on the right side of the Po River (Italy),are considered to exemplify concretely the proposed suggestions. The aforementioned basin has recently been the object of a detailed study performed in order to evaluate its safety conditions following the new national seismic classification. An in-depth survey was carried out within the study and the necessary information needed to define a reliable geotechnical modelling of the embankment and soil foundation was obtained. Seismic stability analyses of the embankment of the reservoir basin were performed on a number of representative sections using both pseudo-static and Newmark displacement methods. The peak ground acceleration values and the acceleration time histories at the base of the embankment were assessed by means of one-dimensional ground response analyses. Reference input motions for ground response analyses were obtained from the recent Italian seismic hazard estimates in accordance with NTC-08 requirements. Return periods of the seismic event of 50,475,and 975 years were considered. Stability analyses discussed in the present paper were performed referring to the 475-year return period of the earthquake and relate to the internal side of the embankment of the most critical section in the reservoir conditions of rapid water drawdown.
2011
Evaluation of Geotechnical Aspects of EC8
ERTC-12 workshop on evaluation of EC8
Atene
11 settembre 2011
C. MADIAI; G. VANNUCCHI
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/606993
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